Heavy Wheel Research Articles

Poster Session II, July 14th 2010 — Abstracts: Improvements in the design of a kayak-ergometer using a sliding footrest-seat complex

As observed previously in rowing, kayaking an ergometer becomes more and more popular. Nowadays, indoor kayak championships are organized performed on ergometer designed with a fixed footrest-seat complex. The main goal when one designs ergometers is to reproduce as closest as possible the on-water conditions. The reliability with on-water condition is usually assessed using both physiological and kinematics parameters. The previous studies of our research group have shown that the dynamics of the in situ movement has also to be reproduced. In other words, major muscular groups (who generated the joint torque and by the way the contact forces) involved in kayaking should be recruit with the same timing during on-water and ergometer kayaking. At the 7th ISEA conference, our research group presented a method based on numerical optimization to design a kayak ergometer equipped with a sliding footrest-seat complex that reproduces the acceleration generated in flatwater kayak. Based on these preliminary results, we have constructed a new ergometer. Then, the purpose of this study was to present the last developments performed on this ergometer and preliminary 3D kinematics analysis from elite kayakers. The characteristics (stiffness and damping) of the bungee cord linking the back of the frame with the trolley were determined using our previous results. An air brake, composed of a flywheel with a heavy wheel and two freewheel-pulleys on a shaft, simulated the water drag on the blades. However, a magnetic brake was added for specific training sessions. The paddle was linked to the pulleys by two ropes. Each side of the frame is equipped with one slide (1 dof in translation) in order to always keep the directions of the ropes parallel to the long axis of the ergometer whatever the instant of the cycle. First trials performed with elite athlete showed the robustness of all the mechanisms developed. 3D kinematic analysis showed the relevance of the adding slides when compared with on-water paddle trajectories observed during the propulsion phase. An instrumentation (3D force sensors at each contact) coupled with a specific interface that allows real time feedback is under development. This innovative ergometer will be used to collect dynamic and kinematic parameters. They will serve as input data of our simulator in order to carry out intra-athlete comparisons and to still improve the design of kayak ergometers.

Evaluation of effects of heavy wheel load on steel truss bridges by using 3D dynamic FEA

Evaluation of effects of heavy wheel load on steel truss bridges by using 3D dynamic FEA

Static and Fatigue Behavior of Thick Pultruded GFRP Plates with Surface Damage

Glass fiber-reinforced polymer (GFRP) bridge decks suffering frequent cyclic loading of heavy wheels require relatively thick pultruded composites. To examine the behavior of 12 mm thick pultruded GFRP plates containing surface layers and to study the influence of surface damage, which may be present on such decks, static and fatigue tensile tests were carried out. Severe indentation yielded not only visible damage, but also an invisible damage in the unidirectional layer. Loss of cross section area due to both damages affected the static ultimate loads. Fatigue cracks were found around higher stress concentrations on the surface layer as early as approximately 10% of the total fatigue life. These initial cracks, however, barely affected the fatigue life because delamination of the surface layers prevented the cracks from propagating. The invisible shear crack due to indentation barely affected the fatigue life since earlier splitting between initially damaged and undamaged fibers mitigated the crack prop...

Bainitic steel grade for solid wheels: metallurgical, mechanical, and in-service testing

Bainitic steel grades generally have superior rolling contact and thermal fatigue resistances, but poorer wear characteristics when compared with ‘conventional’ pearlitic steel wheels. To improve the wear characteristics, the manufacturing process of bainitic materials needs to be carefully controlled. In this article, the manufacturing process of the ‘MICRALOS’ bainitic steel grade has been described. The main focus is on metallurgical testing activities performed in order to compare the new steel grade with standard pearlitic steels and to predict the service behaviour of the solid bainitic wheels. Further, on-going field tests on the iron ore line between Luleå and Narvik have been reported, with details about measurement methods and results. The performance of the wheels is reviewed and compared with the current scientific knowledge of bainitic steel grades and the deterioration of heavy haul wheels. Finally, benefits of and challenges for bainitic wheels in general and for the MICRALOS grade wheels in particular will be discussed.

