Effects of thermal residual stresses on failure of co-cured lap joints with steel and carbon fiber–epoxy composite adherends under static and fatigue tensile loads

• Published in: Composites. Part A, Applied science and manufacturing Vol. 37; no. 3; pp. 476 - 487
• Main Authors: Shin, Kum Cheol, Lee, Jung Ju
• Format: Journal Article
• Language: English
• Published: Oxford Elsevier Ltd 01.01.2006; Elsevier
• Subjects: Adhesive bonding; Application fields; Applied sciences; Co-cured joint; Exact sciences and technology; Joining, thermal cutting: metallurgical aspects; Metals. Metallurgy; Polymer industry, paints, wood; Stacking sequence; Static and fatigue tensile loads; Surface roughness; Technology of polymers; Thermal residual stresses; Thermal residual stresses; Surface roughness; Co-cured joint; Stacking sequence; Static and fatigue tensile loads; Thermal stress; Laminate; Fiber reinforced material; Roughness; Epoxy resin; Adhesive bonding; Mineral fiber; Property processing relationship; Modeling; Composite material; Finite element method; Metal fiber; Curing(plastics); Fatigue strength; Adhesive joint; Surface properties; Adhesive; Delamination; Carbon fiber; Lap joint; Mechanical properties; Tensile property; Steel; Fracture criterion; Experimental study; Residual stress
• ISSN: 1359-835X; 1878-5840
• DOI: 10.1016/j.compositesa.2005.03.031

A co-cured joint, which uses excess resin extracted from the composite material (or the polymer material) as the adhesive, has several advantages compared with the adhesively bonded joint. It has no need of the surface treatment of the composite adherend and any adhesive for bonding. In addition, its manufacturing process is very simple because the bonding process is achieved during the curing process of the composite adherend. Thermal residual stresses are important in analyzing failure of the co-cured joint because composite materials are different from metal alloys in thermal and mechanical properties. In general, effects of the thermal residual stresses on failure of the adhesive joint are analyzed through experimental and analytical results. Therefore in this paper, two design parameters, namely the surface roughness of the steel adherend and the stacking sequence of the composite adherend, are considered for static and fatigue tensile tests of the co-cured single and double lap joints. Stress distribution at the interface between the two adherends is used to analyze failure of the co-cured lap joints through the finite element method. Based on the stress distribution, two failure criteria, namely the three-dimensional Tsai–Wu failure criterion and the Ye-delamination failure criterion, are considered to predict the tensile load bearing capacity of the co-cured lap joints. Finally, effects of thermal residual stresses on failure of the co-cured single and double lap joints with the steel and composite adherends under static and fatigue tensile load conditions are presented through comparing the experimental and analytical results.