Characterising performance of automotive materials at high strain rate for improved crash design

Abstract

This paper investigates the effect of specimen geometry on the measured dynamic mechanical properties of a high strength sheet steel material derived from tensile testing at 15 m/s on a high speed servo-hydraulic test machine. In this study, stochastic modelling is used extensively to support experimental investigations. The current objective is to develop a tensile specimen design and test procedure, which more closely matches the capabilities of the new IARC high speed test machine, to enable accurate and precise measurement of tensile mechanical properties over a range of strain rates up to 600 s - 1

Hopkinson bar techniques for the intermediate strain rate testing of bovine cortical bone

“…Material testing in the ISR range has no universally accepted testing method, even though a variety of techniques have been developed [12][13][14][15][16][17]. The unique challenge of the ISR regime is that it lies above the upper limit of standard tensile test machines and below the lower limit of typical SHB arrangements and is therefore also referred to as the medium strain rate regime [13] or the sub-Hopkinson bar regime [16].…”

“…Custom-built lightweight machines are sensitive to changes in the specimen stiffness, which results in nonlinear displacement histories [12,15,17], while the inherent compliance of ESH machines causes a similar effect [13,16]. Therefore, specimen-mounted strain gauges [14,16] or optical techniques [13,21] are often required to capture the strain history.…”

“…The relatively short load paths of custom-built machines [12,15,17] are intended to minimize the effect of stress wave oscillations. Similarly, short load cells [16,18] or the strain gauging of specimens [14,19] offer increased frequency response, and signal processing techniques that incorporate vibration models can compensate for some dynamic effects.…”

“…In tension tests, this is accomplished by using 'run-up' fixtures, such as 'fast jaw' grips [14] or 'slack adaptors' [16]; while, in compression tests, an initial gap is left between the specimen and the upper anvil [13].…”

Study on Dynamic Mechanical Properties and Constitutive Model Construction of TC18 Titanium Alloy

“…At the same time, the BE120-3AA strain gauge pasted on the incident bar and the transmission bar will record the pulse signal. Through the processing of the corresponding variable bar signal, the change course of the load at the end of the bar with time can be measured [24], thus the dynamic stress-strain curve of the material can be obtained. When doing the high temperature pressure bar experiment, it is necessary to install the hightemperature synchronization device on the Hopkinson pressure bar device.…”