Specimen geometry effect on the accuracy of constitutive relations in a superplastic 5083 aluminum alloy
- Pacific Northwest National Lab., Richland, WA (United States)
- Washington State Univ., Pullman, WA (United States)
Current experimental methods are influenced by the end effects that cause non-uniform strain rates in the gauge section and material flow within the grips. A series of tension tests and finite element models confirm this for an Al-5083 alloy. Both the tests and the finite element simulations predict that the actual strain rate begins at about 60 percent of the desired strain rate and increases gradually with strain. Material flow from the grips into the gauge effectively ``slows`` the strain rate at the initial stages of the test. As the test proceeds thinning of the gauge section occurs and most of the strain occurs in the gauge section due to the relative cross-sectional areas of the grip and gauge section. Testing and models were also run comparing specimens with and without alignment holes in the grips. It was shown that alignment holes increase flow from the grips and thus introduce additional error in the tests. Further modeling was performed to evaluate the improved accuracy of specimens with increased length-to-width ratios. This work showed that a specimen with 50% reduction in the standard gauge width and double the standard gauge length (4:1 increase in length-to-width ratio) gave strain rates within 10% of the desired value throughout the test.
- DOE Contract Number:
- AC06-76RL01830
- OSTI ID:
- 233895
- Journal Information:
- Scripta Materialia, Vol. 34, Issue 9; Other Information: PBD: 1 May 1996
- Country of Publication:
- United States
- Language:
- English
Similar Records
On the control of superplastic deformation rate during uniaxial tensile test
Accuracy issues in modeling superplastic metal forming