The thermal residual stresses and the stress distributions of short fiber reinforced metal matrix composite under tensile and compressive loadings were studied using large strain axisymmetric elasto plastic finite ele...The thermal residual stresses and the stress distributions of short fiber reinforced metal matrix composite under tensile and compressive loadings were studied using large strain axisymmetric elasto plastic finite element method. It is demonstrated that the thermal residual stresses can result in asymmetrical stress distributions and matrix plasticity. The thermal residual stresses decrease the stress transfer in tension and enhance the stress transfer in compression. The fiber volume fraction has more important effects on the thermal residual stresses and the stress distributions under tensile and compressive loadings than the fiber aspect ratio and the fiber end distance. [展开更多
Deposition patterns can significantly affect residual stress distribution in additive manufacturing processes.In this paper,a novel pattern,the S-pattern,is proposed for the metal additive manufacturing process.The fi...Deposition patterns can significantly affect residual stress distribution in additive manufacturing processes.In this paper,a novel pattern,the S-pattern,is proposed for the metal additive manufacturing process.The finite element method is used to study the temperature field and the stress field of a cuboid structure under the S-pattern and five other representative patterns:zig-zag,raster,alternate-line,in-out spiral,and out-in spiral.The results show that the S-pattern achieves the lowest values of both equivalent residual stress and maximum principal residual stress,and the warpage of the S-pattern is close to that of counterparts.By analyzing the temperature and stress fields under all patterns,it is found that the residual stress distribution is determined by the uniformity of temperature distribution which is correlated with the peak temperatures of corners.The equivalent residual stress and the maximum principal residual stress are inversely correlated with the average peak temperature and the minimum peak temperature of corners,respectively.These correlations between temperature and residual stress provide an effective approach to evaluate the residual stress of different patterns and guide the deposition process in practice.展开更多
For researching the residual stress distribution characteristics of the different large thickness titanium alloy joints by electron beam welding,under heat treatment or non-heat treatment conditions,the changes in res...For researching the residual stress distribution characteristics of the different large thickness titanium alloy joints by electron beam welding,under heat treatment or non-heat treatment conditions,the changes in residual stress distribution characteristics of electron beam welding joints,which thickness is 50 mm,were measured using blind-hole method with local layer-by-layer removal.Effect of post-welding heat treatment on the residual stress distribution also studied.The results show that blind-hole method with local layer-by-layer removal is suitable to measure residual stresses in thick plate,and good to reflect the welded residual stress distribution of large gradient.Residual stress of the test samples in the weld and heat affected zone has high stress level,and internal stress dramatic changes with thickness in this areas.After heat treatment,the samples' stress distributions were significantly reduced.The samples' transverse and longitudinal residual stress are basically the same.Homogenization is obvious.展开更多
文摘The thermal residual stresses and the stress distributions of short fiber reinforced metal matrix composite under tensile and compressive loadings were studied using large strain axisymmetric elasto plastic finite element method. It is demonstrated that the thermal residual stresses can result in asymmetrical stress distributions and matrix plasticity. The thermal residual stresses decrease the stress transfer in tension and enhance the stress transfer in compression. The fiber volume fraction has more important effects on the thermal residual stresses and the stress distributions under tensile and compressive loadings than the fiber aspect ratio and the fiber end distance. [
基金funded by the Chinese Scholarship Council and the Research Council of Norway through the Petromaks2 program(Project No.281927)the BIA Program(Project No.269558)。
文摘Deposition patterns can significantly affect residual stress distribution in additive manufacturing processes.In this paper,a novel pattern,the S-pattern,is proposed for the metal additive manufacturing process.The finite element method is used to study the temperature field and the stress field of a cuboid structure under the S-pattern and five other representative patterns:zig-zag,raster,alternate-line,in-out spiral,and out-in spiral.The results show that the S-pattern achieves the lowest values of both equivalent residual stress and maximum principal residual stress,and the warpage of the S-pattern is close to that of counterparts.By analyzing the temperature and stress fields under all patterns,it is found that the residual stress distribution is determined by the uniformity of temperature distribution which is correlated with the peak temperatures of corners.The equivalent residual stress and the maximum principal residual stress are inversely correlated with the average peak temperature and the minimum peak temperature of corners,respectively.These correlations between temperature and residual stress provide an effective approach to evaluate the residual stress of different patterns and guide the deposition process in practice.
文摘For researching the residual stress distribution characteristics of the different large thickness titanium alloy joints by electron beam welding,under heat treatment or non-heat treatment conditions,the changes in residual stress distribution characteristics of electron beam welding joints,which thickness is 50 mm,were measured using blind-hole method with local layer-by-layer removal.Effect of post-welding heat treatment on the residual stress distribution also studied.The results show that blind-hole method with local layer-by-layer removal is suitable to measure residual stresses in thick plate,and good to reflect the welded residual stress distribution of large gradient.Residual stress of the test samples in the weld and heat affected zone has high stress level,and internal stress dramatic changes with thickness in this areas.After heat treatment,the samples' stress distributions were significantly reduced.The samples' transverse and longitudinal residual stress are basically the same.Homogenization is obvious.
