S195型曲轴强度有限元分析及试验研究

运用APDL语言建立了S195型六缸曲轴有限元模型,实现载荷和边界条件的参数化加载,并运用有限元方法对S195型六缸曲轴静态工作特性进行分析,获得曲轴的静态条件下最大应力、最大变形量及其出现的位置。模拟结果表明,第3个工况条件下(第三缸发火),曲轴所承受的静态应力最大,达506MPa,超过材料的屈服极限,最大应力出现在连杆轴颈和主轴颈的过渡区域,进而导致曲轴失效。同时,结合有限元模拟结果对不同工况条件下曲轴进行了试验验证,结果表明上述有限元分析结果与静态应力试验结果基本一致。     

砼密封体摩擦过程的热固耦合非线性分析

利用有限元分析软件ABAQUS,建立砼密封体热固耦合数值模型.分析混凝土压力、密封体与输送缸摩擦系数对密封体Von Mises应力、摩擦应力及温度的影响.分析结果表明:密封体与输送缸的接触位置的Von Mises应力、温度和摩擦应力最大,因而最易失效,这与密封体实际损坏位置一致;接触对的摩擦因数是导致温度和摩擦应力增加的重要因素,可通过改善润滑效果来降低接触对温度,从而提高密封体的使用寿命.     

水泥环破碎器矩形异形活塞密封性能分析

针对传统圆柱形液压活塞承载力不足问题,提出一种矩形异形活塞,研究其在不同工况下的密封性能。基于Abaqus软件建立异形活塞有限元模型,研究介质压力、密封间隙、活塞运动状态以及摩擦因数对密封性能的影响,并分析异形密封环不同位置处的应力分布和翻转情况。结果显示：静密封时,介质压力越大,密封环的最大Mises应力和最大接触应力越大;密封间隙越小,最大Mises应力与最大接触应力越大;相比静密封,内行程过程中最大Mises应力和最大接触应力都有明显增加,且随摩擦因数增加而增加,而外行程中最大Mises应力和最大接触应力相比静密封差异较小;各工况下应力最大值均出现在密封环圆弧段;在活塞运动过程中密封圈并未发生翻转,只是存在位置的平移情况。研究结果证明了异形活塞的可行性以及良好的密封性能,为活塞结构设计与优化提供了依据。     

重卡六缸内燃机曲轴不同位置角静力学分析与结构优化

为研究内燃机曲轴在实际工况下不同位置角的应力应变分布特征,利用Creo软件建立材质为QT700-2的重卡直列六缸内燃机左式曲轴三维模型,根据内燃机实际受载情况对曲轴施加约束和载荷并进行静力学仿真。结果表明：曲轴上最大应力发生在曲轴轴颈与曲柄臂的过渡圆角处,连杆轴颈中心出现最大形变,工作过程中第4缸对应曲轴轴段部分的应力变化最大。据此对曲轴结构进行优化,将过渡圆角半径增加40%后,最大应力值减小了约10%;结合企业曲轴故障返修情况,发现优化之后减少了曲轴早期故障率,提高了内燃机曲轴的可靠性。     

V8发动机曲轴有限元分析

对某V8发动机曲轴进行运动学分析与动力学分析,利用Pro/Engineer软件建立三维模型,然后根据有限元理论,应用ANSYS软件分析了曲轴的静态力学性能。分析第一左缸与第三右缸爆发时的应力云图和变形图,从结果可以看出,曲轴的应力集中在轴颈与曲柄臂连接处、油孔处以及连杆轴颈中央截面处。进行模态分析,曲柄臂和主轴颈、曲柄臂和连杆颈相连处是曲轴振动中危险的区域,由振型图可以发现它们是曲轴振动中变形最大的区域。     

