Fracture Mechanics and the Time Dependent Strength of Adhesive Joints

Abstract

The strength of technical joints formed with (soft) polymeric ad hesives is discussed from the detailed viewpoint of fracture mechanics. A new approach to the analysis of technical joints has been attempted by considering the variety of complex modes by which fracture can progress in such joints. Particular attention has been given to separat ing the geometric and loading factors of a joint from strength charac teristics attributable entirely to the properties of the materials in volved. By drawing on the creep or relaxation behavior of the polymer and on the fracture energy of the bond interface, or of the adhesive, the time-dependence of the process is discussed in the absence of a corrosive atmosphere. Finally, analytic reasons and a criterion are given for the possible rate dependence of the failure path location along different interfaces of adherends and the adhesive.