International Journal of Scientific and Research Publications ISSN 2250-3153 www.ijsrp.org Design and Analysis of Steering Gear and Intermediate Shaft for Manual Rack and Pinion Steering System Thin Zar Thein Hlaing * , HtayHtay Win ** , Myint Thein *** * Department of Mechanical Engineering, Mandalay Technological University ** Department of Mechanical Engineering, Mandalay Technological University *** Department of Mechanical Engineering, Mandalay Technological University Abstract- Manual rack and pinion steering systems are commonly used due to their simplicity in construction and compactness. The main purpose of this paper is to design and analyze the rack and pinion steering system. In this paper analyzed the two components of the steering system. Firstly, this paper investigates the characteristics of a rack and pinion gear system mainly focused on bending and contact stresses of the pinion gear and rack bending stress using analytical and finite element analysis. To estimate the contact stress, the-dimensional solid models for different materials are generated by SolidWorks software and the numerical solution is done by ANSYS, which is a finite element analysis package. The analytical investigation is based on Lewis stress formula. This paper also considers the study of contact stresses induced between two gears. Present method of calculating gear contact stress uses AGMA equation. To determine the contact stresses between two mating gears the analysis is carried out on the equivalent contacting cylinders. The results obtained from ANSYS are presented and compared with theoretical values. This paper also deals with the stress analysis of the rack. By using FEM a stress analysis has been carry out. Steering rack deflection and bending stresses are found. This stresses are compared with analytical result. Secondly, Fatigue analysis of intermediate steering shaft is done to find the life of the intermediate steering shaft in cycles and determined the factor of safety of the shaft. The Software results, mathematical and logical calculation implementation in a research will increase the performance and efficiency of a design. Index Terms- Rack and Pinion Steering Gear, Contact Stress, Rack Bending Stress, Steering Intermediate Shaft, Life Cycle, Safety Factor, ANSYS Software. I. INTRODUCTION wo main types of steering systems are used on modern cars and light trucks: the rack-and-pinion system and the conventional, or parallelogram linkage, steering system. On automobiles, the conventional system was the only type used until the 1970s. It has been almost completely replaced by rack-and-pinion steering. Figure 1. A Simplified Rack-and-pinion Steering System Rack-and-pinion steering is a simple system that directly converts the rotation of the steering wheel to straight line movement at the wheels. The steering gear consists of the rack, pinion, and related housings and support bearings. Turning the steering wheel causes the pinion to rotate. Since the pinion teeth are in mesh with the rack teeth, turning the pinion causes the rack to move to one side. The rack is attached to the steering knuckles through linkage, so moving the rack causes the wheels to turns.All steering systems contain several common parts. Every steering system, no matter what type, will have a steering wheel, a steering shaft and column, universal joints, steering tie rod, and steering arm. T Steering Wheel Steering Column Universal Joint Rack Housing Rack and Pinion Assembly Steering Shaft Rack Pinion Gear Tie Rod Torsion Bar Rack Housing Intermediate Steering Shaft 861
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International Journal of Scientific and Research Publications, Volume 7, Issue 12, December 2017 1 ISSN 2250-3153
www.ijsrp.org
Design and Analysis of Steering Gear and Intermediate
Shaft for Manual Rack and Pinion Steering System
Thin Zar Thein Hlaing*, HtayHtay Win
**, Myint Thein
***
* Department of Mechanical Engineering, Mandalay Technological University **Department of Mechanical Engineering, Mandalay Technological University ***Department of Mechanical Engineering, Mandalay Technological University
Abstract- Manual rack and pinion steering systems are commonly used due to their simplicity in construction and compactness. The
main purpose of this paper is to design and analyze the rack and pinion steering system. In this paper analyzed the two components of
the steering system. Firstly, this paper investigates the characteristics of a rack and pinion gear system mainly focused on bending and
contact stresses of the pinion gear and rack bending stress using analytical and finite element analysis. To estimate the contact stress,
the-dimensional solid models for different materials are generated by SolidWorks software and the numerical solution is done by
ANSYS, which is a finite element analysis package. The analytical investigation is based on Lewis stress formula. This paper also
considers the study of contact stresses induced between two gears. Present method of calculating gear contact stress uses AGMA
equation. To determine the contact stresses between two mating gears the analysis is carried out on the equivalent contacting
cylinders. The results obtained from ANSYS are presented and compared with theoretical values. This paper also deals with the stress
analysis of the rack. By using FEM a stress analysis has been carry out. Steering rack deflection and bending stresses are found. This
stresses are compared with analytical result. Secondly, Fatigue analysis of intermediate steering shaft is done to find the life of the
intermediate steering shaft in cycles and determined the factor of safety of the shaft. The Software results, mathematical and logical
calculation implementation in a research will increase the performance and efficiency of a design.
