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International Journal of Emerging Technology and Advanced Engineering

Website: www.ijetae.com (ISSN 2250-2459,ISO 9001:2008 Certified Journal, Volume 4, Issue 6, June 2014)

552

Structural Analysis of Steering Knuckle for Weight Reduction

Purushottam Dumbre

1

, A. K. Mishra

2

, V. S. Aher

3

1Amrutvahini College of Engineering, Sangamner. 2Prof and Head of Mechanical Engg. Dept. AVCOE, Sangamner 3

Asst. Prof. Department of Mechanical Engineering, AVCOE, Sangamner

Abstract--The weight of the vehicle is going on increasing due to additional luxurious and safety features. The increasing weight of the vehicle affects the fuel efficiency and overall performance of the vehicle. Therefore the weight reduction of the vehicle is the real need of today’s automotive industry. Steering knuckle is one of critical component of vehicle. It links suspension, steering system, wheel hub and brake to the chassis. There is scope to reduce the un sprung weight vehicle. Steering Knuckle is a non-standard part and subjected to various loads at different conditions. Weight reduction of steering knuckle is the objective of this exercise for optimization. Typically, the finite element software like OptiStruct (Hyper Works) is utilized to achieve this purpose. For optimization, Nastran / Ansys / Abaqus could also be utilized. The targeted weight or mass reduction for this exercise is about 5% without compromising on the structural strength.

Keywords- un sprung weight, Steering Knuckle,

I. INTRODUCTION

The steering knuckle on your vehicle is a joint that allows the steering arm to turn the front wheels. The forces exerted on this assembly are of cyclic nature as the steering arm is turned to maneuver the vehicle to the left or to the right and to the centre again.

Steering knuckles come in all shapes and sizes. Their designs differ to fit all sorts of applications and suspension types. However, they can be divided into two main types. One comes with a hub and the other comes with a spindle.

In this investigation, steering knuckle was used as component for study. Mass or weight reduction is becoming important issue in car manufacturing industry. Weight reduction will give substantial impact to fuel efficiency, efforts to reduce emissions and therefore, save environment. Weight can be reduced through several types of technological improvements, such as advances in materials, design and analysis methods, fabrication processes and optimization techniques, etc. Steering Knuckle is subjected to time varying loads during its service life, leading to fatigue failure. Therefore, its design is an important aspect in the product development cycle.

Automotive makers continuously develop new vehicles with more luxury, convenience, performance, and safety. Often, they reduce vehicle weights which results in reduced energy consumption. A reduction in the weight of suspension components also improves the vehicle’s handling performance. Therefore, design optimization should be implemented to obtain a minimum weight with maximum or feasible performance, based on conflicting constraints, design boundaries, and design uncertainties, such as design clearance and material defects. Among the vehicle structural components, the knuckle is one of the important parts in the suspension system. It plays a crucial role in minimizing the vertical and roll motion of the vehicle body, which implies a poor passenger experience, when a vehicle is driven on a rough road. A knuckle component is required to support the load and torque induced by bumping, braking, and acceleration and also helps in steering the tire connecting tie rod and rotating at the kingpin’s axis centre. In the design optimization of the knuckle component, a weight should be minimized, while design factors such as strength, stiffness and durability should be satisfied with design targets. The steering knuckle accounts for maximum amount of weight of all suspension components, which requires high necessity of weight reduction. Under operating condition is subjected to dynamic forces transmitted from strut and wheel. The weight reduction of steering knuckle is done such that the strength, stiffness and life cycle performance of the steering knuckle are satisfied.

II. LITERATURE SURVEY

1. A workshop report published by an agency of the United States government (Feb2013) focused on the development in light weighting and the technology gap for light duty vehicle. Also the set the goal for weight of vehicle for year 2020 to 2050.The target for reduction of weight of LDV chassis and suspension system is 25% by the year2020.

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International Journal of Emerging Technology and Advanced Engineering

Website: www.ijetae.com (ISSN 2250-2459,ISO 9001:2008 Certified Journal, Volume 4, Issue 6, June 2014)

553

The study identifies scalability as the major challenge for design optimization techniques. GAs is the most popular algorithmic optimization approach. Large-scale optimization will require more research in topology design, computational power and efficient optimization algorithms.

3. S. Vijayaranganet.al.(2013) uses the different material than regular material for optimization of steering knuckle. They use Metal Matrix Composites (MMCs) as it have potential to meet demanded design requirements of the automotive industry, compared with conventional materials. Structural analysis of steering knuckle made of alternate material Al-10 wt% Tic was performed using commercial code ANSYS. It is found from the analysis; the knuckle strut region has maximum stress and deflection during its life time. The results obtained from numerical analysis and experimental testing using particulate reinforced MMCs for steering knuckle with a weight saving about 55% when compare with currently used SG iron.

4. Prof.R. L. Jhala et. al. (2009) assesses fatigue life and compares fatigue performance of steering knuckles made from three materials of different manufacturing processes. These include forged steel, cast aluminum, and cast iron knuckles. Finite element models of the steering knuckles were also analyzed to obtain stress distributions in each component. Based on the results of component testing and finite element analysis, fatigue behaviors of the three materials and manufacturing processes are then compared. They conclude with that forged steel knuckle exhibits superior fatigue behavior, compared to the cast iron and cast aluminum knuckles.

