Jacek Jackiewicz

Kazimierz Wielki University in Bydgoszcz · Faculty of Mathematics, Physics & Technical Science

Regenerative braking is a technique that employs electric motors to convert the dynamic mechanical energy from the motor's spinning rotor and any attached loads into electricity. However, such a type of regenerative braking can only slow but not stop the vehicle because there is too little energy to excite the motor acting as a generator at low spe...

It is a well-known fact that piston engines shake, among which some of them more than others. Therefore, such type of vibrations, created by piston engines, should be controlled somehow. For the reduction of torsional crankshaft vibrations, torsional dampers are often used. The crankshaft vibrations are intrinsic in any internal combustion engine b...

During the traction and braking of trains, substantial longitudinal dynamic forces might occur in couplers. The method of modeling these forces for two different electric multiple units (EMUs) is presented in this study. For the EMUs consisted of independent vehicles, each of which rests on two bogies, computer simulations were carried out. Simulat...

During traction and braking of multiple-unit trains, substantial longitudinal dynamic forces might occur in couplers due to the non-optimal distribution of traction and braking forces generated by self-propelled carriages. These dynamic forces might create shocks affecting the reduction of endurance of the weakest train structural components primar...

Short Communication Mechanical engineering is not only one of the oldest engineering disciplines but also the broadest one, i.e., with the wide-scope as well as a large number of its branches. This engineering discipline requires a clear understanding of the principles of engineering physics, engineering mathematics, and materials science to design...

The Sandia Fracture Challenges provide a forum for the mechanics community to assess its ability to predict ductile fracture through a blind, round-robin format where mechanicians are challenged to predict the deformation and failure of an arbitrary geometry given experimental calibration data. The Third Challenge (SFC3) required participants to pr...

Two distinctive features of challenging control engineering problems are commonly taken into consideration in design of dynamical, mechatronics systems, namely operation ranges, of such systems with nonlinear effects, which are not always near to equilibrium states, as well as a fairly high level of uncertainties of their physical description with...

This article focuses on 3D printing of compound elements, fully connected components or elements, which can be used as instructional aids for students. By means of traditional manufacturing technologies such as machining, forming or molding, the manufacturing cost of such items would be high, and in addition they would be sometimes difficult to fea...

The original Gurson model for porous materials has undergone numerous modifications in order to improve its adequacy with experimental or numerical results. In this chapter various modifications of Gurson’s model and models created on the basis of the idea of Gurson’s model are presented. This chapter includes the following issues: (i) development...

In this paper, a new hybrid evolutionary-gradient algorithm is proposed to solve global numerical problems of topology optimization. The proposed algorithm is developed as a compromise between the direct and gradient-based optimization approaches. A short comparative study of computational results demonstrates the validity of the proposed method, a...

The paper discusses issues related to the damage accumulation and cracking in steels. Special attention is paid to the selection of appropriate methods in the modeling of progressive damage development. In special cases, the damage accumulation and crack propagation may lead to the brutal destruction of machine parts. Hence, some attention is drawn...

The research work has an interdisciplinary character. Some aspects of problems of materials science, fracture mechanics and computer methods have been taken into account. The subject of this work is computer modeling of damage growth and fracture taking place at steel parts of cryogenic tanks, which allows to find out the temperature range of ducti...

In the paper the modified Gurson model is developed for the simulation of damage growth and ductile fracture under low, medium and high stress triaxiality loadings. A new coalescence criterion is introduced based on a simple assumption that singular value of the effective stress triggers the coalescence of microvoids in materials. According to the...

Changes of stress or strain ratios during an operation can have an effect on cracking during metalworking processes. Therefore, there is a substantive interest of the aluminum and steel industries of the manufacturing sectors in numerical simulations of the fracture processes of typical structural materials. In this paper, a calibration procedure o...

The aggregate-objective optimization technique has been used to assess the optimal set of coefficients of the Barlat yield criterion for anisotropic alloy sheets by means of the evolution strategy. The aggregate-objective problem has been quantified by the Euclidean-type objective function. Computational results indicate that standard procedures, b...

The paper discusses a method for numerical simulation of the transition from ductile to brittle cleavage behavior in some steel elements of a liquefied natural gas terminal. To determine an onset of material failure, a coupled mechanistic model is developed for the effect of preceding ductile damage on cleavage fracture. The aim of the research is...

The article discusses a contour element method applied to numerical simulations of crack problems in elastic structures. Because the boundary integral equation degenerates for a body with two crack-surfaces occupying the same location, one of the forms of the displacement discontinuity method is implemented. According to the implemented method, res...

Possibilities for manufacturing cellular metallic materials are reviewed. However, this study primarily concerns the role of a cell-wall structure in influencing the mechanical behavior of metallic foams. A porous low-carbon steel with a controlled porous structure is processed from spark plasma sintering of ferromagnetic metal segments with a spec...

This paper discusses a mesomechanics behavior of the polycrystalline microstructure, where grains are bonded to each other via interfaces along boundaries. For the mesomechanics description the nonlocal constitutive model is applied. According to this model, distance effects at the mesostructure level, by which some amount of energy is interchanged...

In this article, the developed numerical techniques for assessment of deformation and fracture response of ferritic steel during its manufacturing are considered. Because microdefects of ferritic steel are thought to nucleate at second-phase particles, the formulated strategy for evaluating these particles uses standardized experimental fracture te...

The paper presents an application of the non-local regularization to the finite element modelling of ductile damage and tearing. In order to model the damage growth in ductile materials of structural components, integral limiters have been introduced. These integral limiters, which are spatial averaging operators, can prevent the problem of mesh-se...

The design of mechanical systems in modern industrial plants requires reliable and efficient methods to predict the behavior of structural materials. For complex loading conditions, the behavior of the structural materials is determined by damage evolution, strain rate and temperature. The subject of the article is the modeling of the damage evolut...

This contribution presents the development of the boundary element method to provide an efficient and accurate method of analyzing the potential problems. A distinctive feature of a proposed new variant of the boundary element technique is a divergence free property of the boundary integrand. The divergence free property has been applied to solve l...

The present paper further develops the boundary element technique to provide an efficient and accurate method of analysing the crack propagation processes in 2-D linear elastic structures. Based on both the direct boundary integral equations, for source points located on the external boundary of the plane elastic region, and the indirect boundary i...

This paper is an introduction to a boundary element technique which allows discrete modeling of planar fatigue crack propagation. The key features of a mathematical determination for the crack propagation model are discussed. A shifting boundary grid which moves with the crack tip is used. Crack contact problems are considered.