Open-Hole Tensile Behavior and Progressive Damage of Hybrid Fiber Metal Laminates

Abstract

Fiber metal laminates (FMLs) are typical multilayer composites including metallic foils and fiber reinforced polymers. These are considered as the attractive skin materials for lightweight vehicle, especially GLARE laminates for aircraft fuselages. The open-hole tensile behavior and progressive damage of GLARE laminate are studied experimentally and numerically. A combined progressive failure model with strain-based damage evolution laws are imposed on the composite layer based on the subroutine Abaqus-VUMAT. The cohesive zone model and equivalent plastic strain criterion with isotropic hardening is respectively employed to describe the interlaminar and metal layer damage. The effects on the geometry characteristics of open-hole are discussed, exploring the variation of residual strength, damage evolution process and damage affected zone. The two fracture modes and delamination failure are observed, all numerical results show good agreement with experiment obtained. The damage evolution of fiber both gradually vary from “butterfly” to “funnel” pattern for circluar and square open-hole. However, the different evolution emerges for matrix damage. Compared with circular one, the square open-hole can lead to more fiber damage than matrix one. The transition fillet can effectively disperse stress concentration, improving the residual strength of GLARE with square open-hole. The 45° off-axis is the optimal design of square open-hole to fully activate the reinforcement effect of fiber. All suggest the open-hole design is important to guarantee the application security for GLARE plate-like structure.