On the importance of encapsulation environment for lateral gauges

Abstract

Abstract. In principle, embedded wire-element lateral manganin pressure gauges allow the lateral component of stress during shock loading to be directly monitored. However, such gauges require target materials to be sectioned before insertion into an encapsulating Mylar TM /epoxy layer, leading to debate over their analysis. In particular, recent computational modelling has suggested that, amongst other factors, gauge response may be linked to the nature of material flow within the encapsulation under shock loading. Here, this phenomenon was experimentally and computationally investigated by variation of the geometric environment of embedded lateral T-gauges (Vishay Micro-Measurements ® type J2M-SS-580SF-025) in Tantalum (Ta) targets. In particular, inclusion of high impedance backing plates allowed restriction of encapsulation material flow under shock. Subsequent comparison to hydrocode simulations provided additional insights into lateral gauge interpretation.

The Dynamic Response of Dense 3 Dimensionally Printed Polylactic Acid

“…A slight misalignment of the gauge could increase the response time because of the time it takes for the shock to equilibrate across the gauge length. Although the initial rise in the gauge traces has been attributed elsewhere to gauge equilibrium [32], essentially, polymer densify to large strain against weaker inter-chain Van-der-Waals [24] forces before material begin to exhibit a steady state behind the shock front. This implies that the stress state stability can only be achieved once the polymer has been loaded to compression at which the carbon atoms interact at a maximum density which suggests that rate of compression determines the amplitude and time to stable state.…”