Calculation of Transient Stress Field During Laser Transformation Hardening Process

IntroductionHighpowerCOzlaserssdsetransformationhardeningtechniquehasbeensuccessfullyusedinindusnyforWYears.BecausethetemPeratUrefleldislocalizedinmaterialdurllglasertransfonnationhMngProcess,highthermstrCsswillgenerateinmatgrialduringlasertfansformationhardeningProcess.Therisalsohighresidualstressinmaterial,bothintCnsionandcomPression['-'].ComPressresidualstressishelptoincreasethefatigueldrimeofthelasertreatedmaterial,butthetensilestresswillshortenthefatiguelifetmeofthelasertreatedmator…     

Finite Element Method Analysis of Stress Field Considering Thermal Coupled Force During Laser Process

IntroductionLaserphasetransformationhardeningisanewtechnologyduringwhichlaserheatresourceactsdirectlyonsurfaceofmaterialandcompositionscharacteristicofmaterialischanged.Thetechnologyproce8sesacharacterofrapidheatvelocity,highheattempelatureandquickcoolingspeed(l0'col0'aC/s).Thecompositionandcharacteristicofmaterialvariedwithvariousinnertemperaturewillleadtothermalresidualstress.Itiswellknownthattheresidualstressaffectssignificantlyoncharacteristicofmaterial,suchasimProvingstrengthoffatigUere…     

Computer Prediction on Stress Distribution During Laser Quenching

IntroductionInprocessofindustry,theproblemscoupIedwiththermaIandfOrceareusuaIIymet.LaserqueIlchinginvolvingphasetransformationisoneofthem.HowtosetupafitmatheInatica1modeltosimulatetl1elaserquenchingprocessandhowtocalculateandanalyzenumericallythestresgdistributionarefolIowedwithinterestbymanyresearchersIl'2'3J.Thoseeffol'tsareimportanttooPtilnizethetechnologyparametersandprovideareliablebasisforimprovingthesyntheticallymechanicspropertiesandtheuseagesofmaterials.Alongwithdevelopmentofcomp…     

送粉激光熔覆温度场数值分析

在ANSYS平台上,建立了瞬态三维送粉激光熔覆熔池温度场的物理模型,对在特种钢材34CrNiMo为基材上进行Ni基粉末激光熔覆的过程进行了数值模拟.使用生死单元法来模拟熔覆粉末在熔池形成前后与熔池的交互作用,计算出了激光熔覆熔池的自由表面形状、熔池温度场.计算所得熔池截面形状与试验熔池截面形状基本吻合,证明所建立的瞬态三维激光熔覆熔池温度场的物理模型是正确合理的.     

磨削淬火技术的温度场仿真研究

目前对磨削淬火的研究,多采用实验的方法,通过大量的实验来制定合适的工艺参数,但由于磨削加工的复杂性,常使得实验研究带有一定的偶然性和盲目性.文中对影响磨削淬火工艺的关键因素——温度场,利用有限元方法进行了仿真研究,得到了磨削温度场的等温线图和工件各处的温度变化历程,预测了工件表层是否发生马氏体相变及相变层厚度,并进行了实验验证.研究表明,磨削淬火技术可以替代常规表面淬火工艺,利用磨削温度场仿真技术可以减少实验量、节省实验费用.     

Application of Computer in the Design of Process Thermal Cycle of Steel

IntroductionSteelingot.steelslabbecomest6elproductsafterheatingandrollingorforging.Steelproductsofforgingneedtobeheattfeatedinheattreatingfumace,fOrexampleannealingnormalization.Heattreatinentcandecreasestress,reducehydrogenconcentrationandimprovetheorganizationandperformanceofsteel.Everyprocessofproductionthatsteelingotschangeilltosteelproductsisaprocessofthermalcycleofsteel.Thisprocesswillconsumealargeamountofeneasmaterialandequipment.Inthepast,inmetallurgicalenterpriseofourcountrythetimeo…     