V-6/8-1型空压机降低润滑油消耗量的探讨

一、飞溅润滑的原理与作用 我厂生产的宰6m～3空压机是V型二级四缸单动水冷无十字头压缩机。该压缩机采用飞溅润滑,在四根连杆的大头瓦盖上各装一个打油针 （溅油管）。当曲轴回转时,打油针划开曲轴箱内的油面,润滑油四处飞溅,油滴或油雾直接落在曲轴连杆机构和气缸的内表面上进行润滑。润滑的主要作用是:1.减少摩擦功率,提高机械效率;2.减少机械磨损。延长机器寿命;3.对冷却机件的摩擦表面,可带走摩擦产     

汽油机活塞组件的摩擦损失研究

基于一台三缸涡轮增压汽油机,分析了曲轴位置、连杆比以及发动机运行工况对活塞组件摩擦损失的影响。研究结果表明,在连杆比一定时,随着曲轴偏置量从0mm增加到15mm,活塞组件的摩擦损失量减小,在曲轴偏置为15mm时,活塞组件的摩擦损失量减少达到最优。然而,当曲轴偏置量增加到20mm后,活塞组件的摩擦损失量有所增加。当曲轴偏置量一定时(15mm),随着连杆比从0.29减小到0.25,活塞组件的摩擦损失逐渐减少;随着连杆比从0.29增加到0.31,摩擦损失有所增加。当转速从1000r/min增加到2000r/min时,活塞组件的摩擦损失有所增加,而随着转速一直增大,摩擦损失量有所降低。当转速在1000r/min时,随着负荷的增大,摩擦损失有所改善。而在3000r/min时,负荷对摩擦损失的影响并不明显。最后,对连杆比为0.25和0.31时,发动机不同运行工况下的摩擦损失进行了综合协同优化分析。     

道依茨柴油机两例事故原因分析

<正>1.密封垫装错导致事故1台DWL-48型连续式捣固车作业时,其所配道依茨BF6M1013C型柴油机出现动力不足、整机过热,随即曲轴箱Ⅰ缸部位的下部出现破裂。拆解油底壳后发现,曲轴和连杆均有过热的痕迹,且过热从Ⅵ缸到Ⅰ缸逐渐严重,如图1所示。Ⅰ缸活塞熔化,活塞和连杆分离,连杆大头严重变形,连杆螺栓断裂,连杆瓦盖脱落。曲轴Ⅰ缸连杆轴径磨损严重。     

基于AVL Excite Designer的发动机曲轴主轴承润滑性能分析

以某型直列四缸发动机为研究对象,对曲轴主轴承进行弹性流体动压润滑分析。考虑非线性连接,采用多体动力学软件建立润滑仿真模型对曲轴主轴承进行动力学润滑计算。通过对最小油膜厚度、最大摩擦接触应力和磨损进行分析,揭示了设计中存在的隐患,为该型发动机曲轴主轴承的优化设计提供了参考依据。     

O形橡胶密封圈的热应力耦合分析

研究原油高温热采工具 O 形橡胶密封圈在高温高压下的密封特性。借助于大型有限元分析软件 ANSYS,建立 O 形橡胶密封圈及其边界的二维轴对称有限元模型,研究油压、装配间隙和摩擦因数对密封面最大接触应力、剪切应力和 Von Mises 应力的影响,并采用热应力耦合分析方法,分析温度对 O 形密封圈密封性能的影响。结果表明：摩擦因数对应力影响不大,而油压和装配间隙对应力影响很大,过大的装配间隙会造成 O 形橡胶密封圈最大接触应力下降和最大剪切应力上升,造成密封失效;当温度升高时,密封圈最大剪切应力和接触应力相应减小,而最大 Von Mises 应力明显减小,因此应使 O 形密封圈在适当的温度下工作,以确保密封的可靠性。     

发动机连杆精细有限元分析模型和算法的研究

在总结大量连杆计算经验的基础上,分析了影响计算精度的各种因素,提出了一个精细有限元组合计算模型：摒弃了各种近似处理方法,计算模型完全根据连杆实际结构确定,计入了连杆组装的全部零件以及活塞销、活塞和曲轴,其间所有配合关系用有摩擦的3维弹性多体接触模型模拟。采用有限元参数二次规划算法,并结合多重多支的子结构技术求解。同时指出了这套理论和方法对于解决这类机械工程问题所具有的优点和广泛的适用性。     

