Dynamic wheel-rail contact forces induced by a severe form of wheel tread damage have been measured by a wheel impact load detector during full-scale field tests at different vehicle speeds.Based on laser scanning,the...Dynamic wheel-rail contact forces induced by a severe form of wheel tread damage have been measured by a wheel impact load detector during full-scale field tests at different vehicle speeds.Based on laser scanning,the measured three-dimensional damage geometry is employed in simulations of dynamic vehicle-track interaction to calibrate and verify a simulation model.The relation between the magnitude of the impact load and various operational parameters,such as vehicle speed,lateral position of wheel-rail contact,track stiffness and position of impact within a sleeper bay,is investigated.The calibrated model is later employed in simulations featuring other forms of tread damage;their effects on impact load and subsequent fatigue impact on bearings,wheel webs and subsurface initiated rolling contact fatigue of the wheel tread are assessed.The results quantify the effects of wheel tread defects and are valuable in a shift towards condition-based maintenance of running gear,and for general assessment of the severity of different types of railway wheel tread damage.展开更多
Treading barley (“Mugifumi” in Japanese) is a barley culturing process that is unique and indispensable in Japan. Generally, roller machines or human feet are used to tread young barley several times (Figure 1). As ...Treading barley (“Mugifumi” in Japanese) is a barley culturing process that is unique and indispensable in Japan. Generally, roller machines or human feet are used to tread young barley several times (Figure 1). As a model examination, a stainless steel instrument was used for treading barley in this study (Figure 2(a)). Treading damages plants and decreases growth, such as the height and weight of aerial parts, which then recover gradually. In our study, the total amino acid contents increased with the treading stress. The treading stress induced a 1.7-fold increase in aspartic acid contents and an approximately 1.6-fold increase in glutamic acid, proline, cystine, and methionine contents. Isolation and purification suggested that the main components of the methanol-eluted fraction from the young green barley were six known phenolic compounds. Saponarin and lutonarin were the main components. The saponarin content was about 160 mg/g (methanol-soluble fraction) at 10 days after germination. We found that the higher antioxidant activity was due to the increased lutonarin/saponarin ratio from 10% to 24%. Therefore, our results suggest that treading stress is useful for young green barley.展开更多
A cell is a house to myriad biochemical reactions composed in a symphony of various pathways,both survival and apoptotic.Apoptosis is of fundamental significance to an organ by replacing weary and senile cells with ju...A cell is a house to myriad biochemical reactions composed in a symphony of various pathways,both survival and apoptotic.Apoptosis is of fundamental significance to an organ by replacing weary and senile cells with juvenile cells.展开更多
A finite element modeling technique is employed in this paper to predict the groove wander of longitudinal tread grooved tires. In generally, groove wander is the lateral force acting on a vehicle’s wheel resulting f...A finite element modeling technique is employed in this paper to predict the groove wander of longitudinal tread grooved tires. In generally, groove wander is the lateral force acting on a vehicle’s wheel resulting from the combination of rain grooves. If the lateral force of tire is generated by groove wander, unexpected lateral motion of vehicle will happen and it makes drivers uncomfortable. This paper describes the effect of groove wander according to the shape condition of tire tread groove and highway groove using the finite element analysis based on a static loading or a steady-state rolling assumption. The road groove can be located anywhere relative to the longitudinal tread groove. Therefore, the lateral force of the tire is changing depending on the location of the groove road. The numerical results for groove wander prediction of the longitudinal tread grooved tires are compared with the subjective evaluation. It is found that the waveform for the tire with varying grooved road position has a peak-to-peak lateral force in order to estimate the rating of groove wander. The effect of the road groove width and the pitch length on the peak-to-peak lateral force of tire is discussed. It is found that the prediction of FEA-based groove wander model using finite element analysis will be useful for the reliability design of the tire tread pattern design.展开更多
Tread wear and rolling contact fatigue (RCF) damage propagated on railway wheels are the two extremely important focal points as they can tremendously deteriorate wheel/rail interactions and hunting stability and dest...Tread wear and rolling contact fatigue (RCF) damage propagated on railway wheels are the two extremely important focal points as they can tremendously deteriorate wheel/rail interactions and hunting stability and destroy wheel surface materials, and subsequently, cut down the lifetime of the wheels. The on-board anti-slip controllers are of essence aiming to hold back the striking slipping of the powered wheelsets under low-adhesion wheel/rail conditions. This paper intends to investigate the impact of anti-slip control on wheel tread wear and fatigue damage under diverse wheel/rail friction conditions. To this end, a prediction model for wheel wear and fatigue damage evolution on account of a comprehensive vehicle–track interaction model is extended, where the wheel/rail non-Hertzian contact algorithm is used. Furthermore, the effect of frictional wear on the fatigue damage at wheel surface is considered. The simulation results indicate that the wheel/rail contact is full-slip under the low-adhesion conditions with braking effort. The wear amount under the low-adhesion conditions is observably higher than that under the dry condition. It is further suggested that the wheel tread is prone to suffering more serious wear and fatigue damage issues with a higher anti-slip control threshold compared to that with a lower one.展开更多
The shoe sole geometrical design parameters are believed to be important factors affecting the coefficient of friction （COF） between the shoe/floor interface. This study is concerned with the relationship between th...The shoe sole geometrical design parameters are believed to be important factors affecting the coefficient of friction （COF） between the shoe/floor interface. This study is concerned with the relationship between the measured COF and the tread groove orientation and width on the footwear pad. Friction measurements using the Brungraber Mark Ⅱ slipmeter were conducted. Six tread groove width/orientations designs on the footwear pads under 27 footwear material/floor/contamination conditions were tested. The results show that tread orientation and width affect the measured COF significantly. Wider grooved footwear pads result in higher COF values and footwear pads with tread grooves perpendicular to the friction measurement direction have higher COF values. A regression model using measured COF as the dependent variable and tread groove width, groove orientation, footwear material, floor, and contamination conditions as independent variables was established. The models are significant at p〈0.0001 with R^2 of 0.97, which may be used in predicting the COF at the shoe-floor interface .展开更多
基金funded from the European Union's Horizon 2020 research and innovation programme in the project In2Track3 under grant agreement No.101012456.
