Micro-Mechanical Analysis of Composites Reinforced with Discontinuous Fibers with Large Aspect Ratio

2013 ◽  
Vol 420 ◽  
pp. 269-275
Author(s):  
Milan Žmindák ◽  
Martin Dudinsky ◽  
Zoran Pelagić
Keyword(s):  
Aspect Ratio ◽  
Glass Fibers ◽  
Fiber Composites ◽  
Mechanical Analysis ◽  
Basis Functions ◽  
Large Aspect Ratio ◽  
Domain Boundaries ◽  
Linear Problems ◽  
Far Field Stress ◽  
Continuous Source

Properties of fiber composites reinforced with fibers greatly depend on the choice of fiber and matrix. Their mechanical properties and geometry influence the stress state in composite. In this paper the Method of Continuous Source Functions (MCSF) employing Trefftz Radial Basis Functions (TRBF) is presented. This method does not require any mesh. The focus will be given to the application of TRBF in form of dipoles to the simulation of composites reinforced with fibers of finite length with large aspect ratio. In presented example as well as in other linear problems, only nodes on the domain boundaries and a set of source functions in points outside the solution domain are necessary to satisfy the boundary conditions. Finally employing of MCSF for analysis of patch of glass fibers embedded in epoxy matrix subjected to far field stress is shown.

scholarly journals Thermal Properties of Short Fibre Composites Modeled by Meshless Method

2014 ◽  
Vol 2014 ◽  
pp. 1-8 ◽  
Author(s):  
Vladimír Kompiš ◽  
Zuzana Murčinková
Keyword(s):  
Heat Flux ◽  
Composite Material ◽  
Aspect Ratio ◽  
Meshless Method ◽  
Large Aspect Ratio ◽  
Fibre Composites ◽  
Short Fibres ◽  
Temperature Heat ◽  
The Matrix ◽  
Continuous Source

Computational model using continuous source functions along the fibre axis is presented for simulation of temperature/heat flux in composites reinforced by short fibres with large aspect ratio. The aspect ratio of short fibres reinforcing composite material is often as large as 103 : 1–106 : 1, or even larger. 1D continuous source functions enable simulating the interaction of each fibre with the matrix and also with other fibres. The developed method of continuous source functions is a boundary meshless method reducing the problem considerably comparing to other methods like FEM, BEM, meshless methods, or fast multipole BEM formulation.

Numerical Modeling of Fluid-Induced Rotordynamic Forces in Seals With Large Aspect Ratio

2012 ◽  
Author(s):  
Alexandrina Untaroiu ◽  
Costin D. Untaroiu ◽  
Houston G. Wood ◽  
Paul E. Allaire
Keyword(s):  
Finite Difference ◽  
Aspect Ratio ◽  
Finite Difference Method ◽  
Difference Method ◽  
Dynamic Properties ◽  
Bulk Flow ◽  
Large Aspect Ratio ◽  
Flow Method ◽  
Dynamic Coefficients ◽  
Aspect Ratios

Traditional annular seal models are based on bulk flow theory. While these methods are computationally efficient and can predict dynamic properties fairly well for short seals, they lack accuracy in cases of seals with complex geometry or with large aspect ratios (above 1.0). In this paper, the linearized rotordynamic coefficients for a seal with large aspect ratio are calculated by means of a three dimensional CFD analysis performed to predict the fluid-induced forces acting on the rotor. For comparison, the dynamic coefficients were also calculated using two other codes: one developed on the bulk flow method and one based on finite difference method. These two sets of dynamic coefficients were compared with those obtained from CFD. Results show a reasonable correlation for the direct stiffness estimates, with largest value predicted by CFD. In terms of cross-coupled stiffness, which is known to be directly related to cross-coupled forces that contribute to rotor instability, the CFD predicts also the highest value; however a much larger discrepancy can be observed for this term (73% higher than value predicted by finite difference method and 79% higher than bulk flow code prediction). Similar large differences in predictions one can see in the estimates for damping and direct mass coefficients, where highest values are predicted by the bulk flow method. These large variations in damping and mass coefficients, and most importantly the large difference in the cross-coupled stiffness predictions, may be attributed to the large difference in seal geometry (i.e. the large aspect ratio AR>1.0 of this seal model vs. the short seal configuration the bulk flow code is usually calibrated for, using an empirical friction factor).

scholarly journals Mesoscale flows in large aspect ratio simulations of turbulent compressible convection

2005 ◽  
Vol 430 (3) ◽  
pp. L57-L60 ◽  
Author(s):  
F. Rincon ◽  
F. Lignières ◽  
M. Rieutord
Keyword(s):  
Aspect Ratio ◽  
Large Aspect Ratio
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