5. k. h. Chang and P.S. Tang(2001) discuss an integrated design and manufacturing approach that supports the shape optimization. The main contribution of the work is incorporating manufacturing in the design process, where manufacturing cost is considered for design. The design problem must be formulated more realistically by incorporating the manufacturing cost as either the objective function or constrain function.

6. Patel Nirala and Mihir Chauhan(2013) carry out the topology optimization of clamp cylinder t using CAE tools to reduce weight with the constraints of standard operating condition. The new optimized design of configuration is proposed.FEA of optimized cylinder is also carried out and compared with acceptance criterion. The optimized model is equally strong and light in weight compared to existing model.

The topology optimization of the component is carried out and substantial reduction in weight about 70 kg is obtained and also obtained stress and deformation within acceptance criteria.

7. Rajeev Sakunthala Rajendran et. al. (2013) discuss the process of designing a light weight knuckle from scratch. The design space is identified for the knuckle and subsequently a design volume satisfying the packaging requirements is created from it. Using Opti Struct, topology optimization is performed on the design volume to derive the optimal load path required for the major load cases. Hypermorph is used to create the required shape variable and Hyper Study is used as optimizer. The process of using Topology optimization for load path generation& Parametric study using shape optimization, reduces the design iteration and intermediate concept models and there by reduces the design cycle time.

There are four disciplines for optimization process:

Topology optimization: It is an optimization process which gives the optimum material layout according to the design space and loading case.

Shape optimization: This optimization gives the optimum fillets and the optimum outer dimensions.

Size optimization: The aim of applying this optimization process is to obtain the optimum thickness of the component.

Topography: It is an advanced form of shape optimization, in which a design region is defined and a pattern of shape variable will generate the reinforcements.

III. METHODOLOGY

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International Journal of Emerging Technology and Advanced Engineering

Website: www.ijetae.com (ISSN 2250-2459,ISO 9001:2008 Certified Journal, Volume 4, Issue 6, June 2014)

554

The design is validated further by performing linear static analysis and normal mode analysis using RADIOSS. The complete approach is shown in flow chart.

IV. DESIGNING ACAD MODEL

CAD model of steering knuckle was developed in 3D modeling software CATIA. it consists of stub hole, brake caliper mounting points, steering tie-rod mounting points, suspension upper and lower A-arm mounting points. Knuckle design mainly depends on suspension geometry and steering geometry.

V. MATERIAL SELECTION

There are several materials used for manufacturing of steering knuckle such as S.G. iron (ductile iron), white cast iron and grey cast iron. But grey cast iron mostly used. Forged steel are most demanding material for this application. For this Ferrite ductile iron is used

VI. MESHING

[image:3.612.328.542.135.432.2]

CAD model of knuckle converted into STEP file. This model is imported into Abaqus Workbench simulation. Geometry cleanup was performed prior to meshing of model. Optistruct is used as solver. For better quality of mesh fine element size is selected.

Table 1. Nodes and Elements of model

Element C3D10

No. of Element 55689

Nodes 93694

[image:3.612.92.202.184.436.2]

Material M122-HSS180- max

Fig.1. Meshing of model

The base geometry is simulated for the actual loading conditions. The load conditions are obtained from data acquisition system. The loadings are as follows.

[image:3.612.337.557.504.648.2]
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International Journal of Emerging Technology and Advanced Engineering

Website: www.ijetae.com (ISSN 2250-2459,ISO 9001:2008 Certified Journal, Volume 4, Issue 6, June 2014)

555

Fig.3. Displacement Contour

Fig.4. Stress Contour

After the analysis of base model the maximum displacement is found to be 0.2 mm in the brake clamping holding area as shown in fig.3 The maximum stress is found in junction area brake clamping and shock absorb connecting arm as shown in fig.4

The material density distribution is observed for finding the low stress area where we can modify the geometry. Fig.5 shows the low stress area where we can remove material that not bear the load. For removal of material we have to consider the manufacturing aspect and some functional constraint. The feasibility of tooling required for modified geometry should check at the time of material removal.

The geometry after material removal is shown in fig.6 The new geometry is analyzed for the same loading conditions and observed for displacement and stress pattern.

Fig.5. Material Density Distribution

Fig.6. Modified Geometry

VII.OBSERVATIONS

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International Journal of Emerging Technology and Advanced Engineering

Website: www.ijetae.com (ISSN 2250-2459,ISO 9001:2008 Certified Journal, Volume 4, Issue 6, June 2014)

[image:5.612.72.238.135.352.2]

556

[image:5.612.327.562.217.345.2]

Fig.7. Displacement contour of modified model

Fig.7. Stresst contour of modified model

VIII.RESULT

Initial model of knuckle is shown in Fig.4. It has max. Stress of 232.7 MPa. After applying load and design constraints topology optimization was performed. Fig.6 shows material which can be removed from model (shown in light green) after optimization.

