结构简化弹塑性撞击分析模型及新型防撞吸能器初步试验研究

Elasto-plastic impact model and experimental study of new absorber for structural collision protection

通过引入防撞吸能器的力-位移关系,建立了用于结构防撞设计的简化弹塑性撞击分析模型。同时对新型蜂窝状加气混凝土吸能器开展了系列静压试验,结果表明该吸能器具有良好的塑性变形吸能特性。通过改变水灰比、骨料配比及模具的形状与大小,可制作不同强度及不同几何构型的蜂窝状加气混凝土吸能器。对安装该吸能器的结构模型进行了撞击试验,实测的结构振动响应与简化弹塑性撞击分析模型的仿真结果吻合良好,从而验证了所提出的简化撞击分析模型的有效性。进一步的撞击能量转移及结构振动响应分析表明:吸能器强度越大,则撞击持续时间越短,而直接作用在结构上的撞击能量越大;撞击过程中结构的动力响应主要受吸能器的强度及结构自身刚度的影响;采用拟静力法分析撞击过程中结构的位移响应时需考虑合适的放大系数。

An elasto-plastic impact model based on the quasi-static load-compression relationship of an absorber is presented for the collision protection of structures. Using the proposed model, the entire impact process of the impactor-absorber-structure system can efficiently and automatically be predicted. A cost effective Cellular Reinforced Concrete Absorber （CRCA） is designed to soften the impact and absorb the impact energy. Quasi-static tests show that this concrete absorber has excellent plastic deformation characteristics. To verify the proposed impact model and investigate the energy absorbing characteristics of the present absorber, impact experiment of a frame model with installed CRCA is carried out. The simulated results of the elasto-plastic impact model are in good agreement with the experimental ones. Due to the plastic deformation of the absorber, the impact force and responses of the structure during the impact are considerably reduced. Further structural impact analysis indicates that the time duration of the impact decreases and the impact energy directly applied to the structure increases with the increase of strength of the absorber, and the dynamic response of the structure during the impact mainly depends on the strength of the absorber and the stiffness of the structure.