Mechanical Properties Flashcards
What provides the cohesive forces necessary to produce the solid state.
Chemical Bonds
Chemical Bonds provide what?
the cohesive forces necessary to produce the solid state.
In solids, atomic and molecular movement is restricted to?
Thermal Vibration
If the temperature of a solid is raised, the amplitude of vibration increases and will eventually…
Disrupt the order of the structure.
to disrupt the order of the structure in a solid, we need to.
Increase vibration by raising the temperature.
There’s tendency for high melting point metals to have high
Young’s Moduli
Young’s Modulus is related to…
The strength of the chemical bond
What are the assumptions to Griffith’s theory of fracture
Hooke’s law is obeyed up to fracture point
All stressed solids store strain energy
All surfaces have an associated energy characteristic of the material
The process of the fracture can be considered a conversion of stored strain energy to surface energy
Materials which fail in a brittle manner often contain strong…
Chemical Bonds.
Ceramics are normally found to be extremely weak in their
Bulk Form
What are the defects that can attribute towards weakness in a bulk material (3)
Cracks
Holes
Steps
What do the Stress concentrators (Cracks, Holes, Steps) subject a components surface to
Stress connectors breakdown the chemical bonds at the crack tip and are subjected to stress will in excess of the average stress.
The degree of stress concentration is
proportional to the crack length
The magnitude of stress concentration was first calculated for an..
Elliptical hole by Inglis in 1913.
Stress concentration alone is insufficient to initiate fracture. for crack propagation to occur, two conditions must be fulfilled.
The stored energy released must exceed the energy needed to create the fracture stress.
There must be a molecular or atomic mechanism by which this energy transformation can take place.
What is more important than stress concentration to determine a materials response to stress.
The critical crack length.
What is the greatest safe guard against brittle fracture.
having a very high value of W
The process of slip in which adjacent layers of atoms move relative to each other is known as…
The mechanism of plastic deformation in metals.
The mechanism of plastic deformation in metals, is the process of what.
slip in which adjacent layers of atoms move relative to each other.
The shear stress necessary to cause slip may be calculated from a knowledge of
the strength of the metallic bond.
Metal crystals are perfect arrays of
Metallic Ions
Linear defects are commonly known as
Dislocations
Dislocations are commonly known as
Linear Defects
Plastic deformation in metallic crystals are produced by
The movement of dislocations.
The movement of dislocations in metallic crystals produce
Plastic deformation
