Simulation analysis of wear characteristics of connecting rod bearing bush based on improved mixed lubrication model

The failure rate of crankpin bearing bush of diesel engine under complex working conditions such as high temperature,dynamic load and variable speed is high.After serious wear,it is easy to deteriorate the stress state of connecting rod body and connecting rod bolt,resulting in serious accidents such as connecting rod fracture and body damage.Based on the mixed lubrication characteristics of connecting rod big endbearing shell of diesel engine under high explosion pressure impact load,an improved mixed lubrication mechanism model is established,which considers the influence of viscoelastic micro deformation of bearing bush material,integrates the full film lubrication model and dry friction model,couples dynamic equation of connecting rod.Then the actual lubrication state of big end bearing shell is simulated numerically.Further,the correctness of the theoretical research results is verified by fault simulation experiments.The results show that the high-frequency impact signal with fixed angle domain characteristics will be generated after the serious wear of bearing bush and the deterioration of lubrication state.The fault feature capture and alarm can be realized through the condition monitoring system,which can be applied to the fault monitoring of connecting rod bearing bush of diesel engine in the future.

Modal and Thermal Analysis of a Modified Connecting Rod of an Internal Combustion Engine Using Finite Element Method

The connecting rod is one of the most important moving components in an internal combustion engine. The present work determined the possibility of using aluminium alloy 7075 material to design and manufacture a connecting rod for weight optimisation without losing the strength of the connecting rod. It considered modal and thermal analyses to investigate the suitability of the material for connecting rod design. The parameters that were considered under the modal analysis were: total deformation, and natural frequency, while the thermal analysis looked at the temperature distribution, total heat flux and directional heat flux of the four connecting rods made with titanium alloy, grey cast iron, structural steel and aluminium 7075 alloy respectively. The connecting rod was modelled using Autodesk inventor2017 software using the calculated parameters. The steady-state thermal analysis was used to determine the induced heat flux and directional heat flux. The study found that Aluminium 7075 alloy deformed more than the remaining three other materials but has superior qualities in terms of vibrational natural frequency, total heat flux and lightweight compared to structural steel, grey cast iron and titanium alloy.

Microstructures and mechanical properties of semi-solid squeeze casting ZL104 connecting rod

Semi-solid squeeze casting（SSSC） and liquid squeeze casting（LSC） processes were used to fabricate a ZL104 connecting rod, and the influences of the process parameters on the microstructures and mechanical properties were investigated. Results showed that the tensile strength and elongation of the SSSC-fabricated rod were improved by 22% and 17%, respectively, compared with those of the LSC-fabricated rod. For SSSC, the average particle size（APS） and the shape factor（SF） increased with the increase of re-melting temperature（Tr）, whereas the tensile strength and elongation increased first and then decreased. The APS increased with increasing the mold temperature（Tm）, whereas the SF increased initially and then decreased, which caused the tensile strength and elongation to increase initially and then decrease. The APS decreased and the SF increased as squeezing pressure（ps） increased, and the mechanical properties were enhanced. Moreover, the optimal Tr, ps and Tm are 848 K, 100 MPa and 523 K, respectively.

Photoplastic Experimental Research on Material Plastic Flow Law of Connecting Rods during Finish Process

Photoplastic experiment were conducted with connecting rods of AX100 motorcycle engine during finish forging to investigate material plastic flow law of long -axis forgings with comples geometrie’s by observing

Study on CAD/CAE System of Engine Connecting Rod

The intensive competition of automotive market requ ir es shortening the product development circle and improving the product quality. Many of auto manufacturers in china have introduced some CAD/CAE/CAM systems in product development process, and have got some success. But the special and effi cient CAD system aimed at particular product is absent. This paper provides a CA D/CAE system that can realize the integration of CAD and CAE process for engine connecting rod development. The paper discusses some general methods in connecting rod design process, and s ums up structure characteristics of connecting rod. It introduces feature defini tion and feature classification facing connecting rod CAD/CAE system. Based on t he study of the feature technology and the feature of connecting rod, it creates the feature information model and feature database of engine connecting rod . In addition, it creates the parametric model of engine connection rod and real izes variable parametric design and variable structure design. With the help of Pro/Toolkit and Using C++ program to call the user ’s toolbox of Pro/ Engineer software system, the connecting rod CAD/CAE syst em can create connecting rod model automatically to meet the needs of different structure and different type of connecting rod. Based on Pro/Mechanica platform of PTC, the system can implements the Finite Ele ment Analysis and optimization of the connecting rod. Because using the same database in design and analysis, no data lost and no error occurs during da ta transforming. Using the connecting rod CAD/CAE system, the connecting rod can be meshed automatically and the FEA result can be achieved very fast and is very similar to the experiment. In a word, the connecting rod CAD/CAE system developed in this paper can optimiz e the product development process, realize the data share and concurrent enginee ring in the product design and analysis process, shorten the product develop ment circle, and improve the efficiency.

