A piecewise exponential model for three-dimensional analysis of sandwich panels with arbitrarily graded core

Open Access funded by Engineering and Physical Sciences Research Council Acknowledgements Financial support of this research by the EPSRC (Engineering and Physical Sciences Research Council) (EP/P503299/1, EP/P503930/1), United Kingdom, is gratefully acknowledged.Peer reviewedPublisher PD

Fatigue Fracture of Functionally Graded Materials Under Elastic-Plastic Loading Conditions Using Extended Finite Element Method

In this chapter, extended finite element method (XFEM) has been used to simulate the fatigue crack growth problems in functionally graded material (FGM) in the presence of hole, inclusion and minor crack under elastic and plastic conditions. The fatigue crack growth analysis of alloy/ceramic FGMs, alloy and equivalent composite is done by XFEM in the presence of multiple discontinuities under mode-I mechanical load. The validity of linear elastic fracture mechanics (LEFM) theory is limited to the brittle materials. Therefore, the elastic plastic fracture mechanics (EPFM) theory needs to be utilized to characterize the plastic behavior of the material. A generalized Ramberg-Osgood material model has been used to model the stress-strain behavior of the material. Plasticity has been checked by Von Mises Yield criteria. J-integral has been used to calculate the SIF. Crack growth direction is determined by maximum principal stress criteria

Thermal Shock Fracture Behaviors of Functionally Graded Ceramics

This thesis uses a thermal fracture mechanics model to study the thermal shock fracture behavior of functionally graded ceramics (FGC). The specimen used in this study is a FGC strip with an edge crack on one surface. A severe thermal shock is applied on the cracked surface. The temperature field in a thermally shocked FGC strip is evaluated first using a closed form solution. Thermal stresses, thermal stress intensity factors (TSIF) and critical thermal shocks are evaluated using a thermomechanics and fracture mechanics approach. The effective thermal properties of the FGC specimens are estimated using micromechanics models for conventional composites. Some numerical results of critical thermal shocks are provided for FGC specimens with constant elastic material properties and graded thermal properties in the thickness direction of the strips. Also, examples of thermal stresses and thermal stress intensity factors (TSIFs) are provided. The results show that the components gradation of the FGC composites has significant influence on the specimens\u27 thermal shock behavior. When the volume fraction of the FGC strip is changed rapidly, the critical thermal shock is changed dramatically

Hybrid meshless/displacement discontinuity method for FGM Reissner's plate with cracks

Growing applications of non-homogenous media in engineering structures require the application of powerful computational tools. A novel hybrid Meshless Displacement Discontinuity Method (MDDM) for cracked Reissner's plate in Functionally Graded Materials (FGMs) is presented in this paper. The fundamental solutions of slope and deflection discontinuity for an isotropic homogenous media are chosen as a part of general solutions to create the gaps between the crack surfaces. The governing equation is satisfied by using the meshless methods such as the Meshless Local Petrov-Galerkin (MLPG) and the Point Collocation Method (PCM) with Lagrange series interpolation and mapping technique. The Stress Intensity Factors (SIFs) are evaluated analytically with the Chebyshev polynomials. The accuracy is verified by comparison of numerical and analytical results

Boundary Element Model for Nonlinear Fractional-Order Heat Transfer in Magneto-Thermoelastic FGA Structures Involving Three Temperatures

The principal objective of this chapter is to introduce a new fractional-order theory for functionally graded anisotropic (FGA) structures. This theory called nonlinear uncoupled magneto-thermoelasticity theory involving three temperatures. Because of strong nonlinearity, it is very difficult to solve the problems related to this theory analytically. Therefore, it is necessary to develop new numerical methods for solving such problems. So, we propose a new boundary element model for the solution of general and complex problems associated with this theory. The numerical results are presented graphically in order to display the effect of the graded parameter on the temperatures and displacements. The numerical results also confirm the validity and accuracy of our proposed model