Impact Attenuator (IA)

The IA is a key safety component of the Formula Hybrid and Electric (and every student Formula) competition.

The Mathematical Foundation

The energy an impact attenuator must dissipate is defined by the kinetic energy of the vehicle and driver at the moment of impact:

\(E\) = 1/2 \(m\) \(v\) ²

Where:

• \(E\) = Energy (Joules)

• \(m\) = Total mass of vehicle + driver (kg)\

• \(v\) = Velocity (i.e., \(7 \text{ m/s}\))

Visualizing the Mass-Energy Tradeoff

Decision Flow for IA Reviewers

How to Read the IA Report

When reviewing the report, prioritize these technical benchmarks

• Energy Absorption: The IA must absorb at least 7,350 J of energy (based on a 300 kg vehicle at 7 m/s) or the specific energy calculated for the team’s mass at 8 m/s.

• Deceleration Limits:

  • Average Deceleration: Must not exceed 20 g.

  • Peak Deceleration: Must not exceed 40 g.

• Non-Crushable Objects: Ensure no rigid objects (e.g., steering rack, battery) are located within the IA zone or pass through it unless they were included in the test.

• Physical Dimensions: The IA must be at least 200 mm long, 100 mm high, and 200 mm wide for the final 200 mm forward of the bulkhead.

Standard IA: Chain of Custody

If using the “off-the-shelf” Standard IA, the IA report must prove it is the exact part required.

1. Procurement: PDF of the receipt from SAE or Plascore.
2. Unboxing: Photo of the IA with the manufacturer’s label/part number visible.
3. Assembly: Photo of the IA bonded to the Anti-Intrusion (AI) Plate.
4. Integration: Photo of the AI Plate bolted to the Front Bulkhead.
5. Mass Check: Verification that the vehicle is \(\le 300 \text{ kg}\).

IA Report Components

All IA reports must include:

• Test Identification: The type of test performed (Dynamic or Quasi-static) and the specific location or test site.

• Physical Description: A detailed description and drawings of the Impact Attenuator (IA).

• Attachment Documentation: Information and photographs showing how the IA is attached to the Anti-Intrusion (AI) Plate and how the AI Plate is mounted to the Front Bulkhead.

• Performance Curves: Both a Force vs. Displacement curve and an Energy vs. Displacement curve derived from the test data.

• Visual Proof: Photographs of the test setup, as well as “before” and “after” photos of the IA unit.

• Technical Benchmarks:

  • The total Crush Distance recorded.

  • The Average Deceleration (must not exceed 20g).

  • The Peak Deceleration (must not exceed 40g).