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A D V A N C E D
M A T E R I A L S
&
P R O C E S S E S |
M A R C H
2 0 1 6
2 3
BSS series from Boeing and the AITM
series from Airbus. Finally, some obso-
lete standards are still in use, such as
those published by the Suppliers of Ad-
vanced Composite Materials Association
(SACMA) and the Composites Research
Advisory Group (CRAG).
CONCLUSION
Composite materials offer great
potential for future generations of
lightweight, environmentally friendly
vehicles. These materials are complex
and comprehensive data is needed for
design and modeling. Although a range
of mechanical tests is required to ob-
tain data, the aerospace industry has
already developed, validated, and stan-
dardized these test methods—and the
automotive industry can benefit from
this effort. ~AM&P
For more information: Ian McEnteg-
gart is composites marketing manager,
Instron, 825 University Ave., Norwood,
MA 02062,
.
Low-temperature testing in an environmental chamber.
or hydraulically driven indenter. After
impact, damage is evaluated by either
visual or ultrasonic inspection and/or
determination of residual strength in a
compression after impact (CAI) test. In
a CAI test, an impact-damaged compos-
ite panel is mounted in a support to pre-
vent buckling and loaded in compres-
sion until it fails. High-rate tension or
compression testing can be performed
either using a drop tower with a high-
speed force sensor or with a high-rate
servohydraulic testingmachine. The ser-
vohydraulic machine provides a more
flexible platform for this type of work.
For example, it can test over a wider
speed range and can maintain a con-
stant speed during the test.
CONDITIONING AND
TEST ENVIRONMENTS
The properties of polymer matrix
composites are influenced by environ-
mental conditions. The most common
environmental factors include tempera-
ture and humidity. Testing over a range
of temperatures is normally conduct-
ed inside a temperature chamber with
heating and cooling capability. Evaluat-
ing the effects of humidity requires long-
term exposure of test specimens to a
humid atmosphere in a humidity cham-
ber (a process known as conditioning),
followed by testing. The process of ab-
sorbing and desorbing moisture is slow,
so there is no need to conduct the final
testing in a humid atmosphere.
TEST STANDARDS
The main international composite
testing standards are those maintained
by ASTM, ISO, and CEN (European Com-
mittee for Standardization). In addition
to international standards, a number of
manufacturers’ proprietary standards
are in widespread use including the
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