基于功热等效的减振器温度特性建模方法研究

以某型双筒充气式液压减振器为研究对象，结合其结构特点及产热与传热原理就减振器温度特性仿真的建模方法展开了探究。借助仿真软件AMESim，分别建立了面向减振器机械阻尼特性和传热特性的等效参数化仿真模型。基于功热等效的方法，即以阻尼特性模型仿真出减振器的示功特性，再以此计算出传热模型发热功率的方式对温度特性进行仿真求解。通过仿真结果与实验结果对比可知，该模型的计算精度较高，建模方法切实可行，所建立的仿真模型可用于减振器温度特性的研究与预测。     

汽车液压减振器热-机耦合动力学影响因素分析

建立考虑悬架系统振动、减振器机械阻尼特性、减振器发热及散热的汽车液压减振器热-机耦合动力学闭环系统的数学模型,分析车辆悬架系统参数、减振器结构参数及环境因素对减振器油液最终平衡温度及达到最终平衡温度所需时间的影响,为减振器设计提供理论指导.     

叶片式减振器阻尼特性分析与实验研究

通过对叶片减振器的结构进行分析,建立了叶片减振器的流体力学模型.结合不同温度下叶片减振器的阻尼力实验数据,对减振器流体模型进行了最小二乘拟合,最后通过不同温度下减振器的实验数据和利用拟合参数得到的计算结果相比较,验证了所得参数的准确性,以及该方法的有效性.根据拟合的参数,可以为叶片减振器的结构设计改进以及阻尼特性研究提供依据.     

基于能量法的充气减振器开阀与畸变特性试验研究

通过研究减振器开阀与畸变特性机理,提出了示功总能量、示功能量比两个减振器能量耗散评价指标。利用LabVIEW平台实现减振器能量特性软件编程,将减振器试件充入不同压力气体,并施加不同速度的激励,得到不同充气压力下的减振器能量特性曲线,利用减振器能量耗散评价指标,分析开阀与畸变特性。结果表明:减振器开阀和畸变影响减振器能量曲线梯度,在一定范围内,随充气压力的增加减振器抗畸变能力增强。     

液压减振器节流损失及对阀系参数设计影响

通过对减振器油液状态以及沿程和局部节流损失分析,提出了减振器临界速度概念,建立了沿程节流损失系数和活塞孔等效长度随减振器速度变化曲线.根据减振器速度、流量、压力和阀片变形之间关系,建立了阀系参数设计精确模型.通过实例,利用该模型在考虑局部损失和不考虑局部损失两种情况下,对减振器阀系参数进行设计,对设计结果进行了比较,对局部节流损失对阀系设计参数的影响进行了分析,并对设计减振器进行了特性试验.结果表明,减振器阀系参数设计模型是正确的,参数设计值是可靠的.     

抗蛇行减振器温变特性研究

分析了油液温度对抗蛇行减振器动态特性的影响,比较了不同油液类型不同温度时对减振器动态特性的影响,并对抗蛇行减振器在工作过程中油液温变特性进行了研究。结果表明:随着油液温度的降低,减振器吸收的能量、动态阻尼和动态刚度越来越越大,低温时油液温度对减振器动态特性影响大于高温时。不同油液类型对抗蛇行减振器动态特性影响非常大,A油液对温度敏感程度大于B油液;不论低温还是常温,减振器连续不断工作,短时间(140min)内温度有所上升,但由于散热快,上升都不是很大,温度随时间呈斜率增加式非线性增加,即温度上升越来越快。     

液压减振器散热性能研究

液压减振器是通过消耗机械能实现减振目的的装置,但目前其散热效果并不理想,温度升高导致了减振器整体性能下降。利用路面不平度激励模型、悬架系统振动模型、热量传递模型,通过能量守恒定律建立了液压减振器的热力学平衡数学模型。综合考虑油液泄漏特性、密封特性以及液压减振器阻尼性能界定其许用油温。对液压减振器散热参数进行了分析研究,且试验结果表明分析模型与设计方法正确,为减振器的设计提供参考。     

活塞织构对液压减振器动态阻尼特性影响分析

考虑活塞具有矩形织构的摩擦与润滑因素,研究充气式双筒液压减振器动态阻尼特性.建立双筒液压减振器的阻尼特性数学模型和动压润滑方程,对减振器阻尼特性数学方程的复原和压缩行程进行求解,得到减振器上、下腔压力.采用雷诺空化边界条件,将上、下腔压力作为初始压力,对Reynolds方程采用五点差分法进行离散,利用超松弛迭代法(su...     

