Chapter 6: Mechanical Properties Flashcards
what is the formula σ = 𝐹/𝐴𝑜
σ = tensile stress,
Ft = force of tension
Ao = original cross-sectional area before loading
what is the formula τ = Fs/Ao
τ = shear stress
Ft = force of shear
Ao = original cross-sectional area before loading
what is the formula ε = δ/Lo
ε = tensile strian
δ = change in length
Lo = original length
what is the formula εL = -δL/wo
εL = lateral strain
δL = lateral change
wo = original with
what is the formula γ = Δx/y = tan θ
γ = Shear strain
Δx = change in direction
y = other direction
tan θ
what are the units for stress?
N/m^2
What is elastic deformation?
reversible strain
what is the formula σ = E ε?
σ = tensile stress
E = Modulus of Elasticity (different for every substance)
Do stronger or weaker bonds lead to a larger Young’s modulus?
Stronger
Does elastic modulus vary with direction?
yes
what is the formula 𝜈 =−𝜀𝑋/𝜀𝑍 =−𝜀𝑌/𝜀𝑍
ν = Poisson’s Ratio
𝜀𝑋 = strain perpendicular to stress
𝜀Z = strain parallel to stress
what is the formula τ = G γ
τ = Shear stress
G = shear modulus
γ = shear strain
when does noticeable plastic deformation occur?
when εp = 0.002
what is uts?
the maximum stress on stress-strain curve
list the relative strength of the common material groups
Metals > Ceramics > polymers> Composite/fibers
what is the formula %EL = (Lf - Lo) / Lo x 100
%EL = percent elongation
Lf = Length final
Lo = Length initial
What is the formula %RA = Ao - Af / Ao
RA% = percent reduction in area
Ao = Area initial
Af = Area final
what is toughness?
The ability of a material to absorb energy and plastically deform before fracturing.
What is resilience?
The ability of a material to store energy
what is the formula σT = F/Ai?
σT = True Stress
F = Force
Ai = Area instantaneous
what is the formula σT = σ(1+ε)?
σT = True Stress
σ = engineering stress
ε = engineering strain
what is the formula εT = ln(1+ε)?
εT = True strain
ε = engineering strain
what is the formula εT =ln( ℓi / ℓo)
εT = True strain
ℓi = instantaneous length
ℓo = original length
what is the formula σT = k(εT)^n?
σT = True Stress
k and n (stain hardening exponent) are constants
εT = true strain
