Synchronous in-situ measurement for deformation and temperature fields with high spatial and temporal resolution under dynamic loading

Abstract

Studying the dynamic failure of materials is crucial because this failure occurs extensively in mechanics and earthquake fields. However, obtaining the deformation and temperature fields in high-speed dynamic cases is challenging, particularly when analyzing the mechanics of thermo-mechanical coupling. This study developed a thermo-mechanical coupled in-situ measurement system to acquire synchronized information on the load, deformation and temperature fields during a specimen dynamic failure process with high temporal and spatial resolution. In particular, the deformation field was obtained using a high-speed camera connected to a microscope that could achieve a spatial resolution of 3.6–3.8μm/pixel and a temporal resolution of 1μs. Moreover, a 64 × 64 focal plane array infrared detector was developed to measure temperatures with the time resolution of 1μs. A Newtonian optical system was applied to achieve the infrared detector’s spatial resolution of 25μm. The temperature measurement system could measure temperatures ranging from 100 to 800 °C. The split-Hopkinson pressure bar was used as the dynamic loading device to realize the high strain rate loading of a Ti-6Al-4V hat-shaped specimen, verifying the deformation and temperature measurement capabilities. The results from the Ti-6Al-4V specimen under dynamic loading showed an evident adiabatic shear band and the temperature rise, suggesting that the experimental devices provided was an effective tool to study the thermo-mechanical response of materials under dynamic loading.