2. Abstract:
Steeringknuckle isthe moststresssustainingandcritical componentof All TerrainVehicle (ATV).
Steeringknuckle isthe pivotpointof the steeringandsuspensionsystem, whichallowsthe frontwheels
to turn and alsoallowthe movementof suspensionarmsmotion.The lightweightandhighstrength
componentisalwaysindemandingforracecarapplication.Lightweightandoptimizeddesignof steering
knuckle isproposedtouse fora BAJA SAE INDIA off road racecar. Due to the failure inknuckle interrain
vehicle aftersome instances,ithastobe modifiedforbetterperformance.The 3DCAD model created
by usingCATIA V5and static as well asmodel analysiscarriedoutinANSYS12 to understanditsbehavior
underoperatingconditions.All testforframe wascarriedouton aluminumalloys6061-T6 & for spindle
EN8. The paperdiscussesthe FEanalysisof existingandmodifiedSteeringKnuckle.
3. Introduction:
SAEINDIA and Mahindra & Mahindra have designed an all-terrain vehicle specifically for the 2015 BAJA
race. Engineering design projects and their associated problems are the goal of the competition. Each
team isvyingfor a hypothetical companytoproduce theirconcept. Designing andbuildinganall-terrain
sports car with a single seat for the driver is the primary objective of each team .
A steeringknuckleisapartonwhichawheelhubhasbeenplacedandwhichprovidessupportforsteering
andbrakingwhenworkingundervery stressful conditions.Foreveryracecar,there maybe some variation
in the steeringsystem,whichisnot a typical elementof terrainvehicle components.Toaccommodate a
wide range of applicationsandsuspensiontypes,the designmaybe modified.Itisseenin picture 3 that
the steering knuckle from the CAD model in figure 1 has been integratedinto the racecar. For example,
FEA may be used to forecast how a product responds to real-world forces, such as vibration and other
physical impacts.The results of a FE analysisreveal whetherornot a product will last,break,or perform
as intended.
The lowweightarchitecturemaybe exploredwiththe useof modernoptimizationmethods.Manycasting
componentsmaybenefitfromRajendranandhiscolleagues'discussionof the processof buildingalight-
weight Knuckle from scratch. With this information,a topology optimization can be done on the design
volume and a concept model may then be created from the topology findings. In order to save weight,
the model has been tested to withstand all of the requisite harsh loads as well as the durability load.
Chang and Tang introduced an integrated designand manufacturing technique that facilitates the form
optimization of structural component. The process begins with a simple idea, in which the designer is
providedwithinformationonthe component'sboundaryandloadingconditions.Fora structural layout,
topologyoptimizationiscarriedout. The complete designprocessandnumerousdesignmethodologies
are shown using a 3D tracked vehicle road arm.
It is saidthat the SteeringKnuckle playsakeypart in the vehicle'ssteeringcontrol,aswell as supporting
the vehicle's vertical weight. In this study, a computer model of the steering knuckle's design
characteristics is created using the most up-to-date modelling software, and the loads acting on the
knuckle as a function of time are determined. It's done to identify the weakest link in the chain. [4].
Reliability-based design optimization of an automobile knuckle component under bump and braking
loading circumstances is discussed by Chang Yong Song in this paper In order to fulfil the required
dependabilityobjective,aknuckle component'sweightmustbe minimizedwhile takingintoaccountthe
stresses,deformations,andfrequencylimitations.Anreal vehicle specificationisusedtodevelopthe first
design.ABAQUSis usedfor the finite elementanalysis,andthe movingleastsquares method(MLSM) is
used in approximation optimization to arrive at the probabilistic optimum solutions.
The ultimate goal of thisresearchistocreatearacingsteeringknucklethatisbothrobustanddependable.
An organization's rules dictate the development of racing components. When a race was in progress, a
steeringarmhad splitfromthe knuckle because of weakknuckle andstrong boltedjointdesign,asseen
in figure 2. It should be joined with the knuckle to enhance the steering and braking mechanism since
during steering an arm pulls knuckle towardsthe automobile for turning. There is no bolted connection
in the suggested design to increase the knuckle's strength, and it is joined directly to the knuckle.
