Solids and Structures

This paper contains analysis of the bending beyond the elastic limit of an ideally elastic-plastic beam which contains a through-thickness distribution of high initial stresses. This is relevant to the analysis of service behaviour of components containing high residual stresses, such as might arise from heat treatment followed by quenching, plastic deformation induced by shot-peening, cold rolling, etc. The Timoshenko analysis of plastic bending of a beam is adapted for a particular case of a parabolic residual stress distribution typical of ...

The experiment was carried out to investigate the tip deflections and twists, and stresses of a tube subject to loads to simulate three specific loading cases. The reliability of the analytical analysis adopted was assessed and possible errors identified by comparing experimental and theoretical values for each loading case.
• For the deflections and the twists, the graphs revealed the linear relationships with the load, which can also be deduced from the analytical equations. However, by analysing the calculated data, it was observed that the errors were being induced in steps and this led to the conclusion that the experimental values were being affected by the deflection of the support and by the twist at the weld. This explanation can be confirmed by carrying the same experiment with different sets of loads and expecting a similar pattern in the errors.
• As for the stresses on the tube’s surface, their experimental and analytical values were very close, with percentage errors of less than 2% in most cases. While such results validate the link between analytical and experimental analysis, it has to be underlined that only averaging of the experimental values led to this conclusion. Hence, the use of more strain rosettes could strengthen the conclusion or even reveal errors.

This work aims at understanding the effect of particle–matrix interfacial debonding on the tensile response of syntactic foams. The problem of a single hollow inclusion with spherical-cap cracks embedded in a dissimilar matrix material is studied. Degradation of elastic modulus, cavity formation in the proximity of debonded regions, stress localization phenomena in the inclusion, debonding energetics, and crack kinking are studied for a broad range of inclusion wall thickness and debonding extent. A series solution based on ...

The paper considers rotations at different scales in granular materials: the rotations of individual particles, the rolling and rigid-rotation of particle pairs, the rotational interactions of a particle within its cluster of neighbors, and the rotation of material regions. Numerical, Discrete Element Method (DEM) simulations on two- and three-dimensional (2D and 3D) assemblies show that particle rotations are diverse, that they increase with strain until the material begins to soften, and that they are expressed in spatial patterns, even at small strains. The interactions of a pair of particles are a combination of three modes: a contact deformation mode, a contact rolling mode, and a mode of rigid pair motions. Definitions are presented for each mode, including four different definitions of contact rolling. A rolling curl is also defined, which describes the cumulative rolling of neighboring particles around a central particle or sub-region. At a larger scale, material deformation...

The aim of this paper is to analyze delaminated multilayered plates under classical loads using an alternative model to the existing three-dimensional finite element methods (3D-FEM). The proposed alternative model, named LS1, is a layerwise stress model proving significantly less computationally expensive while accurate and efficient. In particular this paper uses experimental data from different simple test specimens in a finite element code, which is based on LS1, in order to calculate strain energy release rates (SERR) in different modes of delamination. The focus is on two types of delaminated interfaces 0°/0° and 0°/45°. The obtained SERR results are in very good agreement with the experimental values and, in the case of mixed-mode delamination, they are as accurate as the SERR obtained by 3D-FE models. The other interesting property of the LS1 model is the very fast calculation speed as the SERR can be analytically deduced from interfacial stresses. This relation which only d...

This paper is the second part of the research work dedicated to evaluation of mechanical properties of polymer composites reinforced by knitted fabric. Three different approaches were applied for the task. Two of them: a) FEM analysis using Solid Works combined with structural modeling based on experimentally-determined mechanical and geometrical properties of the reinforcement and matrix, and b) direct measurement of mechanical properties (described in Part 1). Present investigation (Part 2) is based on application of vibrational analysis. Modal testing in combination with the mathematical optimization procedure were used for evaluation of elastic properties of a layered material. It is worth mentioning that the application of this approach for materials with high damping ability (laminated composites reinforced by knitted fabric) is still poorly investigated. The inverse technique exploited in this work is based on the direct orthotropic plate free vibration measurements and subse...