Volume 30, Issue 1

Understanding the influence of delamination defects on the damage evolution behavior of carbon-fiber-reinforced polymers (CFRPs) is crucial to improve their engineering applications. This study examined the flexural damage behaviors of CFRP composites by using a combination of acoustic emission (AE) and X-ray micro-computed tomography (micro-CT). Four specimens with different delamination defects and 0.1 wt% cellulose nanofibers (CNFs) were subjected to three-point bending tests. AE was employed to monitor the loading process, and then, micro-CT was utilized to detect the internal damage. The results showed that for the specimens with preset delamination defects near the surface, CNF-reinforced specimen exhibited no obvious enhancement effect on bending strength, and its cumulative acoustic energy decreased by 28% compared with that of CFRP specimens. For the specimen with preset delamination damage in the middle position, CNFs had an obvious enhancement effect on mechanical behavior, and the cumulative acoustic energy decreased by 43%. No obvious kink band was observed in the CNF-reinforced specimens, and during crack propagation, causing cracking and delamination damage was difficult. The results of micro-CT are consistent with those of AE. The results combined the combination of AE and micro-CT reflect the superiority of the hybrid detection system.

With the application of carbon fiber reinforced plastics (CFRPs), the damage behaviors and mechanisms are desirable to understand. In this work, the Bismaleimide (BMI) matrix composites were employed to study the damage mechanism under transverse loading through quasi-static indentation, where optical microscopy, ultrasonic C-scan, and scanning electron microscope were subjected to examine the damaged regions. The results show that cracks first take place in a resin-rich interlaminar region before the loading reached to a threshold value. Then, the cracks would develop into intralaminar cracks in the fiber bundle region consisting of the shear and bending cracks. Subsequently, the cracks randomly extend to adjacent plies and result in delamination. Finally, the back surface of composites presents a remarkable ply splitting and fiber breakage under increasing loading. Furthermore, conical-shaped indentation patterns in cross-sectional and the undamaged zone under the indenter suggest the BMI matrix composites possess potential applications in engineering materials with a superior stress-releasing structure.

The aim of this paper is to investigate the water pressure effects on hydraulic fracture behavior of concrete with wedge-splitting testing under dynamic loading. Five waterproof strain gauges are stuck along the crack path to observe the fracture process during the experiments. Four silicon water pressure sensors successfully measured the water pressure value on concrete face. The results show that the water pressure on crack faces accelerates the crack propagation of the concrete. The critical values of the splitting force decrease 26.7 and 25.6%, respectively, with the external applied water pressure of 0.2 and 0.4 MPa. Moreover, the hydraulic crack propagation speed increases at the beginning and tends to reach a peak value finally. The peak value of cracking speed is 11.08 m/s, which is high. Under dynamic loading, the water fails to fill the crack and only the trapped water interacts with the crack face. The water pressure is mainly a parabolic curve distribution along the crack path and the peak value decreases with the increase in the crack length.

Objective To evaluate the color adjustment potentials of monoshade universal composites in different shades of class I cavities. Methodology About 132 restorations were performed using monoshade universal composites (Omnichroma, OMNI; Essentia Universal; EU; Charisma Diamond One, CDO), and one simplyshade composite (NeoSpectra-ST, NEO) as control. A transparent silicone mold was used to provide standardized restorations on prefabricated class I cavities of acrylic dentures in B1, A2, and C4 shades. The assessment of color adjustment was performed immediately after, at 24 h, and at 2 weeks, through the cross-polarized dental photographs. The quantitative assessments were performed using a software (Digital Color Meter, Macintosh AC). The collected L *, a *, and b * coordinates from the restorations and the adjacent denture surfaces were used to provide Δ E 00 ⁎ \text{&#x0394;}{E}_{00}^{\ast } values. Shapiro–Wilk, three-way Anova and Tukey HSD Test were used for the statistical analyses ( p < 0.05). Results Among all composites and shades, the Δ E 00 ⁎ \text{&#x0394;}{E}_{00}^{\ast } values were significantly the highest (1.27 ± 0.49 a ) for the immediately after assessments compared to the assessments at 1 day (1.01 ± 0.41 b ) and 2 weeks (0.97 ± 0.4 c )( p < 0.05). At 24 h and 2 weeks of evaluations, the Δ E 00 ⁎ \text{&#x0394;}{E}_{00}^{\ast } values for the control (0.42 ± 0.16 H ) were significantly the lowest ( p < 0.05). Only the control presented imperceptible color changes for all the cavity shades (PT ≤ 0.8). After 2 weeks, EU (1.06 ± 0.32 F ) and OMNI (1.12 ± 0.18 EF ) presented significantly lower Δ E 00 ⁎ \text{&#x0394;}{E}_{00}^{\ast } values compared to the CDO (1.29 ± 0.2C D ) ( p < 0.05). Restorations in lighter cavities presented significantly lower Δ E 00 ⁎ \text{&#x0394;}{E}_{00}^{\ast } values. Conclusion Monoshade universal composites presented acceptable but perceptible color adjustment potentials in class I cavities without the shade selection procedure. Simplyshade composites following the shade selection might still be the best options regarding the level of color adjustment. Monoshade universal composites might provide better color adjustments in cavities with lighter shades.

In countries where volcanic activity is widespread, fly ash (FA) formation can represent both a waste to be disposed of and a resource of inorganic substances that can be utilized. Among the technologies able to incorporate FA, geopolymers (GP) or inorganic aluminosilicate amorphous materials are very suitable for this purpose. In this study, GP are realized using metakaolin (MK), sodium hydroxide solution (NaOH 8 M), sodium silicate solution (Na 2 SiO 3 ), and FA as filler (20 wt% with respect to MK content). The samples were cured at 25 or 40°C for 24 h and the physicochemical, thermal, and antibacterial properties of this material through the integrity test, weight loss test, Fourier-transform infra-red spectroscopy (FT-IR), thermogravimetric analysis (TGA), and Kirby-Bauer assay were assessed. Integrity and weight loss tests indirectly revealed the stability of the macroscopic 3D networks and that the curing at 40°C led to more stable GP. The shift of the Si–O–T absorption band (from 1,090 cm −1 of the MK to 1,017–1,012 cm −1 of the specimens with and without FA) in FT-IR spectra suggested the occurrence of the geopolymerizazion reactions, while TGA study confirmed the higher stability of samples cured at 40°C (with a mass loss equal to 7–13% at 800°C under nitrogen atmosphere). Finally, the antimicrobial activity shed light on the ability of the synthesized GP with the filler and treated at 40°C to have a great effect against Escherichia coli and Pseudomonas aeruginosa .

