A review on optimization of composite structures Part I: Laminated composites

Progress update on failure mechanisms of advanced thermal barrier coatings: A review

Experimental and numerical study on the low-velocity impact behavior of foam-core sandwich panels

To understand the thermal insulation and failure problems of the thermal barrier coatings (TBCs) deeply is vital to evaluate the reliability and durability of the TBCs. Actually, experimental methods can not reflect the real case of the TBCs during its fabrication and service process. Finite element modeling (FEM) play an important role in studying these problems. Especially, FEM is very effective in calculating the thermal insulation and the fracture failure problems of the TBCs. In this paper, the research progress of the FEM on the study of the thermal insulation and associated failure problems of the TBCs has been reviewed. Firstly, from the aspect of the investigation of the heat insulation of the TBCs, the thermal analysis via FEM is widely used. The effective thermal conductivity, insulation temperature at different temperatures of the coating surface considering the thermal conduct, convection between the coating and the environment, heat radiation at high temperature and interfacial thermal resistance effect can be calculated by FEM. Secondly, the residual stress which is induced in the process of plasma spraying or caused by the thermal expansion coefficient mismatch between the coating and substrate and the temperature gradient variation under the actual service conditions can be also calculated via FEM. The solution method is based on the thermal–mechanical coupled technique. Thirdly, the failure problems of the TBCs under the actual service conditions can be calculated or simulated via FEM. The basic thought is using the fracture mechanic method. Previous investigation focused on the location of the maximum residual stress and try to find the possible failure positions of the TBCs, and to predict the possible failure modes of the TBCs. It belonged to static analysis. With the development of the FEM techniques, the virtual crack closure technique (VCCT), extended finite element method (XFEM) and cohesive zone model (CZM) have been used to simulate the crack propagation behavior of the TBCs. The failure patterns of the TBCs can be monitored timely and dynamically using these methods and the life prediction of the TBCs under the actual service conditions is expected to be realized eventually.

Modeling of thermal properties and failure of thermal barrier coatings with the use of finite element methods: A review

In spite of the advances in computer technology, there is still a need for more computationally efficient methods for performing stress analysis. One approach which is receiving increasing attention is global/local analysis. Such analyses can take a variety of forms. The form described herein uses two distinct meshes (one global and one local), but retains the same level of accuracy as one would obtain if one was to use a single refined global mesh. The accuracy is retained by using an iterative procedure to enforce equilibrium between the global and local regions. The procedure was tested for two configurations. The good performance observed indicates that the iterative global/local procedure warrants further examination.

Iterative Global/Local Finite Element Analysis

Stacking sequence optimization of composite laminates for maximum buckling load using permutation search algorithm

A statistically consistent fatigue damage model based on Miner’s rule

The objective of this paper is to understand the effect of thermally grown oxide (TGO) on the multiple surface cracking behaviors in an air plasma sprayed (APS) thermal barrier coating system (TBCs). The extended finite element method (XFEM) and periodic boundary conditions are used to investigate the TGO dependences of periodic surface crack driving force and crack propagation path. It is seen that the effect of TGO thickness on the strain energy release rate (SERR) is negligible while ignoring the thickening and elongation strains of the TGO layer. However, the effect of elastic modulus of TGO layer is significant. In particular, for relatively stiff TGO layer the SERR drops to zero as the ratio of surface crack length to coating thickness approximates to one. And vice versa, for a severely damaged TGO layer with relatively compliant modulus, the SERR approaches infinity as surface cracks propagate to the interface. This kind of fracture mechanism is mainly governed by the elastic mismatch across the bimaterial interfaces, which can be used as a guide for the design of good strain-tolerant coating film in APS-TBCs.

Qin Sun

Papers

Stacking sequence optimization of composite laminates for maximum buckling load using permutation search algorithm

A statistically consistent fatigue damage model based on Miner’s rule

The effect of thermally grown oxide on multiple surface cracking in air plasma sprayed thermal barrier coating system

Dynamic mechanical behavior of 6061 al alloy at elevated temperatures and different strain rates

Sequential permutation table method for optimization of stacking sequence in composite laminates