Calculating the contact area of trailer tyres in the field

The spectacular increase in the weight of self-propelled harvesters since the early 1980s also applies to trailed implements such as slurry spreaders, compost spreaders, cutter-blowers and general farm trailers. With axle loads exceeding 10 tonnes/axle (tandem 20 tonnes, tridem 27 tonnes), risks of severe compaction can now be expected, not only in field crops but also in grassland. Calculation tables for accurately evaluating contact surfaces of transport tyre, given their properties, load and inflation pressure, are insufficient at the present time. Equations for traction tyres are not suitable for trailer tyres.To overcome this deficiency, contact areas in the field were recorded on 19 sites, from soft to hard surfaces, using 24 different trailer tyres, with varying loads and inflation pressures. The regression calculations for evaluating the contact area apply to a total of 143 measurements.The dimensions of the tyre (width × unladen diameter), the load on the wheel and the inflation pressure are all highly significant variables for evaluation of the soil contact area. Considering the average residual standard deviation for each regression calculation, the best approximations are achieved by taking into account the tyre structure (cross-ply and radial), the width of tyre for cross-ply tyres and the type of tyre, in the case of a radial tyres (low profile or terra profile).Moreover, contrary to expectations, observations show that with low levels of load, reducing inflation pressure can also reduce the contact area.As regards soil hardness, observations show that there is no direct link between a hard soil and a reduced contact area; this relationship does not appear to be linear. The calculations are considered to be reliable on semi-firm to firm soil, frequently found on temporary grassland or natural grassland (penetration resistance 6.5–25.0 MPa).     

路面不平度对车辆制动过程中轮胎动态性能影响的仿真分析

采用作者建立的非线性时变轮胎模型,仿真分析了路面不平度幅值及路面空间频率变化对地面附着性能的影响。得出路面不平度增大时,使路面对车轮的附着能力下降,因而使制动距离增长的结论。同时说明非线性时变轮胎模型能较真实地体现路面不平度的影响,对不平路面上车辆制动性能仿真是一个有效的轮胎力学模型     

准时生产与库存对生产成本的影响研究——以卡莱轮胎公司为例

库存管理是企业管理的重要组成部分,现代物流管理技术可以从根本上降低仓储成本,方法之一就是零库存技术。但卡莱公司实行零库存管理以来,其生产成本却呈现大幅度上升趋势。如何控制好生产成本,并有效获得较大利润,对轮胎制造业发展是个重要的问题。因此,从轮胎生产成本构成要素角度出发,分析计算出频繁转化规格对轮胎的生产成本构成的影响程度及影响结果,并计算出适当的库存对成本的影响。通过成本分析,可以帮助企业找到降低成本的途径和改进管理的措施。     

汽车胎压检测系统中轮胎定位技术的分析与研究

轮胎定位技术是汽车轮胎压力检测系统中的关键核心技术。为此,主要阐述了当前汽车装备轮胎压力检测系统的重要性;分析了轮胎定位原理以及现有轮胎定位技术存在的缺点;提出了一种新型的轮胎定位技术—外置编码储存器式,并对其可行性及特点进行了分析研究。     

驱动胎轮牵引性能的田间试验研究

为了解后轮沿前轮行驶的拖拉饥,在不同土壤条件下的牵引性能,建立其预测模型,通过单轮驱动试验装置试验测定表明,在粘壤土中,行驶在轮辙内的子午线驱动轮胎,其牵引性能优于行驶在轮辙外;而在砂土中却没有多大差别;此外该驱动轮的牵引力系数有随其前进速度增加而减少的趋势。     

轮式车辆轮胎动态参数对传动系扭转振动影响的分析

建立了动态变参数轮胎模型。测量了轮胎的切向动态刚度和阻尼,回归出轮胎切向动态阻尼半经验公式。得出了随着轮胎滚动速度的增加,轮胎的切向动态刚度和阻尼逐渐减小的结论。分析了轮胎的动态阻尼对传动系扭转振动的影响。     

轮胎胎面橡胶块与刚性路面摩擦接触数值分析

建立了轮胎胎面橡胶块与刚性路面摩擦接触非线性有限元分析模型,对轮胎胎面橡胶块与刚性路面相互作用时的变形特性和接触应力分布规律进行了数值分析,讨论了界面摩擦因数和橡胶块的厚度对接触应力的影响。     

生物固体用于固定轮胎灰中重金属元素移动的研究

本文通过室内模拟淋溶实验，研究了用生物固体固定重金属的可行性。淋洗柱中填充的基质为土壤、轮胎灰、土壤与轮胎灰混合后加入不同量的生物固体及是否加入石灰及木屑等处理，连续淋洗７周，结果表明：当基质ｐＨ＜７时，生物固体对重金属无有效的固定作用；生物固体加入量越多，重金属的浓度增高，必须用石灰调节；淋洗时间越长，淋洗液中重金属浓度逐渐下降；随着生物固体用量的增多，渗漏液中ＮＯ３－Ｎ及电导随之增加，有石灰时增加量较少。     

Prevention of traffic-induced subsoil compaction in Sweden: Experiences from wheeling experiments

Abstract

In this paper we describe the susceptibility of Swedish subsoils to compaction and discuss strategies for prevention of traffic-induced subsoil compaction against the background of experiences from wheeling experiments conducted in Sweden during recent years. The susceptibility of Swedish subsoils to compaction must be considered high because subsoils are often wet during field operations and machinery with high wheel loads is used. The risk of subsoil compaction could be reduced by technical solutions, such as the use of dual and tandem wheels instead of single wheels, low tyre inflation pressure or tracks. However, each of these solutions has its limitations. Results from several wheeling experiments on different soils indicate that residual deformations occur even when the applied stress is lower than the precompression stress. Hence, soil compaction could not be avoided completely by limiting the applied stress to the precompression stress.     

Reducing the risk of soil compaction by applying ‘Jordværn Online’® when performing slurry distribution

Abstract

Through a case study, it is shown that the potential of applying JORDVÆRN Online® as a decision-making tool aimed at supporting sustainable in-field traffic provided the farmer with the potential to improve and maintain the soil as a continued growth medium for the future agri-food production. The combination of CTF and optimal selected tyre configurations provides the farmer with the potential of cropping agricultural land without creating permanent soil compaction. Additional, the case study indicates an urgent need for the development of alternative systems for in-field traffic in wet conditions, e.g. multiple-axle trailers with real low-inflation tyres.