This is a example to simulate BULLET MODELING through FEA in LS dyna
10/10/2014
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ALE & FSI Example 1 Description: This example shows a beam falling into a box filled with fluid. The impact of the beam on the fluid surface and the plunging into the fluid is simulated by using the ALE-method (Arbitrary Lagrangian Eulerian) and fluid-stru fluid-structure-couplin cture-coupling g (FSI). The fluid and the air are modeled with the ALE-method, the beam is modeled with the classical Lagrangian approach. The coupling between the structure (Lagrangian) and the fluid (Eulerian) is done by a FSIalgorithm. The red part in the picutre is the fluid, the yellow part is the air, the turquoise part is the beam, which is loaded with an initial velocity.
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To define the material properties of the ALE-parts we need to cards: Boundary
null-material null-mater ial (*MAT_NULL) to define the density of the fluid and Contact Crash Fluid Hourglassing
an equation-of-state (*EOS_GRUNEISEN) (*EOS_GRUNEISEN) to define the pressure-volume relation in the fluid. Here: only the bulk modulus of the fluid is used. A linear relation between volume and pressure is assumed. See also »More... Since the air is assumed to have only little influence on the simulation it can be modeled as void (*INITIAL_PART_VOID). (*INITIAL_PART _VOID). The void part has to be given the same material data like the water, however the void part is treated like it would exist. This method can be used to simplify an calculation. If disered, the air could be modeled with real phyiscal material data.
To activate an ALE-analysis the DCT parameter in the keyword *CONTROL_ALE has to be set to 1 (Don't be confused by the other DCT options explained in the Keyword Users` Manual, they have all the same meaning). All the other parameters remain default. The coupling between the fluid and the structure is done by *CONSTRAINED_LAG *CONSTRAINED_LAGRANGE_IN_SOLI RANGE_IN_SOLID. D. The master-part are the elements of the eulerian elements (here: fluid), the slave-parts are always the elements of the lagrangian elements (here: beam). We use a penalty contact in compression direction only (CTYPE=4; DIREC=2). With NQUAD the number of control points to detect penetration between the contact partners are defined. Set the value valu e in the th e first analysis to 1 and in a second analysis to 3. Check the differents in the results. Due to lack of control points leakage will occur with NQUAD=1. The ALE elements are defined by using elementtype 12 in the *ELEMENT_SECTION card. Element type 12 works only if a void part is used in the analysis! If no void part is used, e.g. the air is modeled with real material data, elementtype 11 has to be used! Used Keywords:
*CONSTRAINED_LAGRANGE_IN_SOLID *CONTROL_ALE *EOS_GRUNEISEN *INITIAL_VOID_PART *MAT_NULL Used Units:
