异质双材料界面端部应力奇异性的实验分析

AN EXPERIMENTAL ANALYSIS FOR SINGULAR STAIE NEAR EDGE OF INTERFACE IN BIMAIERIAL

用高灵敏度的云纹干涉实验方法测量了弯曲载荷作用下异质结构的位移场，并采用局部混合法对实验结果进行处理，根据结果对界面端部区域的应力分布规律进行了讨论；求出了应力奇异性阶数λ和应力强度因子Ｋ，并将这一结果与Ｂｏｇｙ￣［１］等人用理论分析的方法所预期的结果和有限元计算结果进行了比较。本文的工作从实验的角度证实了异质双材料结构界面端部区域的应力状态可以用表达式：σ＿（ｉｊ）（ｒ，θ）＝ｋ·ｒ￣（－λ）ｆ＿（ｉｊ）（θ）来描述。

The stress state and its singularity at the edge of the interface in a bondedbimaterial beam is investigated experimentally by moire interferometry and localized bybridmethod.The bimaterial beam is made of CR-39 and epoxy resin, which glued byan epoxyadhesive.The sensitivity of moire interferometry experiment is 0.41 7μm.The localizedhybrid method,which combine the moire inferometry and finite element method,is usedto evaluate the experimental results from displacements to stresses.For comparing theexperimental results,finite element calculation is also made by using ANSYS 5.0 program.From experimental results,it shows that influence of interface edge is large on the stressdistribution in corner region,which causes a very strong stress concentration.The stressesvalues and gradients are very high in the region.In this paper,it is proved that the stress distribution has singular nature.The valueof stress singular power λ,obtained by experilnental results, is 0.42.It very close to thevalue of theoretied orediction by Bogy and value of the finite element calculation.It isconfirmed by experimental results that Bogy’s theoretical analysis method is applicable todetermine the power of stress singularity.The edge stress intensity factor K is obtained from experiment.In small region near the edge of interface,the K values are nearly constant,that is 3.6(MPa·mm￣0.42))。By this work,it has proved the stress state in the region of interface edge can be formulated as the power of stress singularity λ can be calculated by Bogy’s method and the stress intensityfactor K can be determined from experiment.As the facture mechanics,a fracture anddebonding criterion for dissimilar materials structure could be used to predict failure inregion of interface edge.