MSE280B: Introduction to Materials Engineering
Homework 6: Solutions
1.
(5 Points) Elastic deformation is where bonds between atoms stretch reversibly whereas
plastic deformation involves bond breaking between neighboring atoms and new bonds
forming.
2. (5 Points) Elastic modulus remains constant upon cold working. Slope during unloading and
reloading is parallel to original elastic portion of the curve.
3. Problem 7.9 from Callister
(10 points)
This problem asks that we compute the original length of a cylindrical specimen that is stressed
in compression.
It is first convenient to compute the lateral strain
x
as
ε
x
=
∆
d
d
0
=
30.04 mm
−
30.00 mm
30.00 mm
= 1.33
×
10
-3
In order to determine the longitudinal strain
z
we need Poisson's ratio, which may be
computed using Equation 7.9;
solving for
yields
ν
=
E
2
G
−
1 =
65.5
×
10
3
MPa
(2)
(
25.4
×
10
3
MPa
)
−
1 = 0.289
Now
z
may be computed from Equation 7.8 as
ε
z
=
−
ε
x
ν
=
−
1.33
×
10
−
3
0.289
=
−
4.60
×
10
-3
Now solving for
l
0
using Equation 7.2
l
0
=
l
i
1
+ ε
z
=
105.20 mm
1
−
4.60
×
10
−
3
= 105.69
mm

This
** preview**
has intentionally

**sections.**

*blurred***to view the full version.**

*Sign up*