Two-dimensional (2D) braided composites have excellent structural integrity and damage tolerance. Currently, there are few researches focused on the effect of temperature on tensile failure behaviors of 2D braided composites. In this study, 2D biaxial braided composites with different fiber materials were prepared, and the tensile properties and failure mechanisms of these braided composites at different temperatures were studied by means of the tensile test and the high-definition charge coupled device optical microscope. The results show that temperature has significant effects on the tensile properties and fracture damage of 2D braided composites. As the temperature increases, the tensile properties of the two braided composites decrease obviously, and their external fracture failure becomes subtle, while their internal deformation damage becomes significant. Moreover, the differences between the two fibers in tensile fracture behaviors of composites can be more conspicuously observed at higher temperatures.

Generally, 316L stainless steel instrumentation tubes working in a humid environment with a large amount of Cl − all the year round have serious corrosion problems, so the stainless steel substrate should be gradiently coated with nano-ZrO 2 /α-Al 2 O 3 slurry. In this article, the slender 316L stainless steel tube was first ground by magnetorheological fluid and then coated with the slurry, which can not only increase the contact area between the coating and the substrate but also prevent the generation of new substances that have adversely affected the adhesion of the coating. The properties of the samples were characterized and analyzed; the results showed that the substrate ground by magnetorheological fluid is more favorable for bonding with coating under the grinding conditions that the speed of the tube is 210 rpm, magnetic induction intensity is 40.83 mT, and mass ratio of micron and submicron magnetic particles is 2.3. The coating prepared under the above conditions has uniform thickness, flat surface, and can better inhibit the diffusion of Cr of the substrate to its surface. It can be obtained from corrosion resistance analysis that the coating has the highest self-corrosion potential of −0.016 V and the lowest corrosion current density of 0.491 μA/cm 2 , which indicate that the coating has the strongest corrosion resistance. According to the composition analysis of the coating, the composition of the corroded coating is similar to that of the coating itself, but accompanied by a small amount of Fe, which indirectly indicates that the coating is relatively compact, the coating is well bonded with the substrate, and the coating can protect the substrate; thus, the service life of 316L stainless steel instrumentation tubes is extended.

The reinforced efficiency of steel fibers in composites is closely related to their spatial orientation, which can be generally driven by the external magnetic force and restricted by the wall effect of rigid boundaries of the container. To clarify the spatial orientation of steel fibers in composites considering the effect of rigid boundaries under the electromagnetic field, a series of two-phase models consisting of fibrous particles and homogeneous matrix are generated, in which the fibers are separately simplified as spherocylindrical, cylindrical, and linear particles. Based on these models of the semi-periodic boundaries, the effect of fiber characteristics (e.g., the fiber content V f , fiber aspect ratio ε , fiber length l sf , and fiber style) on both the spatial distribution and orientation degree of fibrous particles is studied before and after the fibers are aligned by the magnetic force. The results revealed that (1) both the effective number N A and orientation degree ξ of fibrous particles at a cross-section of the container can be greatly increased when the electromagnetic field is applied and (2) the wall effect of rigid boundaries shows an adverse impact on the amelioration of N A and ξ , and the range size of the affected region is essentially equal to the effective length of fibrous particles of different shapes (e.g., l sf  +  D sf ) for spherocylindrical particles and l sf for cylindrical and linear particles).

The aim of this paper is to study the effect of friction coefficient and impact angle on the failure behaviors of glass fiber reinforced aluminum laminates (GLARE) under the low-velocity impact (LVI) loading. A methodology is developed in commercial software ABAQUS/Explicit, and its accuracy is verified based on the results of comparison between simulation and experiment. In the simulation, Johnson–Cook flow stress model and surface-based cohesive behavior are carried out to simulate the damage evolution of aluminum alloy layers and delamination at the interface. Further, both the dynamic response history and damage mechanism characterization of these hybrid laminates are presented and compared carefully. Additionally, due to the advantage of simulation, it is accurate and easy to discuss on the evolution of the damage contour consisting of the damage degree of composite and metal layers as well as the interface between them. Finally, the influence rules of friction coefficient and angle on the failure behaviors of GLARE under LVI are drawn clearly.

As the main load-bearing component of the bridge structure, the cable is damaged by the impact from time to time, so it is very important to clarify its impact resistance capacity. Based on the method of the drop-weight test, this article mainly studies the degradation law of the mechanical properties of epoxy-coated steel strand (ECSS) under the impact load. Through the impact test of ECSS under different working conditions, the influence law of prestress, impact energy, initial defects and other factors on the impact resistance of the steel strand was revealed. Then, the difference of the impact resistance of ECSS and ordinary steel strand (OSS) was verified under the same impact conditions. Finally, the failure mechanism and the residual-bearing capacity of ECSS were analyzed through the secondary impact test. The results show that the initial prestress is helpful to improve its impact resistance when it is less than 0.11 f u {f}_{{\rm{u}}} , and exceeding this value will accelerate its failure process. The effect of impact height on the strain at the impact point of ECSS is significantly greater than that near the anchor end. ECSS has better energy absorption characteristics than OSS. The impact resistance of ECSS with initial defects is very sensitive to the impact energy. The influence on outer strand in the secondary impact is significantly higher than the central strand, and its residual tensile capacity still has 0.85 f u {f}_{{\rm{u}}} .

In this article, axisymmetric deformations of coupled functionally graded conical shells are studied. The analytical solution is presented by using the complex hypergeometric and Legendre polynomial series. The presented results agree closely with reference results for isotropic conical shells of revolution. The symbolic package Mathematica commands is added to the article to help readers search for particular solutions. The detailed solutions to two problems are discussed, i.e. the shells subjected to axisymmetric pressure or to edge loadings. The influence of material property effects is characterized by a multiplier characterizing an unsymmetric shell wall construction (stiffness coupling). The results can be easily adopted in design procedures.

A series of water damage phenomena of asphalt pavement during service show that water is very important. To comprehensively analyze the influence of water vapor factors on the response of pavement structure, this article first tests the water vapor diffusion coefficient of asphalt pavement materials at different temperatures establishes the water vapor concentration field model of the pavement structure, and analyzes the actual water vapor distribution of the pavement structure; then, the relationship between viscoelastic parameters of the mixture and water vapor concentration is established. Based on this, the finite element model of the pavement structure considering the water vapor factor is established, and the influence of the water vapor factor on the pavement structure response and fatigue life is quantified. It is found that water vapor has an important influence on the mechanical response. On the hottest days in summer, the attenuation of surface modulus caused by water vapor has the greatest impact on the upper layer of the pavement structure. Under the influence of water vapor, the position just below the wheel of the upper layer at the bottom of the horizontal tension strain increases by 108.26%, and the horizontal tension strain of the other layers increases by about 5%, increasing the risk of upper layer cracking. At the same time, water vapor reduces the stress that can be borne by the surface layer, while the rest of the stress is borne by the base. Compared with the fatigue life calculation method in the specification, the actual non-uniform water vapor concentration field reduces the fatigue life of the surface layer by 12.246%. This shows that the current structural calculation does not consider the water vapor factor, which makes the pavement structure more dangerous, and the influence of the water vapor factor should be fully considered.

