A Theoretical Analysis of the Ride Vibration of Agricultural Tractor and Trailer Combinations

SUMMARY

A six degree of freedom model of an agricultural tractor and trailer combination has been developed. Results from eigenvalue and frequency response calculations indicated that tractor operator vibration levels will be higher when operating with a trailer than for the tractor alone, due mainly to increased tractor pitch motion.

Although minor improvements could be made to present tractor and trailer combinations by moving the hitch forward of the tractor rear axle or providing some damping at a sprung hitch, the scope for a significant improvement in ride lies in changing the configuration. If higher speed specialised transport vehicles prove economical for agriculture, there are some advantages in ride vibration to be gained by changing the layout of the tractor and trailer combination to resemble an off-road version of a commercial articulated lorry.     

Ride Vibration Measurements of Agricultural Tractor and Trailer Combinations

SUMMARY

Tractor ride vibration levels have been measured when operating with and without a two wheel (2W) unbalanced and a four wheel (4W) balanced trailer. Measurements were made in the vertical, pitch, longitudinal and roll directions with the trailers unladen and laden over four typical farm surfaces

The results showed that tractor ride vibration levels were usually increased in all directions-particularly the longitudinal direction- when operating with the laden trailers. But for the unladen trailers, they were increased only in the longitudinal direction. Predominant tractor frequencies tended to be lower with the trailers attached, and coupling between the tractor longitudinal, vertical, roll and pitch co-ordinates was generally increased

Comparisons of the results with the trends predicted by a simplified theoretical model of a tractor and 2W trailer, suggested that the model should be extended to include, (a) the roll direction, (b) more realistic ground inputs, and (c) a 4W trailer     

Ride Vibration Measurements of Agricultural Tractor and Trailer Combinations

Tractor ride vibration levels have been measured when operating with and without a two wheel (2W) unbalanced and a four wheel (4W) balanced trailer. Measurements were made in the vertical, pitch, longitudinal and roll directions with the trailers unladen and laden over four typical farm surfaces

The results showed that tractor ride vibration levels were usually increased in all directions-particularly the longitudinal direction- when operating with the laden trailers. But for the unladen trailers, they were increased only in the longitudinal direction. Predominant tractor frequencies tended to be lower with the trailers attached, and coupling between the tractor longitudinal, vertical, roll and pitch co-ordinates was generally increased

Comparisons of the results with the trends predicted by a simplified theoretical model of a tractor and 2W trailer, suggested that the model should be extended to include, (a) the roll direction, (b) more realistic ground inputs, and (c) a 4W trailer     

The Simplified Dynamic Model,Measurement and Evaluation of Ride Vibration for the Combination Unit of Agricultural Hand Tractor and Trailer

SUMMARY

In this paper, a mathematical model of four degree-of-freedom of the combination unit has been developed, which was formulated by means of the modal synthesis technique. The spectral matrix of acceleration response of the combination unit was derived on the basis of the model. The relationship between the spectral matrix and the road roughness spectrum was given also.

Measurements of ride vibration of the combination unit on several types of roads were made and recorded, the signals recorded on the tapes were data-processed with the real time signal analyzer. Then, an evaluation of ride comfortability of the combination unit was made according to the relevant international standards.     

The Simplified Dynamic Model, Measurement and Evaluation of Ride Vibration for the Combination Unit of Agricultural Hand Tractor and Trailer

In this paper, a mathematical model of four degree-of-freedom of the combination unit has been developed, which was formulated by means of the modal synthesis technique. The spectral matrix of acceleration response of the combination unit was derived on the basis of the model. The relationship between the spectral matrix and the road roughness spectrum was given also.

Measurements of ride vibration of the combination unit on several types of roads were made and recorded, the signals recorded on the tapes were data-processed with the real time signal analyzer. Then, an evaluation of ride comfortability of the combination unit was made according to the relevant international standards.     

三轴拖车平顺性仿真分析

以某三轴拖车为动力学模型,在ADAMS软件的基础上进行二次开发,得到参数化的建模分析软件。建模中考虑钢板弹簧、减振器和橡胶衬套的非线性特性,并以不同的路面输入条件为激励,通过仿真可以得到整车模型上任意位置的动力学参数的分析结果。通过与该车的试验报告比较,验证了该平顺性分析方法的有效性和高效性。     

牵引车平顺性的影响因素分析

为了对牵引车平顺性的影响因素进行分析,设计了一个相关的试验方法,并通过道路试验综合分析了各因素对平顺性试验的影响程度。试验结果表明路面条件对乘坐舒适性性能指标影响最大。     

论汽车列车的合理匹配

随着我国经济的发展,长途物流在整个物流中所占比例越来越大,用户对重型汽车列车的需求也越来越大.现在组成汽车列车的牵引车和半挂车是2块牌照,用户可自由选择两者组成列车.而对于汽车列车中的铰接列车(即半挂式汽车列车),GB 1589-2004明确规定其总长≤16.5 m(注:自2008年1月1日起,与整体封闭式厢式半挂车组成的铰接列车在高等级公路上使用时,车身最大限值为18.1 m).考虑到半挂车不能单独上路行驶,所以,汽车列车总长限值的实际意义很大.     

Longitudinal Oscillations of Vehicle/Trailer Combinations Induced by Overrun Braking

A mathematical model for the representation of longitudinal oscillations which can occur in car/trailer systems in braking, when the trailer brakes are applied through compression of the towing hitch, is described. The model is used to show how the trailer braking system parameters affect the steady deceleration performance of the vehicle combination, and the stability, in the linear system sense, of the steady motions. The sensitivity of the stability to other system design parameters is also examined.

