Showing papers by "J. N. Reddy published in 1996"

Mechanics of Laminated Composite Plates and Shells : Theory and Analysis, Second Edition

Abstract: The use of composite materials in engineering structures continues to increase dramatically, and there have been equally significant advances in modeling for general and composite materials and structures in particular. To reflect these developments, renowned author, educator, and researcher J.N. Reddy created an enhanced second edit

Variable Kinematic Modelling of Laminated Composite Plates

Abstract: A displacement-based variable kinematic global–local finite element model is developed using hierarchical, multiple assumed displacement fields at two different levels: (1) at the element level, and (2) at the mesh level. The displacement field hierarchy contains both a conventional plate expansion (2-D) and a full layerwise (3-D) expansion. Depending on the accuracy desired, the variable kinematic element can use various terms from the composite displacement field, thus creating a hierarchy of different elements having a wide range of kinematic complexity and representing a number of different mathematical models. The VKFE is then combined with the mesh superposition technique to further increase the computational efficiency and robustness of the computational algorithm. These models are used to analyse a number of laminated composite plate problems that contain localized subregions where significant 3-D stress fields exist (e.g. free-edge effects).

An efficient computational model for the stress analysis of smart plate structures

Abstract: A variable kinematic finite element (VKFE) model based on an hierarchical, multiple assumed displacement field is combined with the mesh superposition technique to determine local stress fields in surface-bonded piezoelectric actuated plates The displacement field hierarchy contains both a conventional 2D plate expansion and the full layerwise expansion of Reddy The combination of VKFE and the mesh superposition technique further increases the computational efficiency and robustness of the computational algorithm to determine local stress fields and global response accurately

Stress Distributions During Fiber Pull-Out

Abstract: Fiber pull-out resistance is an important mechanism of energy absorption during the failure of fiber-reinforced composite materials. This paper deals with axial stress distribution in the fiber during a pull-out. The frictional constraint between the fiber and the matrix is modeled with a perturbed Lagrangian approach and Coulomb's law of friction. Stress distribution has been determined for three cases, using the finite element method. The first case deals with the pull out of a fully embedded fiber. The second determines the stress distribution during fiber pull-out in the presence of a broken-embedded fiber. The third model attempts to solve the pull out of a coated fiber. The results for the first case compares favorably with those in existing literature. A local pinching effect, due to the matrix collapse behind the pulled fiber, is brought out clearly by this model. The second study indicates that the plug effect may not be significant in affecting the stress distribution. Lastly, the effects of coating stiffness and thickness are investigated.

Layerwise fundamental solutions and three-dimensional model for layered media

Abstract: A hybrid method is presented for the analysis of layers, plates, and multilayered systems consisting of isotropic and linear elastic materials. The problem is formulated for the general case of a multilayered system using a total potential energy formulation and employing the layerwise laminate theory of Reddy. The developed boundary integral equation model is two-dimensional, displacement based and assumes piecewise continuous distribution of the displacement components through the system's thickness. A one-dimensional finite element model is used for the analysis of the multilayered system through its thickness, and integral Fourier transforms are used to obtain the exact solution for the in-plane problem. Explicit expressions are obtained for the fundamental solution of a typical infinite layer (element), which can be applied in a two-dimensional boundary integral equation model to analyze layered structures. This model describes the three-dimensional displacement field at arbitrary points either in the domain of the layered medium or on its boundary. The proposed method provides a simple, efficient, and versatile model for a three-dimensional analysis of thick plates or multilayered systems.