Julian Flashcards
(32 cards)
What is the Lennard-Jones Potential Equation
V(r)=4ε[(σ/r)^12-(σ/r)^6 ] V is the potential bonding energy in eV ε the energy required to break the bond σ distance when bond energy is zero. r is the distance between atoms
Which parts of the lennard jones equation represent repulsive forces
(σ/r)^12
Which parts of the lennard jones equation represent attractive forces
(σ/r)^6
what is V(r) at r0 and what does it represent
ε, this is the well depth, where atoms like to sit.
what is an intensive property and give examples
a property that is INdependent of the mass of the object
such as density, bond energy and viscosity
What is an extensive property and give examples
a property that depends on an object’s mass such as weight and momentum.
for a BCC, what is the lattice parameter equation (a)
a=(4/√3) r
where r is the atomic radius
for a FCC, what is the lattice parameter equation (a)
a=(2√2) r
where r is the radius
what is used to represent: Plane, Collection of Planes, Direction, Collection of directions
Plane - (x y z)
Collection of planes - { }
Direction - [x y z]
Collection of directions - < >
What is the equation for lateral strain
εx = -l/d l = length d= diameter
what is the bond stiffness equation
S=Ea0
E = Young’s Mudulus
a0 = atomic spacing
what is the value of a for a central crack
1/2 x length
NOT = LENGTH
What are the (111) plane directions?
[1 -1 0] [1 0 -1] [0 1 -1]
What plane does slip occur on for FCC and HCP
FCC - {1 1 1}
HCP - Close Packed Plane
What is the value for critical resolved sheer stress along a slip direction
τc=σ cosφ cosλ
τc = tauc
What is the equation for cosφ in the critical resolved shear stress equation?
cosφ=((Slip)⋅(Load))/|Slip|*|Load|
What is the equation for cosλ in the critical resolved shear stress equation?
cosλ=([Direction]⋅(Load))/|Slip|*|Load|
when is the critical resolved stress maximum
when φ or λ is 45
When designing a pressure vessel, why do you want to use a ductile material?
So that it will leak before it breaks to prevent an explosion.
how do you lay out a Brinell hardness test results
(hardness)Hb diameter(mm)/force(kgf)/time(s)
What do D and d represent in the Brinell equation
D = ball diameter d = impression diameter
What is the rough strength for carbon fibre and diamond
10,000s MPa
What is the rough strength for Steels
1000s MPa
What is the rough strength for Bone and Cast iron
100s MPa