Index Terms- Rack and Pinion Steering Gear, Contact Stress, Rack Bending Stress, Steering Intermediate Shaft, Life Cycle, Safety
Factor, ANSYS Software.
I. INTRODUCTION
wo main types of steering systems are used on modern cars and light trucks: the rack-and-pinion system and the conventional, or
parallelogram linkage, steering system. On automobiles, the conventional system was the only type used until the 1970s. It has
been almost completely replaced by rack-and-pinion steering.
Figure 1. A Simplified Rack-and-pinion Steering System
Rack-and-pinion steering is a simple system that directly converts the rotation of the steering wheel to straight line movement at the
wheels. The steering gear consists of the rack, pinion, and related housings and support bearings. Turning the steering wheel causes
the pinion to rotate. Since the pinion teeth are in mesh with the rack teeth, turning the pinion causes the rack to move to one side. The
rack is attached to the steering knuckles through linkage, so moving the rack causes the wheels to turns.All steering systems contain
several common parts. Every steering system, no matter what type, will have a steering wheel, a steering shaft and column, universal
International Journal of Scientific and Research Publications, Volume 7, Issue 12, December 2017 14
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(ii) Simulation Result (Contact Stress)
Stress analysis is used to determine equivalent stress and the strain of the rack and pinion gear assembly contact point. The numerical results of stress analysis are carried out by using ANSYS 14.5 software. The numerical results of von-Mises stress and strain are compared with different materials of rack and pinion gear (AISI 4340 steel, aluminum alloy and gray cast iron).
Figure 14.Equivalent (von-Mises) Stress on Rack and Pinion Gear Assembly using AISI 4340 Steel
Figure 14 shows the equivalent (von-Mises) stress on rack and pinion gear assembly using AISI 4340 steel. The maximum equivalent (von-Mises) stress on contact point is 1027.3 MPa and location of maximum stress is at the meshing area of the rack and pinion while the yield strength of the structural steel is 1570 MPa. The steering gear will work safely at this stress.
Figure15.Equivalent Strain of Rack and Pinion Gear Assembly using AISI 4340 steel
The equivalent strain on rack and pinion gear pair using AISI 4340 steel is 0.0046578 and occurs at meshing area of the rack and pinion as shown in Figure 15.
Figure 16.Equivalent (von-Mises) Stress on Rack and Pinion Gear Assembly using Aluminum Alloy
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Figure 16 shows the equivalent (von-Mises) stress on rack and pinion gear assembly using Aluminum. The maximum equivalent (von-Mises) stress on contact point is 1021.4 MPa and location of maximum stress is at the meshing area of the rack and pinion while the yield strength of the structural steel is 225 MPa. The steering gear will not work safely at this stress.
Figure17.Equivalent Strain of Rack and Pinion Gear Assembly using Aluminum Alloy
The equivalent strain on rack and pinion gear pair using Aluminum is 0.014995 and occurs at meshing area of the rack and pinion as
shown in Figure 17.
Figure 18.Equivalent (von-Mises) Stress on Rack and Pinion Gear Assembly using Gray Cast Iron
Figure 18 shows the equivalent (von-Mises) stress on rack and pinion gear assembly using Gray Cast Iron. The maximum equivalent
(von-Mises) stress on contact point is 1030.6 MPa and location of maximum stress is at the meshing area of the rack and pinion while
the yield strength of the structural steel is 170 MPa. The steering gear will not work safely at this stress.
