Material Properties Flashcards
Definition of a load?
Force that acts on a body
Def of stress?
Force per unit area (intensity of an internal force) - Pascals
Strain definition?
Change in length/ original length
What is elastic deformation?
REVERSIBLE changes in shape of a material due to a load
What is plastic deformation?
IRREVERSIBLE changes in shape of an object in response to a load
Def of toughness?
Amount of energy/ unit volume
= Area under the tree/strain curve
What is creep?
Time dependant deformation under a CONSTANT LOAD
What is load relaxation?
Decrease in applied stress under CONSTANT STRAIN
What is hysteresis?
Loading curve does not follow the unloading curve = energy dissapation
Found in viscoelastic materials
What is the elastic zone?
Part of the SSC where a material will return to its original shape
What is the Toe region
Found in tendons and ligaments - represents the crimped fibres uncrimping
What is the Yield point?
Change point between elastic and plastic deformation
What is the plastic zone?
Zone in which object will not return to its original shape for given amount of stress
What is the ultimate tensile strength?
Load to failure
Hookes law?
Material in the elastic zone - stress is directly proportional to strain
What is the Youngs modulus?
Measure of stiffness of materials in the elastic zone
Slope of the SSC
List the Young’s modulus of metals and biologics from 1-11
- Ceramic
- Alloy (Cobalt)
- Stainless steel
- Titanium
- Cortical bone
- Matrix polymers
- PMMA
- Polyethylene
- Canacellous
- Tendon/ligament
- Cartilage
CAST CMP PCT C
What is a brittle material?
Exhibits linar SS relationship until failure
ONLY ELASTIC DEFORMATION
LITTLE/NO PLASTIC DEFORMATION
Define a viscoelastic material?
SS relationship depends on duration and rate of applied load
Ligament and Bone
Isotropic materials possess?
Same mechanical properties in all directions
Anisotropic materials possess?
Different mechanical properties depending on direction of applied load
What is necking?
Localized reduction in cross sectional area in a specimen under a tensile load
Where is necking located on the SS curve?
Between ultimate tensile strength and fracture/rupture
