A unified phase field solution to fracture analyses on (pseudo) elastoplastic solids and structures

Despite that phase field to brittle fracture has been extensively studied and extension towards solving ductile fracture has been reported, crack evolution in pseudo elastoplastic solids is still an on-going research area. Taking engineered cementitious composites (ECC) as example, it is featured with pseudo ductility, by developing multiple fine cracks to withstand excessive deformation, causing significant numerical difficulties. In this regard, pseudo plasticity is introduced into phase field method to form a novel approach, guided by degrading fracture toughness, to ductile failure analyses. Moreover, a yield surface decay model is proposed to consider the progressive loss of strain-bearing capacity in pseudo elastoplastic solids under damage accumulation by multi-cracking development. Based on the proposed model, a unified solution is achieved for fracture analyses on both conventional and pseudo elastoplastic solids. The model robustness is first verified by a numerical benchmark and an in-situ experiment on metallic materials under quasi-static regime, before applying to study the fracture mechanics of bulk ECCs under both direct tension and flexure. The proposed method is presented with an open-source implementation in COMSOL Multiphysics, and is demonstrated to be capable of assisting future analyses and designs on (pseudo) elastoplastic solids and structures.