Biomedical Engineering Reference
In-Depth Information
F
4.17
12.00
15.00
F
FIGURE 4.13
Bone plate used to fix bone fractures, with applied axial load. Dimensions are in mm.
Adapted
from [2].
¼
D
l
l
e
ð
4
:
49
Þ
0
:
00075 mm
15 mm
10
6
¼
¼
50
often reported as 50 m, where m denotes microstrain (10
6
).
The
, relates stress and strain and is a measure of a material's resistance
to distortion by a tensile or compressive load. For linearly elastic (Hookean) materials,
elastic modulus
,
E
E
is a
constant, and a plot of s as a function of e is a straight line with slope
E
:
s
e
E
¼
ð
4
:
50
Þ
For the bone plate,
10
6
Pa
10
E
¼
10
6
¼
200 GPa
50
Materials such as metals and plastics display linearly elastic properties only in limited
ranges of applied loads. Biomaterials have even more complex elastic properties. Figure 4.14
shows tensile stress-strain curves measured from longitudinal and transverse sections of
