Process for design optimization of honeycomb core sandwich panels for blast load mitigation
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Process for design optimization of honeycomb core sandwich panels for blast load mitigation S. K. Nayak · A. K. Singh · A. D. Belegundu · C. F. Yen
Received: 25 February 2012 / Revised: 14 August 2012 / Accepted: 15 August 2012 / Published online: 9 November 2012 © Springer-Verlag 2012
Abstract A general process for optimization of a sandwich panel to minimize the effects of air blast loading is presented here. The panel geometry consists of two metal face plates with a crushable honeycomb or other type of core. Optimization is necessary as there is strong coupling between the several variables and the physics, which makes parametric studies relatively ineffective. Virtual testing is used to develop a homogenized model for the stress–strain curve of the honeycomb core, which can be readily applied to other types of cellular core. The homogenized model has been validated by comparison to existing results as well as to results from detailed finite element (FE) models. A design of experiments (DOE) based response surface optimization method in combination with LS-DYNA is used to minimize dynamic deflection or acceleration of the back face plate. Constraints on total mass and on plastic strain in the face plates are imposed. The mechanism of lowering the backface deflection is by increasing front face plate thickness which effectively distributes the blast load to a larger area of the core and avoids local concave deformation of the front face plate. Further, core depth is increased
S. K. Nayak · A. K. Singh The Pennsylvania State University, University Park, PA, USA S. K. Nayak Brookhaven National Laboratory, Upton, NY, USA A. D. Belegundu (B) Mechanical and Nuclear Engineering, The Pennsylvania State University, University Park, PA, USA e-mail: [email protected] C. F. Yen Army Research Laboratory - WRMD, Aberdeen Proving Ground, MD, USA
which increases panel stiffness. For acceleration minimization, results again produce a stiffer front face plate, but accompanied by a sufficiently soft core. The mechanism of lowering the backface acceleration is by absorbing energy with low transmitted stress. A clear cut comparison between monolithic metal plates and sandwich plates, for the same loading and failure criteria, is presented here. Keywords Honeycomb · Homogenization · Blast · Optimization · Sandwich plates · Virtual testing
1 Introduction Sandwich panels, such as a honeycomb core with two metal facing plates, are finding increasing use over monolithic or solid plates in structural design to withstand intense short duration pressure loads. Applications include protection of land vehicles, ships or other structures. The cellular core has the ability to absorb the impact energy of the pressure pulse by undergoing large plastic deformation at almost constant nominal stress. This characteristic of the cellular core results in significant reduction in the backface acceleration and hence mitigates the damage causing potential of the blast impulse. Though metal sandwich panels have been used for a long t
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