Multiaxial miniature testing system developed to measure materials at small-length scales

Advancing micro- and nano-size components for everything from computing to jet engine manufacturing requires noncontact testing methods for accurately analyzing material deformation and failure mechanisms at small-length scales subjected to high temperatures.

However, major challenges include applying a uniform thermal load and measuring deformation at small-length scales during high-temperature testing. Rahman et al. address these issues in a multiaxial miniature testing system (MMTS) that measures tension, compression, torsion, internal pressure and temperature at small-length scales (micrometer to nanometer) in real time.

The first-of-a-kind noncontact temperature control system uses a hybrid-heating technique and full-field infrared thermography to apply a uniform test temperature. The device incorporates an optimized high-temperature stereo-digital image correlation system that measures material deformation at small-length scales with high accuracy.

“By correlating the thermo-mechanical load and deformation measurement, material properties under high temperature and multiaxial loading can be determined at small-length scales, which was not possible before,” co-author Farhan Rahman said.

The prototype, 290 millimeters long by 53 millimeters high, is designed to be small enough to fit inside a scanning electron microscope (SEM). It maintains testing temperatures up to 500 degrees Celsius through a closed feedback loop and employs a fail-safe mechanism to protect the MMTS load frame components against unanticipated temperature rises.

The researchers used their device to test 22-millimeter-long hollow stainless steel cylindrical bars with a diameter of 1 millimeter and a wall thickness of 89 micrometers. The bars were heated to 500 degrees Celsius. They found good agreement with the literature.

They plan next to perform high-temperature testing with MMTS inside an SEM.

Source: “Non-contact temperature control and stereo digital image correlation for high-temperature testing of miniature tubular specimens,” by Farhan Rahman, Gracious Ngaile, and Tasnim Hassan, Review of Scientific Instruments (2021). The article can be accessed at https://doi.org/10.1063/5.0055718 .