Search results for "guided waves"

Guided Wave Techniques for Damage Detection in Composite Aerospace Structures

2018

Composite materials make up an increasing portion of today’s aerospace structures (see, e.g. Boeing 787 and Airbus 380). These aircrafts’ fuselage, for example, is composed of a laminated composite skin connected to composite stringers and C-frames. Of primary importance is the detection of damage in these built-up structures, whether caused by the manufacturing process or in service (e.g. impacts). A related issue is the characterization of the composite (visco)elastic mechanical properties, that can also be related to the quantification of potential damage. Guided elastic waves propagating in the ~100s kHz regime lend themselves to provide the necessary sensitivity to these two conditions…

Ultrasound measurements in bone using an array transducer

2014

Evaluation of Clutch Plate Integrity with Non-Destructive Methods

2009

Abstract Nondestructive evaluation (NDE) represents an important phase in the life cycle of a product to detect defects both in service and in production. NDE techniques most commonly used to detect surface defects are visual inspection and methods based on eddy current and ultrasound. Laser and non-contact sensors have been recently used to inspect ultrasonically without contact. Components with complex geometry are usually inspected combining several NDE techniques, or simply visually where analysis and evaluation of results are performed by an operator based on specific parameters of acceptance. This last method is currently used to inspect the clutch plates since their complex geometry,…

Experimental Observation of a Large Low-Frequency Band Gap in a Polymer Waveguide

2018

The quest for large and low-frequency band gaps is one of the principal objectives pursued in a number of engineering applications, ranging from noise absorption to vibration control, and to seismic wave abatement. For this purpose, a plethora of complex architectures (including multiphase materials) and multiphysics approaches have been proposed in the past, often involving difficulties in their practical realization. To address the issue of proposing a material design that enables large band gaps using a simple configuration, in this study we propose an easy-to-manufacture design able to open large, low-frequency complete Lamb band gaps exploiting a suitable arrangement of masses and stif…