For ACD’s concept design project we are designing an inflatable bar and are interested in new options to place advertisement or other messages on the material. Since the product will be inflated, deflated, folded and stored, the material will bend, fold, stretch and shrink. It would therefore be interesting the see how EL film will react on these actions.
The main limiting factor for the application of EL on inflatable products is the difference in stretch that will probably occur when in- or deflating the product. Not all products will stretch as much as a balloon does, but all inflatable materials will most likely show some amount of stretch. We were curious about the maximum percentage of stretch that an EL specimen can withstand before it stops functioning. We tested it for Tfcd with a basic test setup. This instructable explains how to do this step by step.
Step 1: Equipment
All that is needed for this test are:
- A specimen of EL on stretchable material
- A power source with two electrodes
- Bench vice
- Two glue clamps
- A small camera with tripod
Step 2: Setup - Attach Specimen to Bench Vice
Attach the specimen to the bench vice with use of the two glue clamps as can be seen in the image. Make sure to place the clamps as close as possible to the part of the specimen with the actual EL paint. We used pieces of paper between the clamps and the specimen to not damage the paint. loosen the bench vice to tighten the specimen but make sure not to stretch it yet.
Step 3: Setup - Attach Electrodes
Attach the electrodes of the power source to the specimen and test to see if they make good connection.
Step 4: Setup - Position Camera
Place the camera on the tripod on such a way that it captures the specimen and the ruler that measures the distance between the two parts of the bench vice.
The second image shows what the camera should capture.
Step 5: Test
Dim the lights, turn on the power source, start recording with the camera and slowly open the bench vice. The specimen will slowly stretch to a point where it will start to crack and stop working. When the specimen stops emitting light you can stop recording.
Step 6: Amalyze
Analyze the recordings. The video will show the distance between the two parts of the bench vice that was started with and the distance at which the specimen stopped working. This way the maximum allowable percentage of stretch can be determined.
Step 7: Our Result and Conclusions
In our case, the specimen we got was already malfunctioning before we started testing. At the time of the actual test, the specimen did not work at all anymore. therefore we could not perform the test the way it should have. Instead we stretched the specimen until it started to show cracks. Assuming that the specimen stops working when it starts to show cracks, the maximum allowable stretch for our specimen was 40%.
This value will probably differ per specimen depending on the method that is used to apply the EL paint and the quality of this process.
Step 8: Reflection
The percentage we found seems way too high. The assumption that the material will stop working only when cracks start to show, is probably wrong. Also, there might have been some slip between the specimen and the bench vise and clamps. Therefore the second reading is too large and the percentage is too high.