| Résumé : |
Fracture tests were conducted on bulk samples of a rubber-toughened epoxy that models the fracture behavior of commercial structural adhesives. The samples were loaded with a variety of loading histories. The histories were selected to examine the dependency of fracture energy on loading rate, loading level, time under load, and recovery after loading. The results suggest that unless the load levels are a substantial fraction of the failure load, the loading history has little effect, at least for the time scales studied here. When the loads are high, however, the time under load becomes important and produces significant increases in toughness. If the sample is unloaded and allowed to recover, some but all of the additional toughness is lost. These results are consistent with a viscoelastic toughening mechanism and can be qualitatively explained with sample crack-tip blunting model. |
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History lesson in ADHESIVES AGE, Vol. 44, N° 6 (06/2001)
