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Abstract The automotive industry relies heavily on sheet metal forming processes for many components. Material data solely from uniaxial testing is insufficient to fully define the material behavior of the complex plastic deformation during numerical simulations of the forming processes. In-plane biaxial testing using a cruciform type specimen is a more comprehensive representation than the traditional uniaxial testing alone. Wide ranging biaxial stress states can be imposed by applying different loading conditions on each cruciform axis. However, this can create a challenge to achieve desired deformation paths due to the non-linear relationship between the control parameter, e.g., displacement, and the output of interest, e.g., strain path. In this paper, an interpolation method to develop the displacement control that produces a linear strain path with a desired strain ratio is revisited and expanded upon from the authors’ previous work [1,2]. In the first iteration, linear biaxial displacements were applied to the specimen and the corresponding strain paths were obtained from the numerical simulations. The non-linear strain paths, due to geometry effects of the specimen, were used to reverse engineer a new displacement path that results in a linear strain path. Interpolation is revisited to show increased success with a second iteration. Analysis of the simulation results shows that linear strain paths of a given model can be determined and improved by successive iterations of interpolating the strain data from adjacent deformation paths.
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Experimental Implementation of SS 316L Cruciform Testing to Achieve Various Deformation Paths
By following varying deformation paths, e.g., a linear path to equibiaxial loading versus a bilinear path of uniaxial loading followed by biaxial loading, the same final strain state can be achieved. However, the stress state that the material is subjected to is considerably different due to the varying deformation. This is of interest in a growing field of stress superposition to improve formability and manipulate final part properties in metal forming applications. One potential application is forming patient-specific, trauma fixation hardware with differing strength and weight reduction requirements in various regions. In this paper, experiments were performed on a custom fabricated cruciform machine with the goal of subjecting stainless steel 316L to various deformation paths. A novel cruciform specimen geometry was designed in collaboration with the US National Institute of Standards and Technology to achieve large strain values in the gauge region. Digital Image Correlation was utilized to measure surface strain fields in real time.
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- Award ID(s):
- 1757371
- PAR ID:
- 10277184
- Editor(s):
- Daehn G., Cao J.
- Date Published:
- Journal Name:
- Forming the Future. The Minerals, Metals & Materials Series
- Page Range / eLocation ID:
- 1981-1990
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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- Free Publicly Accessible Full Text
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Accepted Manuscript1.0
- Conference Paper:
- https://doi.org/10.1007/978-3-030-75381-8_166