非均匀变温场中主缆初始位形的迭代计算

利用解析法推导了变温度场中悬索桥空缆线形的悬链线线形公式;建立了两种已知设计条件时悬索桥空缆线形的迭代方法;根据主缆的温度变化方程导出了温度变化时无应力索长计算公式。计算结果表明:在非设计温度下,主缆的位形及其内力值均与设计理论值有较大误差,因此在悬索桥的结构分析中必须考虑温度变化的影响。     

Computer simulation of the continuous annealing recrystallization for cold-rolled strip in galvanizing line

The continuous heating transformation program is developed to investigate the influence of continuous annealing technological parameters on recrystalization for cold-rolled strip in galvanizing line. This program can be used for the calculation of the continuous annealing temperature field of strip steel, determination of the start and end time of recrystallization in continuous heating process, and procurement of the continuous heating transformation diagram. The temperature field for continuous annealing is simulated by means of finite difference method. Based on the Scheil superposition principle, the continuous heating transformation curve is obtained by using time temperature transformation (TTT) curve which is measured experimentally. The developed program has been used in practice, and the strip speed on production line increases by more than 10%.     

大跨径刚构桥0~#块腹板非荷载裂缝成因分析

对大跨径刚构桥0#块腹板在施工期间出现非荷载裂缝的原因进行了调查,并通过对埋置在0#块腹板内的钢弦应变计和温度传感器监测的混凝土硬化过程中应变和温度数据的结果分析,证实0#块腹板出现的裂缝主要是由收缩和水化热温度应力造成的.     

高速机车牵引齿轮强度的试验研究

对美国和国产要车牵引齿轮进行了强度试验分析，认为只要适当优选材料和工艺，国产机车牵引齿轮要以取代美国的牵引齿轮。     

鼓式制动器循环制动瞬态温度场仿真

依据鼓式制动器结构特点和传热学理论,分析了鼓式制动器生热散热过程,运用有限元软件ANSYS建立某鼓式制动器瞬态温度场仿真模型,得出在重复制动工况下制动鼓的温升过程,分析了瞬态温度场的变化情况。根据国家标准进行热衰退试验,通过修改仿真模型的热边界条件,使仿真温度曲线与试验曲线相吻合,确定了鼓式制动器瞬态温度场分析的边界条件及模拟方法。     

采用间接耦合法分析斜拉桥索塔瞬态温度应力场

针对混凝土斜拉桥索塔,将以传热学原理为基础的温度场分析与采用有限元法的应力场分析间接耦合,准确分析了结构内瞬态温度场和应力场的分布。以实桥为例,求解了索塔上温度应力分布,表明：用有限元法求解瞬态温度场能准确模拟索塔的温度场分布;间接耦合法能准确、有效地处理温度-应力耦合问题,能将温度荷载与其他荷载作用应力场有效组合,从而得到结构上准确的应力分布;对比了瞬态温度场分布与采用温差分布经验公式的不同,证明采用温差分布经验公式计算索塔面板上温度产生的拉应力时误差不大。     

Prediction of Welding Residual Stress in 2. 25Cr-1Mo Steel Pipe

Introduction2.25Cr-1Mo-steel is widely used in thepetroleum industry and in steam power generatingof both nuclear and conventional power plants be-cause of its excellent high-temperature strength,corrosion resistibility,and resistance to high-tem-perature hydrogen attack.Because several alloy el-ements are added into2.25Cr-1Mo-steel,marten-site is prone to form after welding.It has been rec-ognized that phase transformation can radically af-fect the development of residual stresses[1-2].Inor…     

多物理域耦合求解的轮毂电机温度场

为研究温度变化对电动汽车用轮毂电机的工作性能和使用寿命的影响，采用场路耦合法将轮毂电机有限元模型与外电路联合求解，建立了包含轮毂电机本体、外部驱动控制电路的联合仿真模型，充分考虑了外部激励中时间谐波电流对磁场的影响. 然后，将计算得到的绕组铜耗、定子铁芯损耗、永磁体涡流损耗以及杂散损耗等作为热源，采用磁热耦合法将其耦合到各部件进行瞬态温度场研究，综合考虑了电机工作过程中其损耗分布在时间和空间位置上的瞬态变化特性，热源损耗与温度场实时精确耦合. 详细研究了负载运行时轮毂电机各部件温度随时间的变化情况，以及温度的空间分布特性. 多物理域耦合法实现了电磁场与外电路的直接耦合，电磁场与温度场的顺序耦合. 最后，对轮毂电机进行台架试验. 研究结果表明:仿真计算结果与试验结果在额定工况下温度的最大误差为4.96%，峰值工况下最大误差为10.55%.      