抗蛇行减振器温变特性及对车辆安全性影响

基于台架试验分析了油液温度对抗蛇行减振器动态特性影响(即温变特性),并模拟分析了抗蛇行减振器在实际工作服役过程中动态特性变化情况(即时域特性),借助于SIMPACK软件对抗蛇行减振器油液温度对车辆安全性影响进行了仿真分析。研究结果表明:随着油液温度升高,减振器吸收的能量、动态刚度和动态阻尼均减小,油液温度对相位角影响不明显;低温(小于0℃)对减振器吸收的能量、动态刚度和动态阻尼影响大于高温(大于0℃)对其影响。不论是低温还是常温,抗蛇行减振器在模拟时间5 h内,其动态特性变化不是很大。仿真结果表明抗蛇行减振器内部油液温度变化不会影响行车安全。     

油压减振器的油温敏度与散热参数设计研究

以可调式线性油压减振器为研究对象，建立了其额定典型工作点阻尼力受油温影响的数学模型。借助这一模型，在综合考虑油液特性、密封件耐温特性以及油压减振器阻尼性能能否满足车辆运行要求的前提下，求得减振器的许用油温，进而进行减振器散热参数的设计计算。试验结果表明，提出的分析模型和设计方法正确，可用。     

两种CINRAD/SB天气雷达汇流环常见故障及维护技巧

十堰CINRAD/SB雷达于2007年投入运行,在长时间运行中出现不少故障,其中以雷达汇流环的故障频次最高,前后更换过4次两种规格的汇流环组件,文章通过对不同材质汇流环的工作原理、基本结构、以及性能和维护重点加以阐述,以帮助提高维修人员快速判断和维护汇流环故障的能力。     

闭式冷却塔的数值分析

采用已有的数学模型,利用不同作者试验所得的传热、传质系数经验公式,预测了闭式冷却塔的热力性能,得到了不同工况下的出口温度、换热量,并与Hasan的试验测试结果进行对比,采用Mizushina的经验公式得到的预测换热量与试验值的最大偏差达到37.12%,采用Hasan试验所得的经验公式计算得到的结果与试验结果一致性较好。结果表明:预测闭式冷却塔不同工况下的热力性能时,应采用试验范围内所得的传热、传质系数经验公式,否则会产生较大误差。对闭式冷却塔热力性能的合理预测有一定的指导作用。     

Neural network prediction of disc brake performance

An automotive brake's performance results from the complex interrelated phenomena occurring at the contact of the friction pair. These complex braking phenomena are mostly affected by the tribochemical properties of the friction material's ingredients, the brake disc properties, and the brake's operating regimes. In this paper, the synergistic effects of the friction material's properties, defined by its composition and manufacturing conditions, and the brake's operating regimes on the disc brake factor C variation have been modelled by means of artificial neural networks. The influences of 26 input parameters, determined by the friction material composition (18 ingredients), its manufacturing conditions (5 parameters), and the brake's operating regimes (3 parameters) on the brake factor C variation, have been predicted. The neural model of the disc brake cold performance has been developed by training 18 different neural network architectures with the five different learning algorithms. The optimal neural model of disc brake operation has been shown to be valid for predicting the brake factor C variation of the cold disc brake over a wide range of brake's operating regimes and for different types of friction material.     

直流降膜式旋风除雾器的性能测试

测试了表观气速和液气比对直流降膜式旋风除雾器分离性能的影响，讨论了气液两相流流型对分离性能的影响，确定了最佳操作条件。以粉尘代替雾滴，解决了除雾器分离效率难以测定的难题，为评价旋风除雾器的分离性能及工业放大提供了依据。     

Prediction of brake friction materials recovery performance using artificial neural networks

The brake friction materials in an automotive brake system are considered as one of the key components for overall braking performance of a vehicle. The sensitivity of friction material performance and accordingly brake performance, versus different operating regimes, has always been an important aspect of its functioning. In this paper, the influences not only on the brake operation conditions but also on the formulation and manufacturing conditions of friction materials have been investigated regarding friction materials recovery performance by means of artificial neural networks. A new neural network model of friction material recovery performance, trained by the Bayesian Regulation algorithm, has been developed.     

