Component parts assembly with joints. Adhesive-mechanical Part 4. Analysis and test of bonded and wellbonded lap joints

Abstract

In Block 20, If different from Report) 18. SUPPLEMENTARY NOTES 19. KEY WORDS (Continue on reverse side if necessary and Identify by block number) Adhesive-bonded joints; bonded joints; cyclic loading; debond analysis; double-lap-joint analysis; fatigue tests; finite element analysis; joints; nonlinear analysis; single-lap-joint analysis; single-lap-joint bending; spotwelded joints; weldbonded joints. 20. ABSTRACT ("Cotrtfotie on rvvers* sftto If n*ce^aaiy aad Identify by block number) Finite element computer techniques were used to study the linear and nonlinear structural response of bonded and weldbonded lap joints. Although the techniques used are applicable to either single-lap or doublelap joints, the emphasis was on the single-lap joint problem with the attendant complication of joint bending. Nonlinear algorithms were developed to account for nonlinear stress-strain characteristics of the adhesive, and the joined metal .^heet, weld-heat softening of the metal sheet, progressive debonding of the DO , j^^Ta 1473 EDfTlOM OF » MOV 65 IS OBSOLETE Unclassified SECURITY CLASSIFICATtON OF THIS PAGE (When Data Entered) Unrlassif led SECURITY CLASSIFICATION OF THIS PAGECl*TiBn Data Entered) 20. Abstract (continued) adhesive, and nonlinear cyclic loading. The nonlinear modes of response were simulated by sequences of linear solutions. Eight different single-lap joint configurations, designed so as to constitute an experimental parameter study, were studied in a laboratory testing program. Representative specimens were subjected to quasi-static tensile strength and cyclic-load tests and to tensile fatigue tests. The quasi-static and fatigue data generally plot into clear S-N patterns that are in a reasonable relationship to the lap joint design parameters. For the most part, strains measured on the surfaces of the test specimens were in reasonably good agreement with those computed by finite element analysis, provided out-ofplane bending effects were accounted for. The dominant failure modes were consistent with the computer analyses. Unclassified SECURITY CLASSIFICATION OF THIS P ACECWhen Data Entered)