This work presents a unique non-invasive method for monitoring glucose levels in blood using a planar Yagi–Uda antenna as a microwave sensor. The proposed antenna, operating at 5.5 GHz, exhibits a directional radiation pattern with a peak gain of 6.74 dBi. A low-cost FR4 material of size 30 mm × 40 mm × 1.6 mm is used as a dielectric substrate. A human finger phantom, comprising layers of skin, fat, blood, and bone, is created at 5.5 GHz in EM simulation tool for mimicking a real human finger. The finger phantom is positioned at different locations around the antenna and corresponding frequency shifts are remarked to a variation in glucose concentration from 0–500 mg/dL. An exemplary frequency shift of maximum 26 MHz is recorded when the phantom is placed at the bottom of the antenna. Time domain analysis is also carried out to understand the effect of glucose concentration variation on the output signal amplitude and delay. Simulated antenna results are found to be in stupendous agreement with the measured results. An experiment of placing a real human finger around the fabricated antenna also presents a splendid correspondence with the simulated results. Hence, this mechanism can be expedient for monitoring glucose levels in blood.

In this study, the dry–wet cycle test of chloride salt was carried out on aeolian sand concrete with different contents, and the chloride ion content in aeolian sand concrete was determined by taking powder from different depths on one side of the test block. And then combined with Monte Carlo stochastic statistical simulation and Weibull probability distribution function, the service life prediction model of aeolian sand concrete against chloride ion erosion is established. The results show that the free chloride ion content in aeolian sand concrete decreases with the increase in the depth from the surface of the specimen. At the same depth from the surface of the specimen, the free chloride ion content gradually increases with the increase in the number of dry–wet cycles. Through the analysis of life prediction, it is concluded that with the increase in aeolian sand content, the service life of aeolian sand concrete increases first and then decreases. The service life value of concrete with 75% aeolian sand content is the largest, and the greater the thickness of the protective layer, the more favorable the service life value.

In order to quantitatively analyze the mesoscopic damage process of hydroxyl-terminated polybutadiene composite solid propellant under external load, periodic boundary conditions were applied to the representative volume element model based on sample composition and morphology, the mixed matrix containing aluminum powder was homogenized, and the hyperelastic matrix damage and bilinear/exponential particle–matrix interface cohesive model with initial damage were compiled through the secondary development of Abaqus. At the same time, a data interaction platform was constructed by means of Python and MATLAB, matrix and cohesion parameters were inverted according to the optimization algorithm and experimental data, and the whole process of propellant damage and fracture was simulated from the mesoscopic perspective. The results show that combining the adaptive particle swarm optimization algorithm and the Hooke–Jeeves algorithm can achieve the global optimal parameter inversion in 102 calculations, compared with the single local search algorithm, which can cut about 11% of the objective function values. Considering the matrix damage and the exponential cohesion model with initial damage, the optimal objective function value is 0.01635, which can more accurately simulate the propellant damage and fracture process compared with 0.02136 of a bilinear cohesion model.

The method and parameter of mixing are crucial to the quality of concrete, and ordinary vibratory mixing is beneficial to the performance of concrete, which has been explored in numerous studies. In order to study the influence of high-frequency vibratory mixing on the performance of concrete more accurately, ordinary concrete C40, C50 steel fiber concrete, and C60 high-strength concrete are selected to make reach experiments in the article. After determining the optimum mixing ratio, the contrast experiment on forced mixing and high-frequency vibratory mixing (which at a given frequency) was operated first, which is for studying the improvement of workability and mechanical properties of concrete by vibratory mixing and then exploring the change of concrete performance under different vibration frequency in slump test, compressive strength test, and freeze–thaw test. The results indicate that compared with forced mixing, the compressive strength and splitting tensile strength of concrete all have been proposed in different ages (3 days, 7 days, and 28 days) with vibratory concrete mixing, and C50 steel fiber concrete has the highest compressive strength improvement rate. There is a deviation in the mechanism of concrete in different ages, which is affected by high-frequency vibration. But in the context of the whole test, high-frequency vibratory mixing is helpful for the working properties, mechanical properties, and durability of the concrete. Within the scope of the frequency values in the test, the best vibration frequency for C40 ordinary concrete is 190 Hz, and in 212 Hz, C50 steel fiber concrete and C60 high-frequency concrete present the best performance.

To reveal the effects of the microstructure characteristics including fiber shape, void, fiber distribution pattern, and interphase on the transverse moisture diffusivities of unidirectional composites, the steady analysis method based on Fick’s law is adopted. The predicted numerical results are compared with the results from the analytical models to demonstrate the accuracy. From the simulation results, it is found that the increase in the oscillation amplification of non-circular fibers contributes to the orthotropy of diffusivity properties, which attributes to different barrier effects along different directions. The consideration of interphase relieves the barrier effects and the predicted diffusivity values are increased significantly. The effects of voids increase with the void volume fraction and are dependent on the voids’ location. If the fiber random distribution pattern is considered, it is found that the average values of predicted diffusivity decrease gradually with the increase in the number of oscillations.

In this article, gradient-distributed VCp-ZTAp/Fe45 composites were prepared by vacuum sintering, and three-body abrasive wear experiments were carried out to investigate its anti-wear performance. The composite casting of VCp-ZTAp/Fe45 was investigated by using the finite element method and experiments, and the bonding between the Fe45 substrate and 35SiMnCrMoNi steel was fully investigated. Results show the in situ formation of VCp in the VCp-ZTAp/Fe45 composite matrix during vacuum sintering. The anti-wear property of the VCp-ZTAp/Fe45 composite is ca. 7 times that of Hardox450 and NM450 and ca. 8 times of 30SiMn. There forms a solid metallurgical bonding between the Fe45 matrix of VCp-ZTAp/Fe45 and 35SiMnCrMoNi steel, with a ca. 80 μ m thickness of the bonding area during the composite casting.

Velocity sensitivity refers to the possibility and degree of reservoir permeability decline caused by the migration of various particles in the reservoir rock due to the increase in fluid flow velocity and the blockage of pore channels. To improve the development results of M reservoir in Karamay Oil field, two reservoir cores were selected to carry out velocity sensitivity experiments. The permeability of No. 1 core decreases obviously when the flow rate is greater than 0.04 mL/min. Therefore, it can be considered that the injection rate of velocity sensitivity is between 0.04 and 0.06 mL/min, and the displacement rate should be less than 0.04 mL/min in the core displacement experiment. When the flow rate is greater than 0.5 mL/min, the permeability of No. 2 core decreases significantly. This is mainly due to the high permeability and critical velocity of No. 2 core. The study can provide a basis for the selection of displacement velocity in core displacement experiments, and also provide a reference for the determination of reasonable injection-production velocity in actual production.

