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HW #5
Problem 7.12
a. To Find:
Does the single crystal yield under the given applied stress? If not, at what stress will it yield?
b. Given:
= 43.1
o
= 47.9
o
CRSS
= 20.7 MPa
Applied stress
= 45 MPa
c. Assumptions:
(i) The applied force is uniaxial
(ii) Single crystal
(iii) The metal is pure (alloying agents/impurities can change the value of
CRSS
.
(iv) The testing is done at room temperature – the value of
CRSS
can change with temperature.
(v) The values of
CRSS
and applied stress
are accurate.
d. Solution:
Method 1: Calculate applied
R
and compare with
CRSS.
psi)
(3181
MPa
22.0
=
)
47.9
)(cos
43.1
MPa)(cos
(45
=
cos
cos
=
R
R
>
CRSS
Method 2: Calculate yield strength and compare with applied stress.
MPa
42.29
=
)
47.9
(cos
)
43.1
(cos
/
MPa)
(20.7
=
cos
cos
/
CRSS
Y
>
y
The resolved shear stress is greater than the critical resolved shear stress. Hence, the
single crystal will yield.
The applied stress is greater than the yield strength. Hence, the single crystal will
yield.
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View Full DocumentProblem 7.13
a. To Find:
(a)
Most favored slip direction
(b)
CRSS
b. Given:
= 28.1
o
= one of 62.4
o
, 72.0
o
, 81.1
o
Yield strength
y
= 45 MPa
c. Assumptions:
(i) The applied force is uniaxial
(ii) Single crystal
(iii) The metal is pure alloying agents/impurities can change the value of
CRSS
.
(iv) The testing is done at room temperature – the value of
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 Fall '10
 leoindzhiglei

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