Modeling of Passive Constrained Layer Damping as Applied to a Gun Tube

Margaret Z Kiehl,C.P.T Wayne Jerzak

doi:10.1155/2001/817505

Abstract

We study the damping effects of a cantilever beam system consisting of a gun tube wrapped with a constrained viscoelastic polymer on terrain induced vibrations. A time domain solution to the forced motion of this system is developed using the GHM (Golla-Hughes-McTavish) method to incorporate the viscoelastic properties of the polymer. An impulse load is applied at the free end and the tip deflection of the cantilevered beam system is determined. The resulting GHM equations are then solved in MATLAB by transformation to the state-space domain.

Highlights

The production of long slender gun systems to meet increased exit velocity requirements of rounds has subsequently increased the effect of terrain induced vibrations
Given the need for a time domain solution, this study investigates the implementation of the GHM method in formulating a finite element method (FEM) model of a constrained layer gun tube
The configuration of the sandwiched rod considered is that of a cantilevered beam, a finite element formulation for the time domain solution to the forced motion of a cantilever beam system is developed

Summary

Introduction

The production of long slender gun systems to meet increased exit velocity requirements of rounds has subsequently increased the effect of terrain induced vibrations. The Ross-KerwinUngar (RKU) theory uses continuum mechanics to derive a sixth order PDE for a three layer beam which incorporates damping using a complex shear modulus. DiTaranto and Blasingame [4] and Mead and Markus [5] derived a sixth order PDE to model the transverse vibrations of a three layer beam system based on the RKU equations developed for flexural vibrations of layered plates In this approach damping of the viscoelastic layer is incorporated through the use of a complex shear modulus. Given the need for a time domain solution, this study investigates the implementation of the GHM method in formulating a FEM model of a constrained layer gun tube

Viscoelastic constrained layer model

Finite element modeling

GHM method implementation

Space-state formulation

Model results

Discussion and conclusion