5. Designof ExistingKnuckle
Design a steering knuckle with minimal weight and maximum strength is the goal
of the project. As a result of their lightweight, low density, and suitable yield
strength, aluminium 6061-T6 alloys are the finest choice for today's automotive
sector. Aluminum 6061's mechanical and physical characteristics are shown in
Table 1.Figure1 depicts the CADmodel of the steering knucklecreated usingCATIA
V5 after taking into account the information presented above. The model's
suspension geometry was developed with an off-road vehicle in mind. Figure 2
depicts the present knuckle, which is a Hub type. Tyres are fastened to the wheel
hub by useof bearings. Brakecalliper and steering arminstallation is done without
an external joint in this kind of knuckle, however the design of the knuckle
incorporatesforcesexerted by threeelements to savemanufacturingcostsandraw
material requirements the frame of reference the steering arm.
1) Frame
2) Steering Arm
3) Brake Calliper mounting
Loads are taken into account based on their weight and broken down into their
three component axes, x, y, and z. 6.6, 4.6 and 2.3 are G's values for x, y and z
direction force calculations, respectively.
Fig3 racer car
6. Structure and Design of Modified Knuckle
As a response to last year's disaster, the goal of the design is to build a racing steering knuckle
that is both trustworthy and long-lasting. When designing the knuckle, the frame and spindle
might be manufactured from one or more different materials. AL6061-T6 is the material used
to create a vehicle's frame, as shown in table 1. For increased bolted joint strength, the spindle
is composed of EN8 steel, which has a lock nut arrangement on the end to prevent lateral
wheel hub movement. Initially, the design process began with a preliminary investigation of the
steering knuckle element utilised in the previous racecar, including an examination of the
current knuckle design. Additionally, the design must meet all of the requirements and
restrictions set out by the BAJA organizers, which mostly revolve around suspension and
steering geometry, respectively. To connect to an upper arm, lower arm, and tie rod, a steering
knuckle has three connectors on its body section. So the design must place emphasis on these
three connections as well as one side of the connectors to which the brake calliper is
connected. Design evaluation using FEA simulations is then performed in order to determine
the flexural stresses and the overall mass of the structure. Results showed that increasing the
material thickness or adding fillet and chamfer to corners improved the design. Figure 4 depicts
the conceptual design for the proposed system.
Fig4 ModifiedKnuckleDesign
7. Fig 5 ModifiedKnuckle Design
Fig6 ModifiedKnuckleDesign
Material Selection:
The steeringknuckle componentismade of a varietyof materials,includinggreycastironand white cast
iron. Althoughthese materialshave ahighyieldstrength,weightisalimitingfactorforracecars,hence
theyaren't ideal.Inordertofindan alternative material withthe same yieldstrengthandlow weight,
aluminiumalloy6061-T6 waschosenfor these andeconomicconsiderations.
8. Load Distribution
Curb weightof vehicleconsidered=2500N
Weightof One personAsper SAE rule = 1110 N
Gross Weightof Vehicle =3610 N For analysisconsiderwhenvehicleisjumpandlandingonsingle
frontwheel so,total weightof vehiclecomesonspindleI.Loadon spindle =3561 N II. BrakingForce =
3500 N III.BrakingTorque = 331.5 N-mIV.Force On SteeringArm= 600 N
Finite ElementAnalysis
An IGS-formatted 3D model built in CATIA v5 and imported into ANSYS 12.0 was used for the
finite element analysis (FEA) of both the original and the modified knuckle. Table 1 shows the
material qualities that engineers have assigned to the data. The model is a 187-node
hexahedral mesh. X, Y, and Z translations are all possible for the solid components.
It has been determined that the stress level in the knuckle is dependent on the material quality
of the material. Results from ANSYS 12.0 are presented in a tabular manner.
On ExistingDesign
In order to see how much stress is put on the steering knuckle by harsh circumstances, one
existing design is a hub-type steering knuckle. Constraints on the steering knuckle were found
at the upper and lower ball joints. Weight biassing on the front side of each wheel of 60 kg is
taken into account based on loading circumstances. Three components of force were evaluated
in the x, y, and z directions depending on the vehicle's speed. As indicated in figure 7, apply
loads of 1400 N, 2800 N, and 4000 N in the X, Y, and Z directions, respectively. Figure 8 depicts
a mesh representation of an existent knuckle with 181775 nodes and 120120 components.
