沥青层底裂缝几何函数和权函数分析

为了更好分析沥青路面的裂缝开裂问题，以裂缝面受均匀拉应力为参考荷载，利用有限元方法计算出不同沥青层底裂缝长度的应力强度因子，从而得到不同裂缝长度的离散几何函数值，再根据这些离散几何函数值，为沥青层底裂缝拟合出了3个几何函数F(a/b）。并利用另外两种荷载对这3个几何函分别进行了检验，用3个数根据汉函数理论计算出的应力强度因子和有限元计算出的应力强度因子在所有计算范围内都吻合得很好。利用这几何函数得到了裂缝所有计算范围的权函数，并绘图进行了对比分析。     

港区道路交叉口几何线形安全设计研究

针对港口交通构成以大型货车为主的交通特性,从平面、竖向以及平纵组合角度对港区道路平面交叉口的几何线形安全设计进行研究,以保障港区道路平面交叉口安全,降低事故率及事故伤害。     

套筒滚子链条链节的联接固度及其影响因素分析

链节的联接固度对链条的使用寿命影响很大，通过对销轴与链板配合过盈量、链板孔和销轴的几何形状误差、链板硬度、链节静配合连接中的比压等的分析研究，提高了链节的连接固度。     

Nonlinearity in the vertical transmissibility of seating: the role of the human body apparent mass and seat dynamic stiffness

The efficiency of a seat in reducing vibration depends on the characteristics of the vibration, the dynamic characteristics of the seat, and the dynamic characteristics of the person sitting on the seat. However, it is not known whether seat cushions influence the dynamic response of the human body, whether the human body influences the dynamic response of seat cushions, or the relative importance of human body nonlinearity and seat nonlinearity in causing nonlinearity in measures of seat transmissibility. This study was designed to investigate the nonlinearity of the coupled seat and human body systems and to compare the apparent mass of the human body supported on rigid and foam seats. A frequency domain model was used to identify the dynamic parameters of seat foams and investigate their dependence on the subject-sitting weight and hip breadth. With 15 subjects, the force and acceleration at the seat base and acceleration at the subject interface were measured during random vertical vibration excitation (0.25–25 Hz) at each of five vibration magnitudes, (0.25–1.6 ms^?2 r.m.s.) with four seating conditions (rigid flat seat and three foam cushions). The measurements are presented in terms of the subject's apparent mass on the rigid and foam seat surfaces, and the transmissibility and dynamic stiffness of each of the foam cushions. Both the human body and the foams showed nonlinear softening behaviour, which resulted in nonlinear cushion transmissibility. The apparent masses of subjects sitting on the rigid seat and on foam cushions were similar, but with an apparent increase in damping when sitting on the foams. The foam dynamic stiffness showed complex correlations with characteristics of the human body, which differed between foams. The nonlinearities in cushion transmissibilities, expressed in terms of changes in resonance frequencies and moduli, were more dependent on human body nonlinearity than on cushion nonlinearity.     

单层球面网壳的最不利地震作用分析

同时考虑几何非线性与材料非线性,对单层球面网壳在地震作用下结构的最不利荷载进行分析。通过对场地卓越周期及地震波平台段持时的研究,建立结构动力响应与场地卓越周期及地震波平台段持时之间的关系,明确了何种条件下的荷载为结构最不利外荷载。     

光纤非线性偏振耦合引起偏振态抖动的研究

研究了光纤非线性偏振耦合引起的偏振态抖动的现象，从理论上导出了基于NRZ码的偏振复用系统中偏振度降低与两路调制信号的时域波形及他们的初始相位差之间的关系．对于100Gb／s的偏振复用系统进行了理论仿真，结果表明：只有当二路调制信号的光功率相等且初相位差为零或者π/2时，所引起的偏振态抖动最小．     

阀控非对称缸位置系统的非线性建模

针对伺服阀控非对称液压缸系统存在的非线性特性,根据液压系统工作原理,应用功率键合图建模理论,建立了阀控非对称缸位置系统的键合图模型.通过模型仿真及试验结果对比,验证了模型的准确性,为应用各种控制策略改善系统性能提供了理论基础.     

Locomotive dynamic performance under traction/braking conditions considering effect of gear transmissions

Traction or braking operations are usually applied to trains or locomotives for acceleration, speed adjustment, and stopping. During these operations, gear transmission equipment plays a very significant role in the delivery of traction or electrical braking power. Failures of the gear transmissions are likely to cause power loses and even threaten the operation safety of the train. Its dynamic performance is closely related to the normal operation and service safety of the entire train, especially under some emergency braking conditions. In this paper, a locomotive–track coupled vertical–longitudinal dynamics model is employed with considering the dynamic action from the gear transmissions. This dynamics model enables the detailed analysis and more practical simulation on the characteristics of power transmission path, namely motor–gear transmission–wheelset–longitudinal motion of locomotive, especially for traction or braking conditions. Multi-excitation sources, such as time-varying mesh stiffness and nonlinear wheel–rail contact excitations, are considered in this study. This dynamics model is then validated by comparing the simulated results with the experimental test results under braking conditions. The calculated results indicate that involvement of gear transmission could reveal the load reduction of the wheelset due to transmitted forces. Vibrations of the wheelset and the motor are dominated by variation of the gear dynamic mesh forces in the low speed range and by rail geometric irregularity in the higher speed range. Rail vertical geometric irregularity could also cause wheelset longitudinal vibrations, and do modulations to the gear dynamic mesh forces. Besides, the hauling weight has little effect on the locomotive vibrations and the dynamic mesh forces of the gear transmissions for both traction and braking conditions under the same running speed.     

鄂东长江公路大桥活载非线性效应与试验分析

为了分析几何非线性对大跨度斜拉桥的活载效应的影响程度,以鄂东长江公路大桥(主跨926m的双塔双索面混合梁斜拉桥)为背景,利用MIDAS Civil软件建立全桥有限元模型,分别计算该桥在活载作用下考虑非线性效应与不考虑非线性效应的结构内力及位移,并与全桥荷载试验实测结果做对比分析。结果表明:对于鄂东长江公路大桥这样超大跨度的斜拉桥,活载的非线性计算结果更加符合大跨度斜拉桥的实际响应,线性计算结果误差较大,且偏于不安全。     

高烈度区高墩桥梁抗震措施研究

为研究高烈度区(设防烈度8.5度)高墩桥梁抗震措施,以位于高烈度区的某高墩桥梁为例进行分析。建立该桥所有联的线弹性计算模型,进行动力特性分析和反应谱分析。分析结果表明:支座顶面与梁底面发生了相对滑移,支座剪切变形较大,存在落梁隐患。在该桥上设计合适的顺桥向连梁装置、横向弹塑性挡块等抗震措施后,通过非线性时程分析验证其抗震效果。分析结果表明,采用的抗震措施可有效地控制墩顶位移、减小地震反应。