Perimeter Shear Testing for Chassis Structure

Perimeter Shear Tests

• Perimeter shear tests must be conducted to measure the force required to push or pull a 25 mm diameter flat punch through a flat laminate sample.
• The sample must be at least 100 mm × 100 mm with identical core and skin thicknesses to those used in the actual chassis structure.
• The sample must be manufactured using the same materials and processes as the actual chassis structure.

Test Fixture

• The test fixture must support the entire sample, except for a 32 mm hole aligned co-axially with the punch.
• The sample must not be clamped to the fixture.

Structural Documentation

• All teams must submit a Structural Equivalency Spreadsheet (SES).
• The SES spreadsheet form can be downloaded from the competition website.
• Vehicles must be fabricated in accordance with the materials and processes described in the SES.
• Teams must bring a copy of the approved SES to technical inspection.

Roll Hoops

• Both roll hoops must be securely integrated to the primary structure using node-to-node triangulation or equivalent joining methods.
• The minimum radius of any bend, measured at the tube centerline, must be at least three times the tube outside diameter.
• Bends must be smooth and continuous with no evidence of crimping or wall failure.
• The minimum area moment of inertia must be maintained in all areas, including the bends of the manufactured tubes.

Laminate Testing

• Representative test panels must be built for parts of the primary structure or tractive system accumulator container.
• The test panels must measure exactly 275 mm × 500 mm and have the same design, laminate, and fabrication method as used for the respective part of the primary structure.
• The sides of the test panel must not be laminated (core material must be visible).
• A 3-point bending test must be performed on the panel.
• Data from the tests and pictures of the test samples and test setup must be included in the SES.
• Pictures must show the distance between the two supports, dimensions of the load applicator, and test sample marking.

Wheels

• Wheel mounting systems that use a single retaining nut must incorporate a device to prevent loosening of the nut and the wheel.
• Wheel lug bolts and studs must be made of steel or titanium and show good engineering practice with adequate strength by calculations.
• Wheel lug bolts, drive pegs, and studs must not be hollow.
• Aluminum wheel nuts may be used if they are hard anodized and in pristine condition.

Tires

• Vehicles must have two types of tires: dry tires and wet tires.
• Dry tires are defined as the tires on the vehicle when it is presented for technical inspection.
• Wet tires may be any size or type of treaded or grooved tire provided they meet specific requirements.
• Tires on the same axle must have the same manufacturer, size, and compound.
• Tire warmers are not allowed.
• Special agents that increase traction may not be added to the tires or track surface.
• A team can choose to use a single set of tires designed for both “dry” and “wet” conditions.