Volume 62, Issue 5

The study presents an analysis of the frontal impact of a Dodge Grand Caravan car colliding with different obstacles - a rigid barrier, for full and 50 % overlaps, and a pole with 0.5 m. diameter. Simulations were performed using a V-Sim 4 program at three data sets: default data offered by the program, data established by experts on the basis of their experience and identified on the basis of impact simulation via a LS-Dyna program. The results obtained showed that the attainment of a precise simulation is possible only when the data of V-Sim program is formulated in accordance with an advanced MES analysis. This usually pertains to cases when there is no full overlap of the vehicle body in connection with the obstacle. The results of this work may offer some directions for the development of this type of simulation program. They also show users how important it is to provide accurate input data to achieve reliable calculation results.

The effects of adding nickel and cobalt to Inconel 738 along with adding 1 wt.-% of aluminum were investigated in this study. The alloys, with various amounts of nickel and cobalt, were prepared using a vacuum arc melting process. The alloys were heat treated using a standard heat treatment procedure which consisted of solution treatment at 1448 K for 14.4 ks and precipitation aging at 1118 K for 86.4 ks. Increased nickel content was shown to enhance the stability of gamma prime particles and the gamma matrix as well as assist the formation of gamma prime particles. In the case of the addition of cobalt, the coarsening rate of gamma prime particles decreased with increasing cobalt content. Furthermore, a further addition of aluminum to Inconel 738 resulted in an increase in the area fraction of the gamma prime phase and more rapid growth of gamma prime particles during long-term heating compared to standard Inconel 738.

The population of the world is increasing day by day. Accordingly, the amount of production and consumption are increasing. Due to the continuous and rapid development of technology, the duration of the use of some products becomes shorter. That is why the more efficient use of limited resources is even more important. In the developing and growing automotive industry, companies are currently focusing on weight and cost reduction methods to compete. In this study, the optimum design has been achieved by using topology and shape optimization in the suspension cover used in suspension systems. As a result of the topology and shape optimization efforts, The mass of the optimum design achieved was reduced by 35.203 % according to the first design.

This article addresses the bond graph model that allows for better comprehension of what the physical and mathematical concepts involved in electromechanical actuators are. In this study a disc type electromechanical actuator is modeled according to the bond graph method. Nonlinear effects such as flux path permeances, leakage loss and material saturation in a magnetic circuit are taken into account. The model is run on 20-sim 4.7 software, which allows for working directly with bond graph concepts. Simulation run-time is approximately 0.3 s for the simulation time of 12 ms. Results achieved with this model are compared with an MATLAB/Simulink model prepared using magnetic circuit algebraic equations. It was determined that the results of both models are almost identical. The static and dynamic model results are also verified by test results. As a consequence, a simple, fast running, accurate and easy-to-understand comprehensive bond graph model with magnetic circuit characteristics was developed. The model can be adapted to any type of electromechanical actuators with proper arrangement.

Modern welded structures often contain weld ends due to increasing component complexity and economic motives. Under cyclic loading, crack initiation mainly occurs at those weld ends which makes them the failure critical location. So far, no detailed approach for the assessment of the fatigue life of weld ends has been added to known international or national guidelines. A new specimen type was developed at the Materials Testing Institute University of Stuttgart with which the fatigue resistance of weld ends of different welding procedures can be evaluated and compared. Tensile tests and fatigue tests on those new specimens show that the loading capacity is dependent on the welding procedure and the weld end point considered, i. e. weld start or weld end. In a sketched assessment approach, those results can be transferred to components in order to carry out a fatigue strength assessment or to enable the selection of a welding procedure. The assessment with the notch stress concept is preferred for the further development of the assessment approach.

In this study, the effects of sections added to multi-cell square tubes on crash performance are examined. Square, hexagonal and circular sections are added to multi-cell square tubes and their results are examined. Finite element analyses under axial loading are performed to examine the crash performance of the multi-cell tubes. Analyses show that by adding a section to the multi-cell square tubes. the crash behavior of the tubes is improved. According to the results, S5H multi-cell square tube reveals the best crash performance. The optimization of S5H is carried out by using genetic algorithms and radial basis functions. The S5H tube presents a good crashworthiness performance and could be used as an energy absorber.

This study investigated the electrical discharge machining (EDM) performance of Ramor 500 Armor steel, a material used in the defense industry for armor production. In addition, the surface quality and amount of material wear of the treated surfaces were determined using different electrical discharge processing parameters for a copper electrode including pulse on-time (99, 150, 225, 300, 351 μs), pulse off-time (10, 15, 23, 30, 35 μs), and discharge current (3, 4, 6, 8, 9 A), at a constant pressure of 1 mm depth of cut. As a result of the experiments, the values related to the material removal rate (MRR) and the surface roughness (Ra) were obtained and the findings analyzed via response surface methodology (RSM). The increase in amperage and pulse on time resulted in an increase in Ra and MRR values. The minimum and maximum Ra and MRR values emerged at currents of 3 and 9 A, respectively. In the experiments performed applying currents of between 3 and 9 A, the white layer widths were measured as 0.0474 mm and 0.0915 mm, respectively. The statistical test results showed that the most effective processing parameters for the MRR were the discharge current amperage (49.01 %) and the pulse off-time (16.51 %), whereas the most effective parameter for the Ra value was the discharge current amperage (79.07 %).

