Worn Tread Research Articles

Assessment of human health impact based on life cycle assessment: A case study of Thai retread tire

The sustainable production of tire supply chain has been recently highlighted to reduce the environmental and human health impacts. The main environment problem of tire supply chain is waste treatment. When the tires reach the end of their working life, they are recycled (obtaining raw materials and other components for certain manufacturing processes) or burned (obtaining energy). During the exploitation, a tire with worn tread can be processed in a certain way to allow its reuse. The retreated tire should be accepted for further treatment. Hence, this study conducted the human health impacts of retread tire using life cycle assessment. The recipe2016 technique and Sigmaoro 9.0 software were used as the method of human health assessment. The result showed that the total value of human health impact assessment for retreated tire production were 4.3007E-06 Daly. The hotspot of human health impact for retreated tire production was tire material and electricity consumption. Form this finding will help designers or managers recommend the installation scenario of retreated tire production by considering human health impacts.

Analysis on wheel wear tendency of railway vehicle considering worn tread shape

Analysis on wheel wear tendency of railway vehicle considering worn tread shape

Characteristics of footwear worn by people with systemic lupus erythematosus: a comparison with age- and sex-matched healthy controls: a pilot study

BackgroundTo determine characteristics of footwear worn by people with systematic lupus erythematosus (SLE).MethodsTwenty-two people with SLE and twenty matched healthy controls participated in a cross-sectional study. Objective assessments of footwear included: fit, style, structure, motion control, cushioning, and wear. Footwear was classified as poor, average or good based on a standardised tool. Participants completed 100mm visual analogue scales for foot pain and footwear comfort and suitability. Participants with SLE were asked to indicate which footwear features were important to them using a validated checklist.ResultsNo differences were observed between groups for footwear fit, age, style, heel height, forefoot flexion or cushioning (all P>0.05). Compared to controls, a greater number of participants with SLE wore shoes with worn tread (65% vs. 91%, P=0.041), wore shoes with a lower motion control scale (median: 5.0 vs. 1.0, P=0.003), and rated their footwear as less comfortable (median: 90mm vs. 78mm, P=0.024) and less suitable (median: 88mm vs. 76mm, P=0.030). Participants with SLE experienced greater foot pain than controls (median: 17mm vs. 0mm, P=0.038). Comfort (95%), fit (95%) and style (86%) were identified as the most important footwear features by people with SLE.ConclusionsCompared to control participants, people with SLE wear shoes that are more worn and lack motion control. They also report greater foot pain and report their shoes to be less comfortable and suitable. These findings highlight the need for a further focus on the role of footwear in the management of foot problems in people with SLE.

New Wheel-rail Contact Point Algorithm Method Based on the Space Vector Mapping Principle

A new geometric wheel-rail contact algorithm,the space vector mapping method, is presented to solve the railway vehicle dynamic wheel-rail contact problem. Based on the space vector mapping principle and the basic characteristics of wheel-rail shape, this method regards the wheel-rail contact as space surface contact, chooses the track cross-section as a reference and views the track surface width as the possible maximum contact range of the wheel-rail. Then it adopts certain contact point search and verifying principles so that the dynamic contact point of the wheel in postures of different lateral displacement and yaw angle can be accurately located. With a set of self-composed wheel-rail interaction software TPLWRSim, taking LMA wheel tread as an example, a three-dimensional models of wheel/rail, wheel/roller and wheel/trough type rail are established respectively, which can simulate the wheel-rail contact state under different conditions. Comparing the results with the geometry shape of wheel-rail contact and the geometry contact relationship of worn tread verifies the accuracy and effectiveness of the algorithm. Simulation results show that this algorithm can solve the problem of wheel-rail and wheel-wheel contact and quickly and accurately determine the contact point between the wheel and the track in any postures, and also verify a good adaptability to treads and rail with different shapes.

