| Affiliation: | (1) Biomedical Engineering Department, University of Wisconsin-Madison, Madison, WI 53706-1627, U.S.A.;(2) Materials Science Program, University of Wisconsin-Madison, Madison, WI 53706-1627, U.S.A.;(3) Division of Orthopedic Surgery, University of Wisconsin-Madison, Madison, WI 53792-3228, U.S.A.;(4) Department of Engineering Physics, Engineering Mechanics Program, University of Wisconsin-Madison, Madison, WI 53792-3228, U.S.A.;(5) Rheology Research Center, University of Wisconsin-Madison, Madison, WI 53706-1627, U.S.A. |
| Abstract: | Die-cast aluminum alloys are heavily used in small engines, where they are subjected to long-term stresses at elevated temperatures. The resulting time-dependent material responses can result in inefficient engine operation and failure. A method to analytically determine the stress relaxation response directly from creep tests and to accurately interpolate between experimental time-history curves would be of great value. Constant strain, stress relaxation tests and constant load, creep tests were conducted on aluminum die-casting alloys: B-390, eutectic Al–Si and a 17% Si–Al alloy. A nonlinear superposition integral was used to (i) interpolate between empirical primary inelastic creep-strain and stress-relaxation time histories and (ii) to determine the stress relaxation response from corresponding creep data. Using isochronal stress-strain curves, prediction of the creep response at an intermediate stress level from empirical creep curves at higher and lower stresses resulted in a correlation (R) of 0.98. Similarly for relaxation, correlations of 0.98 were obtained for the prediction of an intermediate strain level curve from higher and lower empirical relaxation curves. The theoretical prediction of stress relaxation from empirical creep curves fell within 10% of experimental data.This paper has not been submitted elsewhere in identical or similar form, nor will it be during the first three months after its submission to Mechanics of Time-Dependent Materials |
