Tensile testing Structural Properties Load Deformation Stiffness Ultimate

Tensile testing • Structural Properties – – – Load Deformation Stiffness Ultimate load Ultimate elongation – These properties are dependent on crosssectional 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 N 2 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