Experimental Study of Mechanical Properties on the Sandwich Panel with Auxetic Foam Core and Carbon Fiber

In this research, an efficient method has been used in terms of cost and equipment for the production of sandwich panels with auxetic foam core and ordinary foam. Polyurethane foam has been used for making the auxetic foam. Then, on the foam specimen, a thermal analysis is performed to determine the specified thermal range for making the auxetic foam. Four layers of carbon fiber were used to make the sheet in the panel. After making cores and sheets, the sandwich panel was made up of two different cores. To achieve the mechanical properties of the samples, various experiments were carried out, including a three-point flexural test, edgewise compression test, Charpy impact test, flatwise compression test, and drop-weight impact test. The results obtained from the flatwise compression test showed that the compression modulus of the sandwich panel with auxetic foam core was 8.4 times the conventional sandwich panel modulus with a normal foam core. Its compressive strength was estimated to be about 20 times the sandwich panel strength with the ordinary foam core. The negative Poisson ratio of these materials causes this behavior, which increases their variation range. The results of the drop-weight impact test showed that the impact resistance of the sandwich panel with the auxetic foam core is increased by 12.62% compared to the sandwich panel with the conventional foam core, which is due to the high-energy absorption of these materials.