A Novel Shell Element for Quasi-Static and Natural Frequency Analysis of Textile Composite Structures

2014 ◽  
Vol 81 (8) ◽  
Author(s):  
Wu Xu ◽  
Anthony M. Waas

A shell element for analysis of textile composite structures is proposed in this paper. Based on the embedded element method and solid shell concept, the architecture, geometry, and material properties of a repeat unit cell (RUC) of textile composite are embedded in a single shell finite element. Flat and curved textile composite structures are used to apply and verify the present shell element. The deformation and natural frequency obtained by the present shell element are compared against those computed from full three-dimensional finite element analyses. It is shown that the proposed shell element is efficient, simple, and reliable for textile composite structural analysis.

Author(s):  
James Stolte

Abstract Composite materials are being investigated in advanced technology test beds for use in future armored vehicles. We are particularly interested in the response to impulsive loading for which the knowledge of natural frequency behavior is important. In this paper, we investigate the natural frequency analysis capabilities of the multilayered shell element of the ADINA finite element code as applied to laminated composite beams and plates. Results are compared to those published in the literature or those derived from exact solutions. The ADINA shell element employs a first-order shear deformation theory, and the results are found to agree well with other first-order theories. Although ADINA does not allow for a direct method of incorporating a shear correction factor commonly used in first-order theories, it is demonstrated how this can be included by modifying the material properties.


Author(s):  
Hanadi Abdulridha Lateef ◽  
Abdulamir Atalla

A vibration analysis of circular cylindrical steel liquid storage tanks anchored to rigid base is conducted. Empty, partially and completely liquid filled tanks are considered as well as tanks composed of two courses using ANSYS 11.0 finite element package. The tank wall is modeled using linear elastic shell finite element and a new method, based on the added mass approach, is developed to model the effect of the contained liquid. In this method the properties of the shell element is modified to include the effect of the contained liquid. The analysis includes four tank case studies which are empty, fully filled with water, and filled with changeable liquid level in addition to study the effect of the variable thickness of tank on the natural frequencies and mode shapes. The results show that the natural frequency of completely filled tall tank may be less by 70.7% than the natural frequency of empty tank. It is also found that a maximum value of natural frequency can be obtained when the lower thick course consists 0.75 of tank height and its thickness is four times that of the upper one. The natural frequencies decrease with the increasing in liquid level for tall tank. The natural frequency of completely filled tank is less by 70.7% than the natural frequency of empty tank.


2016 ◽  
Vol 828 ◽  
pp. 215-236 ◽  
Author(s):  
Maria Cinefra ◽  
Erasmo Carrera

This paper deals with the analysis of layered structures under thermal and electro-mechanical loads. Constitutive equations for multifield are considered and the Principle of Virtual Displacements (PVD) is employed to derive the governing equations. The MITC9 shell finite element based on the Carrera's Unified Formulation (CUF) has been applied for the analysis. The models grouped in the CUF have variable through-the-thickness kinematic and they provide an accurate distribution of displacements and stresses along the thickness of the laminate. The shell element has nine nodes and the Mixed Interpolation of Tensorial Components (MITC) method is used to contrast the membrane and shear locking phenomenon. The finite element analysis of multilayered plates and shells has been addressed. Variable kinematics, as well as layer-wise and equivalent single layer descriptions, have been considered for the presented FEs, according to CUF. A few problems are analyzed to show the effectiveness of the proposed approach. Various laminations, thickness ratios and curvature ratios are considered. The results, obtained with different theories contained in the CUF, are compared with both the elasticity solutions given in literature and the analytical solutions obtained using the CUF and the Navier's method.


2007 ◽  
Vol 344 ◽  
pp. 647-654 ◽  
Author(s):  
Xiao Cong He ◽  
Ian Pearson ◽  
Ken W. Young

Self-pierce riveting (SPR) is nowadays widely used in the car manufacturing industry where aluminium alloys are used for body construction. For the design of mechanical structures, formed by the joining of component parts, a knowledge of the vibration characteristics of different joint types (adhesive bonding, spot welding, SPR etc) is essential. The free transverse vibration characteristics of single lap-jointed encastre SPR beams are investigated theoretically in this paper using the three dimensional finite element method (FEM). Numerical examples are provided to show the influence on the natural frequencies, natural frequency ratios and mode shapes of these beams caused by variations in the material properties (E and υ) of the sheet material. It is shown that the transverse natural frequencies of single lap jointed encastre SPR beams increases significantly as the Young’s Modulus of the sheets increases, but only slight changes are encountered for variations of Poisson’s Ratio. It is found that an exponential curve gives an acceptable fit to the relationship between natural frequency and Young’s Modulus. As expected, odd modes shapes were found to be symmetrical about the mid-length position and even modes were anti-symmetrical.


2010 ◽  
Vol 160-162 ◽  
pp. 87-90
Author(s):  
Feng Liu ◽  
Zhong Bo Zhang ◽  
Jun Yan

The three dimensional finite element model of composite laminates made of carbon fiber reinforced bismaleimide resin is built, and the natural vibration of the square composite laminates with clamped edges is analyzed. The natural vibration frequencies and modes of laminates without damage are given based on finite element method. The three dimensional finite element models of the same square laminates with non-penetrating damage repaired by two kinds of bonding methods are built. The natural vibration frequencies and modes are also given. It is showed that the three dimensional models can simulate the geometric and physical features of the real composite laminates. It is concluded that the natural vibration frequencies of the composite laminates all increase after it is repaired either by scarf bonding method or scarf and surface bonding method. After scarf bonding repairing, the lowest natural frequency increases about 3.6% and the second natural frequency increases 3.7%. After scarf and surface bonding repairing, the lowest natural frequency increases about 4.5% and the second frequency increases about 6.4%. The natural vibration modes of different repairing models are similar. The increase of natural frequencies may cause temporary vibration of aircraft skin made of composite laminates. The risk of resonance caused by bonding repairing is small.


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