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F.4.3.1 Primary Structure Laminates
Teams must build representative test panels for each ply schedule used in the regulated regions of the chassis as a flat panel and perform a 3 point bending test on these panels.
a. Test panels must:
Measure one of the two options: 138 mm x 500 mm OR 275 mm x 500 mm
Be supported by a span distance of 400 mm
Have equal surface area for the top and bottom skin.
Have bare edges, without skin material.
b. The SES must include:
Data from the 3 point bending tests
Pictures of the test samples
A picture of the test sample and test setup showing a measurement documenting the supported span distance used in the SES.
c. Test panel results must be used to derive stiffness, yield strength, ultimate strength and absorbed energy properties by the SES formula for the purpose of calculating laminate panels equivalency corresponding to Primary Structure regions of the chassis.
Teams must make an equivalent test that will determine any compliance in the test rig and establish an absorbed energy value of the baseline tubes.
a. The comparison test must use two Side Impact steel tubes (F.3.2.1.e)
b. The steel tubes must be tested to a minimum displacement of 19.0 mm
c. The calculation of absorbed energy must use the integral of force times displacement from the initiation of load to a displacement of 19.0 mm.
F.4.3.3 Test Conduct
a. The load applicator used to test any panel/tubes as required in this section F.4.3 must be:
Metallic
Radius 50 mm
b. The load applicator must overhang the test piece to prevent edge loading.
c. Any other material must not be placed between the load applicator and the items on test.
a. The Perimeter Shear Test must be completed by measuring the force required to push or pull a 25 mm diameter flat punch through a flat laminate sample.
b. The sample must:
Measure 100 mm x 100 mm minimum
Have core and skin thicknesses identical to those used in the actual application
Be manufactured using the same materials and processes
c. The fixture must support the entire sample, except for a 32 mm hole aligned coaxially with the punch.
d. The sample must not be clamped to the fixture.
e. The edge of the punch and hole in the fixture may include an optional fillet up to a maximum radius of 1 mm.
f. The force and displacement data and photos of the test setup must be included in the SES.
g. The first peak in the load-deflection curve must be used to determine the skin shear strength; this may be less than the minimum force required by F.7.4.3 / F.7.6.5
h. The maximum force recorded must meet the requirements of F.7.4.3 / F.7.6.5
F.4.3.5 Additional Testing
When a laminate schedule(s) are NOT a Quasi-Isotropic Layup (F.4.2):
a. Results from the 3 point bending test will be assigned to the 0 layup direction.
b. The monocoque must have the tested layup direction normal to the cross sections used for Equivalence in the SES, with allowance for taper of the monocoque normal to the cross section.
c. All material properties in the weakest direction must be 50% or more of those in the strongest direction as calculated by the SES.
F.4.3.6 Lap Joint Test
a. The Lap Joint Test must be completed by measuring the force required to pull apart a joint comprised of two laminate samples that are adhered together.
b. The sample must:
Have the plane of adhesion parallel to the pull direction
Have skin thicknesses identical to those used in the actual monocoque
Be manufactured using the same materials and processes
c. The force and displacement data and photos of the test setup must be included in the SES.
d. The shear strength of the bond must be greater than the UTS of the skin.