Testing

Testing Methods:

Introduction:

To test the analysis data that was calculated a three-point bend test will be conducted, an infrared gun will be used, a decibel reader will be used, a compression test will be performed, and tensile tests will be done.

Method/Approach:

Tensile Tests:

A tensile test of the layup will be done to see how much the orientation of the plies and epoxy resin affects the material properties of the material. This will give actual values vs. the theoretical values calculated.

Infrared Gun:

An infrared gun will be used to get values of the surface temperatures on the inside and outside of the material to test for heat loss as the car heater is running.

Decibel Reader:

A decibel reader will be used to test the noise reduction between the hardtop and the soft top on the Jeep currently.

Compression Test:

The Tinius machine will be used to get compression values for the composite layup.

https://drive.google.com/open?id=1RNAbOmEhXPCi-L4TMI2u8qgBHszHUW6a

Testing Procedure:

Load:

To test the weight limit requirements, test samples of the composite layup will be made, and the final test will be to load the center of the hardtop with cement bags (up to 4) that weigh 100 lbs. each to ensure that the panels can handle a 200 pound load with a safety factor of two. The preliminary composite layup test samples will test for the optimal composite layup orientation with tests on the three-point bend instrument.

Noise Reduction:

To test for noise reduction, the vehicle operator will drive the Jeep at highway speeds with the soft-top and have an assistant measure the noise level with a decibel reader. Then, the modular hardtop will be installed and tested the same day in the same conditions to ensure accurate results.

Heat Reduction:

To test for heat loss reduction, the car heater will be set on maximum for 15 minutes when the vehicle is 100% warmed up and a Laser Infrared Thermometer will read the temperature on the exterior of the soft top and hardtop. Comparing these two values will give you the heat loss reduction.

Tensile Test:

To compare tensile properties of an original hardtop to the modular one, there will be cutout sections of the original hardtop and laying up test samples made to compare structural integrity to an industry standard hardtop.

For this project, a few of the tests were done before the product was finished to ensure that the product will not have to be modified later.

To ensure that the hardtop composite layup has the strength characteristics necessary, two test samples were tested to failure. The samples were layed up two different ways. One sample had three layers of fiberglass over the foam core and the other sample had four layers. These were then tested on the Tinius machine. These samples both failed at an average of 50 PSI. This was far over the necessary strength required to carry a 200 lb. load.

For the welded frame made in the side panels, a preliminary test was made before the frame was installed in the panel. To ensure the frame and welds are good, the frame was loaded with a 185 lb. load. The maximum load that will be applied will be 200 lbs. and the frame held up under the 185 lb. load without bending. Later test will be made when all the panels are completed with 200 lbs. of weight. The test will comprise of loading the hardtop with two cement bags in various locations of the hardtop when the hardtop is bolted up to the jeep.

The compression tests to compare the properties of an original hardtop to the created hardtop will be done by testing sections of an original hardtop. The compression properties will then be compared to the compression properties of the layed up samples. This will ensure that the hardtop has the structural characteristics of an industry hardtop

The last two tests of ensuring that the hardtop is waterproof and more soundproof will be done following the procedure shown in Green Sheet 11 & 12. (located in Appendix A.11, A.12) By following a single procedure, the final product can be tested accurately.

Deliverables:

The deliverables from these tests are values that will confirm that the materials that are used in this project are adequate for the construction of the hardtop. The tests will provide insight in issues with the calculations and confirm that the function requirements are met.

By testing for these requirements a few small issues were brought to light. One issue during the waterproof test was that there was a leak in the rear top corners of the side panels. This indicated that a seal in the corners was necessary. The assumption that the panels did not need a seal in the corners were made initially. This mistake was easily fixed with some seal material. The next issue was that, when adapting the original windows to the side panels, the windows only had an 1/8” clearance between the window and the panels. This made for a tight fix. With this tight fit, the windows needed more caulk to ensure a good adhesion between the panel and the window. Even though the windows fit, the realization that the measurements should have been checked earlier was made. This would have decreased the cost of the project by $18. The last issue that came to light was that a few of the bolts had slight alignment issues that increased the time to assemble the panels. While a time requirement was not made, this issue could affect whether someone would want to assemble/disassemble the panels themselves. Overall, the hardtop performed well and fulfilled the requirements stated above.

Overall, the design of the hardtop performed well and met the projects success criteria. As the project progressed, the project was modified in quite a few ways. Some of the design modifications that were made were the use of a soft top header bar, the decision of welding on nuts in the side frame(s) and adjusting the seams where the panels came together on the top panels.

By applying a previously designed part to be used, the time to design a bracket for the front hinges to be attached to was eliminated. A soft bar header bar provided a product that was easy to implement into the top front panel and provided an attachment point that would line up perfectly with the font of the jeep.

One method used to optimize the strength of the side panels so that they could handle the load requirement was by welding the nuts onto the frame made for the side panels. By doing so, the foam core structure would make the side panels even stronger. Welding nuts onto the frame eliminated the need to make an access to both sides of the frame. While the strength of the square tubing is designed to handle the 200 lb load that would be applied to the roof of the hardtop, the steel frame does little to support a side load if someone were to step on the panel in storage. By using a foam core on the side panels, the panels become as strong as the other panels and they would be able to handle a 200 lb side load.

To simplify the seam where the top front and top rear panel met, the seam was modified from having an overlapping section of a 1/2" on both panels to having one panel having a 1/8" thick protruding section and the other section having a 3/4" section that overlapped on top. This gave the ability to create a section with just fiberglass. By doing so, the panels would have a 1/8" gap that would be perfect for a rubber seal. This made the process of creating an overlapping section easier and was perfect for creating a water-tight seal.