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The key objective of the present paper is an attempt to create an interface between the existing inconsistent views on the microscopic and macroscopic aspects of the mechanism of plastic deformation and shear fracture. This will be enabled by a focus on the course and effects of the evolution of dislocation structure, and will consist in considering an indirect, i.e. a mesoscopic scale of the discussed phenomena. Thanks to this, a synergy between the mechanisms of deformation and fracture of materials will be proven, which will provide an opportunity for a smooth transfer from the microscopic, through mesoscopic, to macroscopic scale of the analysed phenomena. This in turn will offer an opportunity to define and use the new criteria for controlling the mechanism of shear fracture. These criteria will be applicable to the complete range of temperatures and strain rates which are typical of metal working processes. Some examples of how these criteria may be applied in order to optimise the parameters of metal working will also be provided. These examples have made it possible to prove that the physical approach to shear fracture mesomechanism offers much broader cognitive and utilitarian opportunities than the existing purely mathematical methods. This is due to the fact that the physical approach allows for a deeper understanding of shear fracture meso- and macromechanism, and generates new criteria controlling this mechanism.

This article reports on the corrosion and wear resistance of Ni-P and Ni-P-PTFE nanocomposite coatings deposited on mild steel substrates using the electroless plating technique. The coatings were characterized by scanning electron microscopy (SEM), energy dispersive analysis of X-Ray (EDAX), and X-ray diffractometry (XRD). The coatings were smooth and had thicknesses between 7 and 23 µm. They contained Ni, P, and additionally, F, in the case of the Ni-P-PTFE films. A broadening of the Ni peak in XRD was attributed to the amorphous nature and/or fine grain size of the films. Corrosion resistance was measured using immersion and electrochemical polarization tests in 3.5% NaCl solution whereas wear resistance was determined by the pin-on-disc method. Both Ni-P and Ni-P-PTFE coatings exhibited significant improvement in corrosion (in salty media) and wear behavior. Furthermore, the addition of PTFE in the coatings showed improvement in their corrosion resistance as well as a reduction in friction coefficient. Our testing revealed that the coatings’ wore out following the “adhesive type” mechanism.

This paper studies output statistics of an adaptive line enhancer that is based on an affine combination of two NLMS adaptive filters. Combination of adaptive filters is a new interesting way of improving the performance of adaptive algorithms. The structure consists of two adaptive filters that adapt on the same input signal, one with a large and the other one with a small step size. Such a combination is capable of achieving fast initial convergence and small steady state error at the same time. In this paper we investigate the second order statistics of the output signal of adaptive line enhancer based on the combination in steady state. The result is given in terms of the parameters of the adaptive combination, input process statistics, and the optimal Wiener filter weights for the problem at hands.

The paper presents short profile of analytical and numerical methods used in bioelectromagnetic modeling. Some comparison of different models of human being was made. Author analyzed it in the following points of view: time of calculations and technical specifications

In this paper a short theoretical background about elastic-plastic fracture mechanics is presented and the O’Dowd-Shih theory is discussed. Using FEM, the values of the Q-stress determined for various elastic-plastic materials for two specimens in tension — SEN(T) specimen and CC(T) specimen are presented. The influence of geometry of the specimen, crack length and material properties (work-hardening exponent and yield stress) on the Q-parameter are tested. The numerical results were approximated by closed form formulas. The results are summarized in a catalogue of the Q-stress value, which may be used in engineering analysis for calculation of the real fracture toughness and the stress distribution near crack tip.

In this paper, a dynamical laboratory testing of experimental car body connection with real elastic suspension system (ESS) is described. During the experiment a horizontal force in longitudinal direction was applied, in order to simulate an acceleration and deceleration regime of a vehicle. The experiment was carried out on the example of two car bodies, with identical geometric behavior but implemented engine compartment was made of different materials: in one case it was made of steel and in another one of Al-alloys. The obtained displacement results were compared.

This paper investigates the problem of propagation of planar and non-planar weak shock waves in a non-ideal medium. The mathematical formulation developed in this work leads to a closed system of coupled transport equations which efficiently describes the strength of a shock wave and the first order discontinuities induced behind it. The influence of the parameter of non-idealness and the non planar configuration of the wavefront on the nonlinear distortion, attenuation and shock formation of pulses, are discussed in detail. An analytical expression for the shock formation distance is obtained and a direct comparison between the ideal versus the non ideal gas flow is established. Also, the usual asymptotic decay laws for weak shock are recovered.

Analysis of pile load-settlement behavior is a complex problem due to the participation of many factors involved. This paper presents a new procedure based on artificial neural networks (ANNs) for simulating the load-settlement behavior of pile foundations embedded in sand and mixed soils (subjected to axial loads). Three ANN models have been developed, a model for bored piles and two other models for driven piles (a model for each of concrete and steel piles). The data used for development of the ANN models is collected from the literature and comprise a series of in-situ piles load tests as well as cone penetration test (CPT) results. The data of each model is divided into two subsets: Training set for model calibration and independent validation set for model verification. Predictions from the ANN models are compared with the results of experimental data and with predictions of number of currently adopted load-transfer methods. Statistical analysis is used to verify the performance of the models. The results indicate that the ANN model performs very well and able to predict the pile load-settlement behaviour accurately.

The fatigue life assessment of orthotropic steel decks of highway bridges still hasn’t been sufficiently investigated. The inspection results of orthotropic steel decks have shown that their working life can be shorter than other members of steel highway bridges due to fatigue. This means that particular details of orthotropic decks can be critical regarding the service life of a bridge. The fatigue life of typical details of orthotropic steel decks for the real load models in Croatia and for the standardized load model of highway bridges in Eurocode has been analysed. The reliability indices have also been calculated for these details and they have been used to determine reliable fatigue life. The paper proposed the introduction of the reliable fatigue life concept which is not explicitly specified in the modern standards for structures. This concept has been offered as well as the guidelines for further probabilistic research on reliable fatigue life.

The paper presents analysis of the stress and deflections changes due to creep in statically determinate composite steel-concrete beam. The mathematical model involves the equation of equilibrium, compatibility and constitutive relationship, i.e. an elastic law for the steel part and an integral-type creep law of Boltzmann — Volterra for the concrete part. On the basis of the theory of the viscoelastic body of Arutyunian-Trost-Bažant for determining the redistribution of stresses in beam section between concrete plate and steel beam with respect to time “t”, two independent Volterra integral equations of the second kind have been derived. Numerical method based on linear approximation of the singular kernal function in the integral equation is presented. Example with the model proposed is investigated. The creep functions is suggested by the model CEB MC90-99 and the “ACI 209R-92 model. The elastic modulus of concrete Ec(t) is assumed to be constant in time ‘t’. The obtained results from the both models are compared.