The response of composite sandwich plates to low-velocity impact is predicted by a displacement-b... more The response of composite sandwich plates to low-velocity impact is predicted by a displacement-based, plate bending, finite element algorithm. Fifth order Hermitian interpolation allows three-dimensional equilibrium integration for transverse stress calculations to be ...
Journal of Reinforced Plastics and Composites, 2007
The impact response and the impact-induced damage in a curved composite laminate subjected to tra... more The impact response and the impact-induced damage in a curved composite laminate subjected to transverse impact by a metallic impactor are studied using a three-dimensional finite element method. Several example problems of a graphite/epoxy cylindrical shell are considered and effects of impactor parameter (impactor velocity and impactor mass) and laminate characteristics (shell curvature and fiber orientation of plies) are established. Impact-induced damages (matrix cracking and delamination) are predicted using appropriate three-dimensional stress-based failure criteria. In order to take account of degradation of material due to damage during the impact, the stiffness matrix of the failed region of the laminate is reduced as the solution progresses.
... improve mesh distortion sensitivity. Recently, Rajendran and co-workers [5], [6], [7], [8] an... more ... improve mesh distortion sensitivity. Recently, Rajendran and co-workers [5], [6], [7], [8] and [9] introduced what they called the unsymmetric formulation. Here, two separate sets of shape functions, viz. the so-called isoparametric ...
The use of metric trial functions to represent the real stress field in what is called the unsymm... more The use of metric trial functions to represent the real stress field in what is called the unsymmetric finite element formulation is an effective way to improve predictions from distorted finite elements. This approach works surprisingly well because the use of parametric functions for the test functions satisfies the continuity conditions while the use of metric (Cartesian) shape functions for the trial functions attempts to ensure that the stress representation during finite element computation can retrieve in a best-fit manner, the actual variation of stress in the metric space. However, the issue of how to handle situations where there is locking along with mesh distortion has never been addressed. In this paper, we show that the use of a consistent definition of the constrained strain field in the metric space can ensure a lock-free solution even when there is mesh distortion. The three-noded Timoshenko beam element is used to illustrate the principles. Some significant conclusions are drawn regarding the optimal strategy for finite element modelling where distortion effects and field-consistency requirements have to be reconciled simultaneously.
The response of composite sandwich plates to low-velocity impact is predicted by a displacement-b... more The response of composite sandwich plates to low-velocity impact is predicted by a displacement-based, plate bending, finite element algorithm. Fifth order Hermitian interpolation allows three-dimensional equilibrium integration for transverse stress calculations to be ...
Journal of Reinforced Plastics and Composites, 2007
The impact response and the impact-induced damage in a curved composite laminate subjected to tra... more The impact response and the impact-induced damage in a curved composite laminate subjected to transverse impact by a metallic impactor are studied using a three-dimensional finite element method. Several example problems of a graphite/epoxy cylindrical shell are considered and effects of impactor parameter (impactor velocity and impactor mass) and laminate characteristics (shell curvature and fiber orientation of plies) are established. Impact-induced damages (matrix cracking and delamination) are predicted using appropriate three-dimensional stress-based failure criteria. In order to take account of degradation of material due to damage during the impact, the stiffness matrix of the failed region of the laminate is reduced as the solution progresses.
... improve mesh distortion sensitivity. Recently, Rajendran and co-workers [5], [6], [7], [8] an... more ... improve mesh distortion sensitivity. Recently, Rajendran and co-workers [5], [6], [7], [8] and [9] introduced what they called the unsymmetric formulation. Here, two separate sets of shape functions, viz. the so-called isoparametric ...
The use of metric trial functions to represent the real stress field in what is called the unsymm... more The use of metric trial functions to represent the real stress field in what is called the unsymmetric finite element formulation is an effective way to improve predictions from distorted finite elements. This approach works surprisingly well because the use of parametric functions for the test functions satisfies the continuity conditions while the use of metric (Cartesian) shape functions for the trial functions attempts to ensure that the stress representation during finite element computation can retrieve in a best-fit manner, the actual variation of stress in the metric space. However, the issue of how to handle situations where there is locking along with mesh distortion has never been addressed. In this paper, we show that the use of a consistent definition of the constrained strain field in the metric space can ensure a lock-free solution even when there is mesh distortion. The three-noded Timoshenko beam element is used to illustrate the principles. Some significant conclusions are drawn regarding the optimal strategy for finite element modelling where distortion effects and field-consistency requirements have to be reconciled simultaneously.
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Papers by Surendra Kumar