Numerical Modelling of Ultra-High Molecular Weight Polyethylene Composite under Impact Loading

Abstract

Numerical models are investigated and refined for analysis of ultra-high molecular weight polyethylene (UHMW-PE) composite under ballistic and hypervelocity impact. An existing non-linear orthotropic continuum model implemented in a commercial hydrocode (ANSYS ® AUTODYN ® ) was evaluated using a previously published material data set. It was found that the material through-thickness shear performance was artificially degraded as a result of coupling to the through-thickness tensile properties, significantly affecting the model accuracy for impact velocities in the ballistic regime. In order to correct for this, the composite laminate was discretized into sub-laminates joined by bonded contacts breakable through a combined tensile and shear stress failure criterion. The sub-laminate method allows the through-thickness tension and shear failure to be decoupled in the bulk material. This method was investigated and validated against experimental ballistic and hypervelocity impact tests. Simulations showed improvement in ballistic limit predications for thin targets under low velocity impact. Prediction of target deflection is also significantly improved compared to the baseline model in terms back face deformation. Under hypervelocity impact, good agreement with the experimental ballistic limit and residual velocities is still maintained, with a small variation between the new and baseline models. A third validation case was performed to investigate the model performance with thicker targets (50 mm) for impact velocities between the two baseline studies. Accuracy for this condition is poor and remains a challenge for the numerical model.

Investigation of simulation methodologies for ultra-high–molecular-weight polyethylene

“…7). The ballistic limit was significantly under Comparing experimental results with the previous simulation models of Lässig [9] and Nguyen [10], 265 µs after impact (grey = plastic deformation, green = elastic deformation, orange = material failure); projectile velocity: 674 m/s; target thickness: 16.2 mm (60 layers of HB26).…”

“…The material model developed in Refs [9] and [10] has some shortcomings regarding the simulation of handgun projectiles (see Fig. 7).…”

“…Nguyen et al [10] evaluated and refined the modeling approach and material model parameter set developed in [9] for the simulation of impact events from 400 m/s to 6600 m/s. Across this velocity range, the sensitivity of the numerical output is driven by different aspects of the material model, e.g., the strength model in the ballistic regime and the equation of state (EoS) in the hypervelocity regime.…”

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“…Nguyen et al [9] evaluated and refined the modeling approach and material model parameter set developed in Ref. [8] for the simulation of impact events from 400 m/s to 6,600 m/s.…”

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“…The numerical modeling of composite materials under impact can be performed at a constituent level (i.e., explicit modeling of fibre and matrix elements, e.g., [1]), a meso-mechanical level (i.e., consolidated plies or fibre bundles, e.g., [2] Nguyen et al [9] evaluated and refined the modeling approach and material model parameter set developed in Ref. [8] for the simulation of impact events from 400 m/s to 6,600 m/s.…”