Application of the PA technology to the automatic inspection of elements with complex geometry by robotized trajectory tracking

In the manufacturing processes of the aeronautical sector, the use of composite materials is common practice allowing great advances which is rapidly spreading to other fields. The high-quality standards required for this type of material requires a 100% quality control of the structural elements before these parts are assembled and subsequently used. The increasing use of composite materials in more industries implies finding a suitable way for testing and evaluation. Non-destructive testing using ultrasonics is an appropriate method to detect defects in these types of materials. However, because of their complex structure the most applicable and accurate process for detecting flaws and anomalies has to be found. For conventional ultrasonic testing, single-element probes are used to generate an ultrasonic signal into the material to inspect it. However, when inspections are done on composite materials, phased array probes (PA) are now being used to detect component failures and thereby determine their quality more rapidly. The objective of this work is to apply the PA technique in the development of a new automated system that inspects, not only flat parts, but also for curved geometries following the contour of the part without loss of signal, removing the necessity to delimit different zones of inspection, optimizing the representation of results and reducing the time of evaluation and errors in interpretation. This system has robotized trajectory tracking, applying Pulse-Echo, and Double Transmission techniques with Phased Array technology, as well as TT transmission, with water coupling, so that it is possible to inspect one hundred percent of monolithic structures of solid laminates and sandwich structures. During