EVALUATION OF RESIDUAL STRESS IN A THICK-WALLED TUBE FOR FUNCTIONALLY GRADIENT MATERIAL

本文研究了用离心法制造的功能梯度材料厚壁圆管中的残余应力。以Al/20Vol%碳化硅为母材的Duralcan F3D.20S复合材料为母材。首先通过环压试验验证了考虑性能级配的曲梁理论的有效性。在切割试验的基础上，对残余应力产生的周向应变进行了测量，观测到的应变范围为-750亩~500亩。在此基础上，将残余应力的分布作为反问题进行了分析，并对轴对称的热变形进行了数值分析。当试件均匀冷却时，屈服应力和应变向管外的方向由压缩向拉伸转变，热膨胀系数减小，得出残余应力是由熔点的一半的参考温度冷却到约140K的环境温度所产生的，残余应力随热扩散失配和径向厚度的增加而增大。

A study has been done for examining the residual stress in a thick-walled tube of a functionally gradient material manufactured by a centrifugal method. Duralcan F3D.20S composites that were AL/20vol%SiC were adopted as a master composites. The effectiveness of the curved beam theory considering the gradation of properties was first to eamine by a ring compression test. The circumferential strain generated by residual stress were measured based on the cutting test and the observed strain were in the range of - 750mu strain to 500mu strain. Based on this results, the distribution of residual stress were analyzed as an inverse problem and a numerical analysis was also adopted to solve the thermal deformation of axial symmetry. When the test pieces were cooled uniformly, the yielded stress and strain were changed from compression to tension toward the outside of the tube accompanied with a decrease in a coefficient of thermal expansion., It was concluded that the residual stress were generated by a cooling from a reference temperature of half the melting point to ambient temperature that was about 140K.The residual stress were found to enlarged corresponding to the increase of thermal epansion mismatch and radial thickness.