Motion Resistance Ratio, Net Traction Ratio and Tractive Efficiency of a Riceland Type Tyre
A study was conducted to determine the accuracy of Wismer-Luth and Brixius equations in predicting the tyre motion resistance ratio, net traction ratio and tractive efficiency of a Riceland type tyre. The tyre was tested on a sandy clay loam soil in an indoor UPM tyre traction testing facility. T...
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| Format: | Thesis |
| Language: | English English |
| Published: |
1999
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| Online Access: | http://psasir.upm.edu.my/id/eprint/10287/1/FK_1999_17_A.pdf http://psasir.upm.edu.my/id/eprint/10287/ |
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| Summary: | A study was conducted to determine the accuracy of Wismer-Luth and
Brixius equations in predicting the tyre motion resistance ratio, net traction ratio
and tractive efficiency of a Riceland type tyre. The tyre was tested on a sandy clay
loam soil in an indoor UPM tyre traction testing facility. The experiment was
conducted by running the tyre in two modes; towing mode for the formulation of
tyre motion resistance ratio equation and driving mode for the formulation of tyre
net traction ratio and tractive efficiency equations.
A total of ninety test runs were involved in the tyre motion resistance ratio
determinations at three selected inflation pressures (i. e. 221, 193 and 166 kPa) and
selected wheel numerics ranging between 0 to 70. From the analysis of covariance
(ANCOVA) it was found that both inflation pressure and wheel numeric has
significant effect on the tyre motion resistance ratio. Regression analysis was also
conducted to determine the closeness offit for Wismer-Luth and Brixius equations in predicting the motion resistance ratio of the tested tyre. Finally, 3 new
logarithmic models for the tyre motion resistance ratio were formulated. The 193
kPa inflation pressure revealed a lower tyre motion resistance than the nominated
pressure (i.e. 221 kPa) and the 166 kPa.
For the tyre net traction ratio and tractive efficiency determinations, 126
test runs were conducted in a combination consisting of three selected inflation
pressures (i.e. 221 , 193 and 166 kPa) and two wheel numerics (i.e. 19 and 29)
representing two extreme types of soil strength under different levels of travel
reduction ranging between 0 to 40%. Regression analysis was conducted to
determine the prediction equation describing the tyre torque ratio. Marqurdt' s
method used by Wismer-Luth for predicting non-linear equation was found not
suitable in predicting the torque ratio of the tested tyre for its low coefficient of
determination and inadequacy. The logarithmic model was found to be suitable in
predicting the torque ratio. From the analysis of covariance (ANCOVA) the mean
effect of travel reduction, tyre inflation pressure and wheel numeric were found to
be highly significant where as the interaction of inflation pressure and wheel
numeric was not significant. The 193 kPa inflation pressure was the best, among
the three inflation pressures used, in getting higher net traction ratio and higher
maximum tractive efficiency. |
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