J. Ransom, J. Restis, Fatigue Technology, Inc., Seattle, WA

Summary:

The use of expanded technology products in composite materials can provide structural performance improvements, manufacturing cost savings and life cycle cost reduction. Manufacturing savings and structural benefits have been realized in metallic structure for many years with the use of expanded technology products. These structural benefits are a function of the residual stresses that are formed with the expansion process. In order to use expanded technology products in composite materials, the expansion process must be adapted to the material.

The use of expansion technology in composite material poses new challenges, such as preventing damage to the material, while still providing the desired structural benefits with the expanded product. A test program was undertaken to evaluate the parameters and performance of several expanded products. Six common aerospace composite materials were chosen for this test program. These materials were chosen because of there use on several current or future airframe structures. The test program will include investigations for:

• Installation Damage
• Retention (torque and pushout)
• Static Bypass (tension and compression)
• Fatigue Bypass
• Static Tension Joints
• Fatigue Joints
• Lightning Strike, Conductivity
• Corrosion

This paper will discuss the test program and results to date.