In this study,laboratory testing and numerical simulation methods are used to investigate the mechanical behavior and perform fracture prediction of a novel high-strength and high-toughness steel with a negative Poiss...In this study,laboratory testing and numerical simulation methods are used to investigate the mechanical behavior and perform fracture prediction of a novel high-strength and high-toughness steel with a negative Poisson's ratio(NPR)effect under combined tensile-shear loading conditions.A test device capable of meeting different tensile-shear combination test angles is designed and manufactured,wherein the mechanical experiments on the NPR(Negative Poisson's Ratio)steel specimens are carried out at various testing angles.Q235 steel and MG400 steel are used as experimental control groups.The results show that the mechanical deformation of NPR steel is significantly better than that of Q235 steel and MG400 steel.Its tensile-shear test curve has no yield plateau and it has quasi-ideal elastic-plastic mechanical properties.The loading direction gradually changes from tension-dominated to shear-dominated as the tension-shear angle increases,and the strength and deformation of the specimens show a decreasing trend.Based on the laboratory test results,a finite element numerical model of NPR steel is established.A series of numerical simulations are carried out under the conditions of different tension and shear angles and the average stress triaxiality and fracture strain data are obtained.The fracture data of NPR steel are fitted using the Johnson-Cook fracture criterion,and the Johnson-Cook fracture parameters under the tensile-shear test conditions of NPR steel are thus obtained.The numerical simulation verifies that the fracture model can accurately predict the tensile-shear fracture behavior of NPR steel.展开更多
A combined beam model representing the periodicity of the microstructure and micro deformation of 3D woven composites is developed for predicting mechanical properties. The model considers the effects of off axial ten...A combined beam model representing the periodicity of the microstructure and micro deformation of 3D woven composites is developed for predicting mechanical properties. The model considers the effects of off axial tension/compression and bending/shearing couplings as well as the mutual reactions of fiber yarns. The method determining microstructure by using woven parameters is described for a typical 3D woven composite material. An analytical cell, constructed by a minimum periodic section of yarn and interlayer matrix, is adopted. Micro stresses in the cell under in-plane tensile loading are obtained by using the proposed beam model and macro modulus is then obtained by the averaging method. Material tests and a 2D micro FEM analysis are made to evaluate this model. Analyses reveal that micro stress caused by tensile/bending coupling effect is not negligible in the stress analysis.展开更多
The formation and mechanical properties of amorphous copper are studied using molecular dynamics simulation. The simulations of tension and shearing show that more pronounced plasticity is found under shearing, compar...The formation and mechanical properties of amorphous copper are studied using molecular dynamics simulation. The simulations of tension and shearing show that more pronounced plasticity is found under shearing, compared to tension. Apparent strain hardening and strain rate effect are observed. Interestingly, the variations of number density of atoms during deformation indicate free volume creation, especially under higher strain rate. In particular, it is found that shear induced dilatation does appear in the amorphous metal.展开更多
基金supported by the Postdoctoral Fellowship Program of CPSF under Grant Number GZB20240556.
文摘In this study,laboratory testing and numerical simulation methods are used to investigate the mechanical behavior and perform fracture prediction of a novel high-strength and high-toughness steel with a negative Poisson's ratio(NPR)effect under combined tensile-shear loading conditions.A test device capable of meeting different tensile-shear combination test angles is designed and manufactured,wherein the mechanical experiments on the NPR(Negative Poisson's Ratio)steel specimens are carried out at various testing angles.Q235 steel and MG400 steel are used as experimental control groups.The results show that the mechanical deformation of NPR steel is significantly better than that of Q235 steel and MG400 steel.Its tensile-shear test curve has no yield plateau and it has quasi-ideal elastic-plastic mechanical properties.The loading direction gradually changes from tension-dominated to shear-dominated as the tension-shear angle increases,and the strength and deformation of the specimens show a decreasing trend.Based on the laboratory test results,a finite element numerical model of NPR steel is established.A series of numerical simulations are carried out under the conditions of different tension and shear angles and the average stress triaxiality and fracture strain data are obtained.The fracture data of NPR steel are fitted using the Johnson-Cook fracture criterion,and the Johnson-Cook fracture parameters under the tensile-shear test conditions of NPR steel are thus obtained.The numerical simulation verifies that the fracture model can accurately predict the tensile-shear fracture behavior of NPR steel.
文摘A combined beam model representing the periodicity of the microstructure and micro deformation of 3D woven composites is developed for predicting mechanical properties. The model considers the effects of off axial tension/compression and bending/shearing couplings as well as the mutual reactions of fiber yarns. The method determining microstructure by using woven parameters is described for a typical 3D woven composite material. An analytical cell, constructed by a minimum periodic section of yarn and interlayer matrix, is adopted. Micro stresses in the cell under in-plane tensile loading are obtained by using the proposed beam model and macro modulus is then obtained by the averaging method. Material tests and a 2D micro FEM analysis are made to evaluate this model. Analyses reveal that micro stress caused by tensile/bending coupling effect is not negligible in the stress analysis.
基金supported by the National Natural Science Foundation of China (Grant Nos 10528205, 10772012 and 10432050)Chinese Academy of Sciences Innovation Program and KJCX2-YW-M04
文摘The formation and mechanical properties of amorphous copper are studied using molecular dynamics simulation. The simulations of tension and shearing show that more pronounced plasticity is found under shearing, compared to tension. Apparent strain hardening and strain rate effect are observed. Interestingly, the variations of number density of atoms during deformation indicate free volume creation, especially under higher strain rate. In particular, it is found that shear induced dilatation does appear in the amorphous metal.
