Failure Initiation and Crack Growth in Thick Adhesive Bonded Composite Joints: Computational Mechanics Modeling and Analysis

摘要

A computational mechanics study is conducted on crack initiation, growth andinstability in thick adhesive bonded composite joints. An associated experimentalprogram was previously reported on unique features of failure modes and strengthcharacteristics in thick adhesive bonded joints of glass fabric/vinyl ester composite.Complementary computational mechanics modeling and analysis of the thickadhesive bonded composite joint are conducted in this study to advance further ourunderstanding of the subject. Composite joints of similar geometry but with thinadhesive bonds are also examined and results are compared to elucidate the natureof failure mechanics in the thick adhesive-bonded joints. The computational studyis formulated with composite laminate mechanics, nonlinear fracture mechanics andadvanced finite element methods. The following issues on failure of thick adhesivebonded composite joints are addressed: (1) crack formation and mechanisms, (2)crack growth, its driving force and failure modes, and (3) the effect of adhesivebond thickness. Local material strength criteria are used to identify crack initiationin the joint. Driving force for crack growth in the nonlinear adhesive of the bondedcomposite joint is evaluated by energy release rates associated with the crack. Theadhesive bond thickness is found to govern crack formation and subsequent growthin the joint failure. Comparison of numerical results with experimental observationsand test data are made to assess the validity of the computational mechanicsapproach and to better understand the complex nature of thick-adhesive bondedcomposite joint failure.