Thesis
Finite element analysis of adhesively bonded wide area lap shear joints
Washington State University
Master of Science (MS), Washington State University
08/2014
DOI:
https://doi.org/10.7273/000004301
Handle:
https://hdl.handle.net/2376/125218
Abstract
Investigation of failure criteria for the adhesive joints has been the focus of the research community for decades. The lap shear joint is the most widely used configuration in industrial applications. Adhesive failure has been addressed by different research groups with the use of various failure criteria, depending on their analysis approach. No universally accepted failure criterion has been established yet to predict the exact failure strength of the adhesive joints. In this study, finite element analysis (FEA) was incorporated to investigate different limit failure criteria to predict the bond strength of the wide area lap shear (WALS) joints. Aluminum adherends were bonded with two types of adhesives, i.e. a ductile and a brittle adhesive. Tensile adhesive material properties were required to define the input material model for the adhesive in the FEA of the WALS models. However, only adhesive shear material properties were available from the experiment. Therefore, FEA of the thick adherend lap shear specimen was carried out along with a back substitution-iteration approach to extract the tensile adhesive material properties from the available experimental shear stress-strain response. Stress and strain based various limit criteria were analyzed to compare the FEA results with the experimental observations. Peak values of plastic shear strain, plastic peel strain, maximum plastic shear strain, shear stress, peel stress and maximum shear stress were studied to determine a failure criterion for predicting the joint strength. Shear stress and shear strain based criteria were in fair agreement with experiment in predicting an optimal bondline thickness. However, shear strain was preferred to shear stress, since shear stress was less sensitive to the failure load in the adhesive material model. Peak plastic shear strain was ascertained to be a reasonable failure criterion for this study. With the use of the peak plastic shear strain criterion, an optimal bondline thickness was noticed to occur in the range of 0.003 - 0.005 inch for the ductile adhesive. The range of the optimal thickness for the brittle adhesive was 0.006 - 0.009 inch. The joint strength of the WALS specimens was shown to decrease with an increase in bondline thickness. The gage sections of the lap shear joints were tailored to study the effect of thickness variation along the overlap length on joint strength. Three different geometrical configurations, i.e. concave, convex and tapered, were considered for the tailored profiles. Finite element analysis showed better agreement with the experimental observations for the ductile adhesive than that for the brittle adhesive. For the brittle adhesive, FEA results were more sensitive to the uniform bondline thicknesses and the tailored profiles than the experimental trend.
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Details
- Title
- Finite element analysis of adhesively bonded wide area lap shear joints
- Creators
- Preetam Chandan Mohapatra
- Contributors
- Lloyd V Smith (Advisor) - Washington State University, Mechanical and Materials Engineering, School of
- Awarding Institution
- Washington State University
- Academic Unit
- Mechanical and Materials Engineering, School of
- Theses and Dissertations
- Master of Science (MS), Washington State University
- Publisher
- Washington State University
- Identifiers
- 99900896400101842
- Language
- English
- Resource Type
- Thesis