The C/C–SiC composites were fabricated by the liquid silicon infiltration method. The mechanical and tribological properties of C/C–SiC composites were assessed and compared based on different C/C densities and the carbon fiber textile architecture. The results demonstrated that the bending and shear strengths of C/C–SiC were lower than those of C/C composites, which resulted from the carbon fibers being corroded during the process of infiltration of liquid silicon. In contrast to C/C composites, the compressive strength of C/C–SiC exhibited higher values due to the presence of SiC ceramics. Moreover, the mechanical strength of C/C composites increased gradually with the increase of the C/C preform density. The tribological properties of various C/C–SiC composites showed a stable friction phase at an intermediate braking stage. When the density of C/C preforms was around 1.78 g/cm 3 , the C/C–SiC composites exhibited excellent friction coefficients (0.438 and 0.465), and low wear rates (linear and weight wear rates were 0.450 µm/time and 0.123 g/cycle, respectively). Furthermore, the C/C–SiC composites fabricated with non-woven carbon fiber needling preforms showed relatively a higher friction value and wear rate than those of C/C–SiC with PANOF integral C/C preforms. Therefore, C/C–SiC composites have been considered promising friction materials for braking system applications.

Oil palm empty fruit bunches (OPEFBs) can be transformed into composite boards with higher selling value when their cellulose is used as a fiber. Manufacturing composites with hybridization techniques can improve their properties. This study combined OPEFBs and ramie fibers in an epoxy–carbon nanotube (CNT) matrix. The proportion of OPEFBs and ramie fibers was varied (3:7, 5:5, and 7:3), with a total fiber content of 10% by volume and a matrix of 90% by volume. Alkali treatment using NaOH solution was applied to the fiber to remove impurities from the surface. CNTs were functionalized using nitric acid followed by hydrogen peroxide to improve compatibility. Surface treatment was conducted on fibers and CNTs to increase the bonds between these components in the composite material. The hybridization of OPEFBs/ramie fibers improved the tensile strength in the 3:7TR, 5:5TR, and 7:3TR composites by 127, 37, and 12%, respectively, compared to the 10T composite. The flexural strength of the 5:5TR hybrid composite increased by 120%, and that of the 3:7TR and 7:3TR composites increased by 83% against the 10R composite. The 3:7TR hybrid composite showed the best mechanical properties.

In this article, the concept of low-velocity impact resistance in composite materials is presented. Three existing expressions (e.g., bilinear, parabola, and exponential) that show the relationship between the dent depth and impact energy of composite laminates subjected to low-velocity impact are presented. Because of some flaws in these expressions, new supposed functions between impact energy and impact dent have been established. By means of existing ASTM D 7136 tests and simulation analysis, the new expressions are verified, and the nature of dent formation in composite materials is well explained. The conclusion is reflected in the ending part.

Phthalonitrile (PN) is a highly promising material in the field of high-performance thermosetting polymers due to its ability to maintain its properties even at extremely high temperatures. The goal of this study was to investigate the effects of varying curing agents on the thermal properties of cured PN resin. The curing agents were found to effectively cure the resin, as indicated by the increasing ratio of N and S contents and decreasing the C content as the proportion of curing agents increased, as observed by scanning electron microscopy and energy dispersive X-ray spectroscopy data analyses. Moreover, thermogravimetric analyses revealed that the sample with 20% curing agent showed the highest thermal decomposition rate among the 2, 5, 10, and 20% curing agent dosages. These properties can be further improved by incorporating glass fibers. Overall, these results demonstrate the successful use of curing agents to create an efficient and functional polymer with superior thermal properties that are suitable for use in harsh environments. The findings of this study are a significant step forward in advancing the use of PN as a high-performance thermosetting polymer.

Twisting is an important part in the production process of large package E-glass yarn. To derive the twisting process parameters of large package E-glass yarn, a method from the physical properties of bobbin yarn is proposed based on the study of the twisting principle of E-glass yarn. After unwinding the bobbin yarn and measuring its twist, loop pitch, and corresponding diameter, the calculation is completed according to the steps of first determining the descending speed of the traveler, then fitting the spindle speed data, and finally calculating the elevating speed of the traveler. The result is that the twisting spindle speed of D450 E-glass yarn with 31.8 T/m decreases from 5,015 to 4,550 rpm, the elevating speed of the traveler is 0.91 m/min, and the descending speed of the traveler is 1.50 m/min. The accuracy of the calculation is verified by monitoring the rotating speed of the roving cake and measuring the loop pitch of bobbin yarn in the twisting experiment. The result shows that the prediction error of this method is less than 1.1%, which can effectively derive the twisting process parameters of large package E-glass yarn, and provide a reference for the twisting process design scheme of glass fiber strand manufacturers.

The micro-cracks in a material lead to a reduction in its overall strength and service life. The emerging capsule-based self-healing system provides a new strategy for repairing the cracks, effectively delaying the potential damage of the matrix, and prolonging the service life of composite materials. Determining the optimal size and dosage of microcapsules required to repair cracks in the matrix is essential for the development and design of capsule-based self-healing materials. This paper presents a novel two-dimensional capsule-based self-healing model composite material whose surface is paved by reproducible and random cells and some microcapsules are randomly dispersed in those cells to investigate the rupture behavior of microcapsules forced by growing cracks. An analytical model is proposed from the viewpoint of geometrical probability to express the probability characteristics of the embedded microcapsules stimulated by linear cracks in a two-dimensional capsule-based self-healing model composite. Additionally, the effect of the size and dosage of the embedded microcapsules on the intersection probability is analyzed, and the maximal probability is also found to improve the self-healing efficiency. Finally, the accuracies of these probability values and theoretical solutions are verified via computer simulation, and the results show that the developed model of the geometrical probability of the crack intersection with microcapsules randomly distributed in the cells of the matrix will help to provide a theoretical basis for the quantitative design of capsule-based self-healing materials.

Made a pioneering attempt to use the lattice sandwich structure in prosthetic foot design and pioneered the study for the lay-up design of the prosthetic foot. An innovative carbon fiber bionic prosthetic foot was designed using a sandwich structure. The effect of cross-ply on the prosthetic foot’s energy storage properties and vibration characteristics was investigated using the lattice sandwich structure prosthetic foot. The bionic prosthetic foot’s finite element model was constructed under normal working conditions according to international standards. The results indicate that the storage of strain energy increases with an increase in cross-ply under heel-strict working conditions. Under the toe-off condition, the strain energy distribution increases with the increase in cross-ply. The cross-ply number influences the mode of displacement of the bionic foot. The natural frequencies of the bionic foot increase with the increase in the cross-ply.

