The dynamic response of a single-layer reticulated shell to drop hammer impact
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摘要: 通过单层KIEWITT8型网壳模型在落锤撞击作用下的实验,研究单层网壳在撞击作用下的动力稳定性。利用动态应变仪和力传感器,获取了落锤撞击网壳时撞击力时程曲线、杆件轴力时程曲线和稳定临界力。利用高速摄影机拍摄了撞击历程、撞击失稳模态及破坏形态。结果表明:撞击作用为三角脉冲荷载形式,其最大幅值和脉宽与撞击冲量和网壳所处变形阶段的刚度性能相关;撞击荷载持续作用的时间为3.00~22.36 ms;撞击接触时间的突然增大对应着网壳的失稳;杆件开始响应的时刻比撞击力开始作用的时刻滞后0.2~0.4 ms;对失稳前的撞击,落锤回弹速度较大;对失稳时的撞击,落锤回弹速度很小;模型具有较大的后屈曲抗撞击能力,在顶点垂直撞击下没有发生连续断裂。Abstract: This paper presents an experimental investigation on the dynamic buckling of a Kiewitt8 single-layer reticulated shell model under drop hammer impact. The history curves of impact actions and axial forces were measured. The impact buckling modes and failure patterns were observed with a high-speed camera. The results show that the impact actions of drop hammer on the model have triangular impulse shapes, whose max-values have a close relation to hammer momentum and the model stiffness. Acting periods of impact varied from 3.00 to 22.36 ms and their sudden increase correspond to impact buckling occurrence. The response time of axial force was 0.2~0.4 ms later than the impact. The results also show that the reticulated shell model has the higher resistance to impact after its buckling and has not collapsed progressively under the stronger impact.
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