应用于低速冲击的新型力学超材料

New Type of Mechanical Metamaterials for Low-speed Impact

中文关键词:  低速冲击  准零刚度  多孔结构  力学超材料  落锤试验

英文关键词:low-speed impact  quasi-zero stiffness  porous structure  mechanical metamaterials  drop hammer test

中文摘要:

      目的 针对低速碰撞场景下的吸能缓冲需求，设计一种具有准零刚度特性的新型力学超材料。方法 首先对力学超材料的几何结构进行参数化建模，超材料主要组成包括薄壁结构与格栅结构。薄壁结构为正弦构型的曲梁，格栅结构由圆杆组成，将薄壁曲梁连接成整体。为了缩短不同应用场景下缓冲结构的设计周期，提出了一种结构力学响应的计算方法。首先建立基于欧拉-伯努利梁原理的薄壁结构运动微分方程，随后提出了一种基于四阶龙格库塔法以及打靶法的数值求解方法，最后基于叠加原理，提出了缓冲结构的力学响应预测方法并进行了相应的线性补偿。结果 提出的数值算法可以准确地计算大柔度薄壁结构的力学响应，从而减少设计迭代的次数，大幅缩短设计周期。结论 准静态试验结果表明，提出的超材料构型具有准零刚度的特点，并且压缩率超过70%。落锤冲击场景下缓冲结构无明显的初始峰值，响应载荷得到抑制。这说明这种超材料在缓冲领域具有很大的应用潜力，尤其适用于体积受限场景下的冲击防护。

英文摘要:

      To address the energy absorption and cushioning requirements in low-speed collision scenarios, the work aims to design a novel mechanical metamaterial with quasi-zero stiffness characteristics. Firstly, the geometric structure of the mechanical metamaterial was parametrically modeled, consisting mainly of thin-walled structure and lattice structure. The thin-walled structure was composed of sinusoidal curved beams, and the lattice structure consisted of circular rods that interconnected the thin-walled curved beams into a cohesive unit. To expedite the design cycle of cushioning structures for various application scenarios, a computational method for analyzing the structural mechanical response was proposed. Based on the Euler-Bernoulli beam theory, differential equations for the motion of the thin-walled structure were established. Subsequently, a numerical solution method based on the fourth-order Runge-Kutta method and shooting method was proposed. Finally, based on the superposition principle, the method for predicting mechanical response of the cushioning structure was put forward, and the corresponding linear compensation was carried out. The numerical algorithm presented accurately computed the mechanical response of highly flexible thin-walled structures, thereby reducing the number of design iterations and significantly shortening the design cycle. The quasi-static experimental results demonstrate that the metamaterial configuration proposed in this study exhibits quasi-zero stiffness characteristics and achieves a compression rate exceeding 70%. There is no obvious initial peak of the cushioning structures in the drop hammer impact scenarios, and the response load is suppressed. It shows great potential in the field of cushioning, particularly in impact protection in volume-constrained scenarios.