Powder Forging of a Motorcycle Connecting Rod

A motorcycle connecting rod is one of the major moving parts affecting the engine performance. The traditional manufacturing process results in material waste and excessive machining. A new method of hot forging P/M has been proposed and studied experimentally. In order to achieve uniform density, the punch was divided into three parts to consolidate the loose powder. The multistage movement of the three parts of the punch, called synchronous compaction, results in the desired uniform density. Powder flow during consolidation was illustrated and the density distribution of the compacts was measured. A set of forging dies with flash was used to produce densification and deformation of the sintered compact. Then a set of flashless forging dies was designed to obtain the desired shape and dimensions of the connecting rod. The effects of forging temperature and initial compact density on densification were evaluated through hot forging experiments. Based on properties achieved, Fe-C-Cu-Mo was selected as the

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.

Mechanical characteristic and failure mechanism of joint with composite sucker rod

Composite sucker rods are widely used in oil fields because of light weight,high strength,and corrosion resistance.Bonded technology becomes the primary connection method of composites.However,the joints with composite sucker rods are prone to debone and fracture.The connected characteristics are less considered,so the failure mechanism of the joint is still unclear.Based on the cohesive zone model(CZM)and the Johnson-Cook constitutive model,a novel full-scale numerical model of the joint with composite sucker rod was established,and verified by pull-out experiments.The mechanical properties and slip characteristics of the joint were studied,and the damaged procession of the joint was explored.The results showed that:a)the numerical model was in good agreement with the experimental results,and the error is within 5%;b)the von Mises stress,shear stress,and interface stress distributed symmetrically along the circumferential path increased gradually from the fixed end to the loading end;c)the first-bonded interface near the loading end was damaged at first,followed by debonding of the second-bonded interface,leading to the complete shear fracture of the epoxy,and resulted in the debonding of the joint with composite sucker rod,which can provide a theoretical basis for the structural design and optimization of the joint.

基于FBG连杆变形感知及三维重构方法研究

连杆作为柴油发动机的关键零部件,其变形直接影响动力装备的性能和寿命。因此,检测连杆变形对保证动力装备的使用寿命具有重要作用。文中提出基于光纤光栅(fiber Bragg grating,FBG)船用柴油机连杆的变形检测技术,根据有限元分析连杆变形特点,设计FBG栅点的传感网络,建立连杆受力变形下的三维重构模型,并开发基于FBG连杆变形检测的软硬件系统,实现连杆变形的可视化监测。实验结果表明采用基于FBG的感知和重构技术检测连杆的变形是可行的,为连杆性能的精确检测以及船舶动力装备其他关键件的变形检测提供了新思路。

考虑空穴效应的连杆小头摩擦副润滑特性与冲击影响研究

为改善连杆小头轴承润滑及活塞销冲击特性,基于粗糙峰接触理论、平均流量模型及弹流润滑理论,以某高压共轨4缸柴油机为研究对象,运用AVL EXCITE Power Unit软件搭建混合润滑活塞连杆组多体动力学模型,研究了考虑空穴条件下不同转速对连杆小头摩擦副润滑及冲击特性的影响规律。研究结果表明:标定功率转速2400 r/min下,在做功时刻1080°后峰值油膜压力达到最大值197.1 MPa,最小油膜厚度达到最小值1.8μm,而润滑油填充率在整个发动机循环过程中均低于0.12。在怠速800 r/min、最大扭矩转速1600 r/min、标定功率转速2400 r/min下,进气、压缩、做功、排气4个冲程过程中,空穴区域由连杆小头轴承下半区转移至上半区、再转移至下半区。转速升高会导致峰值油膜压力增大,最小油膜厚度减小,粗糙接触压力增大,活塞销Z向速度峰值加大,对连杆小头轴承冲击加重,在缸内最高燃烧压力时刻,800 r/min,1600 r/min,2400 r/min下的平均润滑油填充率均值为0.84,0.70,0.69,因润滑油填充率随转速的升高而降低,空穴程度加重。

