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Procedure:

 

TEST 1: Assembly Efficiency Test

Appendix H - pg. 1

  • Start with wheel in uncollapsed form, attached to the wheelchair axle.

  • Have stop watch and all accompanied tools ready.

  • Have participant disassemble the wheel when told to “start”.

  • Start timing.

  • Stop timing when wheel is fully in its collapsed state.

  • Record time.

  • Have participant reassemble the wheel and attach it to wheelchair axle when told to “start”.

  • Start timing.

  • Stop timing when wheel is fully assembled and attached to wheelchair.

  • Record time.

  • Have participant read the provided User Manual for instructions on how to properly assemble and disassemble the wheel.

  • Repeat Steps 1-10 and record the new time.

  • Repeat Steps 1-12 with other participants of various ages.

  • Compare assembly time with benchmark and other collapsible wheels.

  • Visually demonstrate the effectiveness of the provided instructions in User Manual.

 

TEST 2: Deflection Under Load

Appendix H – pg. 2

  • Attach wheel in uncollapsed form to wheelchair axle.

  • Attach strain gauges to the critical locations:

    • Rim, midpoint between spokes.

    • Spoke, wall and face.

    • Hub section, adjacent to moving hole.

  • From 4 – 7 inches above the seat, have the 250-pound human specimen sit into wheelchair in a “plopping” motion.

  • Record strain values.

  • Repeat several times.

  • Repeat steps 3 – 5 with 300-pound human specimen.

  • Repeat all steps increasing the weight in increments of 50 until 450 pounds.

 

TEST 3: Terrain Test

Appendix H – pg. 3

  • Attach Collapsible Wheel to wheelchair.

  • Use human specimen of approximately 250 pounds, blindfolded.

  • With the specimen in the wheelchair, have one person push the wheelchair 10 yards on a smooth, flat surface.

  • Have the second person observe and interrogate the Collapsible Wheel as it traverses the surface. The observer will rate the wheels performance on a scale of 1-10 based on these parameters:

    • Stability

    • Wobbling

    • Concentricity

    • Solidness of Assembly

    • Deflection / Bending

    • Fluidity while Moving

    • Ride comfort

  • At the end of 10 yards, the specimen will turn around and propel himself/herself using the push rims for the returning 10 yards.

  • The second person will observe and interrogate again and take special note of how the user interacts with the push rim.

  • Repeat steps 3-6 with various users of different weight and age.

  • Repeat steps 2-7 with various terrain, such as slopes, gravel, mud, grass, rain, etc.

  • Compare the rating from each test to determine the strengths and weaknesses and whether weight is affecting the performance.

  • Repeat with a set of traditional wheels and compare the rating from the Collapsible Wheel.

 

 

Data & Results:

 

TESTING

 

 

Introduction:

 

This report covers several methods of testing the Collapsible Wheelchair Wheel project for Senior Project 2015. There are 3 tests that each corresponds with a particular requirement for the wheel. Test 1, The Assembly Efficiency Test, will determine the wheels speed, efficiency, and ease-of-use. Test 2, The Deflection Under load Test, will determine the maximum vertical deflection at critical locations of the wheel under the required weight capacity. Test 3, The Terrain Test, will determine how well the Collapsible Wheel functions as a wheelchair wheel over different terrain and obstacles compared to a traditional wheelchair wheel.

 

Test Sheets

TEST 1:

 

The collapsibility test revealed that most people could not assemble the wheel within the 5-minute goal or disassemble it within the 3-minute goal. The average time for assembly was 7:05.6 and 4:00.8 for disassembly. The reason the assembly takes longer that expected is because of the welding alignment issues that occurred during the construction phase. This problem forced the wheel sections to have to be assembled in a particular order, ultimately adding time to the assembly process. Another area that can be improved is the hub screw. Replacing the hub fasteners with quick-release bolts would reduce the assembly and disassembly time by over a minute. What helped significantly is the instruction manual. After letting the user read the instructions for 5-10 minutes, the assembly time improved 27.6% and got closer to the requirement goal of 5 minutes. This is also true for the disassembly time of 3:10.5 on average. 

TEST 2:

 

Test 2 was important for testing the maximum weight capactiy and deflection requirements. According to the requirements, a pair of wheels should be able to support a 250-pound load and deflect no more than 0.050 inches in any location. The test at each weight load was performed 4 times and the deflection at each location was recorded. The average deflection of the 4 trials is shown in the table on the left. At only instant did the deflection exceed 0.050 inches. When loaded at 450 pounds, the horizontal spoke deflected 0.060 inches. Even though 450 pounds is far greater than the 250-pound requirement, according to the FEA and Safety factor of 2.0, the spoke should not have deflected more than 0.050 inches. However, this does make sense since this test used impact force to simulate how the wheels would actually be loaded in real-world scenarios whereas the FEA only calculated static loads. 

TEST 3:

 

This test was important for ensuring the Collapsible Wheel performed to the standards of a traditional wheel. It is important that this new wheel does not cause any discomfort and is able to maintain functionality over various terrain just as well as a traditional wheel. 

 

According to the traditional wheel test (top table), the average rating was 84.7%. The average rating for the Collapsible Wheel test (bottom table) was 78.7%. This difference was a result of the Collapsible wheel having some "wobble" due to its profile being thinner. There was also some concern on the gravel, grass, and dirt courses due the gaps between the tire sections getting clogged and causing discomfort and instability. 

PHYSICAL PROPERTIES:

 

It was also important to measure the final dimensions and properties of the actual product to compare with the predicted design values, the benchmark, and other competitive products. The actual dimensions came very close to the predicted values, especially considering some of the difficulties experienced in the construction phase. 

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