QUASI-FRAGILE MATERIAL RUPTURE IN STATIC LOADING AND IN FATIGUE CONSIDERING SCALE CHANGES

Evandro E Pandia Cayro¹; Eduardo Bittencourt¹

¹ UFRGS

doi:10.20906/CPS/CILAMCE2017-0430

Resumo

In this work, the crack growth in static and cyclic (fatigue) loading is studied. The cohesive zone of the crack is modeled by cohesive interfaces, where a damage is introduced when certain conditions of the cyclic loading is fulfilled. Unloading of the cohesive relation occurs at the origin. The material under analysis is quasi-fragile. Such materials present strong non-statistic scale effects, i. e., the ultimate stress changes if specimen scale changes. In very small scales, these materials no longer fail by crack propagation and fail by uniform decohesion. For very large dimensions, on the other side, such materials follow the rules of the Linear Elastic Fracture Mechanics and the rupture by fatigue occurs under the Paris law. In an intermediate scale both static and cyclic ruptures are a direct function of specimen size. The present model is able to capture the transition between the three different scales described above statically as much as cyclically.

Palavras-chave: Fracture; Fatigue; Quasi-fragil material; Cohesive model