With the continuous expansion of the construction scale of the State Grid and the gradual improvement of people’s awareness of environmental protection, the power contradictions and disputes caused by the North–South Power Transmission and Transformation Project have become increasingly prominent, which has attracted widespread attention from all walks of life. This study focuses on the development of conductive silicone gel for UHV transmission lines using carbon fiber (CF) powder, carbon black (CB), and carbon nanotubes as fillers, and organic silicone polymer as the matrix. The aim was to address the issues of corona noise and detachment. We prepared a series of conductive silicone gels with different proportions of CF and CB conductive fillers and conducted a comprehensive analysis of their electrical conductivity, tensile performance, hydrophobicity, and rheological properties. The research results demonstrated that the maximum electrical conductivity of the conductive silicone gel was achieved when the CF and CB contents reached a ratio of 2:1. In the case of a 70% organic silicone polymer gel, the electrical conductivity reached 0.73 S/cm, while it increased to 1.17 S/cm in an 80% organic silicone polymer gel. This indicates that optimizing the proportion of fillers can significantly enhance the electrical conductivity of the conductive silicone gel, meeting the requirements of UHV transmission lines. Additionally, the study evaluated the tensile performance, hydrophobicity, and rheological properties of the conductive silicone gel. The results showed that the 70% organic silicone polymer gel exhibited a tensile strength, Young’s modulus, and elongation at a break of 678.6 MPa, 1.3 MPa, and 15.22%, respectively. The corresponding values for the 80% organic silicone polymer gel were 129.9 MPa, 1.6 MPa, and 55.89%. This indicates that the conductive silicone gel possesses excellent mechanical properties and ductility, enabling it to withstand stress and deformation in UHV transmission lines while providing anti-detachment effects. In summary, this study successfully developed a conductive silicone gel that meets the requirements of UHV transmission lines. By optimizing the ratio of CF and CB contents, the electrical conductivity of the gel was maximized. Furthermore, the conductive silicone gel exhibited favorable tensile performance, electrical conductivity, and anti-detachment effects, effectively addressing corona noise and detachment issues in UHV transmission lines. These research findings are of great significance for the design and application of UHV transmission lines.

In this study, a series of samples of C12A7 derivative was prepared by high temperature sintering in a sealed graphite crucible. The theoretical model of C12A7 derivatives with different carbon occupation numbers was established. The X-ray diffraction (XRD) theoretical calculation was carried out. The conjecture was verified to a certain extent through the comparison of the theoretical calculation of XRD with the experimental results. According to the calculation results, it was found that the XRD patterns of C12A7 and its derivatives changed regularly with the change in the occupation number in the crystal cage. Under the condition that the types of vacancy atoms remained unchanged, the more vacancy atoms occupied in C12A7 crystal, the higher the peak at 2 θ = 33.35° in the diffraction pattern. It was also found that the higher the atomic number of vacancy atoms in C12A7 crystal, the higher the peak at 2 θ = 33.35° in the diffraction pattern. The carbon occupation number of samples at different experimental temperatures was deduced. The results showed that the carbon occupancy of the samples prepared at 990, 1,353 and 1,680°C were 11, 4 and 8, respectively.

The objective of the study was to improve the stiffness and bending strength of laminated bamboo through confinement with softwood. A total of 144 beams were tested, divided into 6 groups of 24 specimens each. The tests were conducted on specimens of laminated bamboo, wood, and composite sections with different levels of confined bamboo laminate (20, 40, 60, and 80%). The results indicated that the composite exhibited optimal behavior when the ratio of bamboo to wood was between 46 and 54%. Furthermore, the composite demonstrated a bending modulus of elasticity that was 16.6% higher and a modulus of rupture that was 18.3% higher than the values predicted by the mixing rule. A mathematical model was developed to predict the design mechanical properties based on composite thickness. This model was validated through 18 additional bending tests. This new material is an environmentally sustainable alternative that has the potential to be used as beams in buildings, providing improved mechanical performance, reduced weight, and lower manufacturing cost compared to bamboo laminates.

Using the starting reactants of Zn(OAc) 2 and 2-mercaptonicotinic acid (H 2 L), we successfully synthesized a fresh Zn( ii ) compound, that is, [Zn 3 (L) 3 ] n (1), under hydrothermal conditions and then successfully loaded with atenolol. Hualuronic acid/carboxymethyl chitosan hydrogels loaded with atenolol drug metal–organic framework were prepared based on a chemical synthesis method. The microscopic morphology of the hydrogels was investigated, and scanning electron microscopic results showed that the hydrogels had a highly porous morphology with good penetration between the pores. For the new hydrogels, the enzyme-linked immunosorbent assay detection was conducted, and the production of sVCAM-1 and TNF-a in vascular endothelial cells was determined. Besides, the levels of inflammatory response in the vascular endothelial cells were also determined with the real-time reverse transcriptase polymerase chain reaction assay.

Natural plant fiber-reinforced polymer composites (PFRP) have emerged as an environmental-friendly material in the construction industry, but their creep behavior is a critical concern for load-bearing structures. This study investigates the creep behavior of flax fiber-reinforced polymer composites (FFRP) using the time–temperature superposition principle (TTSP). Due to the application of TTSP on the tensile creep behavior of FFRP is not fully understood, three potential methods for calculating the critical parameters during TTSP are compared to obtain an efficient application method to build the creep master curve. A 2,000-h long-term creep test is conducted parallelly on the same sample to validate the accuracy of the creep analysis results. The study proposes an ideal method to determine the key parameters in TTSP, providing valuable insights for the practical application of PFRP in the construction industry. Meanwhile, the research results in this study would be helpful in better understanding the creep behavior of FFRP via short-term accelerated tests.

In this work, a novel binary hybrid woven carbon nanotube (CNT) tape/copper wire carbon fiber reinforced epoxy resin composite is prepared. The mode I interlaminar fracture toughness ( G IC ) is employed to critically evaluate the delamination performance. A comparison of the G IC value with that of the carbon fiber reinforced composite confirms that incorporating CNT tapes and copper wires into the composite increases the value by 263%. In the transverse and through-thickness direction, the conductivity of the laminate increases to 458 and 193 S/m, which is increased by 196 and 675%, respectively. The thermal conductivity along the thickness direction is increased to 2.27 W/m K, an increase of 134%. The volume fraction of CNT tapes and copper wire are as low as approximately 0.87 and 0.47 vol%, respectively. 3D woven composites have potential applications in high-performance structures and lightning striking protection such as aircraft, ships, and engines, which benefits by the innovative through-thickness implantation of composites using CNT tape and copper wire.

