摘要
用静力修正法和虚功原理,推导出了爆炸冲击荷载作用下,弹性支撑梁弹塑性动力响应的解析表达式。其中:第一阶、二阶振型的影响用振型叠加法计算,其他高阶振型的影响用拟静力法计算。分析了爆炸冲击持续时间和弹性系数对梁动力响应的影响。结果表明:当冲击持续时间小于简支梁1/2自振周期时,可看作短时荷载,与刚性支撑相比,弹性支撑可有效降低梁跨中截面弯矩和相对位移,从而提高梁的抗爆承载力,且弹性系数越小,减振效果越好,但会引起较大端部位移;当持续时间大于简支梁1/2自振周期时,可看作长时荷载,在冲击作用阶段弹性支撑能够起到减振作用,但在残余振动阶段,若弹性系数选取不当,会使梁跨中截面弯矩增大,出现振动反弹,反而会降低梁的抗爆承载力,此时宜加设阻尼支撑。
The analytical expressions of the elastic-plastic dynamic response of the beam with elastic supports under explosive impact are deduced using the pseudo-static method and the principle of virtual work. The effects of the first and second normal mode shapes are calculated with the mode superposition method. And the effects of the remaining higher normal mode shapes are calculated with the pseudo-static method. The influences of the explosive impact duration and the stiffness coefficient on the dynamic responses are studied. The results show that,when the impact duration is smaller than half the natural period of vibration of the simply supported beams,the explosive impact can be regarded as a short-term load.The elastic supports can effectively reduce the middle section bending moment and the relative displacement of the beams to improve the antiknock bearing capacity of beams. And the smaller the stiffness coefficient is,the better the damping effect is,which may lead to a large displacement at the end of the beams. When the impact duration is bigger than half the natural period of vibration of the simply supported beams,the explosive impact can be regarded as a long-term load. In the action phase of impact,the elastic supports can reduce the middle section bending moment of the beams. But in the residual vibra-tion,the improper elastic supports may increase the middle section bending moment of the beams,and the vibration bounce appears,resulting in reducing the beam antiknock bearing capacity. In this case,the damping supports should be set.
出处
《兵工学报》
EI
CAS
CSCD
北大核心
2014年第S2期61-66,共6页
Acta Armamentarii
基金
国家自然科学基金项目(51308540
51208506)
关键词
爆炸力学
振动理论
弹塑性动力响应
梁
弹性支撑
explosion mechanics
vibration theory
elastic-plastic dynamic response
beam
elastic support
