Papers by Author: Morteza Shakeri

Abstract: In this paper, to investigate energy absorption capability of hybrid (metal-composite) square tubes under axial loading, a new theory is proposed based on collapse mode of metal square tubes and considering off-axis strength of each layer of composite. An expression is derived for mean crushing load and folding wave length in terms of mechanical properties and geometrical dimensions of metal tube and composite prepregs wrapped around it. To validate the theoretical model, predicted values for mean crushing load are compared with experimental and numerical results that show reasonably good agreement.

Abstract: Elasticity solution is presented for simply-supported, orthotropic, piezoelectric cylindrical shell with finite length under local ring load in the middle of shell and electrostatic excitation. The highly coupled partial differential equations (p.d.e.) are reduced to ordinary differential equations(o.d.e.) with variable coefficients by means of trigonometric function expansion in longitudinal direction for displacement and external forces. The resulting ordinary differential equations are solved by Galerkin finite element method. Numerical examples are presented for [0/90/P] lamination with sensor and actuator for different thicknesses.

Abstract: This work deals with fundamental frequency optimization in Multi-Layered laminated composite cylindrical shell which is subjected to strength failure criteria (Tsai-Hill) constraint. Anisotropic cylindrical shell has finite length with simply supported conditions at both ends. Three dimensional elasticity approaches is used to obtain the objective functioin. To perform optimization, genetic algorithms (GAs) have been used. But GAs does not have the capability of constraint handling. In this paper penalty method as an auxiliary method for GAs has been used to take into accounts the constraints. Tsai-Hill criteria is used as failure constraint. Finally the results are presented for a multi-layered composite shell.

Abstract: The objective of this research was to advance understanding of the cracking process via laboratory and computational studies and to convey the obtained results in a form that can be utilized for the prediction of cracking in flexible pavements. The primary purpose of this project reported herein was to evaluate the effects of tire cords on the fatigue response of asphalt mix and to develop recommendations for improving the fatigue performance of asphalt pavements. Based on the results presented in this paper, the indirect tensile strength tests can propose as a simple performance test for fatigue cracking of asphalt mixture. The results clearly demonstrate a great potential procedure for the fatigue cracking evaluation of asphalt mixture.