Direct Load

Question 1

Stress

Answer 1

internal resistance of the material to the applied load per unit area

Question 2

Direct stress=

Answer 2

applied load/cross-sectional area

Question 3

MPa=

Answer 3

N/mm^2

Question 4

psi=

Answer 4

lbs/in^2 (imperial)

Question 5

Direct normal tensile stress

Answer 5

σ (axial load/cross sectional area) pulling out

Question 6

Direct normal compressive stress

Answer 6

σ (axial load/cross sectional area) pushing in ->

Question 7

Direct shear stress

Answer 7

τ (shear force/shear area)

Question 8

Bearing stress

Answer 8

σb=load/contact area

contact area is the area of the interface between two flat surfaces, one supports the other

Question 9

Normal strain

Answer 9

ε or εa, aka axial strain, the deformation per unit length

Question 10

ε=

Answer 10

δ/l= (Δl)/l= (lf-li)/li

Question 11

Axial deformation

Answer 11

δ the change in length

δ=lf-li

Question 12

Lateral strain

Answer 12

εl=(Δh)/h =(hf-hi)/hi

Question 13

Poisson Ratio

Answer 13

v, the ratio of the lateral strain to the axial strain

v=-εl/εa

Question 14

shear strain

Answer 14

γ, the change in the right angle of the stress element, due to shearing load
measured in radians

Question 15

Hooke’s law: Uni-axial loading

Answer 15

E=σ/ε
E a material property representing stiffness
σ stress
ε strain

Question 16

Hooke’s law: shear loading

Answer 16

G=τ/γ
G is the shear modulus of elasticity/rigidity, represents material rigidity
τ shear stress
γ shear strain

Question 17

Axial Loading: design stres

Answer 17

σd, the maximum allowable level of stress the member can develop while performing safely under load

Question 18

Sy

Answer 18

yield strengths

Question 19

Sn

Answer 19

fatigue strength

Question 20

Axial Loading: Design factor N

Answer 20

accounts for uncertainty in factors such as load, material, environment, conditions, misuse

Question 21

Design Criteria based on normal stress: Static stress

Answer 21

σd=Sy/N
σ≤σd
σ=Faxial/Across-section

Question 22

Design Criteria based on normal stress: Dynamic stress

Answer 22

σd=Su/N

• Su is the ultimate strength of the material
• Sy is the yield strength of the material
• Su of the material is correlated to Sn

Question 23

Shear Loading: Design shear stress

Answer 23

τd is the maximum allowable level of shear stress the member can develop while performing safely under load

• τd=Sys/N for ductile material
• Sys is the shear yield strength of the material
• τ≤τd
• τ=Fshear/Ashear

Question 24

design bearing stress

Answer 24

σbd

Question 25

Max stress

Answer 25

σmax=Kt*σnom

• Kt stress concentration factor
• σnom=F/A

Question 26

Deformation due to axial load

Answer 26

δ =ε*L =(σ/E)L ={(F/A)/E}L

• F axial force
• L initial Length
• E modulus of elasticity
• A cross sectional area
• σ direct normal stress
• ε axial strain

Question 27

Deformation due to thermal loading

Answer 27

δ=αL(ΔT)

• δ thermal deformation
• α coefficient of thermal expansion
• L initial length of member
• ΔT temperature change

Question 28

Thermal stress

Answer 28

σ=Eα(ΔT)

• α coefficient of thermal expansion
• ΔT temperature change