Post-buckling finite strip analysis of thick functionally graded plates

M. Hajikazemi,H.R. Ovesy,H. Assaee,M.H. Sadr 국제구조공학회 2014 Structural Engineering and Mechanics, An Int'l Jou Vol.49 No.5

In this paper, a novel semi-energy finite strip method (FSM) is developed based on the concept of first order shear deformation theory (FSDT) in order to attempt the post-buckling solution for thin and relatively thick functionally graded (FG) plates under uniform end-shortening. In order to study the effects of through-the-thickness shear stresses on the post-buckling behavior of FG plates, two previously developed finite strip methods, i.e., semi-energy FSM based on the concept of classical laminated plate theory (CLPT) and a CLPT full-energy FSM, are also implemented. Moreover, the effects of aspect ratio on initial post-buckling stiffness of FG rectangular plates are studied. It has been shown that the variation of the ratio of initial post-buckling stiffness to pre-buckling stiffness (S*/S) with respect to aspects ratios is quite independent of volume fractions of constituents in thin FG plates. It has also been seen that the universal curve representing the variation of (S*/S) with aspect ratio of a FG plate demonstrate a saw shape curve. Moreover, it is revealed that for the thin FG plates in contrast to relatively thick plates, the variations of nondimensional load versus end-shortening is independent of ceramic-metal volume fraction index. This means that the post-buckling behavior of thin FG plates and the thin pure isotropic plates is similar. The results are discussed in detail and compared with those obtained from finite element method (FEM) of analysis. The study of the results may have a great influence in design of FG plates encountering post-buckling behavior.

Post-buckling finite strip analysis of thick functionally graded plates

Hajikazemi, M.,Ovesy, H.R.,Assaee, H.,Sadr, M.H. Techno-Press 2014 Structural Engineering and Mechanics, An Int'l Jou Vol.49 No.5

In this paper, a novel semi-energy finite strip method (FSM) is developed based on the concept of first order shear deformation theory (FSDT) in order to attempt the post-buckling solution for thin and relatively thick functionally graded (FG) plates under uniform end-shortening. In order to study the effects of through-the-thickness shear stresses on the post-buckling behavior of FG plates, two previously developed finite strip methods, i.e., semi-energy FSM based on the concept of classical laminated plate theory (CLPT) and a CLPT full-energy FSM, are also implemented. Moreover, the effects of aspect ratio on initial post-buckling stiffness of FG rectangular plates are studied. It has been shown that the variation of the ratio of initial post-buckling stiffness to pre-buckling stiffness ($S^*/S$) with respect to aspects ratios is quite independent of volume fractions of constituents in thin FG plates. It has also been seen that the universal curve representing the variation of ($S^*/S$) with aspect ratio of a FG plate demonstrate a saw shape curve. Moreover, it is revealed that for the thin FG plates in contrast to relatively thick plates, the variations of non-dimensional load versus end-shortening is independent of ceramic-metal volume fraction index. This means that the post-buckling behavior of thin FG plates and the thin pure isotropic plates is similar. The results are discussed in detail and compared with those obtained from finite element method (FEM) of analysis. The study of the results may have a great influence in design of FG plates encountering post-buckling behavior.

A modified multi-objective elitist-artificial bee colony algorithm for optimization of smart FML panels

H. Ghashochi-Bargh,M.H. Sadr 국제구조공학회 2014 Structural Engineering and Mechanics, An Int'l Jou Vol.52 No.6

In Current paper, the voltages of patches optimization are carried out for minimizing the powerconsumption of piezoelectric patches and maximum vertical displacement of symmetrically FML panelsusing the modified multi-objective Elitist-Artificial Bee Colony (E-ABC) algorithm. The voltages ofpatches, panel length/width ratios, ply angles, thickness of metal sheets and edge conditions are chosen asdesign variables. The classical laminated plate theory (CLPT) is considered to model the transient responseof the panel, and numerical results are obtained by the finite element method. The performance of the EABCis also compared with the PSO algorithm and shows the good efficiency of the E-ABC algorithm. Tocheck the validity, the transient responses of isotropic and orthotropic panels are compared with thoseavailable in the literature and show a good agreement.

PSO algorithm for fundamental frequency optimization of fiber metal laminated panels

H. Ghashochi-Bargh,M.H. Sadr 국제구조공학회 2013 Structural Engineering and Mechanics, An Int'l Jou Vol.47 No.5

In current study, natural frequency response of fiber metal laminated (FML) fibrous composite panels is optimized under different combination of the three classical boundary conditions using particle swarm optimization (PSO) algorithm and finite strip method (FSM). The ply angles, numbers of layers, panel length/width ratios, edge conditions and thickness of metal sheets are chosen as design variables. The formulation of the panel is based on the classical laminated plate theory (CLPT), and numerical results are obtained by the semi-analytical finite strip method. The superiority of the PSO algorithm is demonstrated by comparing with the simple genetic algorithm.

