轿车发动机机械损失的降低

机械损失对现代车用发动机燃料经济性的影响很大，轿车发动机因为其经常在很小的负荷率下运行，故障低机构损失的对改善其油耗和排放将更大的效果，分析了轿车发动机基本参数，零部件设计等对摩擦损失的影响，提出了降低其机械损失的若干措施。     

火灾受损桥梁检测评估与加固处理

介绍回弹 超声综合法在检测评定桥梁结构遭受火灾损伤中的应用。结合实例,给出应用碳纤维布补强技术对其加固处理的方法,并通过桥梁静载试验证实加固取得了很好的效果,其思路可为处理同类病害的桥梁提供有益的参考。     

撞击参数对双层舷侧结构碰撞响应的影响

深入了解船体结构碰撞损伤特性和能量吸收机制是开展船舶耐撞性优化设计的前提。文章利用显式非线性有限元数值仿真技术对不同撞击条件下的双层舷侧结构碰撞响应进行了系列研究。研究结果表明：撞击位置、撞击角度和撞击速度的改变可能导致不同的碰撞损伤过程或结构损伤变形。     

Mechanical Behaviors and Design Parameters of Segmental Tunnel Linings with New Type of Joints北大核心CSCD

Segmental linings in shield tunnelling are composed of segments and joints. Mechanical behaviors of the joints govern overall behaviors of tunnel linings. Two new types of joints are adopted in Shanghai Metro Line 18, including the fast-insertion joints for adjacent rings, and the fast-slide joints for adjacent segments. In order to explore the overall behavior of segmental linings with these new types of joints, the full-scale tests are carried out for new lining structure with aligned and staggered longitudinal joints. The mechanical behaviors of the tunnel linings under different loading conditions are obtained. Furthermore, the calculation models of the tunnel linings are discussed, and regarding the modified routine method, the structural design parameters under different loading conditions are calculated, which provides a reference for the design and the comparison of the assembly method of the tunnel linings with new types of joints. © 2018, Editorial Office of "Modern Tunnelling Technology". All right reserved.     

典型生产工艺对无碳化物贝氏体钢轨组织与性能的影响

基于矫直、回火和在线热处理3种典型钢轨生产工艺,采用不同工艺组合工业试制5种无碳化物贝氏体钢轨;基于扫描电子显微镜、透射电子显微镜、背散射电子衍射法和X射线衍射法,分析无碳化物贝氏体钢轨的微观组织;采用布氏硬度、单轴拉伸、锯切应变片法、冲击韧性、断裂韧性和疲劳裂纹扩展速度测试等试验,研究典型生产工艺对无碳化物贝氏体钢轨组织和力学性能的影响。结果表明:矫直使无碳化物贝氏体钢轨中的残余奥氏体体积分数自12.44%降至10.6%,有利于促进亚稳态残余奥氏体的转变;回火稳定残余奥氏体,提升冲击韧性20%以上;在线热处理降低残余奥氏体体积分数,提高屈服强度19%以上,尤其能提高抗拉强度和冲击韧性,对轨底残余应力的影响不大。据此,为了综合提升无碳化物贝氏体钢轨的耐磨性和抗接触疲劳性能,在提高屈服强度和抗拉强度的同时增大残余奥氏体体积分数,以提升加工硬化能力和塑性。     

服役海上结构物破损状态评估研究

对现有的各种结构破损状态评估方法进行了综述和分析对这些方法在受损船舶和海洋工程结构中的应用作了一些探讨，并尝试用模糊数学方法估算了服役海上结构物的破损状态。最后对模糊数学和专家系统方法在服役海上结构物破损状态评估中的应用前景进行了探讨。     

探讨山洪灾害对公路桥梁的破坏与对策

文章结合山洪对公路拱桥、梁桥两类桥型的上构破坏形式及机理进行分析,提出相应对策,供公路设计和养护部门参考。     

非对称小净距隧道施工力学特性研究及方案优化

非对称小净距隧道合理的开挖顺序对隧道围岩稳定和支护措施优化有很大的影响。文章结合净距2.0 m非对称公路隧道工程实践,通过二维弹塑性有限元数值仿真模拟,研究分析了隧道开挖顺序对支护力学行为特性及围岩稳定性的影响,得出了先开挖较小断面隧道优于先开挖较大断面隧道的结论,为非对称小净距隧道优化设计和施工提供了科学依据。     

土工带物理力学性能的探讨

文章结合广东河(源)龙(川)高速公路工程实例,通过对不同荷载下的土工带的拉伸试验,得出土工带在加载过程中的变形规律,为加筋结构的计算、以及加筋材料在工程上的应用提供参考。     

A comparative study on damage assessment of tubular members subjected to mass impact

This paper focuses on the behaviour of tubular members when subjected to low-velocity mass impact. Particular emphasis is given to the numerical assessment of impact damage and the classification of impact response of tubular members. Damage extents of 12 tubular frame test models were predicted and used for quantifying the modelling uncertainties of the numerical tools. USFOS and ABAQUS software packages were used with beam and shell elements, respectively. Based on the test results and the parametric studies performed, the influence of the geometrical parameters and the interaction between the local shell denting and the global beam deformation modes are discussed. A classification of the impact response of the tubular members based on their relative resistance against shell denting and beam plastic collapse load is proposed. Finally, existing analytical models for each energy dissipation mode are visited and modifications are proposed.