New DIC-Based Material Test Standards: Design and Validation
Within the past ten years, the availability of digital imaging hardware and powerful image processing algorithms has led to the wide diffusion of strain mapping techniques like Digital Image Correlation (DIC). This has open up a new age for the testing of materials where old nominally-uniform or simple stress field configurations can be replaced by more complex ones leading to heterogeneous states of stress and strain. In this case however, the problem is not statically determinate anymore and inverse identification needs to be employed to extract the parameters from the strain maps. Within the last 10 years, the Virtual Fields Method (VFM) has emerged to become the most promising tool for material identification thanks to its spectacular computational efficiency compared to traditional finite element model updating (FEMU). A recent independent study has quoted that the VFM was 125 time faster than FEMU for a hyperelastic model.
This project is part of a strategic partnership between the University of Southampton and MatchID NV. The Virtual Fields Method championed by Prof. Pierron over the last 20 years is now implemented in MatchID and the integrated DIC/VFM tool is now ready for industrial transfer. However, there is a need for the design of novel test configurations that will strongly benefit from the new paradigm as current tests are generally adapted from existing configurations and not optimal. Recently, Prof. Pierron’s research group has set up a procedure based on synthetic image deformation to simulate the complete identification chain from imaging to VFM, so that uncertainties can be propagated through the complex chain and realistic error bounds produced.
This PhD will take this one step further and look at two problems of material identification: anisotropic elasticity (composites) and either anisotropic plasticity (sheet metal forming) or hyperelasticity (rubber sheets). The design space will be explored using finite element simulations coupled to the identification simulator and promising configurations will be tested extensively to produce robust error bounds. This is an essential step before running inter-laboratory round-robin tests to prove the robustness of the new paradigm and convince industry to take on these new tests. The PhD project is therefore both numerical and experimental.
The ideal candidate for this project will have a bachelor or master degree in mechanical, materials or civil engineering and have studied fracture mechanics at undergraduate level. Prior experience with finite element simulations is desirable but not essential.
If you wish to discuss any details of the project informally, please contact Prof. Fabrice Pierron Engineering Materials research group, Email: [Email Address Removed], Tel: +44 (0) 2380 59 2891.
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