Location

Snowmass Village, CO

Start Date

1-1-1995 12:00 AM

Description

Feasibility of using Lamb waves for disbonds and corrosion detections in aircraft fuselage structures was investigated in recent years. Measurement performed on various laboratory-fabricated specimens as well as on panels removed from aircrafts has shown consistent results and demonstrated its potential applications for large area structural integrity evaluation [1–3]. It has been observed that structural flaws existing on the path of Lamb waves not only changed amplitude of waves but also affected their velocities as well. Amplitude change caused by a disbond of size less than 0.5 in. × 0.5 in. was significant and has been measured. Variation in phase velocity was used to quantify the corrosion-induced thickness reduction in aluminum sheets. An area of size 1 in. × 1 in. with 8% thickness loss in subsurface of an 1 mm thick aluminum plate was detected by monitoring the phase velocity increase of SO mode. While these tests made major progresses toward developing a practical and low cost flaw assessment system, effects due to the presence of certain structural elements, such as coatings and fasteners, on the propagation of Lamb waves are becoming important issues, and need to be analyzed. These effects are themselves interesting physical phenomenon and worth investigation, however, it is hoped that propagation variations of waves induced by structural defects can be separated from these effects and be quantitatively correlated to the physical properties of defects.

Volume

14B

Chapter

Chapter 5: Engineered Materials

Section

Bonded Joints

Pages

1569-1576

DOI

10.1007/978-1-4615-1987-4_201

Language

en

File Format

application/pdf

Share

COinS
 
Jan 1st, 12:00 AM

Effect of Rivet Rows on Propagation of Lambn Waves in Mechanically Fastened Two-Layer Aluminum Plates

Snowmass Village, CO

Feasibility of using Lamb waves for disbonds and corrosion detections in aircraft fuselage structures was investigated in recent years. Measurement performed on various laboratory-fabricated specimens as well as on panels removed from aircrafts has shown consistent results and demonstrated its potential applications for large area structural integrity evaluation [1–3]. It has been observed that structural flaws existing on the path of Lamb waves not only changed amplitude of waves but also affected their velocities as well. Amplitude change caused by a disbond of size less than 0.5 in. × 0.5 in. was significant and has been measured. Variation in phase velocity was used to quantify the corrosion-induced thickness reduction in aluminum sheets. An area of size 1 in. × 1 in. with 8% thickness loss in subsurface of an 1 mm thick aluminum plate was detected by monitoring the phase velocity increase of SO mode. While these tests made major progresses toward developing a practical and low cost flaw assessment system, effects due to the presence of certain structural elements, such as coatings and fasteners, on the propagation of Lamb waves are becoming important issues, and need to be analyzed. These effects are themselves interesting physical phenomenon and worth investigation, however, it is hoped that propagation variations of waves induced by structural defects can be separated from these effects and be quantitatively correlated to the physical properties of defects.