To improve the stability of cemented sand and gravel (CSG) dam construction materials, artificial aggregates can be selected to replace missing natural aggregates, and aggregate grading optimization can be carried out to meet the needs of engineering applications. This article uses finite-element analysis software to explore the influence of aggregate characteristics on the performance and destruction characteristics of CSG materials through numerical simulation. The results show that (1) with the increase of circular natural sand gravel aggregates, the peak stress and elastic modulus of the sample increase, while the strength also increases. (2) Compared to circular aggregates, polygonal aggregates have more edges and corners, which exacerbate the deformation disharmony between mortar and aggregates; the phenomenon of stress concentration is more obvious, so under the same loading step, the degree of damage of polygonal aggregates is greater than that of circular aggregates. (3) After the freeze–thaw cycle test, the deterioration of parameters in the CSG resulted in more severe damage and strength loss of the crushed stone aggregate than the circular aggregate sample. This conclusion can provide a reference for the design of CSG mix ratio in engineering sites.

The increasing demand for the impact resistance of ships entails the excellent impact resistance and deformability of air spring (AS) for ships under high internal pressure. However, an AS of traditional structure is difficult to satisfy such new demand since it is designed with only 10 mm maximum deformation under high internal pressure and strong impact. For this reason, an integrated structure of filament winding reinforced bellows is proposed to ensure the structural strength at the connection of AS bellows and flanges under strong impact and high internal pressure. On this basis, a parameterized design of integrated bellows strength is explored, and we analyzed how the strength of the bellows was affected by the parameters of geometrical structure, material features, and filament winding. As proved in tests, the integrated structural design of the bellows could ensure the strength of AS under strong impact and high internal pressure, and the test result perfectly matches with the calculated strength of the integrated bellows as well as the optimized design.

This study proposes a unified modeling method to investigate the dynamic behaviors of the functionally graded porous (FGP) spherical shell with elastic boundary conditions. First, three kinds of FGP distributed patterns are defined. Then, the first-order shear deformation theory is selected to build the governing equations of the spherical shell with elastic boundary conditions, which can be solved by the Rayleigh–Ritz approach. Moreover, Chebyshev polynomials of the third kind are selected as an admissible function to express the motion equation. With the constructed model, the correctness is verified by comparing the natural frequency and forced response obtained from both open literature and finite element method. Ultimately, the parameter study is conducted to conclude the effect of the design parameter on the dynamic characteristics of the spherical shell.

This article presents a comprehensive study on the failure behavior of foam core sandwich beams under three-point bending using theoretical analysis and finite element methods. A displacement formula for the foam sandwich beam is derived, considering the shear deformation of the foam core. Based on this formula, the deflection is obtained using energy and Rayleigh–Ritz methods. The failure loads of face yielding, core shearing, and indentation are combined to construct a failure mechanism map. The proposed theoretical model is then compared with existing theoretical analyses, demonstrating higher prediction accuracy. To investigate nonlinear damage and size effects, a series of finite element analyses is conducted. The results suggest that increasing the face sheet thickness has a greater impact on the ultimate load capacity, while the foam core thickness is more effective in enhancing bending stiffness.

To analyze the influence of basalt fiber on the performance of permeable concrete for road applications, this study focuses on two key performance indicators: compressive strength and permeability coefficient of basalt fiber permeable concrete. Based on orthogonal experimental data, regression prediction equations were established using SPSS software to assess the effects of different fiber parameters on the compressive strength and permeability coefficient. The predicted results were then compared with experimental data. The findings indicate that the average relative error of the predicted values for both performance indicators is within a manageable range of 5%, demonstrating a high prediction accuracy. Using these regression equations, we can examine the variations in the road performance of basalt fiber permeable concrete under different fiber parameter conditions, thereby overcoming the limitations of conducting numerous parameter analysis experiments.

The use of rubber in concrete to partially substitute mineral aggregates is an effort to decrease the global amount of scrap tires. This study investigates the behavior of rubberized concrete (RC) with various replacement ratios (0–50%) by volume and replacement type (fine, coarse, and fine-coarse) using soft computing techniques. The uniaxial compressive strength (CS), elastic modulus (EM), and ductility (D) are measured, and the effect of rubber content and the rubber aggregate type on the properties of RC is investigated. Scanning electron microscopy and X-ray diffraction analyses are made to determine its microstructural and chemical composition. This article compares the efficiency of two RC models using a recently developed artificial intelligence technique, i.e., gene expression programming (GEP) and conventional technique, i.e., response surface method (RSM). Statistical models are developed to predict the CS, TS, EM, and D. The mathematical models are validated using determination coefficient ( R 2 ) and adjusted coefficient ( R 2 adj), and they are found to be significant. Furthermore, both methods (i.e., RSM and GEP) are very well correlated with the experimental data. The GEP is found to be more effective at predicting the experimental test results for RC. The projected methods can be executed for any practical value of RC.

In order to improve the utilization value of recycled materials, the study considers recycled materials such as polyester/nylon/spandex as raw materials. Using polyester/polyamide/spandex as raw materials, the recycled polyester/polyamide/spandex mixed materials were first pretreated to obtain the pretreated mixed materials. Then, the pretreated mixed materials were evenly mixed with hydrogenated petroleum resin. The composite materials were prepared through extrusion and injection molding. By comparing the mechanical properties, the effects of different hydrogenated petroleum resins and their additives on the tensile strength, bending strength, impact strength, elongation at break, and bending modulus of the composites were investigated. And the microstructure of the fracture surface was characterized by scanning electron microscopy. The results showed that: (a) when the addition amount of hydrogenated C5 petroleum resin was 4.5%, the maximum impact strength and fracture elongation were 18.03 kJ/m 2 and 15.92%, respectively. (b) The maximum tensile strength, bending strength, and bending modulus could reach 22.9, 38.72, and 2217.9 MPa, when the addition amount of hydrogenated C9 petroleum resin was 4.5, 29.5, and 39.5%, respectively.

In order to improve the chloride ion penetration resistance of supplementary cementitious materials (SCMs) in blended cement, this study optimizes the particle size distribution of cementitious components based on the Fuller model. Portland cement (PC), fly ash (FA), and ground granulated blast furnace slag (GGBFS) are successfully divided into four particle size ranges by precision air classifier, which are 0–8, 8–30, 30–50, and 50–80 μm, respectively. The optimum cementitious materials in four ranges based on 28-day compressive strength are determined by nine groups of orthogonal tests. The blended cement with optimal performance is obtained by GGBFS in 0–8 μm, PC in 8–30 μm, GGBFS in 30–50 μm, and FA in 50–80 μm. The results show that the blended cement with SCMs based on Fuller model have superior microstructure and chloride ion penetration resistance, which is due to their smaller pore size, a strong volcanic ash effect, and chloride ion binding ability. In addition, this research presents a novel approach for realizing the application of a large amount of SCMs in blended cement.

