Summary
Background Information
The front suspension clevises connect the upper and lower control arms to the chassis.
Requirements
- Safety factor of 3
- 1 million cycle lifetime
Loading and Boundary Conditions
Derivation of Loading Conditions
The following calculations derive equations for the loading loading conditions as a function of the reaction forces on the tire (from the road).
Selecting Tire Forces
Devon Copeland's spring rate research project estimates the normal force on the road for hard braking and cornering as well as the lateral tire force required for cornering. Combinations of these values are used to determine the maximum loading conditions on the clevises. In total, 4 different variables were tested resulting in 16 combinations.
- Braking or no braking
- Steering or no steering
- Inside or outside wheel
- Full rebound or nominal position
The resulting forces on the clevises for each of the 16 combinations is summarized in the following table:
Notes:
- The distribution of the steering force between the outside and the inside tires was estimated to be directly proportional to the distribution of normal force between the inside and outside tires.
- Both the full rebound and nominal position was considered to take into account the effect of suspension travel even thought the angle may not make sense in certain combinations (ex. braking, steering, outside whee, nominal position)
Boundary Conditions
The "Summary" section of the above table shows the maximum radial and axial loading conditions for the clevises based on the 16 cases. Since the radial loading can either be in tension or compression. Two loading cases will be tested: maximum radial tension and maximum radial compression. Both these cases will also have the maximum axial force applied as well.
Case 1: Radial Tension
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Case 2: Radial Compression
Analysis
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