Modular Design And Mechanical Behavior Of Lightweight Mechanical Metamaterials

Lightweight mechanical metamaterials are prospective materials,which is a perfect combination of functional and mechanical properties by the creative microstructure design,in advanced national defense equipment,medical devices,new energy vehicles and other fields.However,the mechanical behavior of metamaterials is closely related to the scale and dimensionality of their microstructure.In addition,there are obvious differences in the mechanical properties of structure-based and mechanism-based metamaterials.Here,structure-based metamaterials have stable deformation modes and efficient energy absorption,while mechanism-based metamaterials have flexible shape transformation and programmable mechanical properties.Moreover,the research on mechanical metamaterials is still not well established.To address the above problems,it is important to carry out research on the modular design and mechanical behavior of multi-scale and multidimensional structure-based and mechanism-based metamaterials for the development of artificial microstructures.Therefore,structure-based and mechanism-based lightweight mechanical metamaterials,such as origami cellular structures and three-dimensional lattice structures,are constructed by modular design and tessellation of tubular structures and mechanisms,such as bio-inspired multi-cell tubes and rigid origami tubes.The mechanical behavior of these mechanical metamaterials,such as bio-inspired multi-cell tubes,origami structures and three-dimensional lattice structures,is systematically studied through experiments,simulations and theoretical analysis.In the bio-inspired multi-cell tubes,the multi-cell tubes with different cross-sectional topologies are constructed through the innovative design of the configuration,and their deformation mechanism and energy absorption are analyzed under the impact load.The theoretical model of the new angle elements is refined in different topological configurations.In addition,a workflow paradigm for structural innovation design is constructed based on Abaqus user-friendly plug-in tool and multi-objective optimization.In the origami structures,the in-situ origami tubes have reconfigurable shapes and curvature,which results from the optimal design of the crease pattern.The theoretical expressions of Poisson’s ratio and stiffness are given during the folding motion of these origami structures.The programmable stiffness and Poisson’s ratio of the curved-crease origami tubes are achieved by changing the geometric parameters of the crease pattern.In addition,the origami metamaterials with different folding modes have been constructed using the tessellation of in-situ and curved-crease origami tubes.The effects of geometric parameters(folding angle,layer height,number of layers)and different order of layers on the mechanical properties of the cellular origami structures are quantitatively analyzed to achieve a programmable transformation between the mechanism and structures.The mechanism of the sudden change of stiffness is explained during the transformation between structure and mechanism.The competition between the structural gradient and the thickness gradient is clarified for the curved-crease origami cellular structures.In the design of 3D lattice-inspired structures,a multi-scale,multi-hierarchy,multimaterial 3D lattice structure is constructed based on the geometric optimization and tessellation of tubular structures.The circular/tapered BCC-inspired lattice structures with different gradients are constructed through topological transformation and gradient spacefilling.Different complex lattice-inspired space-filling structures are constructed by mimicking the complex lattice structures.The effects of microstructure topology,geometry parameters,and configuration on the mechanical properties of the 3D lattice structures are quantitatively analyzed by quasi-static compression experiments.In this paper,modular design strategies are developed for lightweight tubular mechanical metamaterials with multi-dimensional,multi-gradient and multi-configuration,which are on the basis of one-dimensional tubes,two-dimensional cellular structures,and three-dimensional lattice structures.The innovative design of lightweight tubular mechanical metamaterials is achieved from structures to the mechanism.The deformation mechanism and energy absorption are clarified for structure-based and mechanism-based metamaterials.A working paradigm of multi-dimensional and multi-configuration innovative structure design is developed for engineering applications.