动态载荷下半刚性路面应力分析

针对半刚性路面的特点,依据弹性层状体系理论,将半刚性路面的沥青层、半刚性基层、半刚性底基层及土基层按线弹性来考虑,建立了半刚性路面的三维有限元分析模型,采用ANSYS有限元分析软件分析了动态荷载下半刚性路面的应力特性。结果表明,路面的疲劳破坏是动载引起的水平应力、横向应力和垂直应力共同作用的结果,水平应力的交变变化是使路面产生疲劳破坏的主要因素。在一定的车速下,随着载荷的增加,半刚性底基层底部的最大水平拉应力增大;在一定的载荷下,随着行车速度的提高,半刚性底基层底部的最大水平拉应力减小,提高行车速度可以减小路面的损伤程度。     

Dynamic Response Analysis of Fuzzy Stochastic Truss Structures under Fuzzy Stochastic Excitation

A novel method (Fuzzy factor method) is presented, which is used in the dynamic response analysis of fuzzy stochastic truss structures under fuzzy stochastic step loads. Considering the fuzzy randomness of structural physical parameters, geometric dimensions and the amplitudes of step loads simultaneously, fuzzy stochastic dynamic response of the truss structures is developed using the mode superposition method and fuzzy factor method. The fuzzy numerical characteristics of dynamic response are then obtained by using the random variable’s moment method and the algebra synthesis method. The influences of the fuzzy randomness of structural physical parameters, geometric dimensions and step load on the fuzzy randomness of the dynamic response are demonstrated via an engineering example, and Monte-Carlo method is used to simulate this example, verifying the feasibility and validity of the modeling and method given in this paper.     

风作用下缆船拖带非线性系统运动数值模拟

基于船舶操纵性运动方程和拖缆的三雏动力学运动方程，提出了被拖点位置匹配的方法，建立了拖船-拖缆-被拖船系统的非线性整体拖带动力学模型．为了考察被拖船航向稳定性与横向稳性的关系以及风栽荷作用的影响，被拖船采用水平面四自由度运动方程，并引入了风的作用力和力矩．拖船采用PD控制方法较真实地模拟了拖船航向改变的运动过程．对一个拖船拖缆被拖船系统（5000t的拖船和3000t的被拖船）在时域内进行了风作用下拖带运动的模拟．计算结果表明，风力增大拖带航向稳定性降低，拖带航向稳定是横向稳的必要条件．数值计算结果归纳出判别被拖带船航向稳定性的极坐标图，该极坐标图表明顶风航行较顺风具有较强拖带航向稳定能力，但是拖带航向稳定性区域很小，而顺风和顺斜风拖带比顶斜风具有更大的拖带航向稳定性区域．     

镍基熔覆涂层受冲击载荷作用下的性能研究

45钢及1Cr18Ni9Ti表面激光熔覆WFCL-11涂层，研究了激光熔覆涂层与基体界面及表面显微组织和硬度特点，分析在冲击载荷作用下，显微组织、结合性能、硬度变化等特点。发现了不同基材与熔覆材料对结合面性能的影响。     

首钢新建35000m^3／h空分设备的流程及特点

简介了首钢氧气厂新建35000m^3／h空分设备的工艺流程及技术参数，详细分析了常规变负荷和快速变负荷调节时空分设备的运行工况以及快速变负荷调节时的工艺特点。     

锚杆拉拨力影响因素的数值试验研究

判断锚杆拉拔力的大小是锚固支护中的重要问题之一。它涉及到岩石、粘结剂和钢筋材料的性质以及在受力过程中材料之间的相互作用。尝试采用适用于进行非线性、非连续介质复杂机理研究的“岩石破裂过程分析”（RFPA）系统，用正交试验方法进行了一系列数值试验，对影响锚杆拉拔力的6个因素进行了分析研究，并与有关物理试验结果进行了对比，得出几点有参考意义的结论。     

The Post-Yield Behaviour of an Internally Pressurised Cylinder having a Pad Attachment

Abstract:  A study of pressurised cylinders having attached pads was made. The possibility of a fatigue crack developing along one side of the pad was noted. For both defect-free components and components having axial crack-like defects, finite element and limited experimental studies of the local and global deformations were made and results were found to be in close agreement. Both welded and integrally machined pads were studied. It was observed that for defect-free components, the method of pad attachment has little effect on the burst pressure. The presence of a pad was found to increase the burst pressure of cracked components by a small but significant margin. A finite element-based parametric study of pipes with part-penetrating defects and a range of pad geometries has demonstrated that pad size has little influence on the limit load for any of the cracked cases considered. However, pipes with penetrating defects were strengthened by the presence of pads, particularly for thin-walled sections.     

Load combination analysis by ‘Directional simulation in the load space’

The reliability of structures subjected to multiple time-varying random loads is considered herein. It is well-known that the reliability of such systems may be evaluated by considering outcrossings of the load process vector out of a safe domain, and the contribution of individual loads to structural failure may be evaluated by considering outcrossings caused by combinations of one or more loads. In this paper the ‘Directional Simulation in the Load Space’ approach to reliability analysis is developed to consider explicitly outcrossings caused by all possible combinations of loads, during analysis of systems comprising stationary continuous Gaussian loads. To do this, the direction of the load process vector is ‘fixed’ at each point of outcrossing (to physically represent the particular combination of loads causing the outcrossing), and, by considering each possible load combination, all loads not causing an outcrossing are then held constant during radial integration (to model correctly that they do not contribute to each outcrossing). A numerical example demonstrating the validity of the proposed formulation is presented.     

Fully plastic analyses for notched bars and plates using finite element limit analysis

In the present work, fully plastic analyses for notched bars and (plane strain) plates in tension are performed, via finite element (FE) limit analysis based on non-hardening plasticity, from which plastic limit loads and stress fields are determined. Relevant geometric parameters are systematically varied to cover all possible ranges of the notch depth and radius. For the limit loads, it is found that the FE solutions for the notched plate agree well with the existing solution. For the notched bar, however, the FE solutions are found to be significantly different from known solutions, and accordingly the new approximation is given. Regarding fully plastic stress fields, it is found that, for the notched plate, the maximum hydrostatic (mean normal) stress overall occurs in the center of the specimen, which strongly depends on the relative notch depth and the notch radius-to-depth ratio. On the other hand, for the notched bar, the maximum hydrostatic stress can occur in between the center of the specimen and the notch tip. The maximum hydrostatic stress for a given notch depth can occur not for the cracked case, but for the notched case with a certain radius. This is true for both bars and plates. For a given notch radius, on the other hand, the maximum hydrostatic stress increases monotonically with the decreasing notch radius.