文摘Dynamic wheel-rail contact forces induced by a severe form of wheel tread damage have been measured by a wheel impact load detector during full-scale field tests at different vehicle speeds.Based on laser scanning,the measured three-dimensional damage geometry is employed in simulations of dynamic vehicle-track interaction to calibrate and verify a simulation model.The relation between the magnitude of the impact load and various operational parameters,such as vehicle speed,lateral position of wheel-rail contact,track stiffness and position of impact within a sleeper bay,is investigated.The calibrated model is later employed in simulations featuring other forms of tread damage;their effects on impact load and subsequent fatigue impact on bearings,wheel webs and subsurface initiated rolling contact fatigue of the wheel tread are assessed.The results quantify the effects of wheel tread defects and are valuable in a shift towards condition-based maintenance of running gear,and for general assessment of the severity of different types of railway wheel tread damage.
文摘Treading barley (“Mugifumi” in Japanese) is a barley culturing process that is unique and indispensable in Japan. Generally, roller machines or human feet are used to tread young barley several times (Figure 1). As a model examination, a stainless steel instrument was used for treading barley in this study (Figure 2(a)). Treading damages plants and decreases growth, such as the height and weight of aerial parts, which then recover gradually. In our study, the total amino acid contents increased with the treading stress. The treading stress induced a 1.7-fold increase in aspartic acid contents and an approximately 1.6-fold increase in glutamic acid, proline, cystine, and methionine contents. Isolation and purification suggested that the main components of the methanol-eluted fraction from the young green barley were six known phenolic compounds. Saponarin and lutonarin were the main components. The saponarin content was about 160 mg/g (methanol-soluble fraction) at 10 days after germination. We found that the higher antioxidant activity was due to the increased lutonarin/saponarin ratio from 10% to 24%. Therefore, our results suggest that treading stress is useful for young green barley.
文摘A cell is a house to myriad biochemical reactions composed in a symphony of various pathways,both survival and apoptotic.Apoptosis is of fundamental significance to an organ by replacing weary and senile cells with juvenile cells.
文摘A finite element modeling technique is employed in this paper to predict the groove wander of longitudinal tread grooved tires. In generally, groove wander is the lateral force acting on a vehicle’s wheel resulting from the combination of rain grooves. If the lateral force of tire is generated by groove wander, unexpected lateral motion of vehicle will happen and it makes drivers uncomfortable. This paper describes the effect of groove wander according to the shape condition of tire tread groove and highway groove using the finite element analysis based on a static loading or a steady-state rolling assumption. The road groove can be located anywhere relative to the longitudinal tread groove. Therefore, the lateral force of the tire is changing depending on the location of the groove road. The numerical results for groove wander prediction of the longitudinal tread grooved tires are compared with the subjective evaluation. It is found that the waveform for the tire with varying grooved road position has a peak-to-peak lateral force in order to estimate the rating of groove wander. The effect of the road groove width and the pitch length on the peak-to-peak lateral force of tire is discussed. It is found that the prediction of FEA-based groove wander model using finite element analysis will be useful for the reliability design of the tire tread pattern design.
基金This work was supported by the National Natural Science Foundation of China(Grant Nos.51735012,52072317,and 51825504)State Key Laboratory of Traction Power(Grant No.2021TPL-T08).
文摘Tread wear and rolling contact fatigue (RCF) damage propagated on railway wheels are the two extremely important focal points as they can tremendously deteriorate wheel/rail interactions and hunting stability and destroy wheel surface materials, and subsequently, cut down the lifetime of the wheels. The on-board anti-slip controllers are of essence aiming to hold back the striking slipping of the powered wheelsets under low-adhesion wheel/rail conditions. This paper intends to investigate the impact of anti-slip control on wheel tread wear and fatigue damage under diverse wheel/rail friction conditions. To this end, a prediction model for wheel wear and fatigue damage evolution on account of a comprehensive vehicle–track interaction model is extended, where the wheel/rail non-Hertzian contact algorithm is used. Furthermore, the effect of frictional wear on the fatigue damage at wheel surface is considered. The simulation results indicate that the wheel/rail contact is full-slip under the low-adhesion conditions with braking effort. The wear amount under the low-adhesion conditions is observably higher than that under the dry condition. It is further suggested that the wheel tread is prone to suffering more serious wear and fatigue damage issues with a higher anti-slip control threshold compared to that with a lower one.
基金Supported by the National Science Council of Taiwan, China (NSC 92-2213-E-216-006)
文摘The shoe sole geometrical design parameters are believed to be important factors affecting the coefficient of friction （COF） between the shoe/floor interface. This study is concerned with the relationship between the measured COF and the tread groove orientation and width on the footwear pad. Friction measurements using the Brungraber Mark Ⅱ slipmeter were conducted. Six tread groove width/orientations designs on the footwear pads under 27 footwear material/floor/contamination conditions were tested. The results show that tread orientation and width affect the measured COF significantly. Wider grooved footwear pads result in higher COF values and footwear pads with tread grooves perpendicular to the friction measurement direction have higher COF values. A regression model using measured COF as the dependent variable and tread groove width, groove orientation, footwear material, floor, and contamination conditions as independent variables was established. The models are significant at p〈0.0001 with R^2 of 0.97, which may be used in predicting the COF at the shoe-floor interface .
