Influence of Stress Relaxation in Hybrid Composite/Metal Bolted Connections
Project rept. for 1 Apr 2002-15 Jan 2005
MAINE UNIV ORONOCO OFFICE OF RESEARCH AND SPONSORED PROGRAMS
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An experimental investigation of the influence of stress relaxation on watertight integrity of hybrid composite-to-metal bolted connections is presented. This study focuses on the effects of bolt reloading, use of tapered-head bolts versus protruding-head bolts, and briefly addresses environmental effects. All tests were conducted for a time period of at least three months, in order to estimate primary and secondary stress relaxation effects. The reloading tests show that some of the preload in the connections can be maintained with periodic retightening of the bolts. In a limited amount of testing it was observed that temperature shifts caused more rapid stress relaxation rates. Little difference in relaxation was observed when comparing tapered-head bolts with protruding-head bolts, given that roughly equal stress relaxation rates were observed. Further research on this area is required.
- Couplers, Fasteners and Joints