Papers by Keyword: Compressive Loading

Abstract: The paper proposes an approach to studying the influence of changes in the mechanical characteristics of the material under the influence of plastic deformations in foam materials on changes in their mechanical behaviour. The research was conducted for the case of unsteady multi-cycle loading, which caused plastic deformations, but did not cause material failure. The modelling was carried out in a general unsteady formulation within the framework of Cosserat elasticity, which made it possible to take into account the influence of the heterogeneity of the structure of materials. The proposed methodology is based on the combined use of the method of integral transformations and the indirect boundary element approach. To solve the unsteady problem within the framework of couple elasticity, the time integral and discrete Fourier transform were used in the paper. The assessment of the change in the mechanical, physical and microstructural characteristics of foams under the action of loads causing plastic deformations was carried out on the basis of experimental studies of a series of polyurethane foam samples. Using experimental data based on developed analytical-numerical method [4], the change in the distribution of normalized radial stresses in the internal layers of foam media was investigated, taking into account changes in mechanical, physical, and microstructural characteristics. The use of the approach proposed in the paper makes it possible to assess the change in the residual resource of bodies made of foam materials in the case of short-term loads that cause plastic deformations of the medium.

Abstract: This work presents deformation behaviour of gellan gum and gellan gum - bioactive glass composites as novel hydrophilic materials for production of scaffolds in the field of bone-tissue engineering. According to recent studies such materials are attractive for personalized design of implants thanks to their biocompatibility and wide range of available fabrication methods. Batch of samples was subjected to uni-axial compression loading in a custom designed loading device to obtain their elastic and plastic characteristics. However the testing procedure was challenging because of very low stiffness of the material acquired results show a significant reinforcement effect of bioactive glass and its influence to the elastic modulus.

Abstract: The present paper addresses two issues regarding the influence of compressive loadings for fatigue crack growth. The first issue is the crack tip loading in compression. It will be verified that K_max and R are not suitable to account for compressive loading conditions at the crack tip. The second issue is the investigation of some basic load interaction effects in tension-compression loading. Especially loading conditions that were reported leading to an acceleration of fatigue crack growth were revisited. Numerical simulations of the experiments are used to interpret the results.

Abstract: In this paper, elastic-plastic finite element analysis has been performed in order to obtain the fatigue crack tip parameters under tension-compression loading. Two centre-cracked high-strength aluminum alloy with a crack length of 2mm under different tension-compression loading are analyzed. The analysis shows that the compressive loading has a significant contribution towards the crack tip plasticity and the crack tip stress. In a tension-compression loading the crack tip displacement increases with the increase of the compressive stress and the crack tip compress stress increases with the increase of the compressive stress. The maximum stress intensity Kmax in the tension part of the stress cycle and the maximum compressive stress in the compression part of the stress cycle are the main factors controlling the near crack tip parameters.

Abstract: In this paper, a detailed elastic-plastic finite element analysis of the effect of the compressive loading on crack tip plasticity is studied based on the material’s kinematic hardening model. Five centre-cracked panel specimens with different crack lengths are analyzed. The analysis shows that in a tension-compression loading the maximum spread of the crack tip reverse plastic zone increases with the increase of the compressive stress and the near crack tip opening displacement decreases with the increase of the compressive stress at the same nominal stress intensity factor. The applied compressive stress is the main factor controlling the near crack tip parameters.