基于剪切弹簧非线性模型的振动弛张筛动力学分析

振动弛张筛可有效解决潮湿细粒煤炭的干法筛分问题,且剪切弹簧的动态特性对其动力学响应以及筛分效果具有重要的影响。为了深入研究振动弛张筛剪切弹簧动态特性与振幅和频率的相关性,建立了基于非线性弹性力、摩擦力和分数导数力的剪切弹簧非线性模型,其中非线性弹性力用来描述剪切弹簧静态非线性弹性,摩擦力和分数导数力分别用来表示剪切弹簧动态特性的振幅相关性和频率相关性。将剪切弹簧动态测试实验结果与所提出模型的理论计算值进行比较分析,结果显示,在描述剪切弹簧动态特性振幅相关性时,剪切弹簧动刚度及滞后角的理论计算值与实验测试值的平均方差分别仅为0.525和0.007,平均误差分别为0.323%和5.580%;在描述剪切弹簧动态特性频率相关性时,剪切弹簧动刚度及滞后角的理论计算值与实验测试值的平均方差分别仅为0.041和0.011,平均误差分别为0.107%和5.260%,该数据表明,建立的模型可较好的描述剪切弹簧的动态特性。将该模型应用于振动弛张筛动力学分析系统中,利用Newmark算法计算了振动弛张筛在不同系统参数条件下的动力学响应,结果表明,由于剪切弹簧动态特性具有振幅和频率相关性,在二阶共振区内,随着剪切弹簧阻尼的增加,系统共振峰值减小且共振频率增加,随着激振力的增加,系统共振峰值增加且共振频率减小,故在研究振动弛张筛动力学响应时,应考虑剪切弹簧动态特性对系统的影响。

Dynamic analysis of vibrating flip flow screen based on a nonlinear model of shear spring

Vibrating flip flow screen provides an effective solution for the dry screening of wet and fine coal,and the dynamic characteristics of shear spring largely affects its dynamic response and screen performance.In order to study the amplitude and frequency dependency of shear spring equipped in vibrating flip flow screen,a nonlinear model of shear spring is established based on a superposition of elastic force,friction force and fractional derivative force.In the proposed model,the nonlinear elastic force describes the static nonlinear elasticity of shear spring,the friction and fractional derivative forces predict the amplitude and frequency dependency of shear spring’s dynamic characteristics,respectively.Then the experimental results of dynamic test of shear spring is used to compare with the simulation results of the proposed model.The results show that when the amplitude dependency is described,the mean squared errors and mean errors of dynamic stiffness and lag angle between experimental results and the simulation of the proposed model are 0.525 and 0.007,and 0.323% and 5.58%,respectively.When the frequency dependency is described,the mean squared errors and mean errors of dynamic stiffness and lag angle between experimental results and the simulation of the proposed model are 0.041 and 0.011,and 0.107% and 5.26%,respectively.The results demonstrate that the proposed model is capable to describe the dynamic characteristics of shear spring.Furthermore,the proposed model is used in the dynamic analysis of the vibrating flip flow screen,and the dynamic response of vibrating flip flow screen is calculated under different parameters using Newmark algorithm.Results show that as shear spring exhibits amplitude and frequency dependent dynamic characteristics,in the system’s second resonance zone,with the increase of the shear spring’s damping,the peak value in the resonance area decreases while the resonance frequency increases,and an increase of excitation force results in the increase of the peak value in the resonance area and the decrease of resonance frequency.Therefore,the effect of the dynamic characteristics of shear spring on the system should be considered when the dynamic response of vibrating flip flow screen is analyzed.