Biomedical Engineering Reference
In-Depth Information
F
F
F
b
d
R
L
(a)
(b)
(c)
5.2
Schematics of strength tests. (a) Tensile and compression tests
with a traditional dog-bone sample. (b) Flexural strength test. (c)
Diametral compression test.
(2)
(3)
B
(2)
(3)
A
(2)
(3)
C
E
=
s
e
(3)
D
(2)
Secant modulus
Tangent modulus
(1)
0.002
Strain,
e
(unitless)
5.3
Stress-strain graph comparing tensile behaviour of different
types of materials.
the highest practical strength of a material for many applications in which
plastic deformation would render the material useless. When the yield
point cannot be precisely identified, as is the case with many metals
which undergo a gradual elastic to plastic transition, a line parallel to the
elastic slope can be constructed at a specified strain (usually 0.002). The
yield strength is then taken as the stress where the parallel line meets
the curve.
∑
Ultimate tensile strength, is
UtS
.
this is the highest stress a material
experiences during a tensile test. it may or may not be the stress at
which the material fails (compare curves A and D to B and C).
