Dynamic Deformation Model of Thin-Walled Ellipsoidal Shells under Impact Loads
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摘要: 为研究薄壁椭球壳在局部冲击载荷作用下的变形特征,开展了实验研究和仿真分析。利用轻气枪开展弹丸冲击实验,使用三维DIC技术记录变形过程,得到了椭球壳在圆柱弹丸不同初始冲击速度作用下的全局变形形貌以及中心凹陷深度和凹陷边界。在弹丸冲击椭球壳的仿真分析中,重点研究了三种曲率半径变化对椭球壳凹陷深度、凹陷长短轴的影响规律,通过量纲分析方法得出无量纲变形特征所依赖的主要无量纲自变量,通过参数敏感性分析消减影响较小的参数,在保持相同材料、弹体尺寸与壳体厚度同一缩比时,得到了无量纲变形特征与三种曲率半径和速度之间的具体响应面函数表达式,并提出根据凹陷深度、凹陷边界预测全局变形的公式,所得表达式尺寸效应良好,预测精度较高,可为工程中大尺寸曲面薄壳冲击载荷防护设计提供参考。
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Abstract: To delve into the nuanced understanding of the deformation characteristics of thin-walled ellipsoidal shells under localized impact loads, a systematic and comprehensive research approach was employed, integrating both experimental exploration and simulation analysis. The experimental setup featured a lightweight pneumatic gun for conducting projectile impact experiments, with the deformation process meticulously recorded using advanced three-dimensional Digital Image Correlation (DIC) technology. This extensive study necessitated a detailed examination of the overall deformation morphologies of ellipsoidal shells, particularly under varying initial impact velocities induced by cylindrical projectiles. The outcomes of the study provided crucial insights into determining the central depression depth and the corresponding boundary positions of the long and short axes. In the simulation analysis of ellipsoidal shell impacts by projectiles, the primary focus was directed towards elucidating the intricate interplay of alterations in three curvature radii on the complex interactions affecting the ellipsoidal shell's depression depth and the long and short axes. Employing dimensional analysis, essential dimensionless independent variables governing deformation characteristics were identified, refined through parameter sensitivity analysis to eliminate less influential parameters. The resulting specific response surface function elucidates the nuanced relationships among dimensionless deformation characteristics, the three curvature radii, and velocity. Under the condition of consistent material properties and the maintenance of equivalent shrinkage ratios for projectile body size and shell thickness, a predictive formula for global deformation based on depression depth and boundary conditions was derived. This formula demonstrates commendable dimensional consistency and affords high prediction accuracy. The potential application extends to informing the engineering design of impact load protection for large-sized curved shells, holding considerable promise in enhancing structural resilience and mitigating potential risks in engineering applications. The comprehensiveness and depth of this study provide a robust foundation for future research in related fields.
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