# Mechanical Behavior of Hollow Corrugated Sandwich Cylinders Under Inner Pressure Loading
## 1 Introduction  
Pressure-bearing equipment, including pressureed vessels, pressured pipes, pressured chambers, et al., are widely applied in aviation, national defense, the chemical industry, foodstuff, and transportation. Pressure-bearing equipment are key devices for bearing inner pressure as a basic load, facing the threat of leaking and exploding [1]. Lightweight, security, and reliability are key requirements for the design of pressure-bearing equipment. In recent years, with the development of material manufacturing and processing technology, lightweight porous metal sandwich plates have been widely studied in structure-bearing, active cooling, sound absorption, noise lowering, explosion and ballistic impact resistance, and structure actuation, due to their excellent structural efficiency and multifunctional application prospects [2; 3; 4]. Due to the high void ratio and good designability, hollow corrugated sandwich cylinder structures can be used as pressure-bearing equipment instead of homogeneous metal structures [5]. It is promising to reduce the weight while achieving multifunctional effects such as structural support, crashworthiness, energy absorption, et al. [6; 7]. Investigation of the behavior of long hollow cylinders with infinite length under inner or outer pressure loading is one of the classical problems in engineering mechanics. A thick-walled hollow cylinder with an isotropic base material was treated comprehensively in a purely elastic stress state by [PERSON] [8; 9], in a fully plastic stress state by [PERSON] et al. [10] and [PERSON] [11], and in an elasto-plastic stress state by [PERSON] [12] and [PERSON] and [PERSON] [13]. For pressurized hollow cylinders with anisotropic materials, [PERSON] [14] and [PERSON] and [PERSON] [15] presented the elastic closed-form solutions. [PERSON] al. [16] analyzed the response of multilayer composite circular cylindrical shells under different loads based on first-order shear deformation theory. [PERSON] et al. [17] numerically investigated the nonlinear dynamic stability of isotropic and composite cylindrical shells under axial loading. [PERSON] et al. [18] proposed a generalized design model to analyze the stability and initial post-buckling equilibrium trajectory of sandwich cylindrical shells with elastic cores. For cylinder shells with fiber-reinforced composite materials, [PERSON] [19] presented the benchmark solutions to the problem of buckling of orthotropic cylindrical shells under external pressure or axial compression loading. On that basis, [PERSON] [20; 21] constructed the elasticity solution for a cylindrical sandwich shell under different loadings. [PERSON] et al. [22] performed the optimum weight design of hollow sandwich cylinders with ultralightweight cellular cores, considering five different core topologies, i.e., Kagome truss, single-layered pyramidal truss, double-layered pyramidal truss, single-layered corrugated core, and double-layered corrugated core, respectively. Compared to hollow cylinders having solid walls, truss-core sandwich cylinders and single-layer corrugated core sandwich cylinders exhibit superior lightweight advantages, particularly in scenarios involving heavier loads. Taking the engine combustor of an aerospace vehicle as a prototype, [PERSON] et al. [23] conducted further research on the bi-functional optimization of actively cooled, pressurized hollow sandwich cylinders with prismatic cores. In conclusion, research on the structural efficiency of sandwich structures with cellular material cores mainly focuses on the sandwich plate under different loading. Few research studies were related to the optimization of sandwich cylinders under inner pressure loading. Existing research only analyzed the situation of that structure subjected to high-level inner pressure.