Study On Dynamic Caustics Experiment Of Blast-induced Crack Propagation In Material Containing Flaws

The model experiment was carried out by dynamic caustics test system. The stress wave propagation and crack expand mechanism in material containing flaws were studied under blast loading; the coalescence mechanism of multi-joints was investigated; the dynamic behavior of artificially flawed strips was researched; the direction and the critical condition of the crack initiation were analysed by uniting Det.-Criterion with caustics. The results show that (1) the crack propagation laws are different in different flawed media; the direction and position of flaws play a main role in crack advance process; the closed joints and filled joints are relatively conduce to crack running; dynamic energy release rate drives crack extension; (2) the coalescence mode of multi-joints are most mixed breakage subject to blast loading; slant joints sets help to joint flaw coalescence and are propitious to the effect of direction fracture controlling blasting; (3) the tensile stress filed at the tip of oblique edge-crack and slant notch in strips is the main cause initiating and running of crack and notch; (4) uniting Det.-Criterion with caustics is an effective method expressing crack initiation and propagation and has wide-ranging use in the study of dynamic fracture mechanics.