损伤状态下悬索桥静动态响应的模型试验研究

面向健康诊断,设计制作了悬索桥结构整体试验模型。利用该模型,对悬索桥进行了加劲梁、主缆、吊索等基本构件的损伤状态模型试验研究。分析了损伤状态下,加劲梁挠度与应变、主缆应变、吊索应变、固有频率的变化规律。悬索桥结构各种响应对加劲梁损伤的敏感性很低,对加劲梁损伤位置的相关性也不明显。主缆损伤引起的悬索桥结构静动态响应变化最为明显,并且响应的变化对损伤位置和损伤程度都呈现良好的相关性。吊索损伤导致的悬索桥结构响应变化对损伤位置和损伤程度亦呈现良好的相关性,但导致的加劲梁挠度和应变变化幅度很小。

受热复合材料层合板的非线性静动态响应分析

基于高阶剪切变形理论，突出考虑横向正应变和横向剪切应变的影响，对受热和外力联合作用下复合材料层合板的非线性静、动态响应进行分析。动态分析时计及了转动惯量的影响，给出了Ｃ°类有限元公式。文中数值算例同现有文献和三维有限元计算结果进行了比较，证明了本文方法的精确、有效性。文中还对层合反的边界条件、纵厚比及铺设角度对非线性动态响应的影响进行了分析。

液压模块挂车装载方案设计及静动态响应分析

针对重型运输液压模块挂车的合理装载方案设计与静动态响应分析,运用ANSYS与ADAMS之间接口,建立整车刚柔耦合动力学模型,其中把车架看为柔性体。将振动测试实验与仿真计算进行校验,结果表明:仿真计算得到的频谱规律与实验结果比较接近,所建立模型是合理的。由液压悬挂系统的支撑方式与鞍座支架数量及其位置而分为多种装载方案,根据车架有限元静态分析结果,鞍座支架数量为3的装载方案能够满足车架强度要求,且可减少支架数量。考虑挂车在不同路面等级与车速下的运行工况及液压悬挂系统支撑方式,对已选择装载方案的多体动力学模型进行仿真计算,并分析各因素对挂车动态响应的影响。

Dynamic characteristics of coal specimens with varying static preloading levels under low-frequency disturbance load

The mechanical properties of residual coal pillars under the influence of upward mining disturbances significantly affect the safety of residual mining activities on working faces.This study conducted low-frequency disturbance dynamic uniaxial compression tests on coal specimens using a self-developed dynamic-static load coupling electro-hydraulic servo system,and studied the strength evolutions,surface deformations,acoustic emission(AE)characteristic parameters,and the failure modes of coal specimens with different static preloading levels were studied.The disturbance damage is positively correlated with the coal specimen static preload level.Specifically,the cumulative AE count rates of the initial accelerated damage stage for the coal specimens with static preloading level of 60%and 70%of the uniaxial compressive strength(UCS)were 2.66 and 3.19 times that of the 50%UCS specimens,respectively.Macroscopically,this behaviour manifested as a decrease in the compressive strength,and the mean strengths of the disturbance-damaged coal specimens with 60%and 70%of UCS static preloading decreased by 8.53%and 9.32%,respectively,compared to those of the specimens under pure static loading.The crack sources,such as the primary fissures,strongly control the dynamic response of the coal specimen.The difference between the dynamic responses of the coal specimens and that of dense rocks is significant.

Dynamic response and failure behavior of rock under static-dynamic loading

Dynamic response and failure behavior of rock under static-dynamic loading were studied. The effects of initial static load on the total energy dissipated during the failure process of specimen were analyzed. To simulate the engineering situation that in-situ rock experienced and obtain the dynamic loading with an intermediate strain rate, a low cycle fatigue load with the frequency from 0.5 to 5 Hz was adopted by servo-controlled Instron material testing system. The results show that the obtained strain rate increase with the increase of load frequency. The initial static load has great influence on both the energy and dynamic response of rock. Both the energy and the maximum failure load P_f decreases with the increase of initial static load. P_f under the static-dynamic loading is larger than that under only the static loading but less than that under only the dynamic loading. The load-displacement curves become nonlinear as the pre-added static load reaches the transition point which is about one third of static strength. With the increase of initial static load, Young’s modulus decreases and poisson ratio increases. It shows that rock has a lower strength and a tendency to soften under a higher initial static load. Rock may be broken more easily static-dynamic loading than under only the dynamic loading. The proposed method is useful in the investigation of constitutive relationship and failure behavior of rock under quasi-dynamic loading.

Effect of static transmission error on dynamic responses of spiral bevel gears

The effect of static transmission error on nonlinear dynamic response of the spiral bevel gear system combining with time-varying stiffness and backlash was investigated.Firstly,two different control equations of the spiral bevel gear model were adopted,where the static transmission error was expressed in two patterns as predesigned parabolic function and sine function of transmission errors.The dynamic response,bifurcation map,time domain response,phase curve and Poincare map were obtained by applying the explicit Runge-Kutta integration routine with variable-step.A comparative study was carried out and some profound phenomena were detected.The results show that there are many different kinds of tooth rattling phenomena at low speed.With the increase of speed,the system enters into stable motion without any rattling in the region(0.72,1.64),which indicates that the system with predesigned parabolic function of transmission error has preferable capability at high speed.

Lateral static and dynamic characteristics of thin-walled box girder

To analyze the static and dynamic behaviors of the thin-walled box girder in its lateral webs in consideration of shear lag effect and shear deformation, an approach based on the minimum potential principle is introduced in this paper. Both static and dynamic response equations as well as the corresponding natural boundary conditions of the box girder are deduced. Meanwhile, three generalized displacement functions： w （x） , U（x） and O（x） are employed and their differences in the calculus of variation are quantitatively investigated. The comparison of finite shell element results with analytical results of calculation examples validates the feasibility of the proposed approach.