Design Processes & Analytical Explanations of Baja.Student.India

STEERING

The function of the steering system is to steer the front wheels in response to driver command inputs in order to provide overall directional control of the vehicle.

Rack with centrally placed pinion manufactured with sand parts is chosen with following
specifications-

Rack length = 279.4mm,
Weight = 1.02Kg,
Rack travel = 257.15mm (centre to lock), Pinion travel = 270 degrees (centre to lock).

Ackerman steering geometry is used to change the dynamic toe setting, by increasing front wheel toe out, as inside wheel is steered to a greater angle than the outside wheel.

1) Advantages of Ackerman Geometry;

The advantages of the Ackerman Geometry is that during a turn outer front wheel maximizes its tyre grip, at the expense of inside tyre grip, in a negative camber carrying front tyres, Ackerman geometry helps to compensate for negative camber on the inside tyre.

Ackerman helps to reduce tyre wear by providing common centre of rotation for all the four wheels. The inner and outer wheels have different angle displacement which helps to gain common turning centre.

As lighter the tyre load, the higher the slip angle required for peak cornering power, Ackerman geometry is beneficial.

2) Analysis of Tie Rod; Several forces will act on tie rod

1. Axial Compressive force (which is reaction of steering force) of magnitude 544.88 N 2. Bump force (which will act perpendicular to
axial force) of magnitude 1.5G (4267.35 N)

Alloy steel is selected as material of tie rod having yield strength 250MPa. Tie rod analysis by using ANSYS software shows that the maximum deformation is 0.00005627mm and equivalent stress (Von-misses stress) is 25.4MPa which is less than tensile and compressive yield strength i.e. 250MPa.

STEERING PARAMETERS

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