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.

Convergence of Mixed Finite-Element Approximations of a Class of Linear Boundary-Value Problems

Abstract: : Convergence and general properties of mixed finite element models of a general class of boundary-value problems of the type Au + ku + f = 0, u belongs to R, and B(u - g) = 0 on boundary (R sup 1), B*(Tu - s) = 0 on boundary (R sup 2) are considered here where u = u(x) is a function defined on a bounded region R of (E sup n), boundary R is the smooth boundary of R, x is a point in R, A is a linear factorable operator, k is a positive constant, and B and B* are operators describing mixed boundary conditions on boundary R. (Author)

Analysis of thick rectangular plates laminated of bimodulus composite materials

Abstract: : A mixed finite-element analysis is presented for static behavior of rectangular plates having finite transverse shear moduli and different elastic properties depending upon whether or not the fiber-direction strains are tensile or compressive. As a benchmark to evaluate the validity and accuracy of the finite-element analysis, a closed-form solution is presented for the particular case of an unsymmetric-cross-ply plate having freely supported edges and subjected to a sinusoidally distributed normal-pressure loading. (Author)

A Unified Formulation of Micromechanics Models of Fiber-Reinforced Composites

Abstract: In a micromechanics constitutive model the overall instantaneous properties of fibrous composites are defined by relations between overall stress and strain averages Such averaging techniques are also known as ‘homogenization’ The models may account for fiber, matrix and fiber-matrix interface properties and their interactions (see [1–5]) Various micromechanics approaches are used to calculate overall stress and strain fields using different representative micro-geometries (ie unit cells); see, for example, the self-consistent method of Hill [1], the variational formulation of Hashin [2], the vanishing fiber diameter model of Dvorak and Bahei-El-Din [3], periodic rectangular array of Aboudi [4], and the periodic hexagonal array (PHA) model of Teply and Dvorak [5] Although various models use different representative geometries of the unit cell and different approximations of the displacements and/or stresses to obtain the overall properties, they all share certain common basis The present paper has the objectives of finding the common basis so that the models can be related to each other

Continuous Sensitivity Analysis of Fluid-Structure Interaction Problems Using Least-Squares Finite Elements

Abstract: A least-squares continuous sensitivity analysis method is developed for fluid-structure interaction problems to support computationally efficient analysis and optimization of aeroelastic design problems. The continuous sensitivity system equations and sensitivity boundary conditions are derived and the problem is posed in first-order form. A leastsquares finite element solution of the coupled fluid-structure physics is then used to determine the sensitivity boundary conditions. The least-squares finite element method permits a simultaneous solution of the fluid-structure system and the mesh deformation problem within a single numerical framework. A least-squares finite element solution of the linear continuous sensitivity equations is then used to produce computationally efficient design parameter gradient calculations without needing to derive and code the problematic mesh sensitivities. An example nonlinear fluid-structure interaction problem is solved. Continuous sensitivity results for both the local and total material derivatives are presented and compared to gradients obtained by finite-difference methods.

On Delamination in Plates: A Unilateral Contact Approach

Abstract: The unilateral contact of plates on elastic foundation is considered. Both vanishing and finite tensile contact (or adhesion) strength between the plate and the foundation are considered. The approach is used to study delamination due totransverse loads in two layer plates. The relationship with the brittle fracture mechanics approach is also discussed. Numerical results are presented to validate the present approach.

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.