Fate of rubber bush (Calotropis procera (Aiton) W. T. Aiton) in adversary environment modulated by microstructural and functional attributes

Calotropis procera(Aiton)W.T.Aiton,belonging to the family Apocynaceae,is C3 evergreen plant species in arid and semi-arid areas of the Punjab Province,Pakistan.It grows in a variety of habitats like salt affected and waterlogged area,desert/semi-desert,roadside,wasteland,graveyard,forest,crop field,coastline,and river/canal bank.A total of 12 populations growing in different ecological regions were sampled to evaluate their growth,physio-biochemical,and anatomical responses to specific environmental condition.Population adapted to desert/semi-desert showed vigorous growth(plant height,shoot length,and number of leaves),enhanced photosynthetic level(chlorophyll a,chlorophyll b,carotenoids,and total chlorophyll),and apparent anatomical modifications such as increased stem radius,cuticle thickness,storage parenchyma tissues(cortex and pith),and vascular bundles in stems,while the maximum of midrib and lamina thickness,epidermal cells,cuticle thickness,cortical proportion,abaxial stomatal density,and its area in leaves.There was high plasticity in structural and functional features of these populations,which enable them to survive and tolerate under such hot and dry desert environment.Population of saline areas exhibited very critical modifications to sustain under salt prone environment.At physiological level,it possesses the maximum amount of organic osmolytes(glycine betaine and proline)and antioxidants(superoxide dismutase(SOD),catalase(CAT),and peroxidase(POD)),while at anatomical level,it showed intensive sclerification,large phloem region(inner and outer),pith parenchyma cells,and metaxylem vessels in stems and leaves.The population of dry mountains showed very distinctive features,such as increased shoot ionic contents(K+and Ca2+),collenchyma and sclerenchyma thickness in stems,trichomes size,and numerous small stomata on abaxial surface of leaves.It is concluded that no definite or precise single character can be taken as a yardstick for adjudging the biomass production in this rubber bush weed population.

Torsional stiffness modeling and optimization of the rubber torsion bushing for a light tracked vehicle

Taking the rubber torsion bushing of a certain type of all-terrain tracked vehicle as the research object,a theoretical model of torsional stiffness was proposed according to the non-linear characteristics of rubber components and structural feature of the suspension. Simulations were carried out under different working conditions to obtain root mean square of vertical weighted acceleration as the evaluation index for ride performance of the all-terrain tracked vehicle,with a dynamics model of the whole vehicle based on the theoretical model of the torsional stiffness and standard road roughness as excitation input. Response surface method was used to establish the parametric optimization model of the torsional stiffness. The evaluation index showed that ride performance of the vehicle with optimized torsional stiffness model of suspension was improved compared with previous model fromexperiment. The torsional stiffness model of rubber bushing provided a theoretical basis for the design of the rubber torsion bushing in light tracked vehicles.

Analysis of radial stiffness of rubber bush used in dynamic vibration absorber

In order to study the influence of the structural parameters of the rubber bush on its radial stiffness, the constitutive relation of rubber materiel is used to obtain the calculation formula of the dimensionless radial stiffness coefficient. The obtained theoretical result is consistent with previous research results in both long rubber bushes and short rubber bushes. The simulation case was conducted by the finite element method to verify the correctness of the theory. The axial compression experiment was conducted to obtain the parameters needed in the simulation. The result shows that the percentage difference between the theoretical result and the simulation one is only 2.75%. A series of simulations were conducted to compare with previous work, and the largest magnitude of the percentage difference is only about 5%. Finally, the radial stiffness experiment was conducted by using a dynamic vibration absorber, and the influence of the structural parameters of the rubber bush on its radial stiffness is obtained. The result shows that the radial stiffness of the rubber bush increases with the increase in the length and the inner radius, but decreases with the increase in the outer radius.

