局部加强体对预压双稳态结构跳转力学特征的影响分析

基于轴向挤压后屈曲模态的双稳态结构,其跳转力、保持力和跳转行程等双稳态特征与预应力分布和后屈曲模态密切相关,使得难以通过仅调整预压缩量来实现特定双稳态指标的设计。本文提出引入局部加强体调控预压双稳态梁临界屈曲载荷、应力分布及跳转特征的方法,建立了具有对称局部加强体的预压双稳态梁跳转分析模型,分析了预应力、加强体尺寸参数和位置对屈曲临界载荷、跳转力和行程的影响规律。结果表明:局部加强体不影响原结构跳转力和保持力相等的特征;与尺寸参数相比加强体位置参数对跳转力有较大影响,随着位置的变化,跳转力存在由大变小再变大的变化过程,且调控同行程双稳态梁跳转力的幅度可达17.04%;跳转行程主要依赖于局部加强体的刚度和所承受的预应力。

Influences of local reinforcements on the snap-through characteristics of pre-compressed bistable structures

For the bistable structures formed through compressing the strait beams into post-buckling modes, their bistable characteristics such as snap-through/maintain forces and snap-through distance are deeply related to the pre-stress distribution and the buckling mode. Thus, it is difficult to achieve a required specific bistable characteristic through only adjusting the pre-stress load. For this reason, one effective method was proposed for adjusting the critical buckling load and snap-through characteristics by introducing local reinforcements to regulate stress distribution during the snap-through procedure. Then, the snap-through analyzing model was established for the pre-compression bistable beam with symmetrical local reinforcements. Influences of the pre-stress, reinforcement size parameters and their position on buckling critical load, snap-through force and the stroke were analyzed. The results show that the characteristic of equal snapping and maintaining force is not affected by added local reinforcements; compared with size parameters of the reinforcement, its position parameter plays a more important role in determining the snapping force, and the snapping force increases firstly and then decreases with the position changed. The snapping force can be regulated up to 17.04% without changing the stroke; the stroke is deeply related with the reinforcement stiffness and the pre-stress.