一种新型非线性弹簧的限位性能研究

Limiting performance of a new nonlinear spring

低阻尼柔性结构在外界荷载激励下可能产生大幅位移,严重情况下将造成构件损伤,导致结构失效或破坏。研究了一种双向运动的非线性弹簧限位器对柔性结构的缓冲限位性能,推导并采用拟静力试验验证了该装置的出力与变形的理论计算公式。最后基于单自由度主结构模型,对比分析了线性与非线性限位器对主结构的缓冲限位性能,并研究了非线性弹簧刚度对其性能的影响。结果表明:非线性弹簧本构理论式与试验值存在一定差异,并据此提出考虑初位移的理论计算式。在初位移较小时,两种理论计算式均可作为工程运用时的理论依据。非线性弹簧限位器具有准零刚度的特性,在限位器开始工作时,非线性弹簧限位器能够较平缓地降低主结构运动速度。在随机荷载作用下,非线性弹簧具有与线性弹簧相当的限位能力,且能显著减小对结构的反冲作用,同时合理地设置非线性弹簧刚度不仅能有效控制主结构位移,而且能减少非线性弹簧限位器对主结构的反冲力。

Flexible structures with low damping may have large-amplitude displacements under excitation of external loads,which cause damages of the components,and even structural failure in severe cases.Here,the buffering and limiting performance of a bi-directional nonlinear spring restrictor for flexible structures was studied,and the theoretical calculation formula for force and deformation of the device was derived and verified with pseudo-static tests.Finally,based on asingle-DOF main structure model,buffer limit performances of linear and nonlinear restrictors were compared and analyzed,and effects of the nonlinear spring stiffness on its performance were studied.Results showed that the calculated results with the theoretical calculation formula of the nonlinear spring do not agree well with test ones,then a theoretical calculation formula considering initial displacement is proposed;when the initial displacement is smaller,both two theoretical calculation formulas can be a theoretical basis for practical application;the nonlinear spring restrictor has characteristics of quasi-zero stiffness,when it starts to work,it can reduce the main structure’s motion speed more gently;under random loads,the nonlinear spring has the same limiting capacity as that of a linear spring,and can significantly reduce recoil action on structure;the reasonably setting of its stiffness not only can effectively control displacements of the main structure,but also reduce its recoil force on the main structure.