A New Trefftz Based Finite Element for Static Analysis of Laminated Composite Structures

Author(s):  
Subhasankar Dwibedi

Abstract Composite materials have been widely used in industries for several years owing to their capability to perform better than homogeneous isotropic materials. Numerical tools like finite element method are efficiently used for analysis of structures made of composite materials. However, for complex shapes or geometries of structures, it becomes uneconomical (computational resource wise) to use Rayleigh-Ritz based finite element analysis. An unique Trefftz based finite element has been developed in this article to efficiently fill the gap in the above mentioned scenario. Hybrid-Tefftz finite element method’s flexibility to use arbitrary shaped elements comes handy in modelling complex geometries. The developed hybrid-Trefftz finite element approach has been used on symmetric angle-ply laminated composite plate and the obtained results have been compared with bench mark solutions. The present method proposes an approach for development of hybrid-Trefftz type finite elements, by which analysis of antisymmetric structures is also possible, an area of research which has been less explored by such approach as revealed from survey of available open literature.

Author(s):  
Subhasankar Dwibedi

Abstract Analysis of symmetric angle-ply skew laminated composite plates has been presented in the study using a newly developed hybrid Trefftz finite element (hTFE). Mindlin’s plate theory has been used to develop the present hTFE. The forms of displacement are assumed such that governing partial differential equations are satisfied a priori inside the element domain. Particular solutions of the governing equations have been ignored and Trefftz functions are derived using the homogenous solutions only. Inter-element continuity has been established by employing another displacement field along the edges of the hTFEs. The transverse shear stresses have been ignored at the top and bottom surfaces of the laminate. The angle of inclination of the width of the plate with the y-axis has been taken as the skew angle and different forms of skew plates are obtained by varying the skew angle. Sinusoidally distributed load (SDL), uniformly distributed load (UDL), and point load (PL) have been subjected to the top surface of the laminate and the non-dimensionalized center point deflection have been evaluated to assess the performance of the present hTFE. The observation from the present study further reinforce the versatility of the hTFE method for analysis of composite structures with complex shapes or geometries.


2004 ◽  
Vol 13 (1) ◽  
pp. 096369350401300 ◽  
Author(s):  
Evgeny Barkanov ◽  
Andris Chate

Finite element analysis of sandwich and laminated composite structures with viscoelastic layers is performed. The present implementation gives the possibility to preserve the frequency dependence for the storage and loss moduli of viscoelastic materials exactly. Moreover, the storage and loss moduli in this case are defined directly in the frequency domain by an experimental technique for each material and can be used after curve fitting procedure in the numerical analysis. Damping characteristics of viscoelastic composite structures are evaluated by the energy method, the method of complex eigenvalues, from the resonant peaks of the frequency response function and using the steady state vibrations. Numerical examples are given to demonstrate the validity and application of the approaches developed for the free vibration, frequency and transient response analyses.


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