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Hypervelocity impact damage response and characterization of thin plate targets at elevated temperatures.

机译：超高速冲击损伤响应和高温下薄板靶材的表征。

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The performance of a typical International Space Station (ISS) shield against the meteoroid and orbital debris (M/OD) impact threat is generally modeled by damage equations for the outer shield and the rear pressure wall. In their current forms, these damage equations neglect the on-orbit temperature extremes witnessed by the ISS. To address IF and HOW temperature extremes affect the performance of the ISS' typical M/OD shield, a comprehensive study was undertaken that investigated hole diameters in .063" thick 6061-T6 aluminum targets impacted at velocities from ∼2-7 km/s at 20°C, 110°C, and 210°C.;Robust graphical and analytical analyses confirmed the existence of a statistically significant temperature effect, i.e., hole diameters in heated targets were larger than those in room temperature targets. A new temperature-dependent model was found via multivariable regression analysis that incorporates a linear velocity term and a temperature term based on a form of the cumulative distribution function.;Numerical modeling of hypervelocity impacts (HVI) into elevated temperature targets was also performed to determine whether or not currently available material and failure models can adequately simulate the differences observed between room and elevated temperature target hole diameters. Statistical analyses showed that AUTODYN simulated the heated data almost as well as the room temperature data. However, the slightly worse Goodness of Fit (GOF) values between the heated empirical vs. simulated comparisons suggest that the simulations do not completely account for the observed temperature effect.;A series of materials tests and observations were carried out on the post-impacted target plates to help explain the empirical data results with respect to material variability and deformation features. Rockwell B and K macro-hardness tests revealed that the hardness values for the targets impacted at 110°C were statistically significantly higher compared to those targets impacted at 20°C and 210°C. Since hole diameters are expected to increase with target temperature, this observation suggests that a less ductile failure mode was involved for the 110°C holes compared to the room temperature and 210°C holes. Polished micrographs of select 110°C impact hole cross-sections support the idea that these targets failed in spall in a less ductile manner compared to the 20°C and 210°C targets.;Current orbital debris (OD) environment predictions are based, in large part, on in-situ damage of spacecraft surfaces, but do not relate observed surface damage to their temperature at the time of the impact. A first-order prediction was calculated to quantify how much elevated temperature bumpers could potentially affect ORDEM2000 flux predictions, and ultimately the risk of impact. By failing to take into account that larger hole diameters are created in heated targets, ORDEM2000 potentially overestimates the risk of impact by particles in the 3mm range of the environment by at least 68%. These calculations show that, in this range, a small error in predicted particle diameter can result in a significant difference in the predicted orbital debris particle flux and risk of impact. To the extent that these effects are true for other spacecraft surfaces, spacecraft designs may be over-conservative due to an overprediction of large particles in the OD environment.
机译：典型的国际空间站（ISS）防护罩抵御流星体和轨道碎片（M / OD）撞击威胁的性能通常通过外部防护罩和后压力墙的损伤方程来建模。在目前的形式下，这些破坏方程忽略了国际空间站所观测到的在轨极端温度。为了解决IF和HOW极端温度影响ISS典型M / OD屏蔽的性能的问题，进行了一项全面研究，研究了直径为.063英寸厚的6061-T6铝靶的孔直径，其撞击速度约为2-7 km / s在20°C，110°C和210°C时；鲁棒的图形和分析分析证实存在统计学上显着的温度效应，即加热目标的孔直径大于室温目标的孔直径。通过多变量回归分析找到依赖模型，该模型基于累积分布函数的形式将线速度项和温度项合并在一起;还对超高温影响（HVI）进行了数值建模，以确定当前是否处于高温目标现有的材料和失效模型可以充分模拟室温和高温目标孔直径之间观察到的差异。 AUTODYN几乎模拟了加热数据以及室温数据。然而，在加热的经验和模拟比较之间的拟合度（GOF）值稍差，这表明模拟不能完全解决观察到的温度影响。;对撞击后进行了一系列材料测试和观察目标板，以帮助解释有关材料变异性和变形特征的经验数据结果。洛氏硬度B和K的宏观硬度测试表明，与在20°C和210°C冲击的那些靶相比，在110°C冲击的靶的硬度值在统计学上显着更高。由于预计孔的直径会随着目标温度的增加而增加，因此该观察结果表明，与室温和210°C的孔相比，110°C的孔的延性破坏模式更少。精选的110°C冲击孔横截面的抛光显微照片支持这样的想法，即与20°C和210°C的目标相比，这些目标以较小的延展性破裂。;当前的轨道碎片（OD）环境预测是基于在很大程度上是对航天器表面的原位破坏，但与撞击时观察到的表面破坏与它们的温度无关。计算了一级预测，以量化多少高温保险杠可能会影响ORDEM2000通量预测，并最终影响影响的风险。由于没有考虑到在加热的目标中会产生较大的孔径，ORDEM2000可能高估了环境3mm范围内的粒子撞击的风险至少68％。这些计算表明，在此范围内，预测粒径的小误差可能会导致预测的轨道碎片粒子通量存在显着差异，并可能造成撞击的危险。在某种程度上，这些影响对其他航天器表面都是正确的，由于对OD环境中大颗粒的过高预测，航天器设计可能过于保守。

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