Soil compaction—indicators for the assessment of harmful changes to the soil in the context of the German Federal Soil Protection Act

Soil compaction in agriculture induced by large-scale equipment is of growing concern. Heavy wheel loads used in arable cropping have the potential to cause irreversible damage to the subsoil structure and may lead to harmful soil compaction. In order to sustain or improve soil health or fitness on a sustainable basis, indicators are needed to assess the changes in the soil structure and the respective soil functions. This requires an adequate verification of methods for distinguishing between the impairment of soil structure and the disruption of soil functions, and for the respective subject of protection. In this article the link between existing models of soil physical prognosis, practical guidelines, and criteria for the identification of affected soil structure is demonstrated, and a viable concept to distinguish harmful changes to the soil is presented. The concept consists of methods for soil physical analysis such as “ pre-compression stress” and “ loading ratio”, practical recommendations for best management practice, and an indicator-based model for the identification of harmful subsoil compaction derived from a research project for the German Federal Environmental Agency, making it possible to determine for a respective location the required level of action far beyond the common practice of precautions against harmful soil compaction.

Consistent Approach to Calculating Stresses for Fatigue Design of Welded Rib-to-Web Connections in Steel Orthotropic Bridge Decks

The authors discuss fatigue strength of welded rib-to-web junctions at the deck supports with reference to redecking of the Williamsburg and the Bronx-Whitestone bridges, where low available depth necessitated the use of special details, and recommend the use of the “modified nominal stress approach” for the design of such connections. However, experience with thousands of existing orthotropic deck bridges throughout the world shows that applied live load stresses are not the only cause of fatigue cracking and that factors related to fabrication may be of equal, or possibly, greater significance. It has been reported that in many cases, cracks in orthotropic decks developed shortly after fabrication and welding, or early after the deck installation, before the live loads had been fully applied. This led to the conclusion that fatigue cracking occurs where the effects of heavy wheel loads coincide with faulty details or inappropriate fabrication procedures. PSP 2005. Therefore, consideration of the effects of live load stresses alone addresses only one aspect of the fatigue problem. The authors imply that the type of weld used for the rib-toweb connection is accounted for by Detail Category assigned to the fillet, the partial and the full penetration welds. However, many other factors related to welding such as weld size total heat input, welding method manualautomatic, welding speed and sequence, weld imperfections, weld terminations, etc. may be more important. Dimensional fabrication tolerances and the degree of constraint of the plate elements to be welded are further factors that must be considered in the assessment of fatigue resistance. Tensile forces developing at welds due to weld shrinkage upon cooling could be a direct cause of cracking. These forces are directly related to loose fabrication tolerances and the geometric

Bodenverdichtung: Bewegt sich was? - Setzungsmessungen im Unterboden unter hoher Radlast

At the Institute for Production Engineering and Building Research of the German Federal Agricultural Research Centre in Braunschweig, a measurement system has been developed which enables in situ vertical soil displacement measurements in the subsoil, caused by travelling with heavy wheel loads. In contrast to others, this method [1, 2] makes it possible to drastically reduce the input required for field measurements by using further-developed technology. The simple handling permits simultaneous measurements at different soil depths with multiple parallel measurements each time. In field trials, promising and reproducible results were obtained for different soils, under different soil conditions and loads.

Amelioration of soil compaction can take 5 years on a Vertisol under no till in the semi-arid subtropics

Heavy wheel traffic causes soil compaction, which adversely affects crop production and may persist for several years. We applied known compaction forces to entire plots annually for 5 years, and then determined the duration of the adverse effects on the properties of a Vertisol and the performance of crops under no-till dryland cropping with residue retention. For up to 5 years after a final treatment with a 10 Mg axle load on wet soil, soil shear strength at 70–100 mm and cone index at 180–360 mm were significantly ( P < 0.05) higher than in a control treatment, and soil water storage and grain yield were lower. We conclude that compaction effects persisted because (1) there were insufficient wet–dry cycles to swell and shrink the entire compacted layer, (2) soil loosening by tillage was absent and (3) there were fewer earthworms in the compacted soil. Compaction of dry soil with 6 Mg had little effect at any time, indicating that by using wheel traffic only when the soil is dry, problems can be avoided. Unfortunately such a restriction is not always possible because sowing, tillage and harvest operations often need to be done when the soil is wet. A more generally applicable solution, which also ensures timely operations, is the permanent separation of wheel zones and crop zones in the field—the practice known as controlled traffic farming. Where a compacted layer already exists, even on a clay soil, management options to hasten repair should be considered, e.g. tillage, deep ripping, sowing a ley pasture or sowing crop species more effective at repairing compacted soil.