转子式空调压缩机曲轴法兰系统摩擦噪声预测

转子式空调压缩机摩擦噪声主要来源于其内部相互接触的各个运动副.为识别转子式空调压缩机摩擦噪声的来源,通过销盘实验测定曲轴与上下法兰组成的系统中不同摩擦副的摩擦因数,拟合得到摩擦-速度负斜率曲线;建立曲轴法兰系统的有限元模型,以摩擦-速度负斜率曲线加载,提取其复特征值和等效阻尼比,初步分析摩擦噪声可能发生的频率.对实际采...     

Augmented Lagrange方法在钢丝绳捻制成形磨擦接触数值模拟中的应用

钢丝绳中金属线间接触摩擦会影响捻制成形加工应力和结构强度.在经典的Coulom摩擦理论的基础上,本文采用Augmented Lagrange方法计算钢丝绳捻制过程中的法向接触力和摩擦接触力,并应用radial-return径向回映法修正摩擦接触力试算值.以钢丝绳一次捻制成形过程为例,分析并讨论了摩擦系数和自扭转系数对接触应力和加工应力应变的影响,为钢丝绳成形工艺和结构强度的合理设计提供依据.     

Augmented Lagrange方法在钢丝绳捻制成形摩擦接触数值模拟中的应用

钢丝绳中金属线间接触摩擦会影响捻制成形加工应力和结构强度。在经典的Coulom摩擦理论的基础上,本文采用AugmentedLagrange方法计算钢丝绳捻制过程中的法向接触力和摩擦接触力,并应用radial return径向回映法修正摩擦接触力试算值。以钢丝绳一次捻制成形过程为例,分析并讨论了摩擦系数和自扭转系数对接触应力和加工应力应变的影响,为钢丝绳成形工艺和结构强度的合理设计提供依据。     

圆弧接触线回转体摩擦传动运动学研究

针对摩擦传动中的滑动问题，在对圆弧接触线回转体摩擦传动运动学研究的基础上，以曲轴圆角滚压加工为实例，分析了圆弧接触线回转体摩擦传动中减小滑动的方法和思路，避免了求解滑动率这一难点问题。还为曲轴滚压加工中滚刀参数及滚压工艺参数的合理设计提供了优化方法。     

Some Observations on Frictional Force During Fretting Fatigue

Frictional force behavior during fretting fatigue and its interdependence on other fretting variables are investigated. Both coefficient of static friction and the normalized frictional force (i.e., the ratio of frictional force and normal contact load) increase during the earlier part of a fretting fatigue test and then both reach to a stabilized value. The variation of temperature in the contact region and normalized frictional force with increasing cycle numbers and bulk stress show similar trend implying that normalized frictional force represents the average friction in the contact region during a fretting fatigue. An increase in bulk stress, relative slip, and hardness of pad material results in an increase of the normalized frictional force, while an increase in contact load, frequency and temperature decreases the normalized frictional force. The normalized frictional force is also affected by the contact geometry. On the other hand, coefficient of static friction increases with an increase in the hardness of mating material, temperature and roughness from shot-peening treatment, but is not affected by contact geometry and displacement rate. Further, the normalized frictional force is not affected by the contact geometry, roughness and applied bulk stress level when fretting fatigue test is conducted under slip controlled mode, however it increases with increasing applied relative slip and decreasing contact load in this case.     

