Failure Strength Tests

Abstract

Failure strength tests are used for quality control, for adhesive properties development, and for design purposes. Typically, manufacturers provide the average single lap joint (SLJ) shear strength and the peel strength. However, these are not intrinsic adhesive properties and are of limited use for design purposes. The prediction of the joint strength based on stress or strain limit criteria needs the adhesive stress–strain curve. In this chapter, the most important tests for the determination of the adhesive mechanical properties are described. Tests for the three basic loading modes – tension, compression, and shear – are discussed, indicating for each case the advantages and disadvantages. Reference is made to the corresponding standards according to the major standards-setting organizations such as the American Society for Testing and Materials (ASTM) and the International Standards Organization (ISO). Within each category (compression, tension, and shear), tests on bulk specimens and those on joints are compared. Recommendations to select the most suitable test are given, and it is shown that a reasonable relationship exists between adhesive properties measured in compression, tension, and shear.