CADFamily.com: ANSYS AUTODYN-ALE Solver

6/23/2011

Overview

?ALE (Arbitrary Lagrange Euler)

–Nodes on mesh boundaries and material interfaces move with the material (Lagrange)

–All other interior nodes may:

?Move with the material (Lagrange)

?Remain fixed in space (Euler)

?Move independently of the material as prescribed by an applied motion constraint

–Used to model solid continua, fluids and gases including fluid/structure interaction

ALE Applications

?The most efficient way of calculating the blast response of structures that do not deform significantly

?Mesh distortions cannot easily be avoided if gross deformation / failure occurs

ALE Computation Cycle

?The ALE computation cycle is identical to the Lagrange computation cycle except for an additional rezoning step for interior nodes

?Interior nodes are rezoned according to specified motion constraints and the solution is mapped onto the new grid

?By default, all nodes in an ALE Part are Lagrangian

–Motion constraints need to be explicitly applied to the grid

ALE Motion Constraints / Setting Options

?Motion Constraints

–Free (Lagrange)

–Fixed (Euler)

–Equipotential

–Equal spaced in x, y or z

–Equal spaced along I, J and/or K lines

–Geometrically spaced I, J and/or K

–Flow averaged (2D only)

–User defined

?Setting Options

–Cycle Frequency (default: every cycle)

–Iterations per cycle (default: 1)

–Relaxation Coefficient (default: 1-no relaxation)

Example: Explosion in a container

?Single ALE mesh

?Air has one atmosphere pressure

?TNT modeled as high pressure Air region

–No material interface between TNT and Air

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