Parallel algorithms for three-dimensional parabolic and pseudoparabolic problems with different boundary conditions

2014 ◽  
Vol 19 (3) ◽  
pp. 382-395 ◽  
Author(s):  
Raimondas Čiegis ◽  
◽  
Olga Suboč ◽  
Andrej Bugajev
Author(s):  
Mosfequr Rahman ◽  
F. N. U. Aktaruzzaman ◽  
Saheem Absar ◽  
Aniruddha Mitra ◽  
Awlad Hossain

Depending on the type of matrix materials, composites can be broadly divided into three different major classifications: Organic-matrix composites (OMC), metal-matrix composites (MMC), and ceramic-matrix composites (CMC). OMC can be further sub-classified into polymer-matrix composites (PMC) and carbon-matrix composites or carbon-carbon composites. In this paper the main objective is to focus on polyurethane based PMC composites. Polyurethane is one of the widely used polymer matrix materials. It has diversified applications, easily available and cheap. In this computational study a composite shaft with a core made of matrix material completely wrapped around by a woven fiber cloth with a very strong bonding between core and fibers is considered. Three different types of woven fibers: fiber glass, Kevlar 49, and carbon fibers, are considered. A woven fabric is the interlocking or weaving of two unidirectional fibers. This configuration is often used to produce curve surfaces because of the ease with which it could be placed on and conform to curved surfaces. Authors had fabricated these three composites in their in-house laboratory. They had also experimentally measured the mechanical properties of these composites using 3-point bending test which already been published. In this current study finite element analyses has been performed for the modeling of the static response of these three different polyurethane based composite shafts as fiber glass reinforced polyurethane epoxy, carbon fiber reinforced polyurethane epoxy, and Kevlar fibers reinforced polyurethane epoxy for three different boundary conditions. These three boundary conditions are simply supported, cantilever, both end fixed types with bending loads applied at the middle for simply supported case and distributed load along the length of the shaft for the last two types of boundary conditions. A three dimensional model of the composite beam has been implemented in this study using SolidWorks. A finite element commercial software ANSYS is used to investigate the stress response and deformation behavior of the model geometry for these three polyurethane based composite shafts for these three boundary conditions. A twenty node three dimensional element has been implemented for the finite element formulation of the modeled geometry such that it is applicable for the analysis of a layered composite structure, while providing support for linear, large rotation, and large strain nonlinear loading conditions. Convergence has also been ensured for various mash configurations in this work.


2019 ◽  
Vol 25 (19-20) ◽  
pp. 2567-2579 ◽  
Author(s):  
Siamak Mohajel Sadeghi ◽  
Akbar Alibeigloo

In this research based on theory of elasticity, free vibration behavior of a viscoelastic cylindrical shell with different boundary conditions is studied. A constitutive equation for viscoelastic material is assumed to obey the Boltzmann model and Poisson's ratio is held to be constant. Moreover, the Prony series is used to model time dependent modulus of elasticity. Governing equations of motions for simply-supported edges conditions are solved analytically using the state-space technique along the radial coordinate and the Fourier series method along the axial and circumferential directions. In the case of other edges condition a semi-analytical solution is employed by using the differential quadrature method instead of Fourier series solutions. It is worthy to note before solving the problem, that the Laplace transform is employed to convert governing differential equations from the time-domain into the Laplace domain. Then, validation of the present formulation is performed by comparing the numerical results with those published in the literature. Finally, effect of viscoelastic properties, boundary conditions, the thickness-to-radius ratio and length-to-radius ratio on the frequency behavior are studied.


Author(s):  
Vahid Tajeddini ◽  
Abdolreza Ohadi ◽  
Mojtaba Sadighi

This paper describes a study of three-dimensional free vibration analysis of thick circular and annular functionally graded (FG) plates resting on Pasternak foundation. The formulation is based on the linear, small strain and exact elasticity theory. Plates with different boundary conditions are considered and the material properties of the FG plate are assumed to vary continuously through the thickness according to power law. The kinematic and the potential energy of the plate-foundation system are formulated and the polynomial-Ritz method is used to solve the eigenvalue problem. Convergence and comparison studies are done to demonstrate the correctness and accuracy of the present method. With respect to geometric parameters, elastic coefficients of foundation and different boundary conditions some new results are reported which maybe used as a benchmark solution for future researches.


Author(s):  
Y. Wang ◽  
B. Q. Zhang

The SIMPLE (for Semi-Implicit Method for Pressure-Linked Equations) is successfully used in predicting three-dimensional flows in a double-recirculating combustor. Effects of different boundary conditions and turbulence models on the flow are examined. Compared with experiment results, the numerical predictions are satisfactory.


2003 ◽  
Vol 70 (1) ◽  
pp. 101-110 ◽  
Author(s):  
E. Pan

This paper derives, for the first time, the complete set of three-dimensional Green’s functions (displacements, stresses, and derivatives of displacements and stresses with respect to the source point), or the generalized Mindlin solutions, in an anisotropic half-space z>0 with general boundary conditions on the flat surface z=0. Applying the Mindlin’s superposition method, the half-space Green’s function is obtained as a sum of the generalized Kelvin solution (Green’s function in an anisotropic infinite space) and a Mindlin’s complementary solution. While the generalized Kelvin solution is in an explicit form, the Mindlin’s complementary part is expressed in terms of a simple line-integral over [0,π]. By introducing a new matrix K, which is a suitable combination of the eigenmatrices A and B, Green’s functions corresponding to different boundary conditions are concisely expressed in a unified form, including the existing traction-free and rigid boundaries as special cases. The corresponding generalized Boussinesq solutions are investigated in details. In particular, it is proved that under the general boundary conditions studied in this paper, the generalized Boussinesq solution is still well-defined. A physical explanation for this solution is also offered in terms of the equivalent concept of the Green’s functions due to a point force and an infinitesimal dislocation loop. Finally, a new numerical example for the Green’s functions in an orthotropic half-space with different boundary conditions is presented to illustrate the effect of different boundary conditions, as well as material anisotropy, on the half-space Green’s functions.


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