In situ disulfide bond formation affords a new flexible dicarboxylic acid ligand of 3,3′-dithiobisbenzoic acid (3,3′-H 2 DTBA), which assembled with Co( ii ) ions under hydrothermal conditions, generating a novel metal–organic framework (MOF), namely, [Co(3,3′-DTBA) 2 (H 2 O) 2 ] n ( 1 ). This compound is assembled from layered structures, featuring weak interlayer interactions that can reduce pore blockage through relative sliding. The results of photocatalytic experiment indicate that MOF 1 is a good semiconducting material and it can function as photocatalyst for degrading methylene blue under the ultraviolet light irradiation. Cyclic experiments demonstrated its good stability and long-lasting photocatalytic performance, indicating its potential application value.

The mixed-mode fracture characterization of adhesively bonded glass fiber-reinforced polymer (GFRP) plate joints is studied based on theoretical and experimental techniques. An improved beam model is used to estimate the compliance and the mixed-mode energy release rate (ERR) for GFRP four-point mixed-mode bending specimens. In this model, the deformation of the upper and lower GFRP plates is mutually independent, and the deformable adhesive is considered to satisfy the displacement compatibility conditions on the bonding interface. The explicit theoretical solutions of the compliance and ERR using the compliance method are reduced. The present theoretical solutions fit well with the finite element solutions by comparison with the rigid joint model. From the critical loads in experiment, the variation in fracture toughness on mixed-mode I/II has been determined by modifying the stiffness of the composite GFRP/GFRP substrate.

In this article, ABAQUS finite-element software is used to establish an asphalt pavement structure model under high-temperature environment in summer. The changes in the temperature field and moisture concentration field of asphalt pavement are studied under the condition of 1-day continuous temperature change. The creep model is used to analyse the influence of ambient temperature and humidity on the rutting deformation of asphalt pavement. The results show that the maximum temperature of asphalt pavement can reach 60°C in the high-temperature environment in summer. The temperature accumulation effect causes the temperature of the middle and lower layers to increase by approximately 10°C, which easily induces rutting. Ambient humidity has a great influence on the change in moisture concentration in the upper layer. Considering the influence of ambient humidity in the high-temperature environment, the rut depth increases by 67%.

The paper industry is one of the biggest sources of trash and stands out for its effects on both human health and ecological harmony. However, these waste could also help the building sector become more ecologically friendly. Beyond ecological considerations, modern construction often requires materials to make concrete durable, resisting heavy loads and less harmful environmental influences. This creates opportunities for waste management and practical application. This review provides a detail overview of eco-friendly construction ideas that deal with the practical use of materials that are often discarded (paper pulp ash). The impact they had on the characteristics of the construction material, the best mixture composition, and a discussion of the benefits and drawbacks of the “green” addition received the majority of the attention (paper pulp ash). The essential concrete properties such as consistency, setting time, flowability, compressive strength, flexural strength, tensile strength, and impact strength are reviewed. Furthermore, the cost benefits and environmental benefits of paper pulp ash as construction materials are also discussed. The study concludes by suggesting a line of inquiry for the creation of an environmentally friendly structural material for a sustainable future.

The quantity of carbon dioxide gas released during the manufacturing and acquisition of raw ingredients determines the sustainability of concrete. Industrial garbage dumping is a critical difficulty that humanity is experiencing because of globalization and the increasing population. Through the efficient use of industrial by products, efforts are being undertaken to lower carbon discharges in the concreting process. It has been recommended by sustainable development goals and standards to use byproducts that have lower embodied energy and carbon emissions. Ash from sewage sludge demonstrates its suitability for use in concrete. However, a compressive assessment is needed to determine the past, present, and future research aspects of using sewage sludge ash (SSA) as a construction material. Therefore, this research is carried out on using SSA as a construction material. All the essential properties such as the physical and chemical properties of SSA, its effect on durability properties, and morphology structure study are the main aspect of this review (Part II). The analysis also highlights the research gap for upcoming exploration which further improved its performance.

Sewage sludge is frequently stable and safe when used as construction materials since it bypasses several of the costly and energy-intensive phases of usage. This is supported by numerous studies, particularly when the proportion of sewage sludge is at ideal levels. The primary goal of this article is to demonstrate the use of sewage sludge in building and construction materials. Novel properties such as slump flow and setting time as well as strength properties such as compressive strength, tensile strength, flexural strength, elastic modulus, impact energy, and absorbed energy are the main aspects studied in this review (Part Ⅰ). Part II describes the physical and chemical properties, durability, and morphological structure of the sewage sludge ash. The findings in this review (Part Ⅰ) indicate that the flow of concrete decreased with the addition of sewage sludge ash due to its porous nature, but the strength properties improved with sewage sludge ash due to micro-filling voids and pozzolanic activity, which improved the binding properties of cement paste. However, optimum substitution is critical as a greater proportion decreased the strength due to a deficiency of flowability, which boosted compaction energy leading to more cavities. Different studies recommend different optimum doses. However, the typical range for the optimum dose of sewage sludge ash is 5–10% (by wt) of cement.

Concrete is the most frequently employed man-made material in modern building construction. Nevertheless, the serviceability of concrete structures has been significantly reduced owing to a variety of durability issues, especially when serving in a non-ideal environment and exposed to internal/external attacks such as chloride penetration, carbonation, sulfate, and so on. Several scholars have performed numerous studies on the strength and microstructure features of volcanic ash (VA) concrete and have discovered encouraging findings. However, since the information is spread, readers find it difficult to evaluate the benefits of VA-based concrete, limiting its applicability. As a result, a detailed study is required that offers the reader an easy approach and highlights all essential facts. The goal of this article (Part Ц) is to conduct a compressive review of the physical and chemical aspects of VA and its impact on concrete durability and microstructure properties. The findings demonstrate that VA considerably improves concrete durability owing to pozzolanic reaction and micro-filling voids in concrete materials. Cost–benefit analysis shows that 10% utilization of VA as cement decreased the overall cost by 30%. The assessment also notes a research gap that must be filled before VA may be utilized in practice.

