FEA in Biomedical ApplicationsChallenges

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FEA in Biomedical Applications-Challenges State
of the Art
Dr. Robert Rizza Associate Professor Department
of Mechanical Engineering Milwaukee School of
Engineering Milwaukee, WI
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FEA-Introduction
FEA is a numerical method that employs a
discretization approach to model complex systems.
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Advantages of FEA

• Ability to guide a design process by quickly
  evaluating a design relative to the design
  constraints.

• Quickly provide results in areas where physical
  testing is impractical. This is very important
  in bioengineering where in vivo testing is
  impossible or difficult.

• Unlike physical testing where multiple tests need
  to be performed over a period of months, FEA can
  simulate a physical problem in a week or less.

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Advantages of FEA (Cont.)

• Model three-dimensional components, structures
  etc. including ones with complex geometry.

• This key feature has facilitated FEA becoming on
  of the main approaches used in supplying
  information for FDA certification.

• Model static and dynamic behavior of non-linear
  materials. This is really important for
  biological systems.

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Biomedical Applications
FEA has been used to model (to name a few)

• Hip, knee and joint implants,

• Stents,

• Cardiovascular blood flow,

• The human skeleton, spine and ligaments.

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Challenges-Geometry

• Biomedical applications more often than not have
  complicated non-planar geometry.

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Challenges-Geometry (Cont.)

• Advanced CAD tools such as sweeps, shell, blended
  sweeps may be used.

• Complex geometry may be imported by using CT,
  Micro-CT, or nano-CT, but the data will be
  non-parametric.

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Challenges-Geometry
Furthermore, there are often sub-regions within
the geometry that have different material
properties or structural characteristics.
They may be addressed with using layers and/or
assemblies.
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FEA-Materials

• State of the art FEA packages will support
  anisotropic materials.

• These packages will also support non-linear
  material behavior

• Some packages will allow coding of user defined
  elements and a failure criterion (MARC).

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Geometric Non-Linearity

• Biological tissues are non-linear and under
  applied loading their response is non-linear.

• Some tissues such as tendons and ligaments yield
  a response which is large deformation.

• Therefore, geometric non-linearity must be
  considered.

• Premier, state of the art FEA software packages
  support geometric non-linearity.

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Final Thoughts

• Considerable progress has been made in finite
  element modeling of biological and biomedical
  problems.

• Many if not most problems, exhibit non-linear
  material and/or geometric non-linearity, but
  modern FEA software are able to model such
  problems.

• FEA is an excellent tool for the analysis of
  biomedical engineering problems.