Bond-end stress fields in brittle and tough adhesive layers
- Sandia National Lab., Albuquerque, NM (United States)
The stress state in the region of an interface corner has been determined for brittle and tough adhesive layers fixed between rigid adherends. The asymptotic, bond end problem is simply that of a quarter plane with one edge fixed and the other edge stress free, and the interface corner is the point where the fixed interface intersects the stress-free edge. Asymptotic analyses have been carried out for a linear elastic ({epsilon}{approximately}{sigma}) layer and for a power-law hardening ({epsilon}{approximately}{sigma}{sup n}) layer. In both cases, a stress singularity of type Kr{sup delta} ({delta}<0) exists at the interface corner. When the layer is elastic, the strength of the singularity {delta} depends only on the layer`s Poisson`s ratio v, and {delta} {approximately} -1/3 for v = 0.35. When the layer is power-law hardening, the strength of the singularity depends only of the hardening exponent n, and {delta} {approximately}-1/7 for n=5. Brittle adhesives can be modeled as linear elastic, while tough adhesives can often be modeled by a stress-strain relation that combines linear and power-law behavior ({epsilon}{approximately}{sigma}+a{sigma}{sup n}). Consequently, the predominate nature of the interface corner stress state in a tough layer can change from that of a linear elastic material to that of a power-law hardening material as the applied load is increased. The relation defining the stress intensity factor K of an idealized butt joint composed of a thin, brittle (linear) adhesive layer fixed between rigid adherends and subjected to a transverse tension loading has been determined. This relation indicates that if failure occurs at a critical K value, joint strength should vary as the reciprocal of the cube root of bond thickness.
- Research Organization:
- Sandia National Laboratory
- DOE Contract Number:
- AC04-94AL85000
- OSTI ID:
- 175305
- Report Number(s):
- CONF-950686--
- Country of Publication:
- United States
- Language:
- English
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