含多关节间隙平面柔性六杆机构的动力学分析

为提高机构的动力学分析精度,基于平面六杆机构,同时考虑多个关节间隙与构件柔性对多体机构动力学响应的影响。通过实体建模和引用ADAMS软件中“冲击函数”接触力模型,对含有多个间隙关节与柔性连杆的六杆机构进行动力学模拟仿真,研究间隙数量、间隙位置、间隙大小、柔性连杆及其与间隙耦合对系统动力学性能影响。研究结果表明:与单关节间隙相比,多关节间隙会产生更大的接触力,导致构件的加速度波动更加剧烈;间隙关节距离电机位置越近,则对机构的动力学行为影响越明显;考虑连杆柔性时,可以极大地降低间隙对机构动力学波动的影响。

头部支撑面角对连杆螺栓与大头盖接触应力的影响

国标六角法兰面螺栓对螺栓支撑面角度范围提出设计指导,但没有具体指出最佳角度,且其对螺栓预紧力及支撑面应力的影响尚无明确结论。通过建立发动机连杆螺栓的精细拧紧有限元仿真模型,并利用Yamamoto解析法验证了连杆螺栓有限元模型的准确性。研究了螺栓头部支撑面角对拧紧载荷下连杆螺栓预紧力和应力分布的影响,同时通过计算疲劳安全系数对螺栓头部支撑面的结构可靠性进行综合评估。结果表明:螺栓头部支撑面角取0.5°为最佳;提出了带有U型沉割槽的连杆螺栓结构模型,优化后的螺栓结构在螺栓头部与螺杆结合处的平均应力下降16.2%,平均疲劳安全系数提高19.6%。

基于多变量设计的打纬筘座急回特性分析及优化

为改进筘座后摆急回特性,通过打纬原理分析与机构学推演,提出了一种针对牵手栓最大曲线位移Sm的优化数学模型。利用构件长度(l_(c)、l_(h)、l_(r)、l_(f))和曲柄转角α构建多变量设计空间,实现了短牵手四连杆打纬的参数化功能模型开发,并通过机构学仿真对其运动位姿与质心轨迹进行分析验证。实例研究结果表明,曲柄长度lc和转角α对目标函数F(X)的敏感度影响更大,多变量(DV_1、DV_2、DV_3)耦合可有效增强打纬筘座急回特性的设计可塑性;当牵手栓最大曲线位移Sm增大至71.41 mm时,极位夹角θ和行程速比系数K分别被提高了10.96°和0.131,筘座急回运动效果得到明显提升。优化结果符合杆长条件和机构传动要求,有助于四连杆打纬系统的设计创新和性能改进。

关于16PC2-6V400型柴油机连杆断裂故障原因分析及改进措施

针对某船的16PC2-6V400型柴油机在使用过程中出现的连杆断裂飞出,缸套破损,活塞顶卡滞、连杆大段掉落的故障现象,结合故障出现的环境和使用工况进行分析,通过建立故障树,对各故障原因进行排除,定位故障部位,通过对故障件进行微观形貌分析,明确故障为连杆螺纹根部刀痕应力集中处促使裂纹源萌生并以疲劳的方式发展最终断裂。针对该故障暴露的问题,提出具有可行性的解决方法,避免再次因该类型问题导致较大故障及损失的发生。

摇臂连杆加工工艺与钻专夹设计

文章根据摇臂连杆的结构特点和技术要求,制订了该零件的机械加工工艺规程;在对定位装置、夹具装置及夹具体进行分析的基础上,设计并制造了用于第六道工序Φ35孔的钻孔专用夹具。应用结果表明,该夹具做到了加工精度保证、设计方案合理、结构简单实用,能有效提高摇臂连杆的加工质量及效率。

