Testing
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There were seven tests the bridge underwent. They were the vehicle transversing the bridge test, the articulation showing height test, the bridge resting on abutments test, the 10 grams allowing a gap for 20lb paper test, the 20kg load test, the weight of bridge test, and the max verticle deflection test. The three that were focused on in this project were the articulation height test, the articulation cycle time, and the load and deflection test. The articulation height test would determine whether the bridge was able to reach 140mm vertically about the middle at full articulation. The articulation cycle time was meant to determine whether the bridge would be able to complete a full cycle(up and down)in under 60 seconds with a 10-second pause. The load and deflection test was done to determine if the bridge could maintain a load of 20kg with deflecting less than 25mm. The articulation tests were completed on a desk using measuring tapes, stopwatches, and video recordings to acquire a cycle time and max height. The load test was done on the Inston to acquire load and deflection data.
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Issues that were run into with testing were that the bridge needed an additional bar added to the articulation structure in order for the bridge to articulate properly. This was solved with leftover bridge material so no additional costs were needed, and only pushed testing back about a day. Another issue was scheduling a time to use the Instron as a professor was needed in order to run the machine in addition to special equipment needed to preform the tests.
Figure 1
The Articulation Test
In this test, the goal was to determine whether the bridge fit the 140mm articulation requirement. This was done by articulating the bridge to max height and measuring about the bottom middle of the bridge. This measurement could then be compared to the 140mm and whether it was greater than or less than. This can be seen in figure 1.
Articulation Test Video
The process for the articulation cycle time and articulation height tests were similar, however, the height test used a measuring tape during the pause to take a height measurement
Articulation Cycle Time
Cycle time was preformed using a clock during the process for estiated times, but was gone through after for video review.
In this test, the goal was to ensure te bridge was able to fit the requirement of being able to complete a full cycle in under 60 seconds(lifting up and lowering down) This cycle also included a 10-second pause at the peak. The predicted value was that the cycle time would be about 17.4 seconds
Load and Deflection Test
The purpose of the load and deflection test was to determine whether the bridge was able to support a load of 20kg while deflecting less than 25mm at its lowest point. The predicted values for this test were that the bridge would be able to support 20kg and deflect around 6.5mm
The video shows the process of the load test following mounting the plate to the bridge and installing in the jig in the Instron.
Other Testing
The bridge was weighed with only the wood components, some minor articulation components were left on as they were non removable
Other tests that needed to be completed were whether the bridge was able to slide a sheet of paper underneath from a 10g load, whether the weight of the bridge was under 85g, whether the bridge fit the 400mm gap requirement, and fitting under the design size constraints to allow for motion through the bridge.