13CrMo44钢及焊缝金属的疲劳裂纹扩展速率

本文根据美国ASTM F647-81标准,采用紧凑拉伸试样,对13CrMo44钢及用P5(E309Mo)焊条的手弧对接焊缝金属的疲劳裂纹扩展速率进行了测定.试验采用表面直读法测量裂纹长度、并采用抛物线回归法对大量试验数据进行微机处理.基于Paris公式,得到了13CrMo44钢和焊缝金属的裂纹扩展速率的表达式.     

Finite Differential Method Simulation on Temperature Field in Process of Laser Quenching

IntroductionInfieldoflasertreatment,laserquenchofmetalmaterialsisanimportantcourse.ItisahotspotinresearchoflaserquenchtocalculatetemperaturedistributionandtosimulatethecoursebymeansofcomputerThecalculationandanalogyisnotonlyabasistoca1culateinnerstressdistributionoflaserquenching,butalsoafoundationtooptimizelaserquenchingtechnologyandtocontrolquenchingcourse.Therearemanymethodstocalculatetemperature,suchasfiniteelementmethod(FEM),finitedifferentialmethod(FDM)andsoon.Accordingtodifferentpedi…     

考虑瞬态温度场的水平井水力冲砂临界排量

针对目前油气田水平井水力冲砂施工难度大、难以辨识合理的冲砂排量的问题.基于水平井地层-井筒瞬时温度场模型,提出水平井环空临界流速计算模型,考虑瞬时温度场对冲砂液黏度的影响.通过有限体积法求解瞬时温度场,结合冲砂液温度-黏度方程,求取了水平井全井段全过程环空临界流速,在此基础上建立了临界排量计算新方法.通过对4种常用冲砂液进行实例分析表明:与不考虑温度情况相比,考虑温度时全过程最大环空临界流速分别增大了9.20%、17.26%、9.85%和7.64%,临界排量分别增大了8.33%、18.18%、10.00%和11.11%,说明了水平井水力冲砂排量计算考虑温度影响的必要性.      

Development of Thermal Process and Numerical Modeling

IntroductionWithinrecentdecade,thenumericaIsimulationhasbeenrapidlyachievedandhasaPpliedtothermalmanufacturingprocess.ThephasetransformationiscomplicatedbythefactthatthereareseveralmicrostructuralscaIestoconsideHl1-I4].InordertorevealtheruIeofcomplexphasetransformation,itisnecessarytousethetoolofnumericalsimulationtomodelandcontroltheoverallprocessofphasetransformation.NowthecomputersimulationcangetsomereasonabIeresultSinmanyaspectsofthermalmanufacturingprocess:e.g.,thesimulationoftemperat…     

均匀火焰包围下液化气容器的瞬态应力场分析

针对均匀火焰包围下的球型液化气容器的热响应问题,运用传热学理论和有限元方法计算并分析了均匀火焰包围下的球型液化气容器的瞬态热应力、机械应力和总应力.结果表明对于均匀火焰包围下的球形液化气容器,容器的最大当量热应力远大于最大当量机械应力,最大当量应力位置出现在最高液面附近,液面的波动是产生较高应力的根本原因.应对与液面接触的壁面区域进行重点防护.     

Cr7Mo3V2Si钢的马氏体加下贝氏体复合组织的研究

研究了奥氏体化温度和中温等温时间对 Cr7Mo3V2Si 钢经中温转变后的硬度和组织的影响.结果表明,随奥氏体化温度升高,钢的硬度不断增加,下贝氏体晶粒急剧长大,随中温等温时间的延长,下贝氏体量增多,钢的硬度下降,超细化多要强韧化热处坤使 Cr7Mo3V2Si 钢的冲击韧性显著升高,使 Cr7Mo3V2Si 钢制 M12六角螺母冲头的使用寿命超过1万件.