Testing And Results
Testing on this project included Riding, deflection, accelerometer, visual, weight, and driving test.
The first test preformed was to make sure that with the arms folded inside the frame that the bike could be operated without your legs or body parts contacting the device. This was preformed by Scott Hansberry and he rode the bike 5 times varied between 10 min and 30 mins around town on roads and trails. The test was a success with the rider not contacting the device while riding or any loss of performance experienced from the bike.
Riding test
Deflection test
The next test was to see if the support arms could take the most extreme case of the bike being tilted and the entire weight of the bike being on just one arm. Since the bike weights and the device weight 45lbs i tested up to 60lbs. Testing was preformed by clamping the support arm on the end that connects to the bike into a vice and then applying the weight on the free end like a cantilever beam. I tested 0, 20, 40, 60 lbs and measured the deflection in the arm with a micrometer. The calculated results were less then the predicted values this could have been due to the vice not being tight enough and the arm deflecting more then predicted. The arm did support the 60lbs without failing so it did pass the test.
Accelerometer test
An Accelerometer test was preformed using a smartphone with built in accelerometer to test the g forces the bike would experience while attached to the car and driven around town. First the test was preformed by driving through out town for 25min and the g forces were calculated and the max g forces the bike would experience were calculated using excel. The max g force was found to be 1.464 and then calculated the additional weight the bike would experience to be 27.84lb. Next with the bike attached to the car 30lbs of weight was added to the bike and then the car and bike were shook and bounced to see if the device would fail under the additional weight. The bike was steady and didn't fail and passed the test confirming that it can take the additional forces it would experience while driving in town.
Visual Test
A visual test was preformed on the bike while it is mounted to the trunk of the car to insure that nothing except the foam pads are touching the car so as to prevent damage to the car. The car was also inspected after the bike was removed to insure no scratches or dents to the car where the support arms connect. After inspection the car was undamaged and the bike was at least 0.75 inches away from touching the car.
Driving Test
Using the accelerator data and test results I determined that the device would be able to successfully support the bike while driving in town. Testing this the bike was attached to the car and the car was driven around town stopping every 3 min to see if the bike was still steady and sturdy. After 20 min of the car driving around town and the bike still safely attached to the car the test was determined a success.
Weight Test
The total device weight was predicted in solidworks to weight 3.2 lbs with out the straps so with straps an estimated weight of 3.5 bls was predicted. The requirements for this project was a device weight of under 5 lbs. Using a bathroom scale, a volunteer first weighted himself then picked up the bike and weighted himself and the bike to find the weight of the bike and then with the device attached to the bike he weight the bike with the device to find the weight of the bike and the weight of the device. Since the scale seemed to vary 3 test were preformed finding a device weight of just under 4lbs under our required weight limit of 5lbs. the extra weight was probably attributed to the washer and nuts not calculated into the solidworks.