Forming of Adhesive-Bonded Sandwich Sheets with a Rubber Pad
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The effect of a rubber pad, its quality, and diameter, on the forming limit of adhesive-bonded sandwich steel sheets is studied using hemispherical dome tests. The forming limit curve (FLC) is predicted with finite element simulations and the strain mapping method. The FLCs of sandwich sheets are compared with that of base, i.e., 0.4- and 1.2-mm-thick sheets. The forming limit of sandwich sheets when formed using rubber pads improve significantly, and is equivalent to that of the base sheet of equivalent thickness formed without a rubber pad. The rubber pad leads to a uniform strain distribution due to a cushioning effect provided by the rubber pad which also delays the onset of interface delamination. The polyurethane rubber performs better compared with the silicone rubber in improving the FLC. The effect of the rubber pad diameter is insignificant. The FLCs and forming height predicted by numerical simulations are reasonably accurate, when compared with the experimental results.
The authors thank CIF, IIT Guwahati for permitting us to extend the mechanical testing facility. R. Ganesh Narayanan thanks ARDB, India for sponsoring a project through which the sheet forming facility was developed. The authors also thank Ankita Shende, Pritam K. Rana, Priyabrata Nath, and Sukanta Das of IIT Guwahati for their help while conducting some of the experiments.