HHyyddrroossttaattiicc FFlluuiidd EElleemmeennttss aatt AANNSSYYSS 1133..00 SShheellddoonn IImmaaookkaa AANNSSYYSS TTeecchhnniiccaall SSuuppppoorrtt GGrroouupp ©© 22001100 AANNSSYYSS,, IInncc.. AAllll rriigghhttss rreesseerrvveedd.. 11 AANNSSYYSS,, IInncc.. PPrroopprriieettaarryy Overview • Two new hydrostatic fluid elements, HSFLD241 and 242, are introduced to model the effect of a trapped/enclosed gas or liquid –– AAss tthhee vvoolluummee oorr tteemmppeerraattuurree cchhaannggeess,, tthhee pressure exerted on the structure will change – Not possible to do add this type of relationship accurately via APDL or user subroutines © 2010 ANSYS, Inc. All rights reserved. 2 ANSYS, Inc. Proprietary Tire Inflation Example • Original mesh (Autodesk Inventor model): Tire modeled as homogenous hhyyppeerreellaassttiicc mmaatteerriiaall ffoorr simplicity. (Real tire modeling is much more complex [composite] but the focus here is on HSFLD242 element, not tire modeling.) © 2010 ANSYS, Inc. All rights reserved. 3 ANSYS, Inc. Proprietary Tire Inflation Example (cont’d) • Step 1 – Inflate tire (~1 bar): © 2010 ANSYS, Inc. All rights reserved. 4 ANSYS, Inc. Proprietary Tire Inflation Example (cont’d) • Step 2 – Push tire on rigid road: © 2010 ANSYS, Inc. All rights reserved. 5 ANSYS, Inc. Proprietary Tire Inflation Example (cont’d) • Plot of hydrostatic pressure in tire: Note from this graph that hydrostatic pprreessssuurree iiss nnoott ccoonnssttaanntt.. We could not accurately depict this by just applying constant internal pressure since change in volume influences change in pressure. © 2010 ANSYS, Inc. All rights reserved. 6 ANSYS, Inc. Proprietary Tire Inflation Example (cont’d) • Plot of total volume of air in tire: TToottaall vvss.. oorriiggiinnaall vvoolluummee in tire shown here. Note volume changes as tire is pushed against rigid floor/road. © 2010 ANSYS, Inc. All rights reserved. 7 ANSYS, Inc. Proprietary Motivation • Why introduce a new element? – Provide an element to model gas or liquid trapped in structure. Regular contained fluid eelleemmeenntt FFLLUUIIDD7799//8800 nnoott ssuuffffiicciieenntt ffoorr tthhiiss since it has linear stiffness relationship – This new hydrostatic fluid element does not require the inside fluid to be ‘meshed’ in a typical sense, so more efficient © 2010 ANSYS, Inc. All rights reserved. 8 ANSYS, Inc. Proprietary Note on Fluid Elements • This element should not be confused with other fluid elements in ANSYS: – Unlike contained fluid elements or acoustic eelleemmeennttss,, tthhiiss nneeww hhyyddrroossttaattiicc fflluuiidd eelleemmeenntt has no free surface effects. Not meant to model sloshing. – Not meant for damping effects or acoustic wave propagation. – This element is meant to model pressure loading by enclosed fluid/gas © 2010 ANSYS, Inc. All rights reserved. 9 ANSYS, Inc. Proprietary Element Topology • This is a triangular (2D) or pyramid (3D) element with one pressure node: Here, the grey quad elements ccaann bbee tthhoouugghhtt ooff as the solid structural elements. The dark blue triangular elements are the HSFLD241 elements. Pressure node at center. © 2010 ANSYS, Inc. All rights reserved. 10 ANSYS, Inc. Proprietary