Virtual Experiments

Tensile Testing

A tensile test is a common test used for mechanical characterisation of materials. A sample of a carefully controlled geometry is gripped from two ends and put under tension. The load can be applied as a controlled force whilst measuring the displacement or as a controlled displacement whilst measuring the required load. This provides information about mechanical properties such as Young’s modulus, Poisson’s ratio, yield strength, and strain-hardening.

This methodology is so widely used that there exist many international testing standards for various materials and applications. Our initial implementation of this physical experiment as a virtual test is focused on emulating the standard BS EN ISO 6892-1:2016 for testing of metallic materials at room temperature and specifically for ‘dog-bone’ shaped samples. The parameterised nature of VirtualLab facilitates using our implementation as a template for tensile testing according to other standards or a custom test setup.

To accompany the virtual offering of the platform, the research group have also undertaken a physical experimental campaign with a batch of samples with varying parameters for direct comparison of the experimental and simulation results. This data will be made publicly available in due course.

Fig. 1 (left) ‘Dog bone’ shaped sample designed according to BS EN ISO 6892-1:2016; (right) sample loaded into testing apparatus with strain measured by a gauge and digital image correlation.

Fig. 2 (left) Photograph of batch of samples manufactured with varying parameters to test physically and compare directly with their virtual counterparts; (right) experimental results from digital image correlation measurements.

Fig. 3 Direct comparison of test results from the physical (left) and virtual (right) labs.

Laser Flash Analysis

Similarly, Laser flash analysis (LFA) is a commonly used test for thermal characterisation of materials. A disc shaped sample has a short laser pulse incident on one surface, whilst the temperature change is tracked with respect to time on the opposing surface. This is used to measure thermal diffusivity, which is used to calculate thermal conductivity.

We based our implementation on the testing standards ASTM E1461 / ASTM E2585 for the determination of the thermal diffusivity of primarily homogeneous isotropic solid materials. Other standards can be modelled by varying the parameters of our template.

Fig. 4 (left) Schematic of LFA experimental setup; (centre) photograph of LFA apparatus from a physical laboratory; (top-right) batch of LFA samples; (bottom-right) results from a parameterised virtual LFA experiment.

HIVE

Heat by Induction to Verify Extremes (HIVE) is an experimental facility at the UK Atomic Energy Authority’s (UKAEA) Culham site. It is used to expose plasma-facing components to the high thermal loads they will be subjected to in a fusion energy device. In this experiment, samples are thermally loaded on one surface by induction heating whilst being actively cooled with pressurised water. Further information about this custom experiment can be found in this scientific publication.

Fig. 5 (left) Photograph of sample mounted under induction coil within HIVE; (right) photograph of sample heated during a physical test.

Fig. 6 (left) Schematic of sample manufactured for parameterised physical and virtual testing within HIVE; (right) photograph of a batch of manufactured HIVE samples.

Fig. 7 (top-left & top-right) virtual testing results for temperature and stress respectively; (bottom) physical testing results for temperature measured by an infra-red camera.