Analysis

The analysis is what is used to find important design parameters, such as what material is used for a part or how thick it needs to be. Primary methods of analysis include statics and mechanics of materials to determine the most efficient ways to resist forces encountered during deployment. Thermodynamics and heat transfer will be used to determine how efficient the design is, and ensure no one part of the design overheats.

Requirements

Attains top speed without loss of function.
The RC Baja car is able to corner without loss of traction.
the RC Baja car is able to accept inputs from a control device.
The vehicle must retain speed and handling capabilities after consistent use.
The Drivetrain subassembly is serviceable in case the need for repair or modification arises.
The car withstands the physical demands of the RC Baja event as well as testing undergone during the revision phase of the design process.
The control system and mechanical subsystems in the vehicle must be responsive enough to facilitate split second driving decisions.
1 regulation motor must utilize the required 7.4-volt 2s li-po for a minimum of 2 minutes.
Center of mass must be within 1 inch of the geometric center of the vehicle.
Must achieve a forward velocity of 20 mph within 30 ft of rest on a concrete surface.
The drivetrain must be capable of maintaining 20 mph forward velocity for 75 feet.
The vehicle must come to a complete stop within 25 feet of releasing the throttle on a concrete surface.
The RC Baja car must be able to climb surfaces with up to a 40-degree incline while maintaining static friction, with 50% throttle, on a plywood surface.
Chassis must withstand 10 lbs. of loading without exceeding 1/16th of an inch depression in the center of the chassis, relative to the front, rear, left, and right edges of the chassis.
Chassis must maintain less than 4 degrees of flexion on the rolling axis, measured end to end, under 100% throttle.
Front bumper must deflect no more than 1/8 inches when impacted with a 25 lb. force, directed to the center of the front bumper.
Chassis must not take up more than 45% vehicle weight.
All drive components (excluding motor) must not exceed a temperature of 212 degrees Fahrenheit after 2 minutes of continuous use.
Driveshaft must not exceed 5 degrees of flexion when engaging full throttle from rest
Any Drivetrain component can be removed and replaced in less than 1 minute and 30 seconds.

Analysis one was done to determine the minimum thickness of the beams which would make up the main structural members of the car. With the requirement that the beam could deflect no more than 1/16th of an inch at its center when supported at both ends, it was found that a minimum dimension of 0.168 inches would satisfy the requirement if the beam was made out of 6061 aluminum.

Figure A01-Analysis 1

Analysis two was written to determine whether a steel or aluminum drive shaft would be suitable, as design requirements state that the drive shaft can twist no more than 4 degrees should the drive train ever be locked. This analysis shows that a steel shaft will be far less likely to twist, and will remain under the 4 degree limit.

Figure A02-Analysis 2

Analysis three determined the size of the bolts that would be used in the assembly of the vehicle. By estimating shear forces that would act on the bolts, a fastener size of 1/8 inch made out of stainless steel 504 would be a suitable solution.

Figure A03-Analysis 3