The design report is somehow the summarization of all the key points of the design. when coming to Baja and FSAE steering design report content, the key points of the report are as follow:
1-Fisrt of all the steering geometry
There are mainly two types of steering geometry use in automotive application: the DAVIS steering geometry and ACKERMAN or ANTI-ACKERMAN steering geometry.
For vehicle like Baja all-terrain vehicle or formula SAE it is preferable to use the ACKERMAN or ANTI-ACKERMAN one of the most important reason being its required less space in actual application and is simple.
After deciding the steering geometry come the calcualtions.in the calculation part several things need to be in the report like the Ackerman percentage, the inside and outside turn angle of wheels, and the turning circle radius.
To know more about the calculation you can refer our Go kart steering calculations.
Oversteer or understeer
After calculation if:
Ackerman percentage less than 100%, understeer condition
Ackerman percentage equal to 100%, true Ackerman
Ackerman percentage more than 100%, oversteer condition
2- The steering gear
For baja or Fsae vehicle the rack and pinion steering mechanism is use.
For that rack travel need to be specify either end to end or end to Centre .for our application here the end to end is desirable.
The rack travel is nothing but the horizontal length moved by the rack gear when the pinion gear completes one rotation and it is equal to Number of rotations of pinion* pi*Pitch Circle Diameter of pinion.
– Turn lock to lock
The turn lock to lock need to be given in revolution and the steering ratio in mm per revolution . Usually while buying the rack and pinion from supplier they will provide you easily the values or it can be found online also.
The steering ratio is the ratio between the turn of the steering wheel (in degrees) and the turn of the wheels (in degrees). In passenger cars, it is between 12 and 20:1. Example: If one complete turn of the steering wheel (360 degrees) causes the wheels to turn 30 degrees, then the ratio is 12:1 (360/30=12).
–the IBJ (inner ball joint) Centre distance and the OBJ (outer ball joint) Centre distance
In the rack and pinion steering system, the tie rod is attached to the rack through the inner Ball joint, and attached to the steering arm/knuckle at the outer Ball joint.
In Baja or FSAE middle seating is use so we have for left and right from rack center the OBJ and IBJ have the same distance for both sides.
Tie rod length
For the tie rod length calculation you can refer our Go kart steering calculations, but there is a bit difference with rack and pinion steering mechanism tie rod length, in those calculations the distance is taken nearly from the central axis. In rack and pinion ,the distance of IBJ from rack Centre need to be subtracted from overall length of tie rod.
3- Steering column type
In this section the type of steering column use need to be specify, either the common collapsible or the tilting type like in GO kart where it’s tilted through bearing.
4- The steering wheel diameter and the steering wheel torque.
Here the steering wheel torque is the driver input torque at steering wheel.
Finally all the points mention above and other parameters such as kingpin inclination ( KPI) ,caster angle ,toe In or toe out and camber need to be tabulate properly.
I Hope you enjoy this article about Baja and FSAE steering design report content and it can help you make a better design report. If you like the post pleases comment and share, and if you will like us to cover any related topic suggest, we will do our best to satisfy your queries.
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