Livermore Software Technology Corporation

Todd Patrick Slavik

Systems and methods of simulating an explosion in time-marching finite element analysis are disclosed in the present invention. A method is configured for increasing user (e.g., engineer or scientist) productivity by reducing computation time of simulating fluid-structure interaction due to an explosion. The method comprises a creation of a finite element analysis model that includes structure, surrounding fluid, a blast source of the explosion and a single layer of ambient elements each having a segment representing a boundary of the fluid facing the blast source. Each ambient element is associated with a particular finite element representing the fluid at the boundary. The ambient elements are configured to be situated between the blast source and the structure such that the simulation can be carried on a set of boundary conditions specified thereon. The boundary conditions comprise a set of nodal velocities that are determined from the empirical formula (e.g., Friedlander equation).

Explosion simulation in finite element analysis

A system, method and software product for prescribing rigid body in finite element analysis is described. According to one aspect, user defines a rigid body orientation time history based on a variety of schemes including, but not limited to, direction cosine, orientation angles, Euler parameters, Rodriguez parameters, and Caley-Klein parameters. The unique combination in one of the schemes is converted to direction cosine time histories first. The direction cosine matrix can then be interpolated from either the defined or the converted direction cosine time history at each solution cycle. The time derivative of the direction cosine matrix and the resulting angular velocity matrix are calculated. The solution for the equation of motions is obtained using calculated angular velocity for each solution cycle until the simulation ends. According to another aspect, the present invention interpolates user specified rigid body orientations time history in several schemes including, piecewise linear, cubic spline.

Method and system for prescribing rigid body orientations in finite element analysis

System and method for enabling direct determination of rigid body motion using data collected from a plurality of independent accelerometers are disclosed. A mechanical object that can be theoretically emulated as a rigid body is instrumented with a plurality of accelerometers at different locations. Direct determination of rigid body motion at a location of interest includes following operations at each solution time step: transform local acceleration to global, integrate accelerations to obtain velocities, calculate direction cosine matrix using the angular velocity matrix, form a first set of redundant equations, obtain the angular velocity by solving the first set of equations using either least squares fitting or a selective Gaussian elimination scheme, form a second set of redundant equations and obtain the translational velocity by solving the second set of equations using either the averaged value or a pre-defined rule such as minimizing the contribution from the rotational term.

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Livermore, CA, United States of America

Todd Patrick Slavik