Abstract
ASTM D1002 is a standard test method used to evaluate the shear strength of adhesives. This method is popular due to the simplicity of the test, ease to replicate, and the consistency of the testing results. However, this test is also the most criticized one, as the results can be too misleading to be used as design criteria.
Due to the material elastic mismatch and the eccentricity of the test setup, a mixed mode loading is introduced to the adhesive joint. This paper presents a detailed study on the behavior of the adhesive joint under the shear loading, tested by the ASTM D1002 method. The conventional fracture mechanics theory is utilized.
A crack embedded in the adhesive joint specimens, including both the single thickness and the double thickness, are used for the analysis. The specimen is loaded on a tensile test machine until failure, and the load and displacement are recorded for each specimen. The result from the experiment is used as the data for the stress and fracture mechanics analysis.
From the experimental results, it is seen that the specimen also experiences out-of-plane tensile stress. There is an indication that the final failure might be due to cleavage loading, for the double thickness. The eccentricity of the loading path cannot be eliminated completely. The results of the experiment and the effect of the mixed mode loading are studied in detail.
This paper provides a better understanding of the behavior of adhesives under a mixed-mode fracture. This knowledge is beneficial to understand and design reliable adhesive bond joints.
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