Zixian Yu’s research while affiliated with Huazhong University of Science and Technology and other places

Mechanical behaviors of a new foam filled 2D re-entrant hexagonal honeycomb with negative Poisson's ratio under planar compression have been investigated in this paper. Re-entrant hexagonal unit cell specimens were fabricated by aluminum alloy and polyurethane foam. The deformation modes and force-displacement curves of the unit cell specimens under compression were carried out experimentally and numerically, and a good agreement was observed between experimental results and numerical simulation results. Subsequently, mechanical behaviors of foam filled and void re-entrant hexagonal honeycomb under planar compression were observed by numerical simulation. Compared to the void honeycomb, the foam filled honeycomb has a higher specific energy absorption capability due to a higher plateau stress. According to the mechanism of auxetic effect, the re-entrant honeycomb would move inward when subjected to compression along the orthogonal direction, which cause a biaxial compression of the foam and an increasing of stiffness/strength/energy absorption capability. The present investigations provide thorough insight into the strengthened re-entrant hexagonal cellular honeycomb, and could be used in the development of novel light weight smart functional structures.

Experimental investigations on the mechanical responses of fully clamped circular plates with prefabricated crack at room temperature and low temperature have been conducted. Initial cracks with different lengths were prefabricated by the electrical discharge machining method. Low ambient temperature was created by the liquid nitrogen in a low-temperature chamber, and a dropping hammer was dropped from the same height with a constant impact energy of 5 J to carry out the repeated impact. Experimental test results show that the prefabricated crack has a significant influence on the mechanical behavior of the thin plates. The maximum impact force decreases with increase of the crack length, and the threshold impact number until fracture decreases with increase of the crack length. It is also observed from the test results that the maximum impact force increases with decrease of the temperature, while threshold impact number until fracture and the plastic permanent deformation decreases due to the brittleness of the material in low temperature. The present investigations provide useful insight into the failure mechanism of the clamped thin plate with initial crack under low-velocity repeated impacts in low temperature, which will lead to a guideline for research and design of marine structures in the arctic area.