Mixed-mode I/II dynamic fracture behavior in PMMA driven by stress waves

摘要

Abstract To investigate the dynamic behavior of mixed-mode I/II cracks under stress wave loading, such as crack initiation and propagation, an experimental system that combines the split Hopkinson pressure bar (SHPB) with digital image correlation (DIC) was established. The dynamic fracture experiments for pure mode I and mixed mode I/II were conducted using the single cleavage drilled compression (SCDC) specimen of polymethyl methacrylate (PMMA) with different impact velocities. The displacement and strain field histories of the crack tip from impact to complete fracture were obtained by the DIC method. Then, the dynamic stress intensity factors (DSIFs) were calculated by least-squares analysis of the crack tip displacement field. Moreover, the extended finite element method (XFEM) was used to simulate the crack propagation, and the crack propagation paths were acquired under pure mode I and mixed-mode I/II loadings, which were basically consistent with the experimental results. Combined with the analysis of energy evolution, the characteristics of fracture and crack propagation of the brittle rock-like materials caused by stress waves were revealed.