Figure19.Equivalent Strain of Rack and Pinion Gear Assembly using Gray Cast Iron
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Then, the factor of safety on steering intermediate steering shaft is also shown in Figure 29. The maximum and minimum factor
of safety is 15 and 3.8631.
TABLE XVI
COMPARISON OF THEORETICAL AND SIMULATION RESULT FOR INTERMEDIATE STEERING SHAFT
Parameter
Results
Theoretical
calculation
Simulation % Error
von-Mises Stress (MPa) 39.092 41.099 4.8%
Fatigue Safety Factor 3.706 3.863 4.1%
Table XVI shows thecomparison of theoretical and simulation resultsfor von-Mises stress and fatigue safety factor of the steering
intermediate shaft.
IV. CONCLUSION
Manual rack and pinion steering system is suitable for solar car. In steering gear design, the diameter of pinion 15mm and face
width 47mm and module 2.5mm was satisfied. The von Mises stress and strain of steering shaft and pinion gear have been compared
with theoretical and simulation result. The contact stress of steering rack and pinion gear pair have been compared in theoretical and
simulation result with different materials. From analysis of rack and pinion gear pair, the von-Mises stress for steel was 1027.3 MPa,
aluminum alloy was 1021.4 MPa and gray cast iron was 1030.6 MPa. From analysis of rack and pinion steering gear pair, strain
results for steel were 0.0046, aluminum alloy was 0.014 and gray cast iron was 0.0097. In structural analysis, steel rack and pinion
steering gear pair is having least strain value. Hence steel rack and pinion steering gear pair was safe for design.
This research also analyzed the stress of the steering rack. By using Finite Element method, a stress analysis has been carried out.
Steering Rack Deflection and Bending stresses are found. These stresses are compared with analytical results. Modeling has been done
by SolidWorks and Analysis has been done by ANSYS software. From analysis of rack, the von-Mises stress was 108.53MPa and a
deformation result was 0.849mm. From analytical result, the von-Mises stress was 96.782MPa and a deformation result was 0.828mm.
Error Percent was 10.8% for von-Mises stress and 2.5% for deformation.
This research has been studied the stress and fatigue analysis for intermediate steering shafts. This research focused on the stress
analysis. It is caused by torsion. The models of intermediate steering shafts are also drawn by SolidWorks software. In the numerical
analysis, stress and fatigue analysis of intermediate steering shafts are considered base on ANSYS software. Fatigue analysis of
intermediate steering shaft is done to find the life of the intermediate steering shaft in cycles and determined the factor of safety of the
shaft. From analysis of intermediate shaft, the von-Mises stress was 41.099 MPa and a safety factor was 3.863. Maximum stress
occurs at the corner points of the circular hole. From analytical result, the von-Mises stress was 39.092MPa and a safety factor was
3.706. Error Percent was 4.8% for von-Mises stress and 4.1% for deformation.
ACKNOWLEDGMENT
The author wishes to express her deepest gratitude to her Excellency, Union Minister Dr. Myo Thein Gyi, Ministry of Education in
Myanmar.
The author is deeply gratitude to Dr. Sint Soe, Rector, Mandalay Technological University, for his kindness, help, permission,
guidance and advice of this paper.
The author would like to thank to Dr. Htay Htay Win, Professor, Head of Department of Mechanical Engineering, Mandalay
Technological University, for her valuable suggestion and giving useful comments.
The author owes a debt of gratitude to her supervisor, Dr. Myint Thein, Associate Professor of the Department of Mechanical
Engineering, Mandalay Technological University, for her enthusiastic instruction, invaluable help, and indispensable guidance in the
preparation of this paper.
Finally, the author wishes to express her heartfelt thanks to her family, especially her parents and all other persons for their supports
and encouragements to attain her destination without any trouble.
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[3] Duryodhan, N. S. et al,Life Determination by Fatigue Analysis and Modal of Intermediate Steering Shaft and Its Optimization, International Journal of Science Technology & Engineering (IJSTE), Volume 2, Issue 1, July (2015)
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