A steel bolt has a modulus of 207 GPa. It holds two rigid plates together at a high temperature under conditions where the creep
of the steel is described by the equation:ε=ε0σσ0nwhere n= 3, andε=127.8 10−×/s when σ= 28 MPa. The bolt is initially tightened to a stress of 69 MPa. What is the stress in it after 1 year? (14 MPa)
1 answer:
You might be interested in
Answer:
Explanation:
For this case we know the following info :
represent the initial volume
represent the final volume
We know that the pressure and volume are related with the following expression:
Where a is a constant given
And we need to calculate the work associated to this process.
We have a compression, and by definition the work is defined with the following general expression:
If we replace the expression for P we got:
If we integrate we got:
Using the fundamental theorem of calculus we have:
And replacing the values we got:
Answer:
a.) I = 7.8 × 10^-4 A
b.) V(20) = 9.3 × 10^-43 V
Explanation:
Given that the
R1 = 20 kΩ,
R2 = 12 kΩ,
C = 10 µ F, and
ε = 25 V.
R1 and R2 are in series with each other.
Let us first find the equivalent resistance R
R = R1 + R2
R = 20 + 12 = 32 kΩ
At t = 0, V = 25v
From ohms law, V = IR
Make current I the subject of formula
I = V/R
I = 25/32 × 10^3
I = 7.8 × 10^-4 A
b.) The voltage across R1 after a long time can be achieved by using the formula
V(t) = Voe^- (t/RC)
V(t) = 25e^- t/20000 × 10×10^-6
V(t) = 25e^- t/0.2
After a very long time. Let assume t = 20s. Then
V(20) = 25e^- 20/0.2
V(20) = 25e^-100
V(20) = 25 × 3.72 × 10^-44
V(20) = 9.3 × 10^-43 V
