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981.
982.
983.
《Vehicle System Dynamics: International Journal of Vehicle Mechanics and Mobility》2012,50(9):1227-1246
The influence of the tyre–road contact model on the simulated vertical vibration response was analysed. Three contact models were compared: tyre–road point contact model, moving averaged profile and tyre-enveloping model. In total, 1600 real asphalt concrete and Portland cement concrete longitudinal road profiles were processed. The linear planar model of automobile with 12 degrees of freedom (DOF) was used. Five vibration responses as the measures of ride comfort, ride safety and dynamic load of cargo were investigated. The results were calculated as a function of vibration response, vehicle velocity, road quality and road surface type. The marked differences in the dynamic tyre forces and the negligible differences in the ride comfort quantities were observed among the tyre–road contact models. The seat acceleration response for three contact models and 331 DOF multibody model of the truck semi-trailer was compared with the measured response for a known profile of test section. 相似文献
984.
《铁道标准设计通讯》2013,(5)
针对某桥预应力混凝土连续梁出现的开裂情况,从设计、施工和运营等环节进行裂缝成因分析,并按照开裂后的截面对结构的安全可靠性进行分析评价。分析表明,梁体结构设计合理;运营阶段超载是导致开裂的主要原因;开裂截面检算表明梁体仍满足规范规定的B类部分预应力结构的要求;限制超载,并对裂缝进行封堵后,梁体结构可满足正常运营要求。 相似文献
985.
《Vehicle System Dynamics: International Journal of Vehicle Mechanics and Mobility》2012,50(8):713-737
A classification of wheel flats according to the different stages of their growth is given, along with the characteristic features of the dynamic wheel–rail interaction for each category. Mathematical expressions and frequency spectra of the corresponding wheel mass trajectories are derived. Difference is made between the subcritical and the transcritical speed regime. A criterion is derived for contact loss for worn flats. Simulations show that the dynamic wheel–rail interaction is governed by the track stiffness for low train speeds or long flat lengths; for high speeds and/or short flat lengths the interaction is governed by the inertial properties of the wheel and the rail. For a given flat geometry, nonlinearities in the relationship between the impact magnitude and the train speed occur in the stiffness-dominated speed domain, whereas this relationship is approximately linear in the inertia-governed domain. In the latter domain, the impact magnitude is found to be linearly dependent upon the maximum trajectorial curvature or inversely linearly dependent on the minimum circumferential wheel tread curvature. The above relationships are valid for the subcritical speed regime, in which no contact loss occurs. Different contributions from the literature are compared with respect to the established relationship between impact magnitude and speed. Significant differences are found, due to insufficiently defined parameters and conditions. Conditions are derived for a consistent application of the so-called equivalent rail indentation in experiments with wheel flats, and the indirect strain registration method for measuring dynamic wheel–rail contact forces is reviewed. 相似文献
986.
987.
预应力锚索广泛应用于软岩、土体边坡加固及明挖隧道支撑体系等工程中。以成绵乐铁路客运专线双流机场隧道大跨段锚索支撑体系工程为依托,分析了拉力分散型预应力锚索在明挖隧道深基坑支撑体系中的受力特点及工作原理,以及新型锚索应用的施工技术要点和施工工艺。 相似文献
988.
简支梁桥上无缝道岔温度力与位移影响因素分析 总被引:13,自引:1,他引:12
将道岔、梁和墩台视为一个系统,建立简支梁桥上无缝道岔的有限元模型。根据变分原理和“对号入座”法则建立有限元方程组。以铺设一组43号道岔的18跨32 m混凝土简支梁桥为例,研究影响简支梁桥上无缝道岔受力与位移的因素,如支座布置形式、轨温变化幅度、梁温差、扣件阻力、道床阻力、限位器间隙、岔枕刚度、限位器位置、梁跨长度和桥墩刚度等。计算结果表明,简支梁桥上无缝道岔在温度荷载作用下,钢轨温度力在限位器处和限位器前梁端处同时出现两个峰值;与桥上无缝线路相比,桥上无缝道岔桥墩处的最大受力显著增大;当梁与导轨同向伸缩时,岔区内钢轨位移较大;限位器应布置在梁跨中部;限位器间隙对桥上无缝道岔的受力与位移有双重影响;岔区内钢轨的受力与位移随桥墩刚度增大而减小;岔区内采用较大的扣件阻力和道床阻力,岔区外采用较小的扣件阻力和道床阻力,可以降低钢轨附加温度力。 相似文献
989.
采用有限元分析程序提取了平台的各阶自振频率,以有效模态质量参与系数作为模态选择的依据,对随机波浪力作用下考虑结构与水耦合的的动力响应进行计算,并分析了附连水质量及动水阻尼对结构随机动力响应的影响。通过施工平台静、动力计算结果的比较,建议在进行施工平台的设计时,应充分考虑到波浪力的动力效应。 相似文献
990.
结合淮安三线船闸的施工实践,通过现场试验的方法,对非对称型钢板桩、地下连续墙、预应力土层锚杆等背拉弹性薄壁墙受力结构的施工方案、质量控制技术等进行分析研究,为推广应用设计技术提供了科学依据。 相似文献