Study on multiple surface crack growth and coalescence behaviors

Abstract

Interaction of multiple surface cracks is studied by experimental and numerical methods. For experiment, a new method to introduce two surface cracks with different sizes is developed. Using this technique, four point bending fatigue tests including coalescence process of two surface cracks are conducted by changing crack sizes of two cracks. Crack growing process is studied by introducing beach marks. Change of crack shapes and coalescence behaviors are observed clearly. Locations of crack coalescence change due to the change of crack sizes. Same problem is simulated by using S-FEM. Two models are simulated. One is Crack coalescence model, and another is Virtual single rack model. Virtual single crack model is based on the proximity rule of JSME maintenance code. Results of both models are compared with those of experiment. Results show the availability of numerical methods to predict coalescence process of two surface cracked specimens. It is also shown that JSME code is useful to simulate coalescence problem.