CURVED
BEAM STRENGTH TEST FIXTURE
(ASTM D 6415)
Model CU-CL (low carbon steel)
Model WTF-CL (17-4PH stainless)
This test method
can be used to determine the interlaminar tensile strength of a
unidirectional composite. ASTM D 6415 (Reference 1) states that it
is for use in determining the curved beam strength of a continuous
fiber-reinforced composite material.
The curved beam
specimen consists of two straight legs connected by a 90 degree bend
with a ¼” inner radius. The specimen is 1” wide and can range from
0.1” to 0.5” thick depending on the material and laminate being
tested. An out-of-plane (through-the-thickness) tensile stress is
produced in the curved region of the specimen when load is applied.
The fixture is
shown in the following photograph, with a model specimen installed.
The specimen is supported and loaded by 3/8” diameter cylinders
mounted in ball bearings. A 1”-14 UNF threaded hole is provided in
both the top and bottom of the fixture, for attachment to the base
and cross head of the testing machine.
Curved Beam
Strength Test Fixture (ASTM D 6415)
A compressive
force is applied in displacement control until one or more
delaminations form in the specimen, causing the applied force to
drop. ASTM D 6415 gives the equations required to calculate the
specimen strength.
Another view of
the standard fixture is shown in the following photograph, to better
indicate its size.
Curved Beam
Strength Test Fixture (ASTM D 6415)
Source
of Additional Information:
1)
ASTM Standard D6415-99 (1999), "Standard Test Method for Measuring
the Curved Beam Strength of a fiber-Reinforced Polymer-Matrix
Composite," American Society for Testing and Materials, West
Conshohocken, Pennsylvania (first published in 1999).
