Showing papers by "Defence Research and Development Laboratory published in 1985"
TL;DR: In this article, the Ritz finite element approach is used to study the nonlinear free vibrations of a beam considering shear deformation and rotary inertia effects, and the governing nonlinear equations are derived using Lagrange equations at the point of reversal of motion.
Abstract: The Ritz finite element approach is used to study the nonlinear free vibrations of a beam considering shear deformation and rotary inertia effects. The governing nonlinear equations are derived using Lagrange equations at the point of reversal of motion. The nonlinear strain-displacement relations include the curvature terms based on three-dimensional incremental deformations, as used in Trefftz theory. A simple and efficient beam element, with three independent degrees-of-freedom at each node, and with linear polynomial distributions within the element, is made use of. The reduced integration technique is adopted on the shear related matrix to eliminate spurious constraints occurring when exact integration is used for the same in the case of slender beams. The governing equations are solved using a direct iteration scheme. Numerical results are presented in the form of tables for hinged-hinged immovable beam. When the present results are compared with the available ones wherever possible, good agreement is in general, found.
10 citations
TL;DR: In this paper, the authors calculated the heat of decomposition of double base propellant from the knowledge of the composition and decomposition enthalpy of the ingredients and found that the condensed phase contribution is very marginal (one twentieth of the total calorimetric value).
Abstract: Heat of decomposition of the double base propellant has been calculated from the knowledge of the composition and decomposition enthalpy of the ingredients. This was compared with the experimentally observed value of the propellant decomposition which suggested that condensed phase contribution is very marginal (one twentieth of the total calorimetric value) in double base propellants unlike composite solid propellants where condensed phase contribution is as high as one third. The condensed-phase in double base propellant was attributed to the nitration of the 2n-diphenylamine stabilizer in the propellant matrix.