边界效应模型在复合材料断裂损伤预测中的应用OA

With the widespread application of carbon fiber,glass fiber,and natural fiber-reinforced composites in aerospace,civil engineering,and high-end equipment manufacturing,fracture and failure issues induced by surface defects have received increasing attention.These composites typically exhibit quasi-brittle fracture characteristics,with crack propagation behavior influenced by material heterogeneity,anisotropy,and size effects.In engineering practice,the fracture performance of large-scale components is often evaluated based on small-scale specimen tests;however,conventional fracture mechanics methods cannot effectively eliminate the influence of size effects on fracture parameter identification,thereby limiting the applicability of experimental results to engineering structures.Therefore,developing a theoretical model capable of stably predicting intrinsic fracture parameters from small-scale specimens holds significant engineering relevance. The boundary effect model provides an effective theoretical framework to address the size effect problem in quasi-brittle material fracture.The model posits that the essence of size effects originates from the interaction between the fracture process zone at the crack tip and the specimen boundary conditions,and it quantitatively characterizes this effect by introducing the equivalent crack ae.Building on this concept,the boundary effect model further incorporates the characteristic composite unit Cch,introducing material microstructural features into the fracture analysis.This approach allows a unified description of crack propagation behavior and actual failure modes while reducing computational complexity.Within this framework,the fracture behavior of composites can be classified into three regimes:strength-controlled,toughness-controlled,and transitional ones.This classification facilitates the elucidation of the intrinsic relationship between crack propagation mechanisms and the governing fracture parameters. Based on the boundary effect model framework,this review systematically summarizes its application progress in the fracture analysis of quasi-brittle composites,including carbon fiber,glass fiber,bamboo fiber,and ceramic-reinforced materials.The focus is placed on its application to predicting crack propagation behavior,ultimate load capacity,and damage modes.Relevant studies indicate that the model can stably identify intrinsic tensile strength ft and fracture toughness KIC using small-scale three-point bending test data,effectively mitigating the influence of size effects on fracture parameter determination and significantly improving prediction accuracy.By introducing the characteristic composite unit Cch,the boundary effect model demonstrates good applicability and engineering potential for quantitatively describing fracture behavior in multiphase composites,providing important theoretical support for the safe design,damage assessment,and reliability evaluation of composite structures.