A fatigue test was conducted in which the mean stress was 70 MPa, and the stress amplitude was 210 MPa. (a) Compute the maximum and minimum stress levels. (b) Compute the stress ratio. (c) Compute the magnitude of the stress range

Answer :

Answer:[tex]\sigma _{max}=280 MPa[/tex]

[tex]\sigma _{min}=-140 MPa[/tex]

Step-by-step explanation:

Given

[tex]\sigma _{mean}=70 MPa=\frac{\sigma _{max}+\sigma _{min}}{2}[/tex]

[tex]2\times 70=\sigma _{max}+\sigma _{min}[/tex]-------1

[tex]\sigma _a=210=\frac{\sigma _{max}-\sigma _{min}}{2}[/tex]

[tex]210\times 2=\sigma _{max}+\sigma _{min}[/tex]-------2

From equation 1 & 2 we get

[tex]\sigma _{max}=280 MPa[/tex]

[tex]\sigma _{min}=-140 MPa[/tex]

(b)Stress ratio(R)=[tex]\frac{\sigma _{min}}{\sigma _{max}}[/tex]

R=[tex]\frac{-140}{280}=-0.5[/tex]

(c)Range=[tex]\sigma _{max}-\sigma _{min}[/tex]

Range=280-(-140)=560 MPa

Answer:

Step-by-step explanation:

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