On the performance of dynamically loaded journal bearings lubricated with couple stress fluids

A numerical study of the performance for a dynamically loaded journal bearing lubricated with couple stress fluids is undertaken. First of all, on the basis of micro-continuum theory, the generalized Reynolds equation for dynamic loads is derived. Then it is simultaneously solved with the force balance equation of the journal, thus obtaining the transient oil film pressure, the transient position and velocity of the journal center. Results from this analysis are presented for a typical engine crankshaft bearing. It is shown, compared with Newtonian lubricants, that under a dynamic loading lubricants with couple stress yield an obvious increase in oil film pressure and oil film thickness, but a decrease in the side leakage flow. Moreover, the effects of couple stress on friction force and friction coefficient vary considerably with time.     

ANALYSIS OF THERMAL-ELASTIC STRESS OF WHEEL-RAIL IN ROLLING-SLIDING CONTACT

A coupling thermo-mechanical model of wheel/rail in rolling-sliding contact is put forward using finite element method. The normal contact pressure is idealized as the Hertzian distribution, and the tangential force presented by Carter is used. In order to obtain thermal-elastic stress, the ther-mal-elastic plane stress problem is transformed to an elastic plane stress problem with equivalent fictitious thermal body force and fictitious boundary distributed force. The temperature rise and ther-mal-elastic stress of wheel and rail in rolling-sliding are analyzed. The non-steady state heat transfer between the contact surfaces of wheel and rail, heat-convection and radiation between the wheel/rail and the ambient are taken into consideration. The influences of the wheel rolling speed and wear rate on friction temperature and thermal-elastic stress are investigated. The results show the following: ① For rolling-sliding case, the thermal stress in the thin layer near the contact patch due to the friction temperature rise is severe. The higher rolling speed leads to the lower friction temperature rise and thermal stress in the wheel; ② For sliding case, the friction temperature and thermal stress of the wheel rise quickly in the initial sliding stage, and then get into a steady state gradually. The expansion of the contact patch, due to material wear, can affect the friction temperature rise and the thermal stress during wear process. The higher wear rate generates lower stress. The results can help under-stand the influence of friction temperature and thermal-elastic stress on wheel and rail damage.     

Lubrication Performance of Connecting-Rod and Main Bearing in Di erent Engine Operating Conditions

Only the lubrication performance at rated engine operating condition was generally analyzed in current design and research of engine connecting-rod and main bearing. However, the actual engine(especially vehicle engine) does not always operate in rated operating condition and its operating condition changes constantly. In this paper, a fourstroke four-cylinder engine is taken as the studying object, the load and lubrication of connecting-rod and main bearing in di erent operating conditions are analyzed. The load of connecting-rod bearing is calculated by the dynamic calculation method, the loads of all main bearings are calculated by the whole crankshaft beam-element finite element method, and the lubrication performance of connecting-rod and main bearings are analyzed by the dynamic method. The results show that there are major di erences in the changes and numerical value at corresponding moment of the loads and lubrication performance of connecting-rod and main bearings in an engine operating cycle in di erent engine operating conditions; the most unfavorable case of the lubrication performance of connectingrod and main bearings may not take place in the rated engine operating condition. There are also major di erences between the lubrication performance of connecting-rod bearing and that of main bearing and between the lubrication performances of main bearings one another. Therefore, it will not be reasonable that the lubrication performance of a certain connecting-rod bearing or main bearing is analyzed in the design of the engine bearing. It is necessary to analyze simultaneously the lubrication performances of all bearings in di erent engine operating conditions.     

齿面摩擦力对齿轮接触应力的影响

渐开线齿轮接触疲劳强度设计中忽略了齿面摩擦力的影响。对此 ,众多学者看法不一 ,有的认为齿面摩擦力影响甚微 ,可以忽略 ;而另一些人则指出其影响明显 ,不可不计。文中通过 6组滚子疲劳试验得出 ,齿面摩擦力的影响能否被忽略与齿轮的转速、功率、材质、齿数、模数及润滑剂的黏度等因素有关 ,而这些因素可用一个无量纲参数S来表示。S存在两个临界点S1 和S2 。当S S2 时 ,摩擦力影响较小 ,可以忽略不计 ;当S1 相似文献