Bond Testing Selecting the Right Technique to Inspect Composite and Bonded Structures

Bond testing is a relatively less well-known nondestructive testing (NDT) technique. This practical guide provides an overview of existing dedicated bond testing techniques, including pitch-catch, mechanical impedance analysis (MIA), and resonance, and explains how they apply to various material systems, such as honeycomb sandwich panels, composite laminates, and metal-to-metal bonds. The strengths, limitations, and optimal use cases of each technique are presented to help NDT inspectors make informed decisions in real-world applications. By linking material characteristics to inspection physics, this tutorial explains how to select the most effective bond testing approach for reliable defect detection across different composite materials and bonded structures.

https://doi.org/10.32548/2026.me-04596

Introduction

The increasing demand for weight reduction, fuel efficiency, and structural performance has driven the widespread adoption of advanced lightweight materials and bonded assemblies across multiple industries. In general, these include modern lightweight materials such as composites—carbon fiber reinforced polymers (CFRP) and glass fiber reinforced polymers (GFRP)—and sandwich panels (with honeycomb or foam cores), in which components are joined with adhesives rather than bolts or rivets to reduce weight and improve structural efficiency.

In the aerospace sector, composite materials now account for over 50% of the structural weight of modern commercial aircraft such as the Boeing 787 Dreamliner and the Airbus A350. Similarly, the automotive industry is rapidly increasing its use of CFRP and bonded aluminum structures to meet stringent emissions and efficiency targets. Lightweight bonded components are also widely used in wind turbine blades, which can exceed 80 m (262 ft) in length, as well as in rail, marine, and industrial applications.