橡胶球铰径向压缩刚度变化特性的研究

通过试验,系统性分析了某型橡胶球铰径向压缩刚度变化趋势。结果表明,橡胶球铰径向压缩刚度随着试验时间的延长呈现逐渐变小的趋势;随着试验次数和恒温时间的增大慢慢趋于稳定;橡胶层厚度对球铰径向压缩刚度变化趋势的影响不大。

某轻轨车型牵引橡胶关节寿命提升结构优化设计

从应用于比利时布鲁塞尔某轻轨车型的牵引橡胶关节运营使用的失效形式出发,结合其实际运行工况,详细分析原结构牵引橡胶关节功能的失效情况,对失效原因进行分析,对预压量、金属截面和胶层厚度等多方面的结构进行改进优化。通过疲劳仿真分析计算,结果显示,结构优化的橡胶应变降低13.14%,疲劳损伤值由4.12降至0.5,牵引橡胶关节的使用寿命大幅改善。最终通过疲劳试验测试,进一步验证了结构优化后的牵引橡胶关节使用寿命的提升,由2年提高至10年以上,满足用户的运营要求。

轨道车辆用牵引橡胶球铰的结构优化

针对轨道车辆用牵引橡胶球铰(简称牵引橡胶球铰)的失效情况,分析了其载荷工况特点和初始结构的不足,并对牵引橡胶球铰进行结构优化。结果表明:Ogden 4阶超弹本构模型对牵引橡胶球铰的橡胶材料大变形仿真分析精度较高;通过设置合理的径向预压缩量、合理增大橡胶层厚度、采用流线形橡胶型面等可以优化牵引橡胶球铰的结构,有效减小牵引橡胶球铰的橡胶部分应力和应变,从而延长牵引橡胶球铰的疲劳寿命。本研究可为大变形牵引橡胶球铰的设计提供参考。

高速履带车辆履带销轴橡胶衬套连接力学性能研究

针对橡胶衬套材料超弹性特性行为,设计单轴拉伸实验,获得反应销轴橡胶衬套材料的力学属性数据;选择四种常用于描述橡胶材料超弹性的本构模型,基于ABAQUS得到3阶Ogden本构模型拟合效果最优;设计橡胶衬套压缩实验与仿真压缩实验,检验了本构模型的合理性;建立连接结构中带有销轴和橡胶衬套的2个履带板连接有限元模型,结合橡胶衬套实际安装特点,对橡胶衬套有限元模型径向预压缩后,完成履带板拉伸和扭转仿真计算,对仿真数据进行处理,获得橡胶衬套力学性能。通过实验与仿真相结合的方式对预压缩后履带销轴橡胶衬套连接的力学性能进行了研究,得到橡胶衬套拉伸刚度50000 N/m、扭转刚度18600 N·mm/(°),为高速履带车辆行走系统动力学性能研究奠定基础。

考虑缩径影响的橡胶衬套寿命仿真研究

为解决某车型前悬架下摆臂后衬套在路试中出现开裂的问题,提出一种考虑缩径工艺影响的寿命仿真方法。首先,通过仿真分析获得缩径后衬套的静刚度,结合多目标优化,得到可准确描述衬套力-位移特性的超弹性本构参数;然后,在考虑缩径预应变的基础上,采用裂纹扩展法预测衬套寿命,危险位置损伤达到2.01,并复现了路试开裂问题;最后,通过结构优化设计,将危险位置损伤降低至0.943。路试验证结果表明,优化后衬套的疲劳寿命得到有效提升,证明了所提出方案的有效性。

