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Testing Design Guide: ASME Mini-Baja Car

Steering and Suspension Systems

Introduction:

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

The basic requirements are as follows:

•             Shocks will have to be designed that can dampen the force of a drop from up to 24 inches.

•             Suspension must support up to four pounds from a drop of 24 inches without chassis.

•             Suspension must have at least 1.5” of up travel.

•             Steering and suspension systems must operate, and articulate fully without interference between components.

•             Steering system must allow vehicle to turn 180 Deg. in a 50” radius

•             As per competition rules a minimum20% of steering components must be store bought.

•             As per competition rules design 50% of parts for interchangeability to allow for smaller parts stock.

•             Systems must be fastened together with easily sourced fasteners.

The parameters of interest are performance of the vehicle, this entails the suspension must be able to withstand the rigors of the competition’s course by supporting the vehicle without bottoming out and absorb shock sufficiently enough to prevent damage to any parts of vehicle. The steering must operate in a predictable manner and turn the vehicle in a fairly small radius so it will be easy to steer through complex obstacles and terrain.

It is predicted that the vehicle will meet or exceed all of the above listed requirements. Data Acquisition will be performed by my partner Jason Moore, and myself depending on the test, the primary method of acquisition will be filming, a stop watch and written records of performance.

The primary method intended to test the functions of the vehicle are different obstacles found on campus and some courses that will simulate the predicted rigors of the competition. This will include obstacles with different height drops, different surfaces can be found all over campus, and the FLUKE lab in Hogue will provide a wide enough space to test top speed and slalom abilities. The vehicle will only be tested as a whole while completely assembled. The testing will focus on the requirements listed in 1c: Requirements.

 

Most of the test environment for the vehicle systems will be found on campus or constructed on campus in the Hogue FLUKE lab. The indoor lab is a convenient location for testing, it is free, out of the weather and generally at a consistent humidity and temperature.  A variety of different surfaces such as bark, grass, gravel, concrete, asphalt, and wood sheeting can all be found and is readily available on campus. Card board boxes, 2x4 and a bottle jack will be used to make a platform of adjustable height, to test vehicle drops from different levels. A measuring tape will be needed to measure obstacle lengths and heights. Calipers will be used to measure the amount of travel of the steering and suspension components. Masking tape will be used to mark locations for testing steering accuracy, as well as used in outlining a turning radius. A cell phone will also be used as an accelerometer, stop watch, camera, and recording device. All of the equipment necessary for the proposed testing methods is readily available for free, for this reason testing is currently omitted from cost and budget. The speed and slalom test will be covered by my partner Jason Moore, as the drive train components are key to predictions and testing.

Method/Approach:

Most of the test environment and resources for testing the vehicle systems will be found on campus or constructed on campus in the Hogue FLUKE lab. The indoor lab is a convenient location for testing, it is free, out of the weather and generally at a consistent humidity and temperature.  A variety of different surfaces such as bark, grass, gravel, concrete, asphalt, and wood sheeting can all be found and is readily available on campus, these will be used to simulate the cometition course. Card board boxes, 2x4 and a bottle jack will be used to make a platform of adjustable height, to test vehicle drops from different levels. A measuring tape will be needed to measure obstacle lengths and heights. Calipers will be used to measure the amount of travel of the steering. The following is an overview of testing procedures.

 

Formal Test Procedures:

 

1. Shock Dampening test/ Bottom-out Test

 

Location: Hogue technology fluke lab.

  • Step 1: Record Mass of vehicle, and drop heights.

  • Step 2: Place carbon paper at vehicle landing zone (this will test to see if vehicle bottoms out         during drop).

  • Step 3: Mark 12”, 18”, and 24” heights on wall, mark locations with masking tape.

  • Step 4: Drop vehicle from lowest height 1st, then drive to ensure all components still are operational. Record if vehicle is unharmed and system components are functional.

  • Step 5: Record if there was interference with carbon paper at landing area (ie bottoming out)

  • Step 6: Repeat steps 4 and 5 with greater heights.

 

Risk (safety) : Little risk of safety issues, but to be sure wear safety glasses during drop test should any components come flying off of vehicle.

 

 

 2. 1.5” Obstacle test

 

Location: Hogue technology fluke lab.

  • Step 1: Place a 2x4 (standard 2x4 is approximately 1.5” tall) on floor of lab.

  • Step 2: Weight 2x4 so that it will not move, when the vehicle drives over it.

(A person standing on each side of it will be sufficient)

  • Step 3: Attempt to drive vehicle over 2x4.

  • Step 4: Record if vehicle is successful or not.

Risk (safety): Little risk of safety issues, be sure to keep balance while standing on 2x4.

 

3. Vehicle predictability & Straightness test  

 

Location: Hogue technology fluke lab.

  • Step 1: Outline a 12” wide 25’ long lane on lab floor in masking tape.

  • Step 2: Place vehicle in center of lane at one end.

  • Step 3: Straighten wheels so that they are not turning in one direction or the other.

  • Step 4: Depress acceleration but do not touch steering wheel, until the vehicle veers out of lane or it reaches the end.

  • Step 5: Record if test was successful, if unsuccessful record location of veering out of lane.

(Success is determined by the vehicle making it to the end of the lane without veering 6” in either direction.)

  • Step 6: Repeat steps 4-5 five times to determine an average operating predictability.

 

Risk (safety) : Little risk of safety issues, but to be sure to be wary of runaway vehicles.

To test the turning radius an arc with a 50” Radius will be outlined on the FLUKE lab floor in masking tape. The vehicle will have to complete a turn without exceeding the radius of the turn. The test is pass/fail, if vehicle stays within outlined arc it is a pass.

 

4. Turning radius Test

 

Location: Hogue technology fluke lab.

  • Step 1: Mark a starting location on fluke lab floor with masking tape.

  • Step 2: Mark a location 50 inches to either side of start point on fluke lab floor with masking tape.

  • Step 3: Place vehicle centered on starting location.

  • Step 4: Rotate steering all the way to the right.

  • Step 5: Depress accelerator while maintaining full right turn.

  • Step 6: Record if turn was inside or outside of the 50” turn radius, as well as total turn radius for that turn.

  • Step 7: Repeat 3-6 five times to obtain averages.

  • Step 8: Repeat steps 3-7 except turning vehicle to the left.

Risk (safety): Little risk of safety issues.

 

 

RADIUS TEST

SPEED TEST

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