1、Deformation and failure mechanisms of lattice cylindrical shells under axial loadingYihui Zhang, Zhenyu Xue, Liming Chen, Daining Fang *Department of Engineering Mechanics, FML, Tsinghua University, Beijing 100084, PR China1. IntroductionThe interest of lattice structures with various core topologie
2、s has grown rapidly over the last decade for their superior properties of high specic stiffness and strength, effective energy absorption, shock mitigation and heat insulation 14. These studies have shed light on that well-designed lattice structures are able to outperform the solid plate and shell
3、components in many applications. In general, the structural topology, as the primary concern in the design, plays a signicant role in dominating the overall mechanical response of the structures. Understanding the deformation mechanisms of various topologies undoubtedly aids to attain the best desig
4、n. Most of the previous studies were focused on the twodimensional planar lattices. Figs. 1(a)(d) exhibit four types of the planar lattice congurations, namely diagonal square, hexagonal, Kagome and triangular, respectively. Each of them has the periodic patterning formed from a two-dimensional geom
5、etric shape with an innite out-of-plane thickness. The overall effective in-plane stiffness and strength of the diagonal square, hexagonal, Kagome and triangular lattices have been analyzed recently, and they show a rich diversity in deformation 58. For the diagonal square and hexagonal lattice plat
6、es, each truss member undergoes bending deformation under most in-plane loading conditions, except for the diagonal square lattice plate uniaxially loaded along the axial directions of its truss member. For the triangular and Kagome lattice plates, the deformations of their truss members are always
7、dominated by their axial stretching or compressing, resulting in higher stiffness and load capacity than the former two. The hexagonal lattice structure can be processed easily using standard sheet metal fabrication method. The elastic modulus, plastic yield as well as buckling behavior of the hexag
8、onal honeycomb have been extensively explored 1,9,10. A new kind of fabrication method named powder processing technology has been developed recently 11, thus activating more varieties of complicated congurations to be fabricated by this approach. Wang and McDowell 8,12 systematically analyzed the s
9、tiffness, strength and yield surfaces of several types of planar lattice patterns. Fleck and Qiu 13 estimated the fracture toughness of elastic-brittle planar lattices using nite element method for three topologies: the hexagonal, triangular and Kagome lattices. Zhang et al. 14,15 proposed two novel
10、 statically indeterminate planar lattice structures and furthermore formulated their initial yield surfaces and utmost yielding surfaces. As an ultra-light-weight material, lattice material is an ideal candidate of traditional material in aerospace engineering. For example, utilizing the winding tec
11、hnology, one can manufacture lattice cylindrical shells, which, as depicted in Figs. 1(e)(h), are the key components of aerospace craft and airplane. The three dominating geometrical parameters of the representative unit cell are demonstrated in Fig. 2 by exemplifying the triangular lattice cylindri
12、cal shell, where is the arc Fig. 1. Congurations of four 2D lattice plates and the corresponding cylindrical shells: (a) diagonal square lattice plate; (b) hexagonal lattice plate; (c) Kagome lattice plate; (d) triangular lattice plate; (e) diagonal square lattice cylindrical shell; (f) hexagonal la
13、ttice cylindrical shell; (g) Kagome lattice cylindrical shell; (h) triangular latticecylindrical shell. length of each beam,and denote the thickness of the beam in the radial direction of the cylinder and the thickness of the beam in the shell face, respectively. The hexagonal lattice sandwich cylin
14、drical shell has been popularly utilized in practical applications as fuselage section of aircrafts and load-barring tubes of satellites for several decades 1619. Under axial compression, this lattice sandwich cylindrical shell possesses better mechanical performance than the traditional axial stiff
15、ened cylindrical shells. Although much attention has been paid on the mechanical behavior of hexagonal lattice, the previous investigations were mainly focused on the simple planar hexagonal lattice structures such as beams and plates, and the delicate investigation on the mechanical behavior of hex
16、agonal lattice cylindrical shell has been scarce. Therefore, the lattice cylindrical shell of hexagonal topology is one focus in this paper. The lattice cylindrical shells made from Fig. 2. The sketch of triangular lattice cylindrical shell with one unit cell in the axial direction (a) and the three-dimensional gure of the representative unit cell with illustration of its geometric parameters (b).Fig. 3. Deformation modes and the non
