轿车地毯材料热学性能研究

采用差示扫描量热(DSC)法对3种不同组分的轿车地毯复合材料的热物性参数一比热进行了测试。基于对试验结果的对比分析，探讨了，影响轿车地毯复合材料热学性能的因素及原因，并建立了轿车地毯复合材料热学性能的数学模型，为轿车地毯热成型工艺和模具设计提供了基础性数据。     

旧水泥混凝土路面沥青加铺层温度应力有限元分析

文章基于路面温度场理论,采用ANSYS程序建立旧水泥混凝土路面沥青加铺层结构温度应力有限元模型,分析了降温幅度、加铺层厚度和土工布夹层材料模量及典型防止反射裂缝措施对旧路接缝处沥青加铺层底温度应力的影响,为选择合理材料和设计参数进行沥青加铺层设计提供参考。     

柴油机活塞的低周热疲劳寿命预测与安全性评价

运用ＡＤＩＮＡＴ和ＡＤＩＮＡ程序计算了１２Ｖ１８０和４２－１６０柴油机活塞的轴对称温度场和循环弹塑性应力应变场以及Ｍｉｓｅｓ当量应力应变场。根据“起动－停车”波形，采用带环状缺口的圆柱形试件，进行了热疲劳和高温低周疲劳模拟试验试验和计算表明：当量应变范围与疲劳寿命之间存在着Ｍａｎｓｏｎ－Ｃｏｆｆｉｎ公式关系，且不受试件结构形状和尺寸的影响；     

用热喷涂层防止锰铜合金螺旋桨腐蚀的研究

对锰铜合金螺旋桨表现热涂涂层的性能进行了试验，并对采用热喷涂涂层防止螺旋桨腐蚀的可行性进行了研究。试验结果表明：采用高速氧燃料喷涂技术形成的Ｃｕ９５超涂层人有优良的耐空蚀，耐海水腐蚀性能，可作为锰铜系合金螺旋桨表面的防腐涂层。     

主机废热利用系统探讨

从主机废热利用系统的组成与基本原理入手,研究了系统的流程,分析了系统的经济性。最后得出结论：主机废热利用系统的实质就是提高燃油利用率。     

多年冻土隧道工程中的隔热层参数优化设计研究

隔热层经常被用于多年冻土隧道中,来防止隧道结构的冻融破坏。文章根据多年冻土特点及优化理论,推导了多年冻土隧道隔热层的数学优化模型;并以风火山隧道为例进行求解,分析研究了隔热层用于多年冻土隧道的合理性和经济性。结果表明,该多年冻土隧道隔热层的数学优化模型是合理的,求解方法是可行的;对于多年冻土隧道,地表温度对隧道围岩影响深度是有限的,因此多年冻土隧道隔热层应根据隧道埋深、年平均温度以及年较差分段设计,才能达到既合理又经济的目的。     

一种新型电弧喷涂气缸套的工业化应用及质量检测方法

近年来,随着全球变暖问题日趋严重,各大汽车制造商正在采用各类技术减少发动机油耗及尾气排放。作为减少发动机重量、增强发动机缸体内壁耐磨性能、减少摩擦力的新技术,气缸套热喷涂沉积技术成为了节能减排的重要技术手段。文章首先介绍了气缸套热喷涂技术的原理、加工工序以及几种常用的热喷涂沉积技术,而后引出了对一种新型电弧喷涂气缸套的工业化应用的介绍,进而重点阐述了某品牌汽车发动机制造厂商技术人员对新型电弧喷涂气缸套的质量检测方法。     

On maximum forces exerted by floating ice on a structure due to constrained thermal expansion of ice

The problem of interaction between a floating ice cover and an engineering structure is considered, in which the ice–structure contact forces are caused by an increase in ice temperature due to solar radiation in situations, when the lateral thermal expansion of ice is constrained. The focus is on the determination of the maximum thermally-induced horizontal force exerted on a structure wall, assuming that the magnitude of this force is bound by the smallest force capable of fracturing the ice cover due to its buckling. The ice cover is modelled as a rectangular plate of uniform thickness, with its four edges being constrained by vertical rigid walls, and it is assumed that ice deforms, and eventually fails, by the mechanism of viscous creep buckling. The plate is subjected to in-plane axial compressive stresses developing in ice to prevent its thermal expansion due to solar heating, and is transversely (vertically) bent by the forces caused by the reaction of underlying water. The floating ice is treated as a material whose elastic and viscous properties depend on temperature and the ice porosity, and therefore they vary with time and the depth of ice. The results of numerical simulations, conducted for a variety of the ice plate horizontal dimensions, thicknesses and daytime temperature-change scenarios, illustrate the evolution of the plate deflection surface prior to its failure, and show the time variation of the maximum forces exerted by ice on a structure wall as functions of the ice thickness and maximum daytime temperature rise at the top surface of ice.     

Stress and failure analyses of thermoplastic composite pipes subjected to torsion and thermomechanical loading

The interest of using thermoplastic composite pipes has increased in offshore deepwater oil fields. Thermoplastic composite pipes consist of several carbon/glass fiber reinforced laminate layers to confer stiffness and strength located between inner and outer homogeneous thermoplastic layers for fluid containment and protection. This paper presents a theoretical analysis for thermoplastic composite pipes under combined pure torsion and thermomechanical loading from operational thermal gradients, considering the inner and outer isotropic homogeneous layers and intermediate transversely isotropic laminate ply layers. Perfect bond between adjacent layers and interfaces continuities are assumed. Based on the obtained stresses in the principal material directions, through-thickness failure indexes related to the von Mises and Maximum Stress or Tsai-Hill criteria are respectively evaluated for homogeneous and laminate layers. For each thermal gradient, the limit torque (i.e. when the failure index is equal to 1) is calculated. From the case study, it is observed that without thermal loading or for small operational temperature, failure occurs in the laminate, otherwise it is observed in the inner homogeneous layer. The thickness of the homogeneous layer significantly affects the limit torque and the absolute values of the limit clockwise and anticlockwise torque slightly differ when the operational temperature is included.     

Size effect on residual stress in low transformation temperature welded joints

It has been reported that low transformation temperature (LTT) weld metals are beneficial to generation of compressive residual stress around weld zone. In this study, the relationship among residual stress, size effect of LTT welded joints with different plate width and thickness as well as martensite start (Ms) temperatures was investigated by experimental and finite-element analysis. It was found that heat dissipation and thermal expansion coefficient of LTT weld metal had a significant impact on residual stress. Welded joint with a small plate width led to greater compressive residual stresses in the LTT weld, which was due to the lower heat dissipation and smaller thermal expansion coefficient of the LTT weld metal in due course of cooling process. Additionally, the finite-element analysis revealed that increasing plate width mainly affected the longitudinal residual stress, while increasing the plate thickness influenced all the residual stress components in the LTT weld. Furthermore, the LTT weld with a lower Ms temperature of 191 °C resulted in greater compressive residual stresses, and was less sensitive to the LTT joint size, as against the Ms temperature of 398 °C.