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- RPI SCOREC - Technical Reports

constraint forces at key joint locations and the subsequent highly efficient determination of system state time derivatives The algorithm uses a novel hybrid direct and iterative solution scheme which allows a substantially higher degree of parallelization than is generally obtainable using the more conventional recursive O N procedures It is shown that at the coarsest level the parallelization obtainable easily exceeds that indicated by the topology of the system The

Original URL path: http://www.scorec.rpi.edu/reports/view_report.php?id=118 (2015-07-15)

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so that largely independent multibody subchain systems are formed These subchains in turn interact with one another through associated unknown constraint forces at the cut joints The underlying feature of this new hybrid low order algorithm is the increased parallelism through cutting the joints and explicit determination of associated constraint loads combined with sequential O n procedure In other words sequential O n procedures are performed to form and solve

Original URL path: http://www.scorec.rpi.edu/reports/view_report.php?id=119 (2015-07-15)

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implementation can currently accommodate the general spatial motion of chain systems but key issues for its extension to general tree and closed loop systems are discussed Explicit algebraic constraints are used to increase coarse grain parallelism and to study the influence of the dimension of system constraint load equations on the computational efficiency of the algorithm for real parallel implementation using the Message Passing Interface MPI The equation formulation parallelism

Original URL path: http://www.scorec.rpi.edu/reports/view_report.php?id=120 (2015-07-15)

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for efficiency and problem size considerations once the interpolation errors are reduced to acceptable levels the adaptive refinement is done only in regions affected by the vortical flows To do this a novel vortex core detection technique is used to capture vortex tubes The combination of interpolation error estimate and vortex core detection technique proved to be very effective in computing vortical flow field of rotor blades Example adaptive parallel

Original URL path: http://www.scorec.rpi.edu/reports/view_report.php?id=121 (2015-07-15)

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small enough in these directions Anisotropic meshes with small dimensions in the directions of strong gradients and large sizes along others can significantly reduce solution costs This research focuses on two classes of problems requiring generation of such anisotropic tetrahedral meshes Viscous flow problems exhibit boundary layers and free shear layers in which the solution gradients normal and tangential to the flow differ by orders of magnitude The Generalized Advancing Layers Method is presented here as a method of generating meshes suitable for capturing such flows The method is designed to reliably generate anisotropic elements in boundary layers for arbitrarily complex non manifold domains The boundary layer mesh is created by tetrahedronization of prismatic transition and blend polyhedra constructed on top of an initial surface mesh The method includes several new technical advances allowing it to mesh complex geometric domains that cannot be handled by other techniques and is currently being used for simulations in the automotive industry Anisotropic meshes are also desirable in problems with a strongly non linear solution across thin sections of the analysis domain A procedure has been developed to transform an isotropic mesh with insufficient refinement through thin sections into one with a user defined

Original URL path: http://www.scorec.rpi.edu/reports/view_report.php?id=122 (2015-07-15)

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plasticity based on additive split of rate of deformation and hyperelasticity is presented This approach is valid for finite elastic and plastic strains while rendering the choice and numerical integration of objective stress rates superfluous as the results are automatically objective For small elastic strains our method reduces to the classical hypoelastic corotational formulation provided that the Dienes objective stress rate is employed while in the absence of inelastic deformation

Original URL path: http://www.scorec.rpi.edu/reports/view_report.php?id=123 (2015-07-15)

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value problem describing damage phenomena in a brittle composite material The mathematical homogenization method based on double scale asymptotic expansion is generalized to account for damage effects in heterogeneous media A closed form expression relating local fields to the overall strain and damage is derived Nonlocal damage theory is developed by introducing the concept of nonlocal phase fields Stress strain free energy density damage release rate etc in a manner

Original URL path: http://www.scorec.rpi.edu/reports/view_report.php?id=124 (2015-07-15)

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Hierarchical assumed strain vorticity shell element with drilling degrees of freedom Year 1998 Abstract The formulation of stabilized assumed strain vorticity degenerated shell element with six degrees of freedom per mode is developed The penalty formulation is employed to alleviate rank deficiency caused by drilling degrees of freedom The assumed strain vorticity formulation for p type shell elements is utilized to circumvent membrane and shear locking at lower polynomials as

Original URL path: http://www.scorec.rpi.edu/reports/view_report.php?id=125 (2015-07-15)

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