Study of frontal impact of passenger bus

M. S. Ramaiah School of Advanced Studies 1

Final Project Presentation

Study of Frontal Impact of a Passenger Bus

Manjunath Rao T SBBB0906034

M. Sc. (Engg.) in Automotive Engineering

Academic Guide :Mr. Madan JProject Manager,SASTECH, Bangalore


Aim and Objectives of the Project

Aim :To study frontal impact of a passenger bus and to recommend methods to improve safety

Objectives :• To review the literature on effects of impact on passenger

buses• To study relevant analytical models that are available in

the literature• To simulate the frontal impact behavior of the passenger

bus• To analyze and interpret the results with the experimental

data available in literatures• To suggest some design changes in order to improve

structure safety


Methodology

• Literature review on Crashworthiness of bus will be carried out by referring reviewed journals, books and related documents

• Geometric modeling of bus structure will be carried out using CATIA V5 R16 / Pro-E 2001

• FE model generation for all the parts will be carried out using Hypermesh 7.0

• Input deck for simulation will be created using Hypermesh 7.0• Frontal impact simulation will be carried out using LS-DYNA

and post processing will be carried out using LS-POST• Investigation of the analysis results in order to improve the

crashworthiness


Introduction•Among all the accidents that take place, frontal impact has got a major share of 40%. Again in these conditions the injury caused to drivers or the front passenger is extremely high.

•In automotive domain more emphasis has been given to the safety of passenger cars, but seldom the importance is given to passenger bus.

•Though the damage due to frontal impact of the bus is lesser when compared to other vehicles, the consequences of such impact on drivers are fatal.

•According to the study during frontal impact of bus more than 80% of drivers die than any other members of the bus.

•In frontal impact scenario more significance should be given on structural integrity, and hence this project work is carried out in this direction.


DesignBus Specifications:

Dimension (mm) (as per IS 9435) LPO 1510/55

Wheel base 5334

Front overhang 1775

Rear overhang 3200

Overall length 10309

Max. width 2375

Track front 1930

Track rear 2050

Min. ground clearance in mm 240-275

Max. Seating capacity 53

Weights (kg.)

Bare chassis kerb weight 4010

Max. G.V.W 12500

Permissible F.A.W. 5080

Permissible R.A.W. 10160

Fuel Tank Capacity 160 litres

Engine & subsystems 500

Powertrain 400

Drivetrain 300


Construction


Design

Material : Structural steel

Std. : IS 2062


DesignGeometric Modeling:

Geometric modeling has been carried out using Pro-E 2001 software. All the geometric datas were collected from “KMS Coach Builders Pvt. Ltd.”(Official partners of KSRTC for coach building). All the structural details were as per the 2D drawings provided.

Various views of modeled bus is shown in following sections:


DesignAssumptions:

• Parts which are not directly related to the frontal impact or which have

no significant effect on the final output have not been considered.

• All the sub-systems that were discarded in design process have been

considered as lumped mass at appropriate locations.

• All structural designs are as per the documents obtained from KSRTC.


FE ModelMeshed bus with shell elements and 1-D Beam Elements

Total Elements 264139Shell Elements 2607791D Elements 2963Total Parts 105


FE ModelParts replaced with Mass Element

Mass Elements

Rigid Elements


Boundary ConditionsContact interface is done by defining the box and providing *CONTACT_AUTOMATIC_SINGLE_SURFACE


Boundary Conditions

Friction between tyres and rigid plane


Simulation Inputs

Material Properties assigned

Material DensityKg/mm3

Young’s modulusGPa

Poisson’s Ration

Yield Stress MPa

MAT_PIECEWISE_LINEAR_PLASTICITYMAT_24 7.85e-6

3.55e-6

7.85e-6

3500.3210

210 0.3

210 0.3

MAT_RIGID

MAT_ELASTICMAT_1

Simulation Inputs

Velocity 30 km/hrSimulation time 0.2 secs


Simulation & Results


Simulation & Results (contd.)











Design ImprovementComparison of various crush initiators


Design Improvement

Comparison of bead type crush initiators







Comparison of Load pattern with both designs


Conclusion

•It has been understood that the load distribution on the structures are not uniform, which lays down the road to improvement in buckling characteristics of the structures.

•By having crush initiators, the peak load can be reduced. This has been achieved by implementing such designs to some of the structural members, which is around 4% reduction in peak load.

•The design improvement that has been achieved is just for few structural elements, if this approach is followed for many other key structural members then the design could be far superior.

•The floor deceleration is around 12g, which is well in agreement with ECE R80 regulation that specifies the floor deceleration to be around 8-12g at 30km/hr.


Future Work

•In today’s automotive body engineering advancements there are various systems that improves the crashworthiness of the vehicle significantly. Many such systems can be implemented in order improve the structural safety.

•Simulation of the frontal impact behavior of the passenger bus can be carried out by considering various subsystems of the vehicle like engines, transmission, steering system etc..

•Positioning of dummy in the driver’s seat helps in finding the injury parameters.

•Seat belt concept in passenger bus is an alien concept in India, efforts can be made in developing such a concept.

•More understanding is required in order to improve the structural behavior of chassis, which can be detrimental in overall design.


References

[1] VINCZE-PAP Sándor, CSISZÁR András, “Real and Simulated Crashworthiness Tests on Buses” ESV 19th Conference, NHTSA, Paper Number 05-023, 2005

[2] Jeffrey C. Elias, Lisa K. Sullivan, Linda B. McCray, “Large School Bus Safety Restraint Evaluation” NHTSA, Paper No. 345, 2001

[3] Yoshiriro Sukegawa, Fujio Matsukawa, Takeshi Kuboike, Motomu Oki, “Heavy Duty Vehicle Crash Test Method in Japan”, NHTSA, Paper number 98-S4-O-13, 1998

[4] Mátyás Matolcsy, “Technical Questions Of Bus Safety Bumpers”, NHTSA, Paper number 05-0161, 2005

[5] Willibrordus J. Witteman “Improved Vehicle Crashworthiness Design by Control of the Energy Absorption for Different Collision Situations”


Thank You

Documents

Study of frontal impact of passenger bus