TESTING
SUMMARY
There will be three components of the RC Baja car that will be needed to be tested and reviewed during the yearlong senior project in spring quarter. These components being tested will mainly be the chassis and suspension side of the RC Car. These will include the chassis, shock towers, and front bumper. These three tests will be conducted by creating written procedures that will guide each test. The procedures will be implemented as so to guide someone else that was not apart of the project. The student will also use a recording device to take pictures and videos to record what had happened. The student will also take data from testing and put into a data sheet via excel.
The biggest testing issue the student experienced was the breakage of the rear swing arm. At the beginning of testing, the rear swing arm broke twice during the drop test. The students initial reaction was to reinforce breakage location on the swing arm with aluminum. During the last trial of the impact test, the rear swing arm failed in the same location even with the aluminum reinforcement. The student then modified the design of the rear swing arm by adding a .5in thickness of material to the whole rear swing arm. During the last test, the rear swing arm did not show any breakage during the shock tower force test. It can be inferred that the modification of the thickness to the rear swing arm has solved the testing issue the student experienced.
CHASSIS
The chassis will undergo loading and integrity testing in the spring based on related requirements found in the proposal. The related requirements to the chassis are listed below:
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The RC Baja car must be able withstand the 506.27N force from the impact test.
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The RC Baja chassis must be able to withstand a 1.5ft drop test if landed upright.
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Chassis must be able to withstand at least 120N of force applied to the front end upwards.
SHOCK TOWERS
The shock towers will undergo loading tests in the spring based on the related requirements found in the proposal. The related requirements to the shock towers are listed below:
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Front/Rear Suspension tower must be able to withstand a 15lb force from the Suspension strut.
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Rear Shock tower must be able to hold rear shock at an angle of between 30 and 60 degrees.
FRONT BUMPER
The front bumper will undergo impact testing in the spring to ensure that it can withstand the required force on the front end based on related requirements in the proposal. The related requirements to the front bumper are listed below:
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The RC BAJA car must be able to go 25 mph.
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The RC Baja car must be able withstand the 506.27N force from the impact test.
Test Descriptions
To summarize all the testing that needs to be done, the main tests that will be done will be force tests, loadings tests, mounting and integrity test. The three most important tests will be the chassis loading/integrity test, shock tower force tests, and front bumper impact test. All requirements stated in the introduction will be evaluated and reviewed. The integrity and loading test will be conducted by running the RC car at normal speed for a certain amount of time to see how it holds up. During this operation different number of weights will be added to the chassis to see how the car performs and components will be inspected for any yielding or stress. The shock tower force test be conducted by dropping the car from different heights, including the requirement height of 1.5 ft to ensure that the car can withstand many different forces from the heights The front and rear shock towers will be inspected after being exposed to different drop heights. The front bumper impact test will be conducted on a long stretch of road to allow the car to get to max speed. Once the car is at max speed it will be driven into the wall to see how it withstands the force. After the Collison, the front bumper and car will be inspected and disassembled from the car to look for any critical damage.
Drop Test
The drop test of the RC Baja car will be tested by dropping the car from 1.5ft and measuring the deflection of the chassis, front swing arms, and rear swing arms. The goal of this test is to see if the suspension system will be able to withstand the force from drop and return the car back to its original resting position before being dropped.
Table T.1 Drop Test Blank Data
Figure T.1 Broken Rear Swing Arm
Figure T.2 Side View
Figure T.3 Whole Car View
Figure T.4 Drop Test Side View
Figure T.4.2 Drop Test Front View
The pictures and videos are the results from the all three drop test trials. One can see in these figures how the rear swing arm broke during the drop.
Figure T.4.3 Drop Test Rear View
The test went as planned according to the written test procedure. The test procedure was able to guide the test and did not present any issues to the student. However, the results from the testing did cause some issues for the student. The first test that was conducted ended up breaking the rear swing arm, this slowed down the student since new swing arms had to be printed. After two days, the student was able to further conduct testing with three brand new swing arm printed out of ABS. The second trial went well with the rear swing arm not breaking, but the swing arm did break on the third and final trial. The student was able to gather good data and will be able to use what was learned for the future.
Impact Test
The impact test of the RC Baja car will be tested by driving the car from varying distances at max speed into a perpendicular surface and measuring the the force the car experiences on the front bumper. The goal of this test is to see if the front bumper will be able to meet the requirement of withstanding a 507N force on the front end.
Table T.2 Impact Test Blank Data
Figure T.5 19 Feet Starting Distance
Figure T.6 Initial Impact Trial 1
Figure T.7 Trial 3 Rear Swing Arm Failure
The pictures above are from trials during the impact test. One can see the two pictures on the left are from the first trial and the picture on the right shows the breakage of the rear swing arm during trial 3.
The testing for the impact test went according the written procedure that was created to guide the testing. There was a minor issue that student was able to solve which was the starting distance for the car. The initial starting distance proved to be too short and didn't give the car enough time speed up, the student simply increased the distance so the car could record good data. During the three trials, the car was able to reach a speed of 7.4 mph generating a force of 146.3N, unfortunately the cars rear swing arm did fail. The student can infer that if the car reached a force of 507N, the car would fail more in multiple spaces, thus not meeting the requirement for the car. The student has modified the rear swing arm by increasing the thickness by .5in in hopes to give the rear swing arm more strength.
Shock Tower Force Test
The Shock Tower Force Test of the RC Baja car will be tested by applying various loads to the rear and front shock towers
and measuring the the force the shock towers experience. The goal of this test is to see if both shock towers will be able to meet the requirement of withstanding a 15lbf force if applied
Table T.3 Shock Tower Force Test Blank Data
Figure T.8 15 lb load on rear shock tower
Figure T.9 15lb load on front shock tower
Figure T.10 initial testing setup
The pictures above are from trials during the shock tower force test.. One can see the two pictures on the left are from the last trial at 15lbs and the picture on the right shows the initial testing setup that was used.
The testing for the shock tower force test went according the written procedure that was created to guide the testing. The student conducted the tested by adding little weight at a time, eventually getting up to the 15lb load requirement. Since both rear and front shock towers were able to hold the 15lb load, the student can say that the shock towers meet the criteria of the requirement. The rear swing arm also did not break during the testing, this is mostly like because of the increased .5in thickness that student added.