齿轮齿条复合曲柄连杆机构的长冲程往复泵仿真及分析

曲柄连杆往复泵在石油钻采行业中应用广泛,但因为冲程短、冲次高、易损件寿命短等缺陷,限制了其进一步发展。文中针对上述缺陷提出了一种基于齿轮齿条和曲柄连杆的复合机构,将传统往复泵中的十字头结构替换为直齿圆柱齿轮,配合固定的上齿条和移动的下齿条,实现了活塞的长冲程往复运动。建立了活塞的运动方程,使用该复合机构的三缸往复泵动力学仿真模型,探究了在负载下活塞的运动特性和齿轮齿条的动力学特性,并对齿轮进行了疲劳分析。结果表明:新型往复泵活塞冲程比相同曲柄半径的传统往复泵增大了1倍,流量脉动率不会增大但脉动频率降低1倍,有效减少泵阀的开关次数,能较大地延长易损件的使用寿命;齿轮的疲劳寿命可以达到13000 h以上。研究结果证明了该复合机构的可行性,为后续产品的开发提供了理论支持。

含柔性连杆的曲柄滑块机构动力学分析与实验研究

为了研究柔性连杆、带有固体润滑涂层MoS_2的铰链接触副对含间隙铰链机构的动力学特性的影响规律,以曲柄滑块机构为研究对象,使用Adams软件进行数值仿真分析,研究了柔性连杆材料、铰链间隙、铰链接触副材料和铰链接触副表面固体润滑涂层对曲柄滑块机构动力学特性的影响。通过搭建与数值仿真参数一致的含间隙铰链的曲柄滑块试验台,试验验证了柔性大的连杆、较小的间隙值、接触刚度较小的接触副材料能够减小机构的振动,带有涂层的铰链能够有效减小接触面的磨损量。试验结果和数值仿真结果较为一致,能够有效的反应各种工况对含间隙机构的影响规律,为固体润滑涂层在航天领域中含间隙铰链接触副展开机构的减振抗冲击研究提供理论基础和试验依据。

发动机连杆恒定机械拉压损伤自适应检测方法

为提高现有发动机连杆拉压损伤检测方法的检测准确率和检测效率,提出发动机连杆恒定机械拉压损伤自适应检测方法。该方法首先研究发动机连杆的机械运动原理及连杆受恒定机械拉压强度影响的分析,然后获取与发动机连杆机械拉压相关的相对损伤分布数据,计算各项相对损伤分布数据所对应的连杆损伤程度,最后利用遗传算法完成概率神经网络模型的优化,基于上述得到的损伤数据建立连杆恒定机械拉压损伤自适应检测模型,实现发动机连杆恒定机械拉压损伤自适应检测。实验结果表明:所提方法检测准确率高于88%,检测时间不超过0.4s,均优于对比方法,具有一定研究价值。

连杆轴承润滑空化过程动态仿真与抑制

以某重型柴油机的连杆轴承为研究对象,引入运动边界和动网格smoothing网格光顺方法来探究不同入口条件对油膜空化现象的影响,研究了用于抑制轴承润滑空化现象的轴瓦开槽方法,对比开槽数量、深度及开槽形式对抑制油膜空化现象的影响.研究发现,润滑空化的范围和程度是一个动态变化的过程,引起空蚀的并非在空化形成阶段,而在空化溃灭的过程中.因而如果空化现象频繁发生和溃灭,相比持续存在的稳定空化状态,将更易破坏轴瓦表面,引发明显空蚀现象.由于重型柴油机的连杆轴承润滑油来自于主轴承,连杆轴承润滑油入口压力存在显著波动,导致空化程度波动剧烈,进一步恶化空蚀现象,这也解释了重型柴油机连杆轴承穴蚀损伤往往更甚于主轴承.通过轴瓦开槽可以有效缓解空化,从而达到抑制空蚀的效果;增加开槽数目和深度都可以强化抑制效果,但提升的程度有限.相比全槽模型,半槽模型可以强化油膜的轴向流动,对空化的抑制效果更好,可将油膜的气相体积分数最高值从0.94(未开槽)降至0.39.考虑到轴瓦的厚度与强度需求,选择适当槽深的半环单槽即可有效地抑制轴承运动过程中油膜的空化现象.