EVALUATION OF STRAIN IN ASPHALT MIXTURE LAYER UNDER LOW-SPEED HEAVY WHEEL LOADING

In the current design of asphalt pavement in freight container yard, theoretical design method based on multi-layered elastic analysis is applied. Fatigue criteria of subgrade generally become critical under the heavy wheel loads, however, considerable large strain observed in asphalt mixture layer in real scale tests. In this study, the effect of strain rate, slide between layers and tire contact pressure on the strain in asphalt mixture layer was discussed. It was concluded that the strain in asphalt mixture under low-speed heavy wheel loading is properly obtained by multi-layered elastic analysis, when the effect of strain rate, slide between layers and tire contact pressure appropriately considered.

The world's first automobile fatality

The first recorded automobile fatality occurred in a small town in the Irish Midlands in 1869. Mary Ward, a celebrated microscopist, artist, astronomer and naturalist, fell from a steam carriage and died after crush injuries from its heavy iron wheels. The story of first automobile fatality characterizes the individual tragedy that is each premature death. It also illuminates the story of a remarkable Victorian scientific family. Among their many achievements was the building of a reflector telescope in the heart of rural Ireland that was the largest in the world for 74 years.

Stress concentration in steel bridge orthotropic decks

The structural behaviour of orthotropic steel decks is characterized by the complex interaction between its components (deck plate, ribs and floorbeams) and also by the interaction between the structure, the pavement and the vehicle’s wheels tyres. Stress concentration resulting from out-of-plane bending of deck components at typical welded joints can make these structures quite susceptible to traffic-induced fatigue cracks. This paper addresses some of these issues through numerical modeling of orthotropic decks with trapezoidal closed ribs, via finite element method and elastic analysis of the structure under heavy vehicle wheel loading. The numerical model was calibrated with experimental results obtained from laboratory tests on a deck model. The obtained numerical results lead to a better understanding of the complex structural behaviour of slender orthotropic decks, with emphasis on the stress distribution and concentration at the rib to deck plate welded connection. A parametric analysis was performed to determine possible and rational combinations of the geometric parameters leading to the lowest values of stress peaks and the best consequent fatigue performance of the focused welded connection. Hence, the overall output can be addressed towards a safe and rational design as far as fatigue life is concerned.

Vulnerability of Bavarian silty loam soil to compaction under heavy wheel traffic: impacts of tillage method and soil water content

Soil compaction caused by traffic of heavy vehicles and machinery has become a problem of world-wide concern. The aims of this study were to evaluate and compare the changes in bulk density, soil strength, porosity, saturated hydraulic conductivity and air permeability during sugar beet ( Beta vulgaris L.) harvesting on a typical Bavarian soil (Regosol) as well as to assess the most appropriate variable factors that fit with the effective controlling of subsequent compaction. The field experiments, measurements and laboratory testing were carried out in Freising, Germany. Two tillage systems (conventional plough tillage and reduced chisel tillage) were used in the experiments. The soil water contents were adjusted to 0.17 g g −1 ( w 1 ), 0.27 g g −1 ( w 2 ) and 0.35 g g −1 ( w 3 ). Taking the increase in bulk density, the decrease in air permeability and reduction of wide coarse pore size porosity (−6 kPa) into account, it seems that CT (ploughing to a depth of 0.25 m followed by two passes of rotary harrow to a depth 0.05 m) of plots were compacted to a depth of at least 0.25 m and at most 0.40 m in high soil water ( w 3 ) conditions. The trends were similar for “CT w 1 ” (low soil water content) plots. However, it seems that “CT w 1 ” plots were less affected than “CT w 3 ” plots with regard to bulk density increases under partial load. In contrast, diminishments of wide coarse pores (−6 kPa) and narrow (tight) coarse pores (−30 kPa) were significantly higher in “CT w 1 ” plots down to 0.4 m. Among CT plots, the best physical properties were obtained at medium soil water ( w 2 ) content. No significant increase in bulk density and no significant decrease in coarse pore size porosity and total porosity below 0.2 m were observed at medium soil water content. The soil water content seemed to be the most decisive factor. It is likely that, CS (chiselling to a depth of 0.13 m followed by two passes of rotary harrow to a depth 0.05 m) plots were less affected by traffic treatments than CT plots. Considering the proportion of coarse pore size porosity (structural porosity) and total porosity, no compaction effects below 0.3 m were found. Medium soil water content ( w 2 ) provides better soil conditions after traffic with regard to wide coarse pore size porosity (−6 kPa), air permeability (at 6 and 30 kPa water suction), total porosity and bulk density. Proportion of wide coarse pores, air permeability and bulk density seems to be suitable parameters to detect soil compaction under the conditions tested.