[image:5.612.71.270.377.593.2]

The mass reduction for the front knuckle was found to be 11%, compared to the currently used model. Optimized model is shown in fig.7 This result is satisfactory considering using topology optimization, with limited design space given and no change in material properties. Summary of results is shown in Table 2.

Table 2 Summery Of Result

Initial Design

Optimised Design

% Reduction

Displacement 0.2 mm 0.21mm

Stress 232.7 MPa 223 MPa

Masss 2.91 Kg 2.6 Kg 11 %

IX. CONCLUSION

Topology optimization can be used to reduce the weight of existing knuckle component by 11% while meeting the strength requirement, with limited design space given with or without change in material properties. Therefore, the overall weight of the vehicle can be reduced to achieve savings in raw material costs and consequently processing cost, as well as, improve fuel efficiency and reduce carbon emissions to help sustain the environment.

REFERENCES

[1] Rick Bornsand Don Whitacre “Optimizing Designs of Aluminum Suspension Components Using An Integrated Approach” SAE Paper 05M-2

[2] US department of energy Vehicle Technology Office “WORKSHOP REPORT: Light-Duty Vehicles Technical Requirements and Gaps for Lightweight and Propulsion Materials” February 2013.

[3] RajkumarRoy, Srichand Hinduja and Roberto Teti “Recent advances in engineering design optimization: Challenges and future trends” CIRP Annals – Manufacturing Technology 57 (2008) 697–715 [4] S.Vijayarangan, N. Rajamanickam and V. Sivananth “Evaluation of

metal matrix composite to replace spheroidal graphite iron for a critical component, steering knuckle” Materials and Design 43 (2013) 532–541

[5] Prof R. L. Jhala, K. D. Kothari and Dr. S.S. Khandare “Component Fatigue Behaviors And Life Predictions Of A Steering Knuckle Using Finite Element Analysis” International Multi Conference of Engineers and Computer Scientists 2009 Vol II

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International Journal of Emerging Technology and Advanced Engineering

Website: www.ijetae.com (ISSN 2250-2459,ISO 9001:2008 Certified Journal, Volume 4, Issue 6, June 2014)

557

[7] Chang Yong Song and Jongsoo Lee “Reliability-based design optimization of knuckle component using conservative method of moving least squares meta-models” Probabilistic Engineering Mechanics 26 (2011) 364–379

[8] K. S. Chang and P.S. Tang “Integration of Design And manufacturing of structural shape optimization” Advances in engineering software32 (2001) 555-567

[9] Dong-chan Lee and Jeong-ick Lee “Structural optimization design for large mirror “Optics and Lasers in Engineering 42 (2004) 109– 117

[10] Patel Niral and Mihir Chauhan “FEA and Topology Optimization of 1000T Clamp Cylinder for Injection Molding Machine” Procedia Engineering 51 (2013 ) 617 – 623

[11] Rajeev Sakunthala Rajendran, Subash Sudalaimuthu and Mohamed Sixth “Knuckle Development Process with the Help of Optimization Techniques” Altair Technology Conference, India,2013

[12] S. Kilian, U. Zander, F.E. Talke “Suspension modeling and optimization using finite element analysis” Tribology International 36 (2003) 317–324

[13] Jong-kyu Kim, SeungKyu Kim, Hwan-Jung Son, Kwon-Hee Lee, Young-ChulPark “Structural Design Method of a Control Arm with Consideration of Strength”9th WSEAS Int. Conference on APPLIED COMPUTER and APPLIED COMPUTATIONAL SCIENCE.

[14] Sonia Calvel and Marcel Mongeau “Black-box structural optimization of a mechanical component “Computers & Industrial Engineering 53 (2007) 514–530

[15] Chau Le, Tyler Bruns, DanielTortorell “A gradient-based, parameter-free approach to shape optimization” Comput. Methods Appl. Mech. Engrg. 200(2011) 985–996

[16] Bernd Ilzhöfer, Ottmar Müller, Pascal Häußler, Dieter Emmrich, Peter Allinger“Shape Optimization Based on Parameters from Lifetime Prediction”

[17] “Optimizing Next-Generation Automotive Structures Using Altair OptiStruct”Plastics in Lightweight and Electric Vehicles Livonia, Michigan November 7-9, 2011

[18] Viraj Rajendra Kulkarni and Amey Gangaram Tambe “Optimization and Finite Element Analysis of Steering Knuckle “Altair Technology conference, India, 2013

[19] A.H. Falah, M.A. Alfares and A.H. Elkholy “Failure investigation of a tie rod end of an automobile steering system” Engineering Failure Analysis 14 (2007) 895–902

[20] Seung K. Koh “Fatigue analysis of an automotive steering link” Engineering Failure Analysis 16 (2009) 914–922

[21] N.A. Kadhim, S. Abdullah and A.K. Ariffin “Effective strain damage model associated with finite element modeling and experimental validation” International Journal of Fatigue 36 (2012) 194–205

Figure

Fig.1. Meshing of model
Table 2 Summery Of Result

References

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