As one of the unconventional oil and gas resources, tight oil is of great development prospect all over the world. The characterization of tight reservoir has important guiding significance for overcoming the problems in exploration as well as improving the development effect. As one of the characteristics of reservoir cores, the specific surface area is very important for the characterization of tight reservoirs. In this study, based on mercury injection data of tight reservoir core from Changqing Oilfield, through the establishment of equal diameter pore model, the specific surface area of pores corresponding to different radii is calculated, respectively, and the overall specific surface area of the core is obtained. Through the comprehensive evaluation of the mercury injection data and the calculation results, it is found that the pores with the medium radius (0.009–0.178 μm) have the greatest contribution to the pore volume, followed by the pores with smaller radius (0.004–0.007 μm), and the pores with larger radius (0.268–53.835 μm) have the least contribution to the pore volume. However, the pores with smaller radius (0.004–0.089 μm) have the greatest contribution to the specific surface area, followed by the pore with larger radius (0.133–6.666 μm), and the specific surface area of individual pores in the middle range (8.917 μm) has the least contribution. Therefore, the adsorption loss of surfactant and so on must be considered in the process of tight oil development. In the development process, a series of main technologies such as fracturing, new water/gas injection, and horizontal well development should be explored. Through the overall design and scale implementation of reservoir scale, the investment cost of unit-producing reserves can be effectively reduced, and ultimately, the maximum benefit of tight oil development can be realized.

The present article investigates the effect of elliptical cutouts and geometric imperfections on the vibrational response of functionally graded material (FGM) sandwich plates. Generalised governing equations for the sandwich FGM (SFGM) plate are derived based on non-polynomial higher-order shear deformation theory. Geometric discontinuities have been incorporated as elliptical cutouts in the plates, and the various geometric imperfections are modelled using the generic function. The mathematical modelling has been carried out using the C 0 continuity isoparametric finite element formulation by considering four-noded elements with seven degrees of freedoms per node. Convergence and validation studies have been performed to demonstrate the efficiency and accuracy of the present methodology. The influence of volume fraction index, geometric imperfections, and elliptical cutouts on the vibrational frequency of SFGM plates have been analysed under the mixed boundary conditions.

In this study, the micromechanical scratch behavior of unidirectional glass fiber reinforced polyester (GFRP) using several wear conditions was highlighted. Single-indenter scratch tests (SSTs) were carried out on GFRP composite material perpendicular (SST ⊥ ) and parallel (SST // ) to fiber direction. Damage modes dominating the material removal process (MRP) and friction exhibit significant sensitivity to both attack angle and normal load. From findings, damage modes and apparent friction coefficient substantially accentuate when increasing the attack angle. The inspections of the damage state at different testing conditions using a scanning electron microscope (SEM) reveal the dominating modes governing the MRP through the different phases. The response surface methodology (RSM) was adopted to develop a mathematical model based on the measured data. The RSM approach was found very promoting for predicting friction evolution versus attack angle and normal load. The proposed model reveals good ability not only in predicting apparent friction coefficient but also in detecting separately its ploughing and adhesive component. To emphasize the correlation between friction coefficient and MRP, the wear maps have been drawn up.

Specific nano- and micro-scale morphologies of composites can affect the resulting optical and UV reflectivity of the materials. One example is “Vantablack ® ” made from aligned carbon nanotubes (CNTs) with 99.96% absorption. A similar material with CNTs grown on surface-activated aluminum (CNTs/sa-Al) even yielded 99.995% absorption, one order of magnitude higher than Vantablack®. On the other hand, fresh snow reflects 90% or more of the incident electromagnetic radiation with wavelengths between 400 and 1,000 nm. The reflectivity of snow originates from multiple scattering in the porous morphology made of snow grains. Taking these complex morphologies as inspiration, CFRP epoxy composites with different types, sizes, shapes, and amount of nanoparticles are prepared and compared regarding their optical and ultraviolet (UV) reflectivity. Increasing the reflectivity in the near and far UV may be beneficial for the durability of the epoxy composites, but selective higher or lower reflectivity in certain wavelength ranges may also yield tailored visual effects. Results from different processing approaches with selected nanoparticles are presented and discussed.

Continuous fiber-reinforced thermoplastics (CFRTs) can in combination with high-strength metals offer characteristics that cannot be achieved with mono-material parts. One possible example is the combination of locally high-temperature resistance in the metal component with superior weight-related mechanical properties due to the CFRT component. This approach requires a reliable and durable joining technology, which considers the material-specific properties and allows to exploit the full potential of CFRT/metal hybrid parts. A promising approach in the field of CFRT/metal joining is the use of metallic pins, which can be embedded in the locally heated CFRT component to create a form-fitting joint. In the current state of the art, primarily single-pins are investigated and characterized: especially the distinct fiber orientation in the direct pin pressing process is only described for single-pin joints. Behind this background, the present study aims at creating an understanding of the fiber orientation mechanism for multi-pin arrays. Therefore, in the scope of this study, unidirectional reinforced glass fiber/polypropylene samples are joined via direct pin pressing and infrared heating with different 1D and 2D multi-pins arrays with different pin-diameters, spacing and pin distributions. The resulting joint morphology is consequently analyzed using micro-computer-tomography. Based on the performed investigations, a model for the fiber displacement mechanism is proposed, and the first recommendations for the design of fiber-friendly multi-pin joints with unidirectional reinforcements are given. It showed that especially pin-spacing in fiber orientation in dependency of the pin diameter is critical for a fully reconsolidated joint quality, and it is suggested that a pin-offset in the fiber direction is beneficial for a fiber-friendly joining process.

This study provides an insight into the synthesis of high-strength and corrosion-inhibiting Mg-based biodegradable implant material by the addition of rare earth oxide material for acicular cruciate ligament reconstruction applications. The matrix has been reinforced with a naturally occurring mineral, hydroxyapatite (Ca 5 (PO 4 ) 3 OH) and rare earth oxide, neodymium oxide (Nd 2 O 3 ), in different concentrations. The mechanical response has been assessed by analyzing the samples’ microhardness, ultimate compressive, and tensile strength. In contrast, the corrosion rates were calculated using phosphate buffer saline solution by using different techniques under suitable physiological conditions. The microstructure characterization has been carried out by field emission scanning electron microscope, electron dispersive spectroscopy, optical microscopy, and X-ray diffraction techniques. Moreover, the surface properties of the composites were assessed using surface roughness and contact angle measurements. The sample showed maximum hardness at a concentration of 1.5% rare earth oxide. Moreover, the highest ultimate compressive and tensile strength followed the same order, i.e., 1.5% > 2% > 1%. In addition, the microstructure analysis revealed a refined microstructure and the formation of secondary intermetallic phases. Resistance to dislocation and grain growth barricading were the prominent features highlighted in the study for enhanced mechanical and corrosion properties. Moreover, the hydrogen evolution was lower for Mg–HA–1.5Nd 2 O 3 samples, which was a clear indication of a reduced corrosion rate.

A new type of foam ceramics was prepared with fly ash (CFA). Before sintering, the CFA underwent alkali activation, resulting in an even layer of hydroxy sodalite crystals covering the CFA particles. The pre-treatment of the CFA-alkali-activated material caused it to exhibit a reaction in sintering. The foamed ceramics had the best qualities when sintered at 1,300°C; the leaching toxicity studies of a material used in interior design revealed that during sintering.