Background: The gradation of thermal expansion coefficient was analyzed in the earlier study. The analytical formulation derived here, which is quite different, should be validated to understand the thermal stress distribution in a laminated composite and functionally graded material. Besides this solution, a validated numerical model can also be used to optimize the material gradation of plates in terms of sustainability. Objective: To validate the analytical formulation derived here, an experimental model is presented to understand the thermal stress concentration for functionally graded and laminated composite plates. A numerical model is also validated to extend to understand the effects of the number of layers, the thickness of a layer, the gradation function, the ratio of elastic moduli, and the coating. Methods: The experimental problems in the production of the experimental models with layers of different elastic moduli are discussed here. In the experimental analysis, a three-dimensional photoelastic stress analysis of two- and four-layer composite plate was used to mechanically model the thermal expansion. The analytical solution for the thermal stress in a free plate was derived by the strain suppression method based on the principle of superposition. The numerical models were analyzed using finite element software. The step variation in the experiment was used as a reference point for a continuous or multi-layer (> 2) step variation of material coefficients in the models. Results: The variation of stress concentration is shown for various cases of laminated and continuous gradations of elastic modulus. The four-layer experimental model provides the difference in thermal stress distribution as a result of a layered coating. The validated analytical and numerical models provide reasonable results. An empirical formula to optimize the material gradation in terms of elastic modulus is derived. Conclusions: The experimental model can be used to analyze thermal stress in functionally graded materials. The gradations of the material in the plate or the coating of the plates can be optimized by the validated analytical and numerical models. The empirical formula can be used to determine the elastic modulus of the coating to minimize the stress concentration.

In this study, stress analyses of buried flexible pipes were carried out using a newly designed experimental setup for the method of photoelasticity. Several universal tests using a Dynamical Mechanical Analyzer and the parallel plate test in a polariscope were performed to obtain the mechanical and optical properties of a ring that is made from a thin plate of optically sensitive Araldite, which modeled the pipe cross section. Additionally, the mechanical properties of soil used in the experiment have been determined by unconsolidated-undrained triaxial compression tests and specifically developed photoelastic tests. This test method, which provided satisfactory results for estimating the coefficient of lateral earth pressure, can be used as a fast method to obtain this coefficient for general cases. From the buried ring experiment, the distributions of the circumferential stresses along the inner surface and the absolute value of the Tresca stresses along the outer surface of the ring were calculated by some precise photoelastic measurements. Comparing the results with those from the parallel plate test, the lack of design criteria were clarified. The buried ring experiment clarified that the pipe-soil structure keeps the field of elastic stress-strain that is due to a loading until a higher load is applied. The distributions of stresses were compared to those obtained from the finite element analysis of a half ring under the loads determined by Michell’s formulation.

Absolute effective elastic constants of composite materials analytical method;composites;fiber reinforced;finite element method (FEM);static analysis; The objective is to determine the mechanical properties of the composites formed in two types, theoretically. The first composite includes micro-particles in a matrix while the second involves long, thin fibers. A fictitious, homogeneous, linear-elastic and isotropic single material named as effective material is considered during calculation which is based on the equality of the strain energies of the composite and effective material under the same loading conditions. The procedure is carried out with volume integrals considering a unique strain energy in a body. Particularly, the effective elastic shear modulus has been calculated exactly for small-particle composites by the same procedure in order to determine of bulk modulus thereof. Additionally, the transverse shear modulus of fiber reinforced composites has been obtained through a simple approach leading to the practical equation. The results have been compared not only with the outcomes in the literature obtained by different method but also with those of finite element analysis performed in this study.