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.

Modeling of actuators in laminated composite structures

Abstract: Two global/local finite element modeling procedures are integrated to permit the analysis of localized three-dimensional affects in laminated composite plates with bonded or embedded actuators. The first technique concerns the use of variable kinematic finite elements which are elements that contain several different types of assumed displacement fields. By choosing appropriate terms from the composite displacement field, an entire array of elements with different levels of kinematic complexity can be formed. The different elements can be conveniently connected together in a single domain for global/local analysis. The second technique concerns the use of finite element mesh superposition in which an independent overlay mesh is superimposed on a global mesh to provide localized refinement for regions of interest regardless of the original global mesh topology. Integration of these two ideas yields a very robust, economical analysis tool for global/local analysis of composite laminates.© (1993) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.

Finite element analysis of pseudoelastic behavior of shape memory alloys using a micromechanics based constitutive model

Abstract: In this paper, we describe the finite element formulation and implementation of a micromechanics based constitutive model of pseudoelasticity. The constitutive model describes the behavior of SMA`s through a constitutive element (CE) consisting of several grains. A volume average over the CE provides the macroscopic continuum response. The remarkable feature of this model is its strong similarity to the incremental stress strain relations of elastoplasticity and the internal variable approach. The martensitic transformations are described through the evolution of martensite volume fraction over the CE. The model accounts for behavior similar to isotropic and kinematic hardening of elastoplasticity. The finite element formulation involves the linearization of the weak form, computation of the tangent stiffness, and a stress update based on the operator split method. A numerical result is presented to illustrate the accuracy of the finite element formulation with respect to the theoretical model.

Evaluation of geometrically nonlinear and elastoplastic behavior of functionally graded plates under mechanical loading–unloading

Abstract: Geometrically nonlinear and elastoplastic behavior of a circular FGM (functionally graded material) plate under mechanical loading–unloading condition is investigated employing three-dimensional fi...

I and i

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 …

Fast parallel algorithms for short-range molecular dynamics

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.

Robot dynamics and control

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.

A Simple Higher-Order Theory for Laminated Composite Plates

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.