Evaluating lifetime performance of limited slip differentials

Extensive research has been performed regarding wet clutch function and performance. Although wet clutches are used in both automatic transmissions and limited slip differentials in cars, most research has been performed for wet clutches incorporated in automatic transmissions. The operating conditions of wet clutches in automatic transmissions differ from the operating conditions of the wet clutches used in limited slip differentials. Therefore, a method and a test bench to use in the investigation of the degradation of limited slip differentials were developed in this work. The typical operating conditions of the limited slip differential and the differences compared with wet clutches incorporated in automatic transmissions were also addressed. Tests performed showed that the developed test bench and method can be used to address differences in frictional response over time for different types of operating conditions. Copyright © 2013 John Wiley & Sons, Ltd.     

An experimental investigation into the micro-electrodischarge machining behavior of p-type silicon

The present study aims to investigate the feasibility of micro-structuring in p-type silicon, using conventional die-sinking electrodischarge machining (EDM). The EDM behavior of the silicon material is studied in terms of the effect of major operating parameters on the performance characteristics during the micro-hole machining. In addition, microelectrodes are fabricated successfully on the conventional EDM machine for machining different micro-structures in silicon. Three different types of micro-structures??micro-hole, blind slots, and through slots??are fabricated in p-type silicon successfully by using optimum parameters setting. It has been observed that p-type silicon is machinable by EDM using both the polarities. Moreover, like other electrodischarge machinable materials, the selection of optimum operating parameters is very important for improved performance, as those parameters are found to influence the EDM performance of silicon significantly. Finally, it has been concluded that p-type silicon is machinable into different forms of micro-structures by understanding its electrodischarge machining behavior and by careful selection of optimum parameters.     

A measuring complex for time-of-flight spectrometry of fast neutrons

A measuring complex for solving problems of fast neutron spectrometry using the time-of-flight method has been developed on the basis of an ЗГП-15 electrostatic tandem accelerator operating in a pulsed mode. The pulse repetition rate of the accelerator is 2.5 MHz, and the pulse duration is τ ≤ 1 ns. The accelerator components, some features of their performance, and their main parameters are described. The complex has been used to investigate the differential neutron emission cross sections for different constructional materials. A method providing the stable performance of its measuring channels has been proposed and tested.     

Performance of aluminum alloy graphite bearings in a diesel engine

Performance of connecting rod small end bearings made of AlCu4.5 and AlSil2CuNiMg 1.5 alloys containing three percent by weight of dispersed graphite particles has been studied in a 5 hp diesel engine. Their performance has been compared under identical operating conditions with that of commercial leaded bronze bearings. Results from standard 100 h engine tests (conforming to IS 1600, 1960) under normal engine operating conditions, and from 50 h tests under adverse lubricating conditions, indicate that compared to leaded bronze bearings aluminium alloy graphite bearings show: (1) up to a three-fold reduction in the dimensional wear of the bearing surface, (2) a marked reduction in the scoring of the gudgeon pin surface as indicated by surface roughness measurements. These results have been supplemented with others from wear tests on the same alloys carried out using a pin on disc wear testing machine. Superior performance of the aluminium alloy graphite bearings is attributed to the formation of a triboinduced graphite-rich layer on the bearing surface. The presence of this layer has been confirmed by scanning electron microscopy (sem) and x-ray photoelectron spectroscopy (xps).     

A novel family of traction fluids deriving from molecular design

An investigation has been undertaken into the fundamental molecular design features that may be seen to correlate with high traction coefficients of lubricants operating under elastohydrodynamic conditions. With the assistance of computer-aided molecular mechanics modelling, a novel family of fluids has been designed which display excellent tractional performance. Prospects for the further development of these modelling techniques and also the practical usage of the designed fluids are discussed.