Effect Of Surface Roughness On The Self-organization Behavior Of Multiple Shear Bands In Titanium Alloy Cylindrical Shell

Adiabatic shear band is a common damage form of metal cylindrical shells in high strain rate collapse experiments.The research on its formation mechanism has always been one of the theoretical and practical topics in the field of mechanics and materials science.In this paper,the micro-dynamics of the effect of surface roughness on the self-organization behavior of multiple shear bands of two kinds of titanium alloy cylindrical shells is studied by means of the collapse experiment of thick walled cylinder under explosive loading.The main conclusions are as follows:(1)Surface roughness plays an important role in the self-organization behavior of multiple shear bands in TC4 and TA7 titanium alloy cylindrical shells.The number,length and nucleation rate of shear bands increase with the increase of inner surface roughness;The larger the surface roughness is,the larger the shear band propagation rate is,the more discrete the shear band length difference is,and the more obvious the shear band shielding effect is;With the increase of surface roughness,the phenomenon of shear band bifurcation and convergence gradually presents various forms.(2)The surface roughness has an effect on the distribution of the shear band spacing.The experimental results and model analysis results show that the actual shear band spacing is basically in accordance with the W-O model and M model prediction results.The specific values are affected by the surface roughness of the sample.With the increase of surface roughness,the experimental results are gradually smaller than the predicted values.(3)The effect of surface roughness on the self-organization behavior of multiple shear bands of titanium alloy cylindrical shell is microstructure sensitive.Under the same surface roughness,loading and deformation conditions,the number of shear bands,nucleation rate and propagation rate of TC4 titanium alloy are higher than those of TA7 titanium alloy;The shear band of TC4 titanium alloy cylindrical shell is more prone to phase transformation.In other words,the multiple shear band self-organization behavior of TC4 titanium alloy is more sensitive to surface roughness than TA7 titanium alloy.