考虑材料硬度与缩径量的橡胶衬套各向刚度优化设计

【目的】通过对橡胶衬套各向刚度的优化设计以指导产品设计,以期大幅缩短橡胶衬套的研发周期。橡胶衬套作为新能源汽车、特种车辆、动车组等载运工具的重要连接件,对整车操纵稳定性起着至关重要的作用。【方法】为了避免工程实践中反复调试的繁琐工作,提出了一种考虑材料硬度与缩径量的橡胶衬套各向刚度(径向刚度、轴向刚度、偏摆刚度和扭转刚度)优化设计方法。首先,采用Ogden模型作为橡胶衬套的本构模型,通过试验设计与有限元分析相结合的方法,计算不同内芯外径、橡胶高度、缩径量和材料硬度下衬套各向刚度;然后,建立各向刚度的二阶响应面模型,利用拉丁超立方抽样和方差分析,检验响应面模型精度;最后,根据遗传算法,建立含各向刚度为设计变量的多目标优化模型,并对优化结果进行试验验证。【结果】研究表明:径向刚度、轴向刚度、偏摆刚度和扭转刚度的试验结果与目标值的相对误差分别为7.72%,9.06%,-6.33%和9.16%,均在±10%以内,满足工程应用的要求。【结论】试验结果验证了所建立的各向刚度二阶响应面模型的有效性,以及所提出优化设计方法的可行性,为橡胶衬套产品设计提供指导,可极大地缩短橡胶衬套的研发周期。

新型小径向/轴向刚度比的橡胶节点设计

为满足高速动车组电机悬挂要求,文章设计了一种新型小径向/轴向刚度比(径向刚度与轴向刚度比值)的橡胶节点,并通过有限元仿真分析、静刚度试验、疲劳试验及装车试验进行了验证。结果表明,这种结构的橡胶节点符合技术要求,且其预压缩简单有效,刚度范围可调,抗疲劳性能良好,具有良好的高温耐受性,满足电机运行环境的要求。

橡胶衬套动刚度理论模型分析及验证

为了研究橡胶衬套的动态刚度特性,使用了Berg橡胶衬套模型,并结合橡胶衬套的摩擦效应,建立了具有摩擦特性的Adams/Car多体动力学模型。通过实验确定了包含摩擦特性的橡胶衬套模型的关键参数,并将其用于多体动力学模型。同时在Adams/Template中建立六分力模型,描述橡胶衬套在不同方向上的力学特性,验证动刚度橡胶衬套模型动态力学特性的多体动力学整车模型的精确性。结果表明:动刚度橡胶衬套模型结果更贴近实验,多体动力学模型比Kelvin-Voigt模型更精确;同样,当考虑对橡胶衬套进行预加载时,动态刚度橡胶衬套模型的多体动力学模型与实验的一致性更好。

Optimal Design and Mechanical Simulation of Rubber bushing with Convex Hull Structure Based on Bionics

Inspired by the safe landing of cats falling from high altitudes,a bionic flexible rubber bushing structure is proposed and its motion characteristics are systematically studied to explore its potential application in the suppression of vibration.The convex hull structure on the bushing surface is abstracted from the cat’s claw pad,and the hyper-viscoelastic model is selected as the constitutive model of the rubber material.In addition,the design with the best vibration damping effect is finally obtained by reasonably adjusting the amount of radial compression and distribution of bionic structures.Finally,under the same conditions,the test results of the dynamic characteristics of the bushing verify the accuracy of the simulation results.Research results show that the convex hull bionic structure designed in this paper can effectively change the motion characteristics of the rubber bushing under various working conditions,which provides new inspiration or potential possibility for the design of rubber bushing in the future.

两种典型橡胶衬套在不同荷载下的动刚度特性

驱动电机总成悬置系统的隔振性能对整车噪声、振动与声振粗糙度(NVH)性能有着重要的影响意义。目前纯电动汽车悬置普遍采用橡胶衬套类结构,结构相对简单,但对其动刚度性能要求高。文章选取两种典型的橡胶衬套,利用有限元技术详细分析了两种衬套在不同荷载下的动刚度表现形式,并着重分析对比了第一个峰值位置与不同预载的关系。分析结果表明,同为衬套类结构,因结构不同,其动刚度表现特性差别较大。

