Investigation on Crashworthiness of Locally Manufactured Bus Structural Frame by using Numerical Approach
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Date
2021-12
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Addis Ababa University
Abstract
The thesis aimed to investigate the crashing behavior of locally manufactured 60 seated bus
structural frames in case of frontal and side impacts. In addition to studying the crashworthiness
of current structure, the most severe impact condition was identified by referring to crash test
and an improvement on structure for a better crash performance for that impact condition was
proposed.
A full frontal and an offset impact position were used for frontal impact testing while analysis
for side impact a perpendicular and angled/oblique impact position were used. Full-frontal crash
analysis was done according to the ECE-R29 involving a frontal crash pendulum test in which
impacting energy is set to 55 kJ and safe space between steering model and manikin is checked.
while for offset frontal impact a simulation of bus structure impacting a rigid wall with an initial
velocity of 56km/hr was done to check structures response to such kind of accidents. For sideimpact,
residual space specified on ECE-R60 was used to check side frame deformation in case
of perpendicular and angled/oblique impact. An impacting trolley with an initial speed of 48
km/hr was used for the side-impact test.
Commercial software CATIA and ABAQUS were used for geometrical modelling and analysis.
The study focused on identifying the crashworthiness of the bus structure by analyzing the
structural deformation, crash pulse, crash force efficiency, HIC, and energy absorbing capacity.
The results showed that the current structure had failed to meet regulation in the case of both
frontal impacts and side perpendicular impact. In full frontal impact an intrusion of 17.32 mm
in to manikin is seen and side frame has intruded residual space by 8.22 mm. Amongst the tests
most severe impact damages was observed in the case of full-frontal and off-set frontal crash
tests.
For improving crashworthiness of the structure, three models were proposed and tested
according to ECE-R29, the first two were based on increasing the thickness of frames and the
last was by adding a reinforcement profile. The simulation results for improved models
showed, by adding a reinforcement profile has improved the crashworthiness of the bus by
creating a space between manikin and steering model of 36.33 mm structure and meets with
regulation.
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Keywords
Crashworthiness, locally developed 60 seat bus, Frontal impact, Side impact, Dynamic/ explicit analysis, optimization