Abstract-Terahertz applications in the aerospace industry

M.J. Bohn, D.T. Petkie,

https://www.sciencedirect.com/science/article/pii/B9780857092359500185


Aerospace applications for terahertz (THz) imaging will be examined in this chapter. The outer skin of the aircraft consists of thin (~ millimeter) sheets of fiber composites that are bonded to honeycombed composites for structural support. During the manufacturing process, quality-assurance inspections could be performed on these thin sheets using a transmissive THz system. A transmissive system can accurately determine the optical path length of the sheet which provides useful information regarding the epoxy homogeneity and regions of delamination. For inspections after the aircraft has been manufactured, reflective THz geometry is required because there are often structural components beneath the layer of interest that obstruct the penetration of the transmitted THz wave. Experiments demonstrating the utility of both of these techniques using both pulsed and continuous (CW) THz systems will be explained in detail. Results from CW THz experiments will also be presented and compared to the pulsed THz experiments. The chapter concludes with an experimental study comparing traditional non-destructive imaging techniques to THz imaging systems.

Abstract-New trends in non-destructive assessment of aerospace structures

Wieslaw M. Ostachowicz ; Pawel H. Malinowski ; Tomasz Wandowski

http://proceedings.spiedigitallibrary.org/proceeding.aspx?articleid=2213453

Wieslaw M. Ostachowicz, Pawel H. Malinowski, Tomasz Wandowski

The Szewalski Institute of Fluid-Flow Machinery (Poland)

Proc. SPIE 9435, Sensors and Smart Structures Technologies for Civil, Mechanical, and Aerospace Systems 2015, 943502 (March 27, 2015); doi:10.1117/12.2178155

The scope of the paper includes non–destructive assessment of the structure's material condition, for the aerospace structures during its useful lifetime. The paper presents multidisciplinary technologies devoted to development and implementation of methods and systems that realize inspection and damage detection by non–destructive methods. The paper covers several disciplines which are based on topics such as piezoelectric transducers, elastic waves propagation phenomenon, structural vibrations analysis, electro–mechanical impedance method, terahertz technique, laser induced fluorescence and 3D laser vibrometry applications. Among various techniques available the paper presents selected numerical simulations and experimental validations of considered structures. Authors address also the problem of adhesive bonding in the case of carbon fiber reinforced polymers (CFRP). Techniques for detection of weak bonds are presented together with signal processing approaches. The reported investigations concern weak adhesive bonds caused by both manufacturing (e.g. release agent, poor curing) and in–service contaminations (e.g. moisture). Also the paper provides helpful information about dispersion, mode conversion and wave scattering from stiffeners and boundaries. It addresses the problem of optimisation of excitation signal parameters and sensor placement, as well as analysis of signals reflected from damage. It also includes a variety of techniques being related to diagnostics (damage size estimation and damage type recognition) and prognostics. © (2015) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE). Downloading of the abstract is permitted for personal use only.