重型牵引车驾驶室前悬置稳定杆总成后橡胶衬套的优化

针对驾驶室前悬置稳定杆总成后衬套在终端市场出现橡胶开裂的问题,以后衬套使用工况变形为理论计算基础,分析衬套失效原因;结合台架试验进行验证并对衬套进行优化;对优化后的衬套通过ABAQUS有限元分析软件进行多轮刚度分析,得到所需刚度曲线并制作样件进行台架及终端实车试验验证。结果证明,优化后产品的疲劳性能是原结构的2.6倍以上,为后续同类产品的开发提供了设计思路。

仿真与试验相结合的衬套耐久失效解决办法

针对耐久性路试出现的衬套开裂问题,基于虚拟试验场(VPG)技术搭建整车多体动力学模型在特征路面进行仿真,提取该衬套在特征路面上的受力及变形,通过仿真结果初步判断出了开裂原因为衬套轴向变形增大及径向受力方向与空心方向夹角偏大的共同作用导致衬套开裂,并通过有限元仿真模拟及零部件台架试验进一步验证了这一判断。基于VPG技术对衬套优化方案进行了正向设计,随后通过台架试验验证了优化方案的有效性,最终顺利通过耐久性路试验证。

液压衬套和橡胶衬套对整车舒适性影响分析

文章主要通过计算机辅助工程(CAE)整车模型仿真、整车主观评价、客观测量,从理论分析和实践两个方面阐述液压衬套和橡胶衬套对整车舒适性的影响。结果表明,减速坎工况,液压衬套比橡胶衬套X向冲击减少40%。通过以上工作,为后续项目采用液压衬套打下坚实基础。

基于ABAQUS的动力总成悬置静刚度分析

汽车动力总成悬置系统的设计应满足支撑作用,合理的悬置静刚度能够抵抗静载荷作用下的结构变形。为了研究悬置静刚度特性,利用Catia软件对某乘用车的悬置建立三维模型,通过Hypermesh对模型进行六面体网格划分,将网格文件导入Abaqus进行有限元分析后处理。基于橡胶静刚度求解公式,拟合支座反力与位移函数求得橡胶衬套在X、Y、Z三向的静刚度数值,为橡胶衬套结构设计与优化提供了数据参考。结果显示,前悬置橡胶衬套在Y向的静刚度数值最大。

基于ABAQUS二次开发的橡胶-金属衬套仿真技术研究

基于ABAQUS-Python提出了一种橡胶-金属衬套快速仿真技术。该技术将典型橡胶-金属衬套结构参数化,并通过开发的独立图形用户界面和ABAQUS脚本程序,实现自动前处理、仿真计算和后处理;读取仿真结果文件中力、扭矩、位移和角度值,采用最小二乘法计算出多向静刚度值,导出应力、应变等云图;对比仿真与实测结果,误差在10%以内,满足工程化应用要求。此外,该方法进行一次仿真分析约需8~15min,极大地提高了分析效率。

橡胶衬套对汽车转向器的质量影响研究

针对某型汽车转向器上的橡胶衬套展开研究,详细介绍了其造成的装配尺寸超差与振动试验共振问题及相应的质量风险,深入分析了导致问题的根本原因并提出了合适的改进措施。经过更新橡胶衬套尺寸成功提高转向器整体固有频率,最终通过了振动试验,并将经验教训总结为“潜在失效模式及后果分析”(FMEA)中,为其他类似转向系统的研发工作提供参考。

橡胶衬套电镀锌镍合金层与橡胶粘接工艺改进

对橡胶衬套中钢铁件电镀锌镍合金层与橡胶的粘接工艺进行改进,包括对电镀锌镍合金工艺进行优化、喷涂或刷涂较薄的底涂胶粘剂并预固化、喷涂或刷涂较厚的面涂胶粘剂。结果表明:与传统粘接工艺相比,采用改进粘接工艺的电镀锌镍合金层与橡胶的粘接力明显提高,钢铁件表面附胶率达到90%以上,粘接性能大幅提高。