A gas gun based technique for studying the role of temperature in dynamic fracture and fragmentation

Abstract

Presented in this work is a new experimental technique to facilitate studies of materials under uniform radial expansion at rates of strain typically seen in ballistic and impact studies (10 3 to 10 5 s À1) at temperatures around 100-1000 K. Previous work places a right-cylinder polymer insert in a sample cylinder, into which a matching polymer projectile is launched using a gas gun. The impact and resulting deformation of the polymers imparts radial momentum to the cylinder. This work replaces the polymer insert with a steel ogive. A polycarbonate projectile deforms around the insert and drives radial expansion. The uniform radial expansion created has a less complex interface than previous work as only one material is driving the cylinder wall. As deformation of the insert is no longer necessary, the opportunity to heat or cool the cylinder prior to expansion is now available for studies into the effect of temperature on fracture and fragmentation behavior. This paper describes the design of this new impact configuration alongside how strain rate and expansion profile can be controlled. Validation experiment results with 6061-T6 aluminum and Ti-6Al-4V cylinders using a variety of diagnostics are compared with numerical modelling, where the benefits of this technique in assisting development of material strength and failure models are discussed with methods to control the sample temperature. [http://dx

Fragmentation studies by non-explosive cylinder expansion technique

“…100 s) is notable from Figures 4 to 6, with the X-rays taken at different angles, suggesting good general alignment. Although it is to be noted the creation of a void The expansion velocity has been shown to accelerate to a maximum at a rate dependent on the material properties and strain-rates (Jones et al, 2013;Jones et al, 2012;Vogler et al, 2003). Measurements made from Figures 4 and 5 give expansion velocities of 344 and 392 m s -1 , for the time intervals 0-5 µ s and 10-20 µ s respectively,-a velocity increase of 14%.…”

“…Firstly, the material parameters for actual materials have not been used in model due to unavailability of material data. Secondly, due to lack of failure model, the later stage of expansion, when material starts losing strength can't be correctly modelled (Jones et al, 2013). Despite difference in simulation and experimental velocity, the trend could be modelled and approximate estimation of expansion velocity for different thicknesses was obtained.…”

“…Strain rates of the order of 2x10 4 s -1 were obtained using a polycarbonate projectile at 900 m s -1 . In subsequent work, experimental and numerical studies on expansion and fragmentation of aluminium and titanium alloy cylinders were presented (Jones et al, 2013) including initial work on the effects of the cylinder temperature (Jones et al, 2014). These and other similar studies (Amott et al, 2017;Stirk et al, 2009) demonstrated the potential of gas-gun approaches.…”

Plate-impact-driven ring expansion test (PIDRET) for dynamic fragmentation

“…Consequently, previous experimental studies generally considered simplified reducedscale configurations such as expansion of a hemispherical shell [2,3], a cone [4] or a cylinder [5,6]. In [6], a cylinder of high explosive was also used to accelerate several rings simultaneously.…”

Quantitative evaluation of the mechanical strength of titanium/composite bonding using laser-generated shock waves

“…Shock wave propagation into the multilayer is then simulated by the resolution of the {mass, momentum, motion quantity, and energy} equations with an adapted equation of states to rely energy and stress. 18 We used the SteinbergCochran-Guinan formalism for the TA64V 19 and the MieGr€ uneisen formalism for the epoxy glue and the composite modeling. 20 Illustrations of the simulations are presented in For both simulations, the plasma pressure was 4 GPa and its duration was 15 ns at FWHM in agreement with previous confined interaction characterization.…”