爆炸冲击荷载作用下柔性支撑梁的弹塑性动力响应分析  

Analysis of dynamic responses of beams with flexible supports under explosive impact

作　　者：康婷[1] 白应生 杨慧[1] 孙惠香[1] 吴永根[1] 刘远飞[1] 

机构地区：[1]空军工程大学航空航天工程学院,西安710038 [2]陕西环宇建设工程项目管理有限公司,西安710032

出　　处：《应用力学学报》2015年第5期706-711,889,共6页Chinese Journal of Applied Mechanics

基　　金：国家自然科学基金(51308540;51208506)

摘　　要：利用三次B样条函数的线性组合模拟柔性支撑梁的位移振型函数,根据拉格朗日方程建立了动力计算模型,模型考虑了弹性支撑和阻尼支撑等情况;研究了爆炸冲击荷载作用下柔性支撑对梁动力响应的影响;提出了短时荷载和长时荷载的定量界定建议。分析结果表明:在短时荷载(爆炸冲击持续时间小于简支梁半个自振周期)作用下,弹性支撑可有效降低梁跨中截面的弯矩,从而提高梁的抗爆承载力,且弹性系数越小,减振效果越好;在长时荷载(爆炸冲击持续时间大于简支梁半个自振周期)作用下,弹性支撑的减振效果是有条件的,只有弹性系数较小时才能降低梁的动力效应,若弹性系数超过某一限值,在残余振动阶段会出现振动反弹,反而会降低梁的抗爆承载力,这种情况下加设阻尼支撑,可使结构振动快速衰减,阻尼系数越大,振动衰减越快。The displacement mode shape of flexible supporting beams is simulated with a linear combination of cubic B splines. The dynamic models are established according to the Lagrange method. The elastic and damping supports at both ends of the beam are taken into account. The influence of the flexible supports on dynamic response is studied. Suggestions for a short-time and a long-time load quantitative definition are proposed. Under the short-time load(the impact duration is smaller than half the natural period of vibration of the simply supported beams), the elastic supports can effectively reduce the middle section bending moment of the beams. The antiknock bearing capacity of beams can be improved. And the stiffness coefficient is smaller, the damping effect is better. Under the long-time load(the impact duration is bigger than half the natural period of vibration of the simply supported beams), only the elastic supports with small stiffness coefficient can reduce the dynamic effect of beam. If the stiffness coefficient exceeds a critical value, the elastic supports may increase the middle section bending moment of the beams, and the vibration bounce appears. The elastic supports will reduce the beam antiknock bearing capacity. In this case, the damping supports can make the vibration attenuated, and effectively improve the antiknock bearing capacity of beams. And the damp coefficient is bigger, the attenuation is stronger.

关 键 词：振动理论 动力响应 梁 柔性支撑 爆炸冲击荷载 

分 类 号：O327[理学—一般力学与力学基础] TU311.3[理学—力学]