Part -1:
Question 1
The aluminum (7075 - T7351) panel has on edge crack of 1 inch and is subjected to constant amplitude cycle loading of σmax = 10 sec and. σmin = 0.
![1314_Figure1.jpg](https://secure.tutorsglobe.com/CMSImages/1314_Figure1.jpg)
(a) use the walker growth vote equation and ΔN = 500 to determine the crack length after zoo cycles.
(b) Do the same thing but use the IHT growth rate equation or curve
Kmax = 10√(Πa) [1.12 -.23(a/4) + 10.6(a/4)2 - 21.x(a/4)3 + 30.3(a/4)4]
Question 2
For example +a, use the walker equation to determine the number of cycle required for the crack to become critical use aluminum 2024 T3
Question 3
How many cycles will it take to become critical?
Question 4
How many cycles will it take to reduce the residual strength by 20% ? by 40% ? use the Kmax vs d2a/dx curve given.
Question 5
Refer to the figure below to provide specific values of residual strength for the skin-stiffener structure for each of the following two cases:
a) Stiffener a is used
b) Stiffener b is used
![45_Figure2.jpg](https://secure.tutorsglobe.com/CMSImages/45_Figure2.jpg)
Question 6
Set up a table to determine the crack growth of a panel subjected to the cyclic loading shown in the figure below.
Use the following growth data:
ΔN = 1,000 cycles
ao = 2.0 in
Use the Walker growth rate equation:
da/dN = 10-4 [zKmax/mT]P
z = (1 - R )q
where p = 3.7 , q = 0.6 , mT = 25
As an approximation, consider that the stress intensity of the cracked structure can be calculated at every stage of growth as
K1 = (1.2) σ√(Πa)
![645_Figure3.jpg](https://secure.tutorsglobe.com/CMSImages/645_Figure3.jpg)
Question 7
If the remote stress applied is σ = 20 (ksi) , determine the stress intensity factor for the edge cracked panel of the figure in the following cases:
A) No plastic zone adjustment
B) With plastic zone adjustment for both √Πa and β for plane stress
C) With plastic zone adjustment for both √Πa and β for plane strain
Note: assume the following values
σys = 63 (ksi)
W = 8(in)
a = 2(in)
![1617_Figure4.jpg](https://secure.tutorsglobe.com/CMSImages/1617_Figure4.jpg)