Experimental Studies of Coldworked Fastener Holes
Final rept. 1 Mar 1975-31 Dec 1977
MICHIGAN STATE UNIV EAST LANSING DIV OF ENGINEERING RESEARCH
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This report summarizes the accomplishments of this research and catalogs its resulting papers and reports. When an oversized mandrel is pulled through a hole, the material near the hole edge is coldworked. After the mandrel is removed, the elastic restoring forces of material away from the hole generate compressive stresses at the edge. Subsequent tensile loading must overcome the compressive edge stresses, so a considerable improvement in the ultimate or fatigue loading capability of a structure can be achieved. The research was performed in four phases Phase I-Measurement of the residual strains around coldworked holes. Phase II-Measurement of the location of the boundary between the elastic and plastic regions around the hole. Phase III-A study of fatigue crack initiation and growth from coldworked and noncoldworked holes. Phase IV-A study, similar to Phase III, of holes that had existing cracks and were then coldworked.
- Manufacturing and Industrial Engineering and Control of Production Systems