Influence of Worn Tread on EMUs Dynamic Performance and Passenger Comfort

The tread wear would change the wheel/rail relation and seriously affect the railway vehicle dynamic behaviors. After testing the several EMUs under running ,this paper not only analyses the discipline of tread wear, but also computers the influence on wheel/rail contact geometry by a program devopled in Matlab/GUI. A MBS model of trailer of EMUs is constructed, including the model of passagers. The dynamic performance of EMUs and riding comfort are compared among the standard, worn and turned tread profile. We draw the following conclusions：Tread profile after running for a long time without turning would emerge harmful concave worn；The unsymmetrical wheel/rail contact would increame the risk of derailment and debase passengers comfort of EMUs；After turning , the dynamic performance of EMUs can be improved.

Verification for New Wheel-rail Muti-point Contact Method

A vehicle-track system dynamic model, including multipoint contact wheelset vibration equations, is built to carry out curve negotiation verification of a new calculation and decision method for wheel-rail multipoint contact─trace line extremum method. The position of curve negotiation contact points on the wheel tread, the number of wheel-rail contact points and the wheel-rail normal force are presented. The result shows that the trace line extremum method can solve the wheel-rail multipoint contact problem and obtain the accurate geometric parameters of wheel-rail multipoint contacts and the system vibration characteristics. When two-point contact of wheel flank root and wheel flank occurs, the result obtained by using multipoint contact method is more reasonable and reliable than that by using single-point contact method. If no simultaneous two-point contact of flank root and flank, the results by multipoint contact method and by single-point are almost in full agreement. Compared to the new wheel tread, the worn tread is easy to form two-point contact nearby the depression area of the nominal diameter position of wheel tread. The correctness and effectiveness of the new method are verified.

Effect of Track Structure Parameters on Rolling Contact Stresses of Wheel-rail

The effects of rail base slope, rail gauge and curve radius on the rolling contact stresses and wear index of JM3 wheelset and track in static rolling contact are analyzed by using the rolling contact theory of three-dimensional elastic bodies with non-Hertz form, numerical program of CONTACT and Bossinesq-Cerruti force/displacement formula and the Gaussian numerical integration. The numerical results indicate that the stresses, wear index and normal pressure will achieve the minimal value when the rail base slope is 1/20. The maximal shear stress and equivalent stress can decrease by 40.15% and 39.37% respectively when the rail base slope changes from 1/40 to 1/20. It is suggested that the profile of worn tread is optimized due to bigger contact stresses when the rail base slope is 1/40. The appropriate augment of rail gauge can decrease the maximal shear stress, equivalent stress and normal pressure on the contact patch of wheel-rail. The maximal stress of contact patch under the curve track condition will increase evidently comparing to the tangent track. Moreover, the curve radius will change the distributing of stick-slip area and decreasing curve radius will increase total slip of the contact patch and wear index of wheel-rail.

Follow-up investigations of slip, trip and fall accidents among postal delivery workers

A sample of 40 slip, trip and fall accidents occurring during the delivery of mail were subject to detailed follow-up investigation. Interviews were conducted with accident-involved employees as soon as possible after each incident (mean time between accident and interview=9.5 days). Interviews were held at the location of the accident and covered the sequence of events and related individual, equipment and organisational aspects. The study took place October–March, reflecting the period when most accidents occur. The majority of accidents involved snow or ice (70%). A combination of slippery conditions, use of footwear with worn tread, and time-saving behaviour was found in 50% of accidents. It is suggested that a second important combination is the presence of tripping hazards and the unsafe practice of preparing mail for the next delivery while walking. Poor lighting was considered a problem in 20% of cases. Other problems identified included deficiencies with training and a low level of safety-related activity by local managers. It is concluded that there are opportunities for intervention that should reduce the frequency of these accidents.

Compatibility of Curving Performance and Hunting Stability of Railway Bogie

SUMMARYThe curving performance and high speed hunting stability are important for railway bogies, but generally they are contrary to each other. In this paper we report methods which can realize the compatibility between curving performance and hunting stability. The methods that we adopt are 1) Optimized worn tread profile of wheel, 2) Independently rotating wheels in rear axle and 3) Asymmetric arrangement of longitudinal primary stiffness. For validation of the effects of these methods, we carried out numerical simulation by multi-body dynamics software, full scale stand tests and partly field running tests. According to the results the curving performance of proposed bogie is improved remarkably, for example the lateral force between wheel and rail is 50% reduced, keeping high critical speed against hunting. So we have successfully developed brand new bogies which have not only excellent curving performance but also good hunting stability.