Group 6 Uniaxial Compression Testing of Hydrogels

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Group 6 Uniaxial Compression Testing of
Hydrogels

• Minh Do WriterTyler Hinkle PresenterBhavesh
  Joshi LeaderShaun McLaughlin Researcher

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Objective

• To find an effective replacement for damaged
  articular cartilage due to degenerative joint
  disorders
• Human cartilage is a viscoelastic material with
  biphasic hydrogel composition
• We will use compression to test if hydrogels
  mimic native cartilage.

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TOOLS

• Modulus of Elasticity stiffness
• Poissons Ratio strain ratios (lateral/axial)
• Bulk Modulus volume change due to load
• Compressibility Bulk Modulus Reciprocal

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Method

• Find volume of two samples
• Compression test
• 10mm displacement at 10mm/s
• 10mm displacement at 1mm/s
• 5mm displacement at 10mm/s
• 5mm displacement at 1mm/s
• Compare volumes to test compressibility

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Pretest data
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Compressible?
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1mm/s Stress vs Strain
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10mm/s Stress vs Strain
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Data
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Conclusions

• Increase in Strain ? Increase in E
• Increase in Strain Rate ? Decrease in E
• Increase in Strain Rate ? Increase in v
• Hydrogels were incompressible
• Normal Elastic Modulus for Human Cartilage is
  0.9-1.5 Mpa
• Our highest E was 0.3Mpa
• Hydrogels are not an effect cartilage replacement

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Sources of Error

• Hydrogels were made with points that had to be
  cut off
• Surfaces were non-uniform
• Caliper may have indented hydrogels
• Hydrogels may not have uniform densities