Due to harsh competitive conditions and the transition to new vehicles such as hybrid and full-electrical, the interest in the design of light and low-cost vehicles is increasing. In this paper, a recent metaheuristic procedure which is an equilibrium optimization algorithm (EOA) is used to solve a structural design optimization problem for a vehicle seat bracket to prove how the EOA can be used in solving industrial design problems. This paper is the first application of the EAO to real-world problems in the literature. The results strongly prove the capability of the EOA for designing optimum components in the automotive industry.

The shape optimization of mechanical and automotive component plays a crucial role in the development of automotive technology. Presently, the use of derivative-free metaheuristics in combination with finite element analysis for mechanical component design is one of the most focused on topics due to its simplicity and effectiveness. In this research paper, the mine blast algorithm (MBA) is used to solve the problem of shape optimization for a vehicle door hinge to prove how the MBA can be used for solving shape optimization problems in designing electrical vehicles. The results show the advantage of the MBA for designing optimal components in the automotive industry.

Flexible and digital manufacturing technologies like additive manufacturing (AM) have evolved as the future of modern manufacturing with the capability of obtaining multi-dimensional components and material functionality improvement. In the past decade, the additive manufacturing of steel has advanced into an effective approach for controlling local microstructure and fabricating hybrid build with tailored performance. As an emerging technology, there are still some challenges in the additive manufacturing of steel that need to be circumvented in order to attain the full potentials of this novel technology. This review paper examines the current state of additively manufactured steel as well as the associated microstructure, mechanical properties, and corrosion of as-built steel. An insight into further and future research directions is provided.

This paper aims to improve the calculation efficiency and accuracy of concrete damage degree identification, and then to analyze the damage mechanism of concrete damage. First, the correlation analysis and principal component analysis of 15 characteristic parameters of acoustic emission signals accompanying concrete uniaxial compression and splitting damage process are performed through which the dimension is reduced into 5 non-correlated principal components. Then, based on the analysis of the relationship between each principal component and the damage and cracking mechanism of concrete, the damage degree of concrete is identified as an input variable of the BP neural network. The results show that the 5 principal components effectively eliminate redundant information and carry information on the failure mechanism of concrete damage and the damage process. Principal component analysis and the neural network are used to achieve the accurate recognition of acoustic emission parameters and the degree of concrete damage.

The present research work is focused on the production of aluminum alloy 8011 with 12 wt.-% fly ash composite by using the stir casting method. A three-level central composite design experiment is developed using response surface methodology (RSM) with various parameters. Load, time and sliding velocity are varied in the range of (5-15 N), (5-15 min) and (1.5-4.5 m × s-1), respectively. Dry sliding wear tests are performed as per the experimental design using a pin-on-disc at room temperature. This paper describes how optimization studies were carried out on a dry sliding wear process with multi-response characteristics based on MCDM using the TOPSIS approach. The process parameters, load, time and sliding velocity are optimized with multi-response characteristics, including the wear rate (WR), and the coefficient of friction (COF). A sensitivity analysis is also carried out and compared with the relative impact of input parameters on wear behavior in order to verify the measurement errors on the values of the uncertainty in estimated parameters. The experimental results indicate that the multi-response characteristics of aluminum alloy 8011 with 12 wt.-% fly ash composite used during the wear behavior process can be enhanced through the TOPSIS method.

Plastic injection forming (PIF) is an alternative sheet metal forming method for complex geometrical parts with dimensions in low tolerance. This method is a combination of injection molding and hydroforming in which a molten polymer material has been injected over a sheet metal via a plastic injection molding machine. In this study, aluminum sheets 1.5 mm thick were shaped by PIF at various injection pressures, melt temperatures and injection speed. The effects of these parameters on the formability of the sheet metal were investigated using the experimental design technique. The thinning rate, flange radius and the hardness values of the shaped sheets were considered in the experimental study. Injection pressure was found to be the most effective parameter and melt temperature was the second degree effective parameter for the thinning rate. The usability of the PIF process in industrial applications as an alternative method was emphasized by comparing PIF with conventional hydroforming by means of the finite element method (Ls-Dyna). A 2.07 % deviation was observed between the FE results for hydroforming and the experimental results for PIF.

Sandwich foam composites are mostly used today in structural applications in aerospace and automobile industries due to light weight and high stiffness of the sandwich composites. In this research work, the composites were fabricated by using polyurethane and PVC foam and carbon fiber as skin. Sandwich composites were fabricated by the hand lay-up method. Mechanical tests such as tensile, flexural, impact, double shear, inter delamination and hardness tests were conducted. A thermo gravimetric analysis (TGA) test was also performed for the analysis of the temperature characteristics of the sandwich composites. The internal structures of tested samples were analyzed through a scanning electron microscope (SEM). The results show that the tensile, flexural, impact, thermal and inter delamination strengths of PVC foam composites are superior to those of other composites.