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Abstract:
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Sensitivity analyses assess model output dependency on variation in parameter inputs and identify the most important parameters for model prediction. Understanding the strength properties of Beryllium is strategically important to aerospace and defense research. We apply sensitivity analysis to test and refine Beryllium constitutive strength (plasticity) models, which capture its plastic deformation. Various Preston-Tonks-Wallace (PTW) strength models, with distinct parameter settings, have been calibrated using Hopkinson bar and quasi-static (low-strain rate) experiment data, but have vastly different output when extrapolated to high-strain rates. Flyer plate experiments measure a target material’s free surface velocity (FSV) when struck forcefully. We simulate the FSV of Beryllium flyer plate experiment targets with the LANL multi-physics code FLAG. Our research assesses the sensitivity of the simulated FSV to perturbing the code’s parameters, many of which come from the chosen material strength model - specifically, how variation in simulator output can be apportioned to the strength inputs. This investigation in a high-strain regime will add insight to which strength model parameter settings offer the best fit to experimental data across varied strain rates, and by extension, alongside damage models and EOS information, inform a general material model for Beryllium.
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