Material Testing 2.O
At present, material testing is still mostly performed through standards developed for extensometers or strain gauges, using simple geometries with statically determinate stress states. These tests provide a limited amount of information per test and lead to the need for a large number of tests to calibrate a given material model. This is in stark contrast with numerical simulation, which has seen spectacular progress in the last decades. It is therefore essential to develop the next generation of data-rich image-based tests, coined ‘Material Testing 2.0’.
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Technical Note
The Virtual Fields Method (VFM) in dynamics.
We are often asked whether our VFM module can handle ‘dynamics’. Over the years, we have found that there are often misconceptions about the meaning of that word.
Static: this corresponds to a situation where none of the mechanical quantities depend on time. In practice, it means a constant load (gravity, snow on a roof) and no material non linearities (no creep for instance).
Quasi-static: in this case, the mechanical quantities vary in time but there are no inertial effects. This is the case when testing a sample in a tensile machine, for instance, with the load increasing monotonically in time.
Dynamic: this corresponds to a situation where inertial effects (related to material point acceleration) cannot be neglected anymore.
MatchID’s VFM module can encompass high strain rate experiments (impact, VHS machine, Hopkinson bar) provided that accelerations can be neglected. The objective of this technical note is to clarify the matter.
Relevant publications
1. Towards Material Testing 2.0. A review of test design for identification of constitutive parameters from full-field measurements. F. Pierron, M. Grédiac (2020). Strain 57(1),e12370, 2021, https://doi.org/10.1111/str.12370.
2. Material Testing 2.0: A brief review. F. Pierron (2023). Strain, https://onlinelibrary.wiley.com/doi/10.1111/str.12434.