Digital simulation of the motions occurring in response to a step input of car braking torque is reported, with the results confirming the predictions of the linear stability analysis, and also showing the influence of backlash in the trailer brake actuating mechanism.

The system is shown to be capable of self-excitation in a “shunting” mode, in which the car and trailer motions are in antiphase, with the stability/damping property critically dependent on drawbar damping, and only weakly dependent on other system parameters. The characteristic frequency of the “shunting” mode oscillations is shown to be controllable via the stiffness of the trailer brake linkage, but this frequency is closely related to the steady drawbar deflection which occurs in uniform deceleration.

The model behaviour described provides a basis for the design of relevant systems whose longitudinal dynamic characteristics will be satisfactory.     

采用多体系统动力学的平衡悬架牵引车平顺性研究

采用多体系统动力学理论及相应软件ADAMS，对具有平衡悬架的3轴牵引车平顺性进行研究。建立了其多体系统动力学模型，并经过二次开发形成一套能够进行参数化自动建模的软件系统。对仿真模型进行时域、频域的仿真分析，并研究平衡悬架的一些主要设计参数对平顺性的影响。     

汽车行驶平顺性评价方法述评

“1／3倍频带分别评价法”、“总加权值评价法”和“1／2总加权值评价法”,是目前常用的三种评价汽车行驶平顺性的方法。对此三种方法作了简要的论述,以实例分析了它们之间的差别和应用局限性,并就如何评价汽车的行驶平顺性问题提出了相应的建议。     

平地机振动舒适性的测试与评估

介绍了国际标准ISO 2631和欧共体人体安全委员会法规89/391/EC有关车辆座椅振动的测试、分析和评估方法,对平地机在现场作业和路面行驶工况下的振动进行了测试和分析,并以试验中振动最严重的工况为例,按照ISO2631和89/391/EC对平地机振动舒适性及振动对人体健康的影响进行了分析评估。最后,对如何改善平地机的整车动态性能,提高座椅舒适性提出了建议。     

普通半挂牵引车驾驶室舒适性评价

由于传统半挂牵引车驾驶室采用的是半悬浮被动悬置,减振效果不好,对于经常进行中长途运输的半挂牵引车司机而言,连续较长时间的驾驶会使司机暴露于机械性全身振动(WBV)之中。由于目前还没有确凿的证据证明半挂牵引车司机的腰痛等职业病与全身振动有直接关联,故为探索有关驾驶半挂牵引车的健康风险程度进行了试验验证。对同一辆试验车在不同路面、载荷和车速的多工况下进行了研究,并将试验结果与标准GB/T 13441.1-2007附录B中的健康指南警告区域进行了对比。研究表明,在当前的行驶条件下,我国半挂牵引车司机每天的连续驾驶时间最多不应超过5.5 h。     

试论欧美厢式半挂列车的“减负”（下）——减小厢式半挂列车行驶阻力

3．3空气动力学整流装置 3．3．1牵引车部分 牵引车整流装置包括驾驶室顶整流装置、驾驶室后端整流装置和牵引车侧整流装置（包括油箱侧面整流装置）。     

A Dynamical Analysis of a Towed Two-Wheel Trailer1

The towed trailer method for skid resistance measurements is a practical one for characterizing the friction characteristics of highway pavements, and has been standardized by the ASTM 11). Numerous papers have been published about the improvement of equipment and field-testing techniques but little has been done toward a theoretical explanation.

This paper presents a mathematical model of the trailer which includes roll, pitch, and vertical motion. The skid resistance calculated by using this model gives an excellent check on the standard ASTM skid number formula. The response time and damping effect after locking one test wheel can be clearly seen in this model. Possible effects of the dimensions of trailer, stiffness of suspension system, tire pressure, etc. to skid resistance can also be examined.     

A Dynamical Analysis of a Towed Two-Wheel Trailer1

SUMMARY

The towed trailer method for skid resistance measurements is a practical one for characterizing the friction characteristics of highway pavements, and has been standardized by the ASTM 11). Numerous papers have been published about the improvement of equipment and field-testing techniques but little has been done toward a theoretical explanation.

This paper presents a mathematical model of the trailer which includes roll, pitch, and vertical motion. The skid resistance calculated by using this model gives an excellent check on the standard ASTM skid number formula. The response time and damping effect after locking one test wheel can be clearly seen in this model. Possible effects of the dimensions of trailer, stiffness of suspension system, tire pressure, etc. to skid resistance can also be examined.     

拖挂式房车制动稳定性的研究

在建立6自由度拖挂式房车转弯制动数学模型的基础上,对拖挂式房车的制动过程进行了仿真计算,分析了转向角、转向角速度和房车车轮制动力对房车横摆角速度的影响以及各参数之间的协调优化。为寻求房车车轮制动力与转向角、转向角速度、制动时间等因素的最优关系,达到拖挂式房车在行驶过程中实时控制房车制动力,提高拖挂式房车行驶的稳定性奠定了基础。     

试论欧美厢式半挂列车的“减负”（中）——减小厢式半挂列车行驶阻力

在高速公路上以105km／h行驶的半挂列车，有50％以上的燃油能量是用来克服空气阻力和滚动阻力的。减少空气阻力的整流装置可以安装在牵引车的驾驶室顶部和燃油箱侧面等位置，还可以安装在厢式半挂车侧裙部和后端等位置，以及两者之间的间隙处（如图13）。空气阻力在厢式半挂列车各部分的分配如图14所示，