Failure analysis of laminates by implementation of continuum damage mechanics in layer-wise finite element theory

B. Mohammadi,H. Hosseini-Toudeshky,M.H. Sadr-Lahidjani 국제구조공학회 2009 Structural Engineering and Mechanics, An Int'l Jou Vol.33 No.6

In this paper a 3-D continuum damage mechanics formulation for composite laminates and its implementation into a finite element model that is based on the layer-wise laminate plate theory are described. In the damage formulation, each composite ply is treated as a homogeneous orthotropic material exhibiting orthotropic damage in the form of distributed microscopic cracks that are normal to the three principal material directions. The progressive damage of different angle ply composite laminates under quasi-static loading that exhibit the free edge effects are investigated. The effects of various numerical modeling parameters on the progressive damage response are investigated. It will be shown that the dominant damage mechanism in the lay-ups of [+30/-30]s and [+45/-45]s is matrix cracking. However, the lay-up of [+15/-15] may be delaminated in the vicinity of the edges and at +θ/-θ layers interfaces.

PSO algorithm for fundamental frequency optimization of fiber metal laminated panels

Ghashochi-Bargh, H.,Sadr, M.H. Techno-Press 2013 Structural Engineering and Mechanics, An Int'l Jou Vol.47 No.5

In current study, natural frequency response of fiber metal laminated (FML) fibrous composite panels is optimized under different combination of the three classical boundary conditions using particle swarm optimization (PSO) algorithm and finite strip method (FSM). The ply angles, numbers of layers, panel length/width ratios, edge conditions and thickness of metal sheets are chosen as design variables. The formulation of the panel is based on the classical laminated plate theory (CLPT), and numerical results are obtained by the semi-analytical finite strip method. The superiority of the PSO algorithm is demonstrated by comparing with the simple genetic algorithm.

Delamination growth analysis in composite laminates subjected to low velocity impact

Masoud Kharazan,M.H. Sadr,Morteza Kiani 국제구조공학회 2014 Steel and Composite Structures, An International J Vol.17 No.4

This paper presents a high accuracy Finite Element approach for delamination modelling in laminated composite structures. This approach uses multi-layered shell element and cohesive zone modelling to handle the mechanical properties and damages characteristics of a laminated composite plate under low velocity impact. Both intralaminar and interlaminar failure modes, which are usually observed in laminated composite materials under impact loading, were addressed. The detail of modelling, energy absorption mechanisms, and comparison of simulation results with experimental test data were discussed in detail. The presented approach was applied for various models and simulation time was found remarkably inexpensive. In addition, the results were found to be in good agreement with the corresponding results of experimental data. Considering simulation time and results accuracy, this approach addresses an efficient technique for delamination modelling, and it could be followed by other researchers for damage analysis of laminated composite material structures subjected to dynamic impact loading.

A modified multi-objective elitist-artificial bee colony algorithm for optimization of smart FML panels

Ghashochi-Bargha, H.,Sadr, M.H. Techno-Press 2014 Structural Engineering and Mechanics, An Int'l Jou Vol.52 No.6

In Current paper, the voltages of patches optimization are carried out for minimizing the power consumption of piezoelectric patches and maximum vertical displacement of symmetrically FML panels using the modified multi-objective Elitist-Artificial Bee Colony (E-ABC) algorithm. The voltages of patches, panel length/width ratios, ply angles, thickness of metal sheets and edge conditions are chosen as design variables. The classical laminated plate theory (CLPT) is considered to model the transient response of the panel, and numerical results are obtained by the finite element method. The performance of the E-ABC is also compared with the PSO algorithm and shows the good efficiency of the E-ABC algorithm. To check the validity, the transient responses of isotropic and orthotropic panels are compared with those available in the literature and show a good agreement.

Failure analysis of laminates by implementation of continuum damage mechanics in layer-wise finite element theory

Mohammadi, B.,Hosseini-Toudeshky, H.,Sadr-Lahidjani, M.H. Techno-Press 2009 Structural Engineering and Mechanics, An Int'l Jou Vol.33 No.6

In this paper a 3-D continuum damage mechanics formulation for composite laminates and its implementation into a finite element model that is based on the layer-wise laminate plate theory are described. In the damage formulation, each composite ply is treated as a homogeneous orthotropic material exhibiting orthotropic damage in the form of distributed microscopic cracks that are normal to the three principal material directions. The progressive damage of different angle ply composite laminates under quasi-static loading that exhibit the free edge effects are investigated. The effects of various numerical modeling parameters on the progressive damage response are investigated. It will be shown that the dominant damage mechanism in the lay-ups of [+30/-30]s and [+45/-45]s is matrix cracking. However, the lay-up of [+15/-15] may be delaminated in the vicinity of the edges and at $+{\theta}/-{\theta}$ layers interfaces.