An unsymmetric laminated composite having bi-stability is interesting as a morphing structure because it can sustain large deformation without energy supply and the deformed state is stable. Especially, inducing different curvature values at each stable state is important for the practical application of unsymmetric laminates. In this study, we propose a method for tailoring the curvature of unsymmetric cross-ply laminates by curing the composite on a curved tool plate. The results show that the final normal curvature tensor of unsymmetric laminates is the summation of the tool plate curvature tensor and the normal curvature tensor of the laminates.

Shape memory alloys have been actively studied in various fields in an attempt to utilize their high energy density. In particular, shape memory alloy wire-embedded composites can be used as load-bearing smart actuators without any additional manipulation, in which they act like a hinge joint. A shape memory alloy wire-embedded composite is able to generate various deformation behaviors via the combination of its shape memory alloy and matrix materials. Accordingly, a study of the various design parameters of shape memory alloy wire-embedded composites is required to facilitate the practical application of smart structures. In this research, a numerical simulation of a shape memory alloy wire-embedded composite is used to investigate the deformation behavior of a composite panel as a function of the composite width per shape memory alloy wire, composite thickness, and the eccentricity of the shape memory alloy wire. A curved morphing composite structure is fabricated to confirm the results of the numerical simulation. The deformation of the shape memory alloy wire-embedded composite panel is determined by measuring its radius of curvature. The simulated deformation behaviors are verified with the experimental results. In addition, an analysis of the deformation and internal stress of the composites is carried out. It can be used to obtain guidelines for the mechanical design of shape memory alloy wire-embedded composite panels.

The large recovery force and non-linear deformation behaviour resulting from a change in the temperature in shape-memory alloys (SMAs) make them attractive materials for applications in smart materials and structures, as well as actuators. However, SMAs are limited in their application because they cannot support general loads such as bending or compression. SMA wire-embedded composite materials, where materials such as glass fibre reinforced plastics (GFRPs) are combined with SMAs, are proposed to overcome these limitations. However, the increased stiffness of GFRPs limits the deformation that can be achieved. The inclusion of more compliant materials, such as silicon rubber, into the matrix can improve the achievable deformation, and the characteristics of the resulting hybrid composite can be controlled by varying the conformation of the material. In this study, a numerical simulation method was developed to predict the deformation behaviour of SMA wire-embedded hybrid composites. To verify the simulation procedure, several conformations of SMA wire-embedded hybrid composites were fabricated, and their deformation behaviours were compared with the simulation results. The simulation was then used to achieve a favourable trade-off between the stiffness and the achievable deformation of the structure.

This article aims to study the in-plane stiffness estimation of heat pipe supporter (a large lattice structure) using experimental and numerical methods. The in-plane stiffness of heat pipe supporter for nuclear power plant is very important because of the safety against natural disasters, such as seismic load or tsunami, and has to be evaluated because it greatly affects the durability of the heat exchanger. However, the modeling process of the whole lattice structure for finite element analysis increases resources needed caused by too many nodes and elements. In this study, the mechanical properties of large lattice structures are determined by a unit cell finite element analysis. The mechanical behavior of a large lattice structure has been estimated by finite element analysis through a homogenization process for reducing analysis time and efforts. The finite element analysis results have been verified and show a good agreement with the experimental results.

The U-tubes installed inside the steam generator experience high temperature and pressure as a role of heat transfer. Specially, during the secondary side hydrostatic test which ensures the integrity of steam generator, the U-tube is subjected to high external pressure. The purpose of this paper is to investigate the allowable external pressure of the U-tube in steam generator. In the ASME B&PV Code Section III [1], the allowable external pressure is determined by the rules of NB-3133. Alternatively, NB-3228 analysis may be applied. In order to determining the allowable external pressure of steam generator tube, the buckling analysis is performed. The analysis consists of the collapse pressure and elastic instability pressure analyses. In this study, these pressures are determined by finite element analysis (FEA) using ANSYS computer program. The non-linear static analysis is performed with ideally elastic-plastic material properties for the collapse analysis. On the other hand, the elastic instability pressure is calculated by eigenvalue analysis in elastic range. These allowable pressures are found to be 24.1 ksi and 10.5 ksi. Therefore the lower pressure of 24.1 ksi is the allowable external pressure of tube. In addition, the results of analysis are compared with other research [6] and Det Norske Veritas (DNV) offshore standards [11]. In conclusion, the results of buckling analysis are well matched with other research [6] and standard [11]. For steam generator tubes, the collapse pressure is dominant factor in failure. Also, the collapse pressure is largely influenced by the ovality of tube.