A STUDY ON DEFORMATION CHARACTERISTICS OF FREIGHT CONTAINER YARD PAVEMENT BY SCALE MODEL TEST

In recent years, large forklifts with heavy wheel load are increasingly introduced to the freight container yard. In the current design of freight container yard pavement, theoretical design method based on multi-layered elastic analysis is applied. However in the case of freight container yard, wheel loads of forklifts are significantly larger than the traffic loads on the roads. To investigate the deformation characteristics of asphalt pavement under heavy wheel load, moving wheel loading tests were carried out On the other hand, ground contact area of forklift tires change with carrying containers. Because the tread of forklift tire is greater than the thickness of pavement, strain in the pavement is significantly influenced by ground contact area. In this study, FEM was introduced to estimate the effect of ground contact area on the strain in the asphalt pavement

A MEASUREMENT BASED TYRE CHARACTERISTICS APPROXIMATION

Abstract To derive an approximation from the steady state measurements of tyre characteristics an approach in two steps is chosen. First the measurements of the tyre forces in a preprocessed form are normalized with the maximum contact coefficients and the corresponding slip values. Then, with the measurements now forming a very narrow band, a single curve can be used to approximate the whole tyre characteristics. The mutual influences of lateral and longitudinal forces are taken into account with combined slip values, which cover the whole range from locked wheels to heavy spinning wheels including small camber angles. Different surface conditions are considered with three parameters and the sliding coefficient so that the change of original characteristics can be handled easily. The self aligning torque is described by three components: the lateral force times pneumatic trail, the spin-slip torque and the reaction of lateral deflection and longitudinal force. Once again for the approximation of the pneumatic trail a normalization is used leading to a single curve for the whole characteristic. A similar method was applied to get a feasible approximation for the spin-slip torque. For the validation of the approximation comparisons of calculated and measured characteristics are presented. Whole characteristics for a tyre moving with lateral and longitudinal slip demonstrate the possible range of application.

Acoustic Transmission Technique for Evaluating Fatigue Damage in Concrete Bridge Deck Slabs

This paper focuses on evaluation of a novel acoustic transmission technique (ATT) for tracking fatigue-induced damage in steel-free bridge deck slabs under lab conditions. The technique comprises identification of changes in acoustic waveform attenuation through concrete by comparing integrated waveform amplitudes recorded at 2+ acoustic sensors. This methodology is based on the experimental observation that cracking in concrete leads to increases in attenuation of the acoustic signals. The mapping of cracks and other means of detecting damage induced by cracks were used to independently verify the conclusions from the ATT. Each of 4 deck slab panels was subjected to ~1,700 cycles of a heavy wheel load; damage induced was tracked reliably by the ATT. The procedure of evaluating dimensionless integrated amplitude ratios in lieu of absolute signal magnitudes proved a highly robust, stable means of measuring attenuation, hence damage in the slab.

FEM analysis of subsoil reaction on heavy wheel loads with emphasis on soil preconsolidation stress and cohesion

Heavy sugarbeet harvesters may compact subsoil. But it is very difficult to study this by field experiments that resemble agricultural practice. Therefore, an analysis was made by a finite element method (FEM) for a relevant calcaric fluvial soil profile, the mechanical properties of which were largely known. Measuring data of this Lobith loam soil includes preconsolidation stress, compression index and swelling index, all as a function of depth. Using these three types of soil parameters calculations have been done for tyre sizes, inflation pressures and wheel loads that occur with heaviest sugarbeet harvesters available on the European market in 1999. Because no values on soil cohesion were available, the calculations were done for several cohesion levels. The results include the detection of regions with Mohr–Coulomb plasticity and regions with cap plasticity (compaction hardening). For the soil studied—a typical soil strength profile for arable land with ploughpan in the Netherlands in the autumn of 1977—all studied combinations of wheel load and inflation pressure did not induce compaction in and below the ploughpan. The size of the region with Mohr–Coulomb plasticity decreased with increasing cohesion. It appeared from a sensitivity analysis that, although soil modelling may use a great number of soil parameters, the most important parameters seem to be: preconsolidation stress and cohesion. There is an urgent need for data of these parameters that are measured on a great range of subsoils and subsoil conditions.

