为了对钢-混凝土组合梁在疲劳荷载作用下的弹性挠度和残余挠度分析,建立了组合梁疲劳荷载下的非连续传力模型.通过建立钢材和栓钉等材料的疲劳损伤退化模型,对组合梁在疲劳荷载情况下沿梁长方向的滑移分布情况和跨中挠度进行了计算.结合不同连接程度的组合梁疲劳试验数据,进行了参数分析,并验证了方法的可靠性.提出了疲劳荷载作用下钢-混凝土组合梁变形计算公式,采用该模型计算的滑移值、弹性挠度值与试验值有较高的吻合度.当考虑沿梁长方向各排栓钉的刚度退化情况时,对于组合梁变形计算有较大的影响.通过混凝土承担的轴力和弯矩可知,疲劳荷载作用下,栓钉承载能力降低造成组合梁截面曲率增大,刚度降低,自身截面刚度的退化影响较小.计算结果表明:在疲劳荷载加载时,组合梁界面栓钉出现剪力重分布现象,跨中栓钉承担的剪力由小变大,靠近梁端栓钉承担的剪力由大变小,且呈非线性变化趋势.当接近组合梁疲劳寿命时,组合梁跨中变形、截面滑移都呈指数型上升趋势.当达到疲劳寿命时,梁端栓钉承担的剪力急剧下降,最终造成以栓钉剪切疲劳破坏形式的组合梁疲劳破坏.该方法可供实际试验和工程实际参考.
为分析钢-混凝土组合梁在分别承受正弯矩和负弯矩2种荷载下的破坏形式和受力性能,设计制作了2片组合梁试件并进行了相关试验研究.试验表明,2种荷载模式下,组合梁受力均呈现出弹性、弹塑性和破坏3个阶段,且组合梁在负弯矩荷载作用下更易引起开裂.同时,2种荷载模式下的界面滑移分布规律不一致,正弯矩作用下的相对滑移最大值出现在靠近梁端处,而负弯矩作用下的相对滑移最大值出现在跨中处.
Based on analytic hierarchy process(AHP),a linear quadratic and Gaussian distributed(LQG) controller for active suspension was designed,it could depress body acceleration(BA),suspension working space(SWS) and dynamic tyre displacement(DTD).A 2-DOF dynamic model of a 1/4 vehicle passive and active suspension was firstly established.Then,weighted coefficients of all performance evaluation indicators were determined by adopting AHP and a LQG controller for a vehicle active suspension system was designed by using the optimal control theory.Finally,the model was simulated and analyzed under Matlab/Simulink environment.The comparision of simulation results illustrated that with proper selection of weighted coefficients,the BA,SWS and DTD of the active suspension are 18.73%、22.22% and 4.76% lower than those of the passive one,the RMS of active control force is 535.3994 N.
<正>随着石油危机、环境污染的日益严重和电池技术的显著提高,电动汽车已成为未来汽车工业发展的方向。为了适应这个发展趋势,世界各国的政府、学术界、工业界正在加大对电动车开发的投资力度,加快电动车的商品化步伐。我国现已形成以纯电动汽车、混合动力汽车、燃料电池车为
Based on finite element theory,the 3D model of a bearing block was established with ANSYS software.By using Block Lanczos method,the modal analysis of the bearing block was carried out and the first four natural frequencies and vibration modes were obtained.The results provide a guidance for the optimization design and dynamics analysis of the bearing block.
为缩短设计周期、提高产品质量并降低产品开发成本,文中利用ADAMS软件建立汽车双横臂独立悬架模型并进行仿真分析,研究了车轮定位参数随车轮跳动的变化规律,并据此对悬架定位参数进行了优化设计。
