MECH PROPERTIES OF MATERIALS Flashcards
stress is what equation?
force/cross sectional area
strain is what equation?
elongated length-original length/original length
material property related to the slope of the stress strain curve of a specific material
indicative of the stiffness of the material
allows for comparison of mechanical properties between materials
not used to describe the stiffness or strength of a device
modulus of elasticity
measure of degree of plastic deformation sustained at fracture
measured as % elongation or % area reduction
brittle materials/ductile materials
ductility
time dependent permanent deformation that occurs under stress
viscoelasticity
creep
delayed failure resulting from fluctuating stresses
-fatigue limit
crack initiation and propagation
fatigue
measure of a materials resistance to localized plastic deformation
indicates materials resistance to wear
hardness
what are the important considerations for Podiatric implants
modulus of elasticity similar to bone
sufficient fatigue strength
safety margin against brittle fracture
rapid fixation
high wear resistance
requires minimal bone resection
design maintains integrity of joint
what are the general properties of metals?
high modulus of elasicity
high mechanical strength
high yield point
subject to corrsion
general properties of polymers?
low modulus of elasticity
low mechanical strength
time dependent degradation
bearing material
susceptible to abrasion
general properties of ceramics?
high compressive strength
brittle
corrosion resistant
good biocompatibility
Dr Kawalecs Phd is based on this polymer?
17-28 GPa modulus of elasticity
flexural strength 275-550 MPa
hardness 150-250 DPH
pyrolytic carbon
similar in composition to mineral component of bone
excellent biocompatibility
wide variation in mech properties due to difference in manufacturing
used as porous or solid implants
biocoating
hydroxyapatite
bioglass, ceravital
consists of P, Na, Si and Ca components
direct bone bonding by Ca-P layer
strict adherence to composition
fillers for bone cement
glass ceramics