Prevention strategies for field traffic-induced subsoil compaction: a review: Part 1. Machine/soil interactions

Subsoil compaction is a severe problem mainly because its effects have been found to be long-lasting and difficult to correct. It is better to avoid subsoil compaction than to rely on alleviating the compacted structure afterwards. Before recommendations to avoid subsoil compaction can be given, the key variables and processes involved in the machinery–subsoil system must be known and understood. Field traffic-induced subsoil compaction is discussed to determine the variables important to the prevention of the compaction capability of running gear. Likewise, technical choices to minimise the risk of subsoil compaction are reviewed. According to analytical solutions and experimental results the stress in the soil under a loaded wheel decreases with depth. The risk of subsoil compaction is high when the exerted stresses are higher than the bearing capacity of the subsoil. Soil wetness decreases the bearing capacity of soil. The most serious sources of subsoil compaction are ploughing in the furrow and heavy wheel loads applied at high pressure in soft conditions. To prevent (sub)soil compaction, the machines and equipment used on the field in critical conditions should be adjusted to actual strength of the subsoil by controlling wheel/track loads and using low tyre inflation pressures. Recommendations based on quantitative guidelines for machine/soil interactions should be available for different wheel load/ground pressure combinations and soil conditions.

Heavy Load Rollers in Logistic Systems

Wheels with polyurethane bandages are in common use in logistic systems with friction gear actuation. Many research projects have studied the mechanical construction of these heavy load wheels. The studies have been theoretical as well as experimental. Research interests at the department of machine elements include the wear in the presence of intermediate material on the contact area between the bandage surface and the contact surface on which the wheel rolls off. This problem, which is observed when examining this tribochemical system, has not been studied before. Within this project both one-phase intermediate materials such as sand, water, cutting-cooling-emulsion, metal splinters and two-phase intermediate materials such as sand/water and combinations of the latter were taken into consideration. In addition, the exposure of the bandage hardness, the cross linking agent of the polyurethane, the mechanical stress, and the slip are observed. The analysis of the experimental results indicates that friction gear actuators can be constructed abrasion-optimised, taking into account special interfering effects in the form of intermediate materials in the contact area.

EXAMINATION ON THE DESIGN METHOD OF THE ROADWAY TYPE PERMEABLE PAVEMENT AND THE STORAGE PENETRATION FACILITIES

Generally, the area of the container yard pavement becomes 1.5-2.0ha, length of arrival and departure lines of the railway freight facilities is necessary over 500m. Therefore, it is changeable to the case in which it deals with rain water of the pavement surface and case in which it must make drainage structure in the extension direction and in which large wheel load like the forklift works with the weak point. Permeable pavement and storage penetration facilities of the heavy wheel load correspondence were required in order to solve these problems. Then, flow property resistance of the surface course material as a problem of permeable pavement, strength of permeable subbase course and thickness design, design method of the storage penetration facilities were examined, and the verification was carried out in the experimental pavement installed in the container platforms.

Compaction of a Eutric Cambisol under heavy wheel traffic in Switzerland:: Field data and a critical state soil mechanics model approach

Subsoil compaction has become a problem of world-wide concern, especially under highly mechanised agricultural practices. Severe structural degradation impedes plant growth. Therefore, compaction must be limited to layers which can be structurally reclaimed with reasonable effort by tillage. The purpose of this study was to investigate the impact of a single pass with a sugar beet harvester on the soil properties of an unploughed Eutric Cambisol. In autumn 1998 and 1999 field measurements and laboratory testing were carried out in Frauenfeld, Switzerland. The wheel loads were 107 kN in 1998 and 108 kN in 1999. Changes of bulk density, total porosity, macroporosity and pre-consolidation pressure show that compaction effects were restricted to the topsoil (0–0.25 m depth). Below 0.25 m depth no changes were measured. The compaction beneath the tyre was modelled with a two phase finite element model in the framework of critical state soil mechanics. The model predicts the degree and depth of compaction of an Eutric Cambisol caused by a single pass in Switzerland. Modelled data and field results agree quite well.