A dynamic model of fiber polymer cylindrical shells covered with functional gradient protective coatings (FGCs) is proposed in this work to predict impact characteristics when low-velocity oblique impact loading is considered. The material properties of the FGCs attached to both the inner and outer surfaces of the structures is defined, and the related failure modes and different energy-absorbing mechanisms associated with penetration damage are clarified. Also, by employing the proposed penetration judgement approach based on impact energy, the solution equations are derived to predict the penetrating or non-penetrating dynamic parameters. After constructing the low-speed drop hammer and high-speed gas gun impact systems, detailed tests are conducted to obtain time-history curves of impact forces, force-displacement curves, structural damage areas, and residual impact energies. These results are analyzed for projectiles with different impact velocities and energies. Moreover, these experimental data are compared to the calculated results to fully validate the developed model as well as evaluate the impact resistance of the structure with and without FGCs. Finally, the influence of crucial coating parameters on structural impact resistance is investigated, with several beneficial design suggestions being refined. The dynamic model and solution techniques developed in this work can be readily extended to the impact resistance evaluation of other advanced composite shell structures with coating materials.

中文翻译：

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具有功能性梯度保护涂层的纤维聚合物圆柱形壳体抗冲击性的理论和实验研究


本文提出了一种覆盖有功能梯度保护涂层 （FGC） 的纤维聚合物圆柱壳的动力学模型，以预测考虑低速斜冲击载荷时的冲击特性。定义了附着在结构内表面和外表面的 FGC 的材料特性，并阐明了相关的失效模式和与贯穿损伤相关的不同能量吸收机制。此外，通过采用所提出的基于冲击能量的穿透判断方法，推导出求解方程以预测穿透或非穿透动力学参数。在构建低速落锤和高速气枪冲击系统后，进行详细测试以获得冲击力、力-位移曲线、结构损伤区域和残余冲击能量的时程曲线。这些结果针对具有不同冲击速度和能量的弹丸进行了分析。此外，将这些实验数据与计算结果进行比较，以充分验证开发的模型，并评估有和没有 FGC 的结构的抗冲击性。最后，研究了关键涂层参数对结构抗冲击性的影响，并完善了几个有益的设计建议。这项工作中开发的动力学模型和求解技术可以很容易地扩展到其他具有涂层材料的先进复合壳结构的抗冲击性评估。