Inert solid rocket propellant samples were subjected to dynamic inflation experiments, to characterize the viscoelastic response at high strain rates. An oxyacetylene-driven shock tube created the shock wave, which was used to dynamically pressurize the surface of the samples during the inflation experiments. Two high-speed cameras captured the deforming samples, which were speckled to measure the full-field surface displacements using the digital image correlation (DIC) algorithm. An inverse finite element analysis (iFEA) was used to calibrate parameters of a generalized Maxwell model (i. e. Prony series), which was used to characterize the propellants’ viscoelastic response to shock wave exposure. The viscoelastic parameters calibrated using a Prony series with one Maxwell branch provided a better fit with the out-of-plane displacement data from DIC. At least 50 % of the energy dissipated, within the inert solid rocket propellant, occurred within 5 ms following shock wave exposure. The softening phenomenon, due to debonding of the particles embedded in the inert solid rocket propellant, occurred since there was a decrease in instantaneous elastic modulus with increased strain rate. The results of this study will add to the limited knowledge of the linear viscoelastic behavior of inert HTPB propellant at high strain rates and may improve the predictive capabilities of health-monitoring sensors that assess the solid rocket propellant's structural integrity.

中文翻译：

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暴露于冲击波的惰性固体火箭推进剂的粘弹性

惰性固体火箭推进剂样品进行了动态膨胀实验，以表征高应变率下的粘弹性响应。氧乙炔驱动的激波管产生激波，用于在膨胀实验期间对样品表面进行动态加压。两个高速相机捕获变形样本，使用数字图像相关 (DIC) 算法对这些样本进行散斑以测量全场表面位移。逆有限元分析 (iFEA) 用于校准广义麦克斯韦模型（即 Prony 系列）的参数，该模型用于表征推进剂对冲击波暴露的粘弹性响应。使用带有一个 Maxwell 分支的 Prony 系列校准的粘弹性参数与来自 DIC 的平面外位移数据更好地拟合。至少 50% 的能量消散在惰性固体火箭推进剂中，发生在冲击波暴露后 5 毫秒内。软化现象是由于嵌入惰性固体火箭推进剂中的颗粒脱键而发生的，因为随着应变速率的增加瞬时弹性模量降低。这项研究的结果将增加对惰性 HTPB 推进剂在高应变率下的线性粘弹性行为的有限了解，并可能提高评估固体火箭推进剂结构完整性的健康监测传感器的预测能力。在惰性固体火箭推进剂中，发生在冲击波暴露后 5 毫秒内。软化现象是由于嵌入惰性固体火箭推进剂中的颗粒脱键而发生的，因为随着应变速率的增加瞬时弹性模量降低。这项研究的结果将增加对惰性 HTPB 推进剂在高应变率下的线性粘弹性行为的有限了解，并可能提高评估固体火箭推进剂结构完整性的健康监测传感器的预测能力。在惰性固体火箭推进剂中，发生在冲击波暴露后 5 毫秒内。软化现象是由于嵌入惰性固体火箭推进剂中的颗粒脱键而发生的，因为随着应变速率的增加瞬时弹性模量降低。这项研究的结果将增加对惰性 HTPB 推进剂在高应变率下的线性粘弹性行为的有限了解，并可能提高评估固体火箭推进剂结构完整性的健康监测传感器的预测能力。