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| ==== Time frame ==== | Ideally, this behavior could be defined either along the ligament line of action or locally within a given element. While the local mesh coordinate frames could be used to approximate a ligament's line of action (if hexahedral elements are used), it would also be convenient to incorporate ligament wrapping, without needing to remesh to reflect this behavior (if possible). |
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| ==== Estimated Completion ==== April, 2014 |
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| The ability to define node, element, or surface sets could add convenience to both the pre- as well as post-processing of FEBio analyses. Often, models are made up of multiple components while the output(s) of interest may be limited to a specific component, or an even smaller region of interest. In terms of pre-processing, element sets could be used to assign material properties or request specific types of output for a given region. For post-processing, instead of searching across all elements (or nodes) in a model, and cross-referencing for specific element numbers, one could simply extract the region of interest by name. | |
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| ==== Estimated Completion ==== September, 2014 |
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| Joint level simulations, especially in the knee, often rely on application and/or description of kinetic-kinematic response in commonly accepted joint coordinate systems <REF Grood, Fujie, etc.>. This requires adoption of moving local coordinate systems that are assigned to a given body, e.g. the femur and tibia, to track overall rigid body motions as well as a means to "connect" two coordinate frames. In the case of Abaqus, we often use what's called "connector" elements to set these frames up. Their convenience is evident during both model setup, during prescription of relevant boundary conditions, as well as post-processing of the model results, where the connector outputs can be directly translated into clinically accepted descriptions of motion and/or loading. To accomplish this feature request, we anticipate setting up a test problem with a known input-output relationship. This test problem could act as a surrogate for joint level simulations. ==== Estimated Completion ==== Late 2014 |
Page to describe all feature requests and associated specification for FEBio
Priority List
in situ strain
- Element, node, and surface set definitions
- Connector elements for joint coordinate system
- Penetration based contact
- Spring elements with wrapping
- Shell elements for cartilage
Constitutive
''in situ'' strain
Description
The zero force reference lengths (or "slack length") of the ligamentous knee structures have been shown to be important contributors to overall joint mechanics. As they are difficult to measure, ligament slack lengths are a commonly targeted parameter during optimization of specimen-specific joint level kinetic-kinematic response. Regardless of the level of refinement in the modeling approach, whether continuum or spring based, a parameter based representation facilitates these iterative studies.
Ideally, this behavior could be defined either along the ligament line of action or locally within a given element. While the local mesh coordinate frames could be used to approximate a ligament's line of action (if hexahedral elements are used), it would also be convenient to incorporate ligament wrapping, without needing to remesh to reflect this behavior (if possible).
Estimated Completion
April, 2014
Pre- and Post-Processing
Element, node, and surface set definitions
Description
The ability to define node, element, or surface sets could add convenience to both the pre- as well as post-processing of FEBio analyses. Often, models are made up of multiple components while the output(s) of interest may be limited to a specific component, or an even smaller region of interest. In terms of pre-processing, element sets could be used to assign material properties or request specific types of output for a given region. For post-processing, instead of searching across all elements (or nodes) in a model, and cross-referencing for specific element numbers, one could simply extract the region of interest by name.
Estimated Completion
September, 2014
General Feature
Connector elements for joint coordinate system
Joint level simulations, especially in the knee, often rely on application and/or description of kinetic-kinematic response in commonly accepted joint coordinate systems <REF Grood, Fujie, etc.>. This requires adoption of moving local coordinate systems that are assigned to a given body, e.g. the femur and tibia, to track overall rigid body motions as well as a means to "connect" two coordinate frames. In the case of Abaqus, we often use what's called "connector" elements to set these frames up. Their convenience is evident during both model setup, during prescription of relevant boundary conditions, as well as post-processing of the model results, where the connector outputs can be directly translated into clinically accepted descriptions of motion and/or loading.
To accomplish this feature request, we anticipate setting up a test problem with a known input-output relationship. This test problem could act as a surrogate for joint level simulations.
Estimated Completion
Late 2014
Surrogate Modeling
Penetration based contact
Spring elements with wrapping
Shell elements for cartilage