Modelling of steered and lifted axles on long combination vehicles for performance based measures
Examensarbete för masterexamen
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|Type: ||Examensarbete för masterexamen|
|Title: ||Modelling of steered and lifted axles on long combination vehicles for performance based measures|
|Authors: ||Keshava Reddy, Lohith Reddy|
|Abstract: ||High Capacity transport (HCT) vehicles are much more transport efficient compared
to conventional heavy goods vehicles. They also contribute to increased energy efficiency
and reduction of CO2 emission. In a recent study by Ghandriz et al., it is
shown that long heavy vehicle combinations which are run in heterogeneous fleet
results in around 53% reduction in total cost of ownership (TCO) when compared
to rigid trucks in homogeneous fleet. 
Long combination vehicles (LCVs) can be difficult to operate on city limits because
of the tight corners and roundabouts that the vehicle needs to go through. One possible
way to evaluate these vehicles is a PBS (Performance Based Standard) based
approach in which certain measures with its associated required performance levels
are used for assessment of a vehicle combination.
The target for this thesis work is to add low speed steered and lifted axles to the existing
models in OpenPBS tool and support the main research project "Performance
Based Standards II", by further development of this tool.
Two different methods namely friction-zero side-slip and algorithm-based command
steering methods and three different vehicle combinations (Nordic,A-double and
Tractor-semitrailer) were considered with semi-trailer axles steered at low speeds.
Low speed swept path (LSSP) is considered as the main performance measure of
the vehicle to evaluate the effect of steered and lifted axles on semi-trailer at low
Friction-zero side-slip and algorithm-based command steering methods were implemented
and compared. The results show that both methods provide similar percentage
improvement of LSSP for all three different vehicle combination. It can be
concluded that friction-zero side-slip steering method is a conservative representation
of algorithm based command steering method and hence a simple friction-zero
side-slip steering method is good enough for representing semi-trailer steered axles
For tractor semi-trailer with the last two axles of the semi-trailer steered at low
speed, the percentage improvement in the LSSP is 6 % in 90 degree and 8 % in 180
degree turn respectively.
For nordic combination with the last two axles of the semi-trailer steered at low
speed, the percentage improvement in the LSSP is 10 % in 90 degree and 15 % for
180 degree turn respectively.
For A-double combination vehicle the percentage improvement in the LSSP with
first semi-trailer steered is 13 % and with second semitrailer steered is 7 % in 90
degree turn. The improvement in the LSSP with first semi-trailer steered is 18 %
and with second semitrailer steered is 12 % in 180 degree turn.
Temporarily retractable axles were also investigated and it was shown that lifting
the second semi-trailer axle improves the percentage of the LSSP by 6 % compared
to non-lifted case.
|Keywords: ||High capacity transport vehicles;Low speed swept path;Performance based standards;Modelica;DYMOLA;OpenPBS tool;Steered axles;Lifted axles|
|Issue Date: ||2021|
|Publisher: ||Chalmers tekniska högskola / Institutionen för mekanik och maritima vetenskaper|
|Series/Report no.: ||2021:61|
|Collection:||Examensarbeten för masterexamen // Master Theses|
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