Stress levels on designs are lower than material yield strength and deflections are minimal
under the given loads, according to findings of an investigation. As a result, the CATIA software
is also used to analyse the weight of the models in order to create a lightweight steering
knuckle.
10. Fig9 Equilvalent Stress
Fig10 MaximumPrincipleStresses
On ModifiedDesign
The knuckle's spindle-type modification has been adopted. This design used an interference fit
to attach the spindle to the frame, which in turn turned the wheel hub. The redesigned knuckle
is divided into two pieces with the purpose of lowering weight and accommodating varying
loads.
1) Frame
2) Spindle
Frame:
The steering arm and brake calliper mounting are part of the frame, which is a pivoting
framework for the upper and lower suspension arms. Figure 12 shows a mesh model with
11. 196446 nodes and 127590 elements for FE analysis, as discussed in the load distribution section
and depicted in Figure 11. According to the results, it has a deformation of 0.14115 mm, which
is very low.
Fig 11 BoundaryconditionsforFrame
Fig 12 Meshmodel of modifiedknuckle
12. Fig13 .Equivalentvon-meshesstress
Fig14 . Maximumprinciplestresses
Spindle:
The spindle was subjected to a vertical force due to the car's dynamic weight transfer when it
came to a stop after a jump. Because of this, the spindle is able to withstand all of the stresses
that it encounters in a dynamic state. In light of this, we made the conscious decision to select
EN8 for the spindle. The local market offers EN 8 at a lower cost. Figure 15 shows the boundary
conditions for FEA. There are 147630 nodes and 101000 elements formed after meshing the
spindle.
14. Fig18 .EquivalentStresses
Result& Discussion
In the updated design, the stress distribution is different, but the maximum stress position is
same, according to the results of an examination of the original and modified knuckles. The
upper and lower ball joints are subjected to the most stress in the current configuration. Near
the pivot, the present design experiences a maximum stress of 72.394MPa.
There are no holes for bolting holes in the modified design since the knuckle steering has a
different setup. A new stress maximum has been detected at steering mounting because of
this; for the same boundary condition. Table 2 shows the entire FEA results for the current and
changed design sections.
Conclusion:
The existing knuckle design that will be used in an SAEINDIA BAJA 2015 vehicle was found to meet
the load-bearing specifications. If the vehicle is in Dynamic mode, the external steering arm and
brake calliper arrangement will not function properly. A steering knuckle that can withstand
dynamic loads while maintaining a small weight is the ultimate objective of this research. Due to
15. its excellent physical and mechanical qualities and its low weight, the aluminium 6061-T6 alloy
was chosen as the ideal material for the component. Under the imposed loads, FE analysis
showed that the knuckle models had stress values below the stress threshold and deflection
values far below the critical threshold. The model's excellent stress findings need additional
analysis. A new knuckle must be installed in the terrain vehicle for the SAEINDIA BAJA 2016 racer
in order to increase its strength and decrease joint failure.
References:
[1] SAE India Baja Collegiate Design Series 2015 Baja SAEINDIA Rules.
[2] RajeevSakunthalaRajendran,SubashSudalaimuthuandMohamedSithik2013 Knuckle Development
Process with the Help of Optimization Techniques Altair Technology Conference, India.
[3] K. H. Chang and P.S. Tang 2001 Integration of Design And manufacturing of structural shape
optimization Advances in engineering software 32 555-567.
[4] B.Babu, M.Prabhu, P.Dharmaraj, R.Sampath 2014 Stress Analysis of Steering Knuckle of Automobile
Steering System International Journal of Research in Engineering and Technology.
[5] Chang Yong Song and Jongsoo Lee 2011 Reliability-based designoptimization of knuckle component
using conservative method of moving least squares meta-models Probabilistic
[6] Patel Niral and Mihir Chauhan 2013 FEA and Topology Optimization of 1000T Clamp Cylinder for
Injection Molding Machine Procedia Engineering 51 617 – 623.
[7] Tim Palmer and Eric Nelson 2011 Optimizing Next-Generation Automotive Structures Using Altair
OptiStruct Plastics in Lightweight and Electric Vehicles Livonia, Michigan 7 - 9.
