Virtual Design Development of a Steering System by

Virtual Design Development of a Steering System
Vasanth Kumar .K
Engineer
Defiance Technologies Ltd.
SKCL - Triton Square - Unit No. C3 to
C7 - 7th Floor
TVK Industrial Estate - Guindy
Chennai - 600 032. India.
by Body Block Analysis
E. Jabastin Charles
Team Leader
Defiance Technologies Ltd.
SKCL - Triton Square - Unit No.
C3 to C7 - 6th Floor
TVK Industrial Estate - Guindy
Chennai - 600 032. India.
Krishnamurthy .G .S
Project Manager
Defiance Technologies Ltd.
SKCL - Triton Square - Unit No.
C3 to C7 - 6th Floor
TVK Industrial Estate - Guindy
Chennai - 600 032. India.
Keywords : Design development of Steering System, Occupant Safety, Body Block Analysis.
Abstract
Validation of steering system design involves various experimental testing which indeed tunes the energy absorbing capabilities and
Steering wheel displacement. These parameters are considered as the basic requirement for occupant safety. This process of
evaluating the design of a Steering system built involves high cost and enormous amount of time. Using Finite Element Modelling and
virtual simulation technique with the help of Radioss, design development is made possible to meet the required regulations with
numerous design iterations and reduced cost and time.
Introduction
Steering system plays a vital role in handling a vehicle, which is also one of the most important components
in occupant protection system in automobile. Steering system consist of steering wheel, Steering Column,
intermediate shaft. These are the essential components which adapts to crash & safety of an occupant.
In the recent times, innovation in the automotive field leads to development of dual stage airbag system,
advanced energy absorbing collapsible steering column mechanisms. Altenhof, et al [1] has studied about
the crash performance of steering wheel inserts during impact loading, which indeed helps in the developing
a steering system form scrap. Mohamed Sahul Hamid, et al [2] has studied about crash severity, the
occupant mass, the seat position and seat belt usage, Virtual design development with parallel to safety has
been made possible. Zane Z Yang, et al [3] has studied and categorized various tests for comfort and
safety, thus gives overview to develop a complete steering system from scrap. In recent times most of the
automotive industries are focusing on minimizing the prototyping, development, physical testing and
production costs, with reduction in the development time and enhanced occupant protection and crash
worthiness of the vehicle.
While developing a steering system various government safety requirements as well as manufacturer’s
internal requirements has to be considered. Also, the safety rating system for various crash conditions such
as AIS/Euro NCAP, etc., is becoming a norm of the performance index and hence provides a commercial
advantage to vehicle manufacturers. A virtual build of the vehicle is based on mathematical analytical tool
which is replacing the costly and time consuming prototype build and development cycle. The virtual
prototyping process optimizes the design using simulation software tools before the prototype build.
In head on-collision, the occupants of the vehicle are to be protected from serious injuries. Normally, the
protective schemes includes,
1. Advanced vehicle crumple zone
2. Energy absorbing instrumental panel,
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3. An Energy absorbing Steering column and steering wheel
4. A driver air bag
5. An energy absorbing knee bolster.
The current engineering specification for steering wheels lists about 15 different physical tests to which each
Steering system must be validated. These tests, if performed physically, cost a lot o oof
money for a prototype
wheel. Fortunately, many of the structural tests can be done virtually by numerical methods such as the
finite element analysis.
Recommendations based on analysis results have helped in cost savings by shortening product lead lead-time
and reducing the number of prototype tests. This paper mainly focuses on Steering wheel, Steering column,
and steering column mounting angle change through which the ma maximum ximum energy will be absorbed and also
ensures the regulatory requirements. The designs of the individual components are based on specific
vehicle architecture and the performance requirements which normally would vary widely. This paper will
cover the process and methodology for understanding requirements, developing des designs to meet those
requirements and virtual testing for validating those designs using Radioss. To build and analyze the model
it requires both preprocessing and post processing tool. By using Radioss as the solver the there will be no
need for expensive third party solvers solvers.
Process Methodology
The virtual tests for steering wheels can be categorized by nature into three types: modal analysis, static
analysis, and impact analysis. This paper gives an overview of body block impact test using Radioss.
Emphasis is placed on how to model the physical tests virtually under various conditions using finite element
analysis. . Model setup is shown in Fig Fig.1, constraint and boundary conditions are shown. In addition,
challenges and difficulties in the simulation process are addressed. In particular, various iterations carried
out to develop a Steering system virtually are discussed.
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Figure 11:
Model Setup with boundary conditions
OEMs are required to meet many mandatory government safety regulations in full vehicle system level.
These regulations are stipulated under AIS/FMVSS standards by the he government and cover all types of
vehicle crashes such as head on on-collision, offset frontal tal and side impact etc. in addition to government
requirement, OEMs have their own compliance requirement to increase vehicle rating.
Sub-system system level requirements are provided to verify the functioning of the components assembly. The
component performance e requirement will widely vary depending upon the architecture of the full vehicle. In
general, the individual component specifications may vary from one ne automotive manufacturer to other based
on the vehicle architecture tecture which is shown in Fig Fig.2.
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In this paper, development of the Steering system is purely a CAE driven approach. As considering AIS
096(head on-collision) and IS 11939: 1996(body block analysis) regulations as constraint. Steering system
has been made to pass IS 11939:1996.
When the steering control is struck by a body block released against this control at a relative speed of 24.1
km/h (15mph),the force applied to the body block by the stee steering ring control shall not exceed 11111
daN.
When the steering control rol is struck by an impactor released against this control at a relative speed of 24.1
km/h, the deceleration of the impactor shall not exceed 80 g cumulative for more than 3 milliseconds. The
deceleration shall always be lower than 120 g with Channel Freq Frequency uency Class 600 Hz of ISO 6487 6487-1987.
Body block impact analysis has been carried for numerous iterations such as
1) Increasing collapsible length in the Steering column increases the energy absorbing capabilities as
shown in Fig.3.
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Figure.2: Virtual development architecture
Figure 3: Collapsible stage in the Steering system
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2) Strengthening ng the intermediate shaft as shown in Fig.4 .4 will eventually transmits force obtained from
the head-on on collision with concrete wall.
3) Back ack collapse mechanism plays vital role in head-on on collision with concrete wall as per AIS 096
regulation. Utilizing the maximum collapsible length will reduce the movement of Steering in vertical
and horizontal direction thus will focus with the dummy.
4) Altering Steering mounts with CCB which helps in holding Steering system such that when a force
above 2 KN will disengages the front mounts from the CCB mounts.
5) Altering the Steering angle with respect to universal join joints Fig.5. Steering system angle has been
modified in such a way that wheel engagement with dummy is maximum.
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Figure 4: Full Steering Assembly
Figure 5: comparison of steering system from each iterations
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Results & Discussions
Thus the final result obtained has maximum deceleration value 27g shown in Fig.9 and maximum reaction force
between dummy and Steering system is about 9627 daN shown in Fig.8 with collapsible length of 67mm, Fig.6 and
Fig.7 represents Lower first and second spring behavior with threshold limit of 2KN. So therefore the results obtained
are well within the requirement.
Benefits Summary
Figure 6: Lower First collapsible stage Figure 7: Lower second collapsible stage
Figure 8:Force on Steering Wheel Figure 9:Decceleration Pulse
Benefits attained from this analysis are
1. Reduces prototype costs, physical test setup for each iteration, design development cost by using
Radioss solver.
2. Minimizes overall cycle time to develop steering system from scarp.
Future Plans
Experimental Setup has to be done to validate the results obtained from virtual simulation.
Conclusions
System level design has been virtually analyzed and presence of any minor defects in the design has been
found before physical prototype build. The system level design has to be validated to certain extent with
experimental tests. A sub-system model based on body block was developed to evaluate the assembled
column performance. Once the sub-system model has been correlated, many design changes were
evaluated without actual build and this reduced the development time.
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In conclusion, the virtual prototyping using computational and numerical approach helped to develop and
evaluate a driver protection module in much lesser cost and time. Also, the Radioss provided tools for
impact analysis which indeed reduces time and cost of performing this analysis.
ACKNOWLEDGEMENTS
Authors wish to thank management of Defiance Technologies Limited for permitting to publish this material.
REFERENCES
1) W. Altenhof, B. Arnold, Z. Li, O. Nabeta and R.Turchi, A Comparison of the Crash Performance of Three-spoke and Four-spoke
Steering Wheel Armatures during Impact Loading, Int. J. Vehicle Design, Vol. 35 (2004), No. 3, pp. 186-209.
2) Mohamed Sahul Hamid, Nirmal Narayanasamy and Minoo J.Shah, "System Approach in development of adaptive energy absorbing
steering by virtual engineering ", SAE paper # 2005-01-0705 SAE 2005 World Congress , Detroit, MI, April 11-14,2005.
3) Zane Z Yang, Srini V, Raman and Deren Ma, "Virtual Tests for Facilitating Steering Wheel Development", SAE paper # 2005-01-
1072 SAE 2005 World congress, Detroit, MI, April 11-14,2005.
4) FTSS Free Motion Headform Model, Version 3.2, First Technology Safety System,2000.
5) ECE-R12- Impact Against Steering Mechanism, 1999.
6) FMVSS 203 - Impact Protection for the driver from Steering control System, 2003.
7) HyperMesh 11.0(Radioss) User Manual, Altair Engineering.
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