tensile testing
DESCRIPTION
Structural Properties Load Deformation Stiffness Ultimate load Ultimate elongation These properties are dependent on cross-sectional area and length of specimen. Mechanical Properties Strain energy density Modulus Ultimate strain - PowerPoint PPT PresentationTRANSCRIPT
Tensile testing
• Structural Properties– Load – Deformation– Stiffness– Ultimate load– Ultimate elongation
– These properties are dependent on cross-sectional area and length of specimen
• Mechanical Properties– Strain energy density– Modulus– Ultimate strain
– These properties are independent of CSA and length (i.e. same no matter what geometry is tested
Influences on testing
• Gripping (freeze clamps)
• Strain Rate
• Age
• Temperature
• Hydration
• Immobilization
Freeze clamps
• Also called cyrojaws.
• Use liquid N2 to freeze
• Must maintain freeze line
VDA
• Video extensometer• Local strains
Influences on testing
• Gripping (freeze clamps)
• Strain Rate
• Age
• Temperature
• Hydration
• Immobilization
Strain rates
• Avulsion versus mid-substance-– Some theorize that these effects are due to
strain rate, but REALLY depends on Age.
Influences on testing
• Gripping (freeze clamps)
• Strain Rate
• Age
• Temperature
• Hydration
• Immobilization
Mature versus immature, but then look at mature versus OLD
Age
• Puberty-adult see an increase in ult. Load
• Open epiphysis-avulsion
• Closed epiphysis (skeletally mature)-midsubstance
• Old-usually avulsion
• Stiffness decreases with age
• Ultimate load decreases with age– -see plot
Influences on testing
• Gripping (freeze clamps)
• Strain Rate
• Age
• Temperature
• Hydration
• Immobilization
Temperature
• Increase temp-decrease stiffness
• Race horses
• Tennis shoes
Influences on testing
• Gripping (freeze clamps)
• Strain Rate
• Age
• Temperature
• Hydration
• Immobilization
Waterbath
Influences on testing
• Gripping (freeze clamps)
• Strain Rate
• Age
• Temperature
• Hydration
• Immobilization
• How do we properly store a specimen for transplantation?– Freezing effects??– Irradiation?? Disease transmission
• Pre-tension on graft
Influences on testing
• Gripping (freeze clamps)
• Strain Rate
• Age
• Temperature
• Hydration
• Immobilization
• Exercise