HTPB推进剂复合型裂纹尖端变形场测量及破坏模式分析

Deformation Field Measurement and Failure Mode Analysis of Mixed Mode Crack Tip of HTPB Propellant

为了实现端羟基聚丁二烯(HTPB)推进剂复合型裂纹尖端变形场测量及破坏模式分析,制作了含中心贯穿复合型裂纹的HTPB推进剂试件,进行了动态拉伸观察试验,获得了复合型裂纹的扩展特性,并通过数字图像相关方法(DIC)得到试件表面及裂纹尖端的应变场,对复合型裂纹尖端应变场特点及应变场与裂纹扩展规律的关系进行了研究。结果表明,复合型裂纹试件的拉伸过程可以分为线性段、非线性段和失效段三个阶段,裂纹沿与载荷垂直的方向扩展;数字图像相关方法采用大变形分析方法能有效解决试件大变形的问题,可以定量给出试件表面的应变场,且应变集中区域与理论结果吻合;复合型裂纹的扩展与应变场的变化密切相关,应变场在裂纹尖端产生应变集中,导致裂纹扩展。

To realize the deformation field measurement of mixed mode crack tip and failure mode analysis of hydroxyl‐terminated polybutadiene(HTPB)propellant,HTPB propellant specimens with central through‐mixed mode cracks were made.Tensile observation test was carried out.The propagation characteristics of the mixed mode crack were obtained.Digital image correlation(DIC)method was used to obtain the strain field on the surface of the specimen and the crack tip.The characteristics of the strain field near the mixed mode crack tip and the relationship between the strain field and the crack propagation law were studied.The results show that the tensile process of mixed mode crack specimens can be divided into three stages:linear segment,nonlinear segment and failure segment,and the crack propagates in the direction perpendicular to the load.The digital image correlation method using large deformation analysis method can effectively solve the problem of large deformation of the specimen,and can quantitatively give the strain field on the surface of the specimen and the strain concentration area is consistent with the theoretical results.The expansion of mixed mode cracks is closely related to the change of the strain field.The strain field generates strain concentration at the crack tip,leading in crack propagation.