Compressive mechanical behaviors of PPR and NPR chiral compression–twist coupling lattice structures under quasi-static and dynamic loads

This paper designs two chiral compression–twist coupling lattice structures with positive Poisson's ratio (PPR) and negative Poisson's ratio (NPR), and studies their compressive mechanical behaviors. Experiments and finite element (FE) simulations under the quasi-static load are firstly done. Compared to the PPR case, the maximum rotation of the lattice structure with the NPR effect is increased over 40%. Then dynamic compressive mechanical behaviors of the PPR and NPR lattice structures are investigated with different velocities of loads. Impact resistance performances of present structures are further researched, and gradient designs are introduced to improve the impact resistance performance. It is found that different Poisson's ratios show great effects on quasi-static and dynamic mechanical behaviors. As the velocity of load increases, both the initial deformation region and initial compact region are closer to the side of the applied load. Under the middle velocity load, the NPR lattice structure shows the smaller initial peak stress but less energy absorption. With the further increase of load velocity, the PPR lattice structure presents both the better energy absorption and smaller stress peak. The positive gradient (PG) rises the energy absorption, while the negative gradient (NG) abates the peak stress. As the NG design is used, the peak stress of the NPR lattice structure decreases from 23.3 MPa to 16.5 MPa. Besides, gradient designs diminish discrepancies of mechanical behaviors caused by different Poisson's ratios.