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Experiment 4 : To test the bending of the material by keeping certain points or lines fixed or shifted on the material.
Apparatus and Materials Required : OHP sheet 0.2 mm, Foam sheet 2 mm, heat gun temp 400-550 deg.C, OTG 100-250 deg.C, fevikwik gel as adhesive, threat (to tie).
Procedure :
Form a grid of 50 mm on the longer side of the sheet, use adhesive neatly on the lines and heat with varying temperatures and observe time.
Form a grid of 50 mm on the longer side of the sheet, tie with a cross stitch tightly on the lines and heat with varying temperatures and observe time.
Form grid in all directions and repeat the two techniques mentioned above and heat to observe deformation.
Copy of VID20200819131955.mp4
0.2 mm OHP sheet and 2 mm foam sheet stuck at grid of 50 mm.
The temperature in the OTG was 150 degrees Celsius for a period of 3 min.
Result - The sheet contracts from every direction, except for the fixed points that are tied together.
The foam sheet contracts and hardens a little. The movement of free points is towards the fixed point always.
The form of the sheet is seen to be symmetrical and parallel to the grid.
0.2 mm OHP sheet and 2 mm foam sheet tied at grid of 50 mm.
The temperature in the OTG was 150 degrees Celsius for a period of 3 min.
Result - The sheet contracts from every direction along with the fixed points that are tied together.
The form of the sheet is seen to be asymmetrical and not parallel to the grid as seen in the previous case.
0.2 mm OHP sheet and 2 mm foam sheet tied in the exact same points as the previous experiment.
The temperature in the OTG was 150 degrees Celsius for a period of 3 min.
Result - The sheet crumples unevenly as compared to the previous experiment. The tie loosens due to the pull of the plastic and foam sheet towards the opposite sides.
0.2 mm OHP sheet and 0.2 mm rubber sheet stuck at grid of 25 mm.
A sandwich of 3 OHPs and 3 foam sheets was used that were tied together and keeping alternate grid lines fixed on every sheet.
The temperature in the OTG was 150 degrees Celsius for a period of 3 min.
Result - The plastic sheet forms a corrugation on top of the foam sheet. In turn, the foam sheets take the shape of the plastic and harden a little providing rigidity to the entire sheet.
0.2 mm OHP sheet and 0.2 mm rubber sheet stuck at grid of 25 mm.
A sandwich of 2 OHPs and 2 foam sheets was used that were stuck together and keeping alternate grid lines fixed on every sheet.
The temperature in the OTG was 150 degrees Celsius for a period of 3 min.
Result - The plastic sheet forms a corrugation on top of the foam sheet. In turn, the foam sheets take the shape of the plastic and harden a little providing rigidity to the entire sheet.
This experiment with adhesion gives better results in form as compared to the previous one.
0.2 mm OHP sheet and 0.2 mm rubber sheet stuck at grid of 50 mm and center line.
A sandwich of 2 OHPs and 2 foam sheets was used that were stuck together and keeping alternate grid lines fixed on every sheet.
The temperature in the OTG was 150 degrees Celsius for a period of 3 min.
Result - The sheet contracts from every direction, except for the fixed points that are tied together.
The foam sheet contracts and hardens a little. The movement of free points is towards the fixed point always.
The form of the sheet is seen to be symmetrical and parallel to the grid.
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