内爆炸下管道裂纹渐进式动态扩展机制研究

Study on incremental dynamic crack propagation of pipe subjected to internal explosion

现有研究表明内爆炸下管道裂纹呈现渐进/周期式扩展特征,但具体机制与内在规律尚不明晰。基于耦合损伤演化的热黏塑性本构模型、简化气体爆轰模拟算法以及改进的流固耦合算法,构建了内爆炸下管道裂纹动态扩展分析模型,较好复现了试验中典型裂纹扩展行为与管道断裂形貌。在此基础上,深入探究了管道应力波传播、管道径向振动与裂纹动态扩展间的互作关系,在微秒尺度上解析了裂纹渐进扩展速率与历程。研究阐明了内爆炸下管道裂纹渐进式扩展实际上是管道轴向传播弯曲波与裂纹尖端相互作用的物理机制,给出了裂纹渐进扩展频率的理论计算公式,进而研究揭示了内爆载荷速率与裂纹渐进扩展长度间的内禀定量关系。研究结果增进了对裂纹动态扩展的认识,并可为管道爆炸事故分析中爆炸强度与类型的推演提供新方法。

Current studies have shown the crack propagation of pipe under internal explosion is incremental or cyclic.However,the specific mechanism and law is still unclear.A numerical model for analyzing the dynamic fracture of pipe under internal explosion was established based on the thermo-viscoplastic constitutive model with damage evolution,simplified gaseous detonation modeling and improved fluid-structure coupling,which well reproduces the propagation behaviors of typical cracks and final fracture profiles of pipes in the test.Further,the relation between stress wave propagation,pipe radial vibration and crack dynamic growth was deeply explored.Also,the incremental crack growth rate and process were analyzed on the microsecond scale.The study clarified that the incremental crack growth of pipe under internal explosion is actually the result of the interaction between axially propagating flexural waves and crack tips,gave the theoretical formula for calculating the incremental crack growth frequency,and revealed the intrinsic relation between internal explosion load rate and the incremental crack growth distance.The results can improve the understanding of dynamic crack growth,also can provide a new method for the deduction of explosion strength and type during pipe explosion accident analysis.