This paper discusses the development of an Acoustic Emission (AE) wireless node and its application for SHM (Structural Health Monitoring). The instrument development was planned for applications monitoring steel and concrete bridges components. The final product, now commercially available, is a sensor node which includes multiple sensing elements, on board signal processing and analysis capabilities, signal conditioning electronics, power management circuits, wireless data transmission element and energy harvesting unit. The sensing elements are capable of functioning in both passive and active modes, while the multiple parametric inputs are available for connecting various sensor types to measure external characteristics affecting the performance of the structure under monitoring. The output of all these sensors are combined and analyzed at the node in order to minimize the data transmission rate, which consumes significant amount of power. Power management circuits are used to reduce the data collection intervals through selective data acquisition strategies and minimize the sensor node power consumption. This instrument, known as the 1284, is an excellent platform to deploy SHM in the original bridge applications, but initial prototypes has shown significant potential in monitoring composite wind turbine blades and composites mockups of Unmanned Autonomous Vehicles (UAV) components; currently we are working to extend the use of this system to fields such as coal flow, power transformer, and off-shore platform monitoring.
This work deals with the non destructive analysis of different composite parts and structures using Line Scanning
Thermography (LST), a non-contact inspection method based in dynamic thermography. The LST technique provides a
quick and efficient methodology to scan wide areas rapidly; the technique has been used on the inspection of composite
propellers, sandwich panels, motor case tubes and wind turbine blades, among others.
In LST a line heat source is used to thermally excite the surface under study while an infrared detector records the
transient surface temperature variation of the heated region. Line Scanning Thermography (LST), has successfully been
applied to determine the thickness of metallic plates and to assess boiler tube thinning.
In this paper the LST protocols developed for the detection of sub-surface defects in different composite materials
commonly used in aerospace applications, plates will be presented. In most cases the thermal images acquired using LST
will be compared with ultrasonic c-scans. The fundamentals of LST will be discussed, as well as the limitations of this
technique for NDT inspection.
Today, the increasing energy demand and the need for clean power generation has lead to the
improvement of wind turbines and the development non invasive inspection techniques for the
assessment of wind turbine blades to maintain long term reliability as well as to avoid catastrophic
Given the complexity of the geometry, the material composition and material thicknesses, finding a
NDT technique to effectively and rapidly inspect the blades is a challenging task. Wind turbine
blades are fabricated using different materials like fiber glass, carbon composites, foam and/ or balsa
wood. Layers of these materials are bonded together using an epoxy type resin. Inspection of the
bond quality between external layers and structural elements of the blade is of fundamental
importance for quality control and service of the blade.
In this study our efforts towards the applications of Line Scanning Thermography (LST) for the
analysis of test coupons fabricated using the materials employed in the manufacture of wind turbine
blades, as well as some wind turbine blade sections. LST utilizes a line heat source to thermally
excite the surface to be inspected and an infrared detector to record the transient surface temperature
variation produced by disbonds, and other subsurface imperfections. The LST technique has
provided a quick and efficient methodology to scan large composite structures, which makes it
desirable for the inspection of wind turbine blades. The scanning protocols developed for the
detection of sub-surface disbonds (delamination) in coupons and parts will be presented. The
successes and limitations of the technique will be discussed.
An innovative Line Scanning Thermography (LST) inspection method is being developed as part of a
Structural Damage Assessment System to access the health of in-service composite structures. The system
utilizes a line heat source to thermally excite the surface inspected and an infrared detector to record the
transient surface temperature variation and to detect regions of increased heat resistance associated to
interlaminar disbonds, cracks and other imperfections found in composites structures. In this study our efforts
towards the applications of LST for the analysis of carbon fiber sandwich composites will be discussed. The
LST technique provides a quick and efficient methodology to scan wide areas rapidly. The scanning protocols developed for the detection of sub-surface disbonds (delamination) in composite sandwich parts will be presented. The results presented correspond to scans of test coupons with manufactured defects.