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© 2008 ANSYS, Inc. All rights reserved. 1 ANSYS, Inc. Proprietary
2008 International ANSYS Conference
Bringing Finite Element and Musculoskeletal Modeling together using Any2Ans Interface
Can Ozcan, MSMEDirector of EngineeringOZEN ENGINEERING
© 2008 ANSYS, Inc. All rights reserved.2 ANSYS, Inc. Proprietary
What is AnyBody and ANSYS?
• AnyBody is a multibody dynamics system which includes muscle modelling capabilities
• AnyBody is developed by Aalborg University and AnyBody Tech., Denmark
• ANSYS is the industry leader computational simulation software company, providing Multiphysics codes
• ANSYS has offices worldwide and HQ in Pittsburgh
© 2008 ANSYS, Inc. All rights reserved.3 ANSYS, Inc. Proprietary
What is Any2Ans?
• Interface between AnyBody and ANSYS• Easy and convenient way of performing rigid-
flexible analysis using two best of the market software
• A nice integration to the Biomedical design process
© 2008 ANSYS, Inc. All rights reserved.4 ANSYS, Inc. Proprietary
Test Case – Spine Implant
• As a test case; a simple spine implant is studied
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Test Case – Spine Implant
• AnyBody project standing lift (lateral bending) from Aalborg repository is used
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Test Case – Spine Implant
• Movement of spine vertebrae are restrained by implant
• AnyBody uses a spinal rhythm model for determining individual vertebra movements by approximating the segments as a bending beam with variable stiffness
• To effect the immobilization from the implant, the stiffness coefficient between the two vertebra is set to zero
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Test Case – Spine Implant
• Any2Ans is used to extract the movement, force and geometry data from AnyBody study
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Test Case – Spine Implant
• Bone geometry is brought into ANSYS DesignModeler in IGES format
• Parametric redesign of implant in ANSYS DesignModeler • Design positions can be multiplied with different export
operations using Any2Ans• Rigid-Flexible dynamics
capability in Ansys Workbench is used
• Movements are established using body-to-ground connections
• Force is applied at L1-L2 joint location
• Displacements are specified at L3 segment
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Test Case – Spine Implant
• Stress, Safety Factor, Fatigue results are extracted
• Joint forces between L2-L3 vertebra is extracted
• Effect and performance of implant can be studied with realistic movement and force data
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Test Case – Spine Implant
• Joint force between L2 & L3 vertebra is decreased ~40%
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Test Case – Arm Curl
• Upper Arm (Humerus) and Fore Arm (Ulna) modeled holding a dumbell
• Build in Anybody for proof of concept with two bones and four muscles
• Joint movements are specified for motion
© 2008 ANSYS, Inc. All rights reserved.12 ANSYS, Inc. Proprietary
Test Case – Arm Curl
• Rigid Body representation built in Ansys Environment, and confirmed to match AnyBody results
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Test Case – Arm Curl
• Fore Arm is replaced with flexible body and corresponding forces & joint connections are carried on to new finite element mesh
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Test Case – Arm Curl
• Stress, strain, fatigue analysis and more detailed type of analysis becomes available with the integration
© 2008 ANSYS, Inc. All rights reserved.15 ANSYS, Inc. Proprietary
• AnyBody project is created / modified– Project file saved under *.main.any
• Any2Ans can read main project files and search through referenced AnyBody files (*.any) for bone data
• Main project file is modified automatically to extract bone movement data
• AnyBody is called in batch mode in the background to generate the movement / force data
How does Any2Ans work?
*.main.any
*.main.any
Modified *.main.any
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• Bone geometry in AnyBody is in *.anysurf and/or *.stl format and sent to ANY2ANS
• Movement and force data is written to .csv files by AnyBody and sent to ANY2ANS
• ANY2ANS writes out XML files and/or APDL input files of movement and force for Ansys Workbench environment
• ANY2ANS also writes out geometry files
How does Any2Ans work?
STL/AnySurf Files.csv Files
Repository IGES
STL
.XML Files / ANSYS Input Files
IGESANSYS
WORKBENCH
© 2008 ANSYS, Inc. All rights reserved.17 ANSYS, Inc. Proprietary
Any2Ans Capabilities
• Dynamically read and understand AnyBody projects by parsing using ANTLR
• Extract bone geometry & movements, muscular forces and joint reactions from AnyBody
• Quasi-static or dynamic movement for full motion• Selective export of bones based on analysis needs
© 2008 ANSYS, Inc. All rights reserved.18 ANSYS, Inc. Proprietary
Any2Ans Capabilities
• Export ANSYS APDL input files which rebuilds the Anybody model
• Export ANSYS format XML files of movement for the related STL file
• Converts AnyBody geometry format to STL• Display bones & movements for inspection at all time steps
before export
© 2008 ANSYS, Inc. All rights reserved.19 ANSYS, Inc. Proprietary
Next Steps
• Improve user interface to enhance quality & detail of the analysis performed– User inputs are welcome
• Add coupling capabilities as needed– Backward coupling to Anybody Software– Two-way coupling with Anybody Software
© 2008 ANSYS, Inc. All rights reserved.20 ANSYS, Inc. Proprietary
Contacts
• Ozen Engineering, Inc.Address: Internet:1210 E. Arques Ave.www.ozeninc.comSuite 207/208Sunnyvale, CA 94085
Phone Lines: Fax:408-732-4665 408-834-4557
Email:Information - [email protected] (Account Managers) – [email protected] – [email protected]