【摘要】 为研究单层球面网壳在冲击荷载下的失效机理,在ANSYS/LS-DYNA中建立60m跨度K8型单层球面网壳与圆柱形冲击物的数值模型并进行数值分析,总结了网壳结构的4种失效模式。通过对失效全过程的分析,从能量的角度将失效过程分为能量施加、能量传递与损失、能量消耗3个阶段。之后分别从能量传递与杆件破坏形式2方面揭示了网壳的失效机理。能量分析表明:剩余能量(Elf)对结构最终动力响应及失效模式起决定作用,而Elf只是初始冲击能量中除去冲击物穿透损失与网壳局部破坏损失后的剩余部分。通过对杆件破坏形式的分析发现:杆件的破坏可能滞后于冲击荷载的作用,且杆件的破坏形式决定其传递能量的能力,当杆件发生拉伸破坏时,其强度被充分利用,传递的能量最多,Elf值较大,网壳整体破坏严重。杆件的破坏形式与Elf及网壳整体的失效模式间有很好的对应关系。更多还原

【Abstract】 Numerical models for single-layer Kiewitt-8 reticulated domes with the span of 60 m and cylinder impactors were established by the ANSYS/LS-DYNA program and a series of numerical simulations were carried out. Four failure modes for the reticulated domes were put forward according as the displacement and plastic deformation. The whole failure process was divided into three steps including energy applying, energy loss and energy transfer, energy consumption, by the dynamic response characteristics of each step. Failure mechanisms of the reticulated domes were explained at the two aspects of energy transfer and failure types for members in impact zones. Energy analysis displays that the left energy (Elf) is the main factor to decide the final dynamic response and failure mode, but Elf is the initial impact energy eliminated penetrating loss by the impactor and local breakage loss by members in the impact zone. Analysis for failure types of members indicates that failure of members may lag by contrast the end of impact load, and failure types of members decide the ability of energy transfer. When remembers undergo tension failure, intensities of members are made full use of, the most energy is transferred, the left energy is more, and the whole reticulated dome experiences severe breakage. Moreover, there is a good consistent relationship among failure types of members, failure modes of the reticulated dome and left energy.更多还原