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J. N. Reddy

Bio: J. N. Reddy is an academic researcher from Texas A&M University. The author has contributed to research in topics: Finite element method & Plate theory. The author has an hindex of 106, co-authored 926 publications receiving 66940 citations. Previous affiliations of J. N. Reddy include Instituto Superior Técnico & National University of Singapore.


Papers
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TL;DR: In this paper, the conservation and balance laws for fluent continua are derived by incorporating both internal rotation rates arising from the velocity gradient tensor and the rotation rates of the Cosserats.
Abstract: This paper presents a non-classical continuum theory for fluent continua in which the conservation and balance laws are derived by incorporating both internal rotation rates arising from the velocity gradient tensor and the rotation rates of the Cosserats. Specifically, in this non-classical continuum theory we have (1) the usual velocities ( $$\bar{ \pmb {\varvec{v }}}$$ ), (2) the three internal rotation rates ( $${}_i^t\bar{ \pmb {\varvec{\Theta }}}$$ ) about the axes of a fixed triad whose axes are parallel to the x-frame arising from the velocity gradient tensor $$(\bar{ \pmb {\varvec{L }}})$$ that are completely defined by the antisymmetric part of the velocity gradient tensor, and (3) three additional rotation rates ( $${}_e^t\bar{ \pmb {\varvec{\Theta }}}$$ ) about the axes of the same triad located at each material point as additional three unknown degrees of freedom, referred to as Cosserat rotation rates. This gives rise to $$\bar{ \pmb {\varvec{v }}}$$ and $${}_e^t\bar{ \pmb {\varvec{\Theta }}}$$ as six degrees of freedom at a material point. The internal rotation rates $${}_i^t\bar{ \pmb {\varvec{\Theta }}}$$ , often neglected in classical fluid mechanics, exist in all deforming fluent continua as these are due to velocity gradient tensor. When the internal rotation rates $${}_i^t\bar{ \pmb {\varvec{\Theta }}}$$ are resisted by deforming fluent continua, conjugate moment tensor arises that together with $${}_i^t\bar{ \pmb {\varvec{\Theta }}}$$ may result in energy storage and/or dissipation, which must be considered in the conservation and balance laws. The Cosserat rotation rations $${}_e^t\bar{ \pmb {\varvec{\Theta }}}$$ also result in conjugate moment tensor that together with $${}_e^t\bar{ \pmb {\varvec{\Theta }}}$$ may also result in energy storage and/or dissipation. The main focus of this paper is a consistent derivation of conservation and balance laws for fluent continua that incorporate the aforementioned physics and associated constitutive theories for thermofluids using the conditions resulting from the entropy inequality. The material coefficients derived in the constitutive theories are clearly defined and discussed.

15 citations

Journal ArticleDOI
TL;DR: In this paper, a micropolar cohesive damage model for composites is proposed, which incorporates micro-rotation degrees of freedom within a continuum model to account for the micro-structural effects during delamination.

15 citations

Journal ArticleDOI
TL;DR: In this paper, the linear transient response of composite plates using radial basis functions and collocation method was studied using the Kansa method and Radial Basis Function (RBF).
Abstract: This article presents a study of the linear transient response of composite plates using radial basis functions and collocation method. We use the Kansa method and radial basis functions in a pseud...

15 citations

Journal ArticleDOI
TL;DR: In this paper, the octet formalism for thin plate bending was further developed for the Kirchhoff anisotropic plate theory and the fundamental elastic plate matrix associated with the eigenrelation referring to the dual coordinate systems, N(0), was studied.
Abstract: This work presents further development of the octet formalism established by the authors for the classical Kirchhoff anisotropic plate theory. The structure of the fundamental elastic plate matrix is fully explored and the explicit expression is provided. The matrices N 2 and -N 3 are proved to be positive semi-definite. Thus, H and L are positive definite. Further studies are concerned with a rotated coordinate system. The transform relation between the eigenvectors in the original and the rotated coordinate system is given. The fundamental elastic plate matrix associated with the eigenrelation referring to the dual coordinate systems, N(0), is studied. The major properties that hold in the Stroh sextic formalism for generalized plane strain problems are also valid in the octet formalism for thin plate bending problems. In particular, we generalize a property in Stroh's formalism for any non-semisimple matrix N(0). We show a new property in the octet formalism. The non-semisimple cases of N(0) are discussed. Finally, we make it transparent that the mixed/hybrid formalism of others is precisely one of sixteen permuted forms of the octet formalism.

15 citations

Journal ArticleDOI
TL;DR: In this paper, rectangular finite elements based on a Reissner type variational statement for plate bending are applied to stability and free vibration of rectangular plates, which yield better accuracies for the critical loads and natural frequencies when compared to conventional finite elements.

15 citations


Cited by
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08 Dec 2001-BMJ
TL;DR: There is, I think, something ethereal about i —the square root of minus one, which seems an odd beast at that time—an intruder hovering on the edge of reality.
Abstract: There is, I think, something ethereal about i —the square root of minus one. I remember first hearing about it at school. It seemed an odd beast at that time—an intruder hovering on the edge of reality. Usually familiarity dulls this sense of the bizarre, but in the case of i it was the reverse: over the years the sense of its surreal nature intensified. It seemed that it was impossible to write mathematics that described the real world in …

33,785 citations

01 May 1993
TL;DR: Comparing the results to the fastest reported vectorized Cray Y-MP and C90 algorithm shows that the current generation of parallel machines is competitive with conventional vector supercomputers even for small problems.
Abstract: Three parallel algorithms for classical molecular dynamics are presented. The first assigns each processor a fixed subset of atoms; the second assigns each a fixed subset of inter-atomic forces to compute; the third assigns each a fixed spatial region. The algorithms are suitable for molecular dynamics models which can be difficult to parallelize efficiently—those with short-range forces where the neighbors of each atom change rapidly. They can be implemented on any distributed-memory parallel machine which allows for message-passing of data between independently executing processors. The algorithms are tested on a standard Lennard-Jones benchmark problem for system sizes ranging from 500 to 100,000,000 atoms on several parallel supercomputers--the nCUBE 2, Intel iPSC/860 and Paragon, and Cray T3D. Comparing the results to the fastest reported vectorized Cray Y-MP and C90 algorithm shows that the current generation of parallel machines is competitive with conventional vector supercomputers even for small problems. For large problems, the spatial algorithm achieves parallel efficiencies of 90% and a 1840-node Intel Paragon performs up to 165 faster than a single Cray C9O processor. Trade-offs between the three algorithms and guidelines for adapting them to more complex molecular dynamics simulations are also discussed.

29,323 citations

Journal ArticleDOI
TL;DR: In this article, a new finite element formulation for convection dominated flows is developed, based on the streamline upwind concept, which provides an accurate multidimensional generalization of optimal one-dimensional upwind schemes.

5,157 citations

Book
01 Jan 1989
TL;DR: This self-contained introduction to practical robot kinematics and dynamics includes a comprehensive treatment of robot control, providing background material on terminology and linear transformations and examples illustrating all aspects of the theory and problems.
Abstract: From the Publisher: This self-contained introduction to practical robot kinematics and dynamics includes a comprehensive treatment of robot control. Provides background material on terminology and linear transformations, followed by coverage of kinematics and inverse kinematics, dynamics, manipulator control, robust control, force control, use of feedback in nonlinear systems, and adaptive control. Each topic is supported by examples of specific applications. Derivations and proofs are included in many cases. Includes many worked examples, examples illustrating all aspects of the theory, and problems.

3,736 citations

Journal ArticleDOI
J. N. Reddy1
TL;DR: In this paper, a higher-order shear deformation theory of laminated composite plates is developed, which accounts for parabolic distribution of the transverse shear strains through the thickness of the plate.
Abstract: A higher-order shear deformation theory of laminated composite plates is developed. The theory contains the same dependent unknowns as in the first-order shear deformation theory of Whitney and Pagano (1970), but accounts for parabolic distribution of the transverse shear strains through the thickness of the plate. Exact closed-form solutions of symmetric cross-ply laminates are obtained and the results are compared with three-dimensional elasticity solutions and first-order shear deformation theory solutions. The present theory predicts the deflections and stresses more accurately when compared to the first-order theory.

3,504 citations