Input Files
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Introduction
It is possible to have Solid elements break into SPH particles using ‘Sol2SPH’ method in OpenRadioss for simulation of high deformation of solid structures.
In this simple demonstration model, solid elements become SPH particles when a /FAIL/TENSSTRAIN criteria is reached
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Options and Keywords Used
Keyword documentation may be found in the reference guide available from
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/FAIL/TENSSTRAIN
/MAT/PLAS_JOHNS
/PROP/TYPE34 (SPH)
/INIVEL
Model Description
A rigidised steel ball of approx 1kg mass and 13.5mm diameter impacts a 5mm thick solid aluminium plate modelled with 3 solid elements through the thickness at a a velocity of 100000 mm/s
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The model has following characteristics.
Model Method
The property of the solid elements (Belonging to PART 1) refers to a 2nd SPH part (PART 5) into which eroded solid elements are ‘converted’ on erosion
/INIVEL/TRA is used to set ball with initial velocity 100000 mm/s
An /INTER/TYPE19 is defined between the ball and plate
Other remarks
The animation out uses both /ANIM and the H3D format via /H3D. /H3D gives better visualisation of the SPH particles as shown in the screenshots.
Results
As the solid elements are eroded they are replaced by SPH particles per the specification defined in the property ‘Ndir’ (in this case Ndir is set as 2, so 2x2x2 or 8 SPH particles per solid element)
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The Interface Force between the bird and the windshield is shown in Figure 7.
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Conclusion
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The mesh size and the number of particles of the bird model seem to be a good compromise between the accuracy of the problem and the CPU calculation time.
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For interface parameters, default values could be used. In TYPE7 contact interface, the interface stiffness Istf has to be set to zero.
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In the model a simplified hydro viscous law is used, which is well suited to describe (represent) the most important properties of the bird model.
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The smoothing length h should be set to a value larger than the inter-cell distance (to avoid excessive de-cohesion), but not too large to avoid excessive energy absorption by the particles of the bird.
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Conclusion
Sol2SPH may be used to represent a solid part experiencing high deformation, converting solid elements to an SPH representation when a failure criterion is met
See Also
OpenRadioss User Documentation
SOL2SPH overview in Help Documentation
/BCS (Starter)
/INTER/TYPE2 (Starter)/INTER/TYPE7 TYPE19 (Starter)
/RBODY (Starter)
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