STUDY ON THE ANISOTROPIC TEST AND YIELD CRITERIA OF METAL CORRUGATED HONEYCOMBS

The honeycomb structure, due to its high specific strength, excellent energy absorption efficiency, and superior impact resistance, has broad applications in impact cushioning fields. Compared to traditional honeycombs, the corrugated honeycomb solves the problem of significant load-bearing differences between out-of-plane and in-plane directions that makes it difficult to achieve multi-directional load-bearing and energy absorption. In this study, 316L metallic corrugated honeycombs were fabricated, and compression tests were conducted in different directions to analyze the deformation, load-bearing, and energy absorption characteristics of the corrugated honeycomb in various directions. The results showed that, at different angles of the out-of-plane direction, the platform stress of the corrugated honeycomb exhibited an increasing and then decreasing trend as the deflection angle increased. The maximum platform stress of 1.28 MPa occurred at 30°, while at 90°, the platform stress was minimum, about 0.38 times that at 30°. In the in-plane directions, the platform stress of the corrugated honeycomb was almost constant, displaying isotropic behavior. The trend of specific energy absorption in different directions of the corrugated honeycomb followed the same pattern as the platform stress. Furthermore, a comparison was made between the load-bearing and energy absorption characteristics of traditional honeycombs and corrugated honeycombs under the same fabrication process and honeycomb parameters. The results indicated that, except for the slightly lower load-bearing and energy absorption at the out-of-plane 0° direction, the platform stress and specific energy absorption of the corrugated honeycomb were significantly higher than those of the traditional honeycomb at all other angles, especially in the out-of-plane 90° (in-plane) direction, where the platform stress and specific energy absorption were 23 and 16 times that of the traditional honeycomb, respectively. Finally, an improved Hill 1948 anisotropic yield criterion was established to characterize the platform stress of the corrugated honeycomb, and by comparing with experimental data, it was verified that the improved yield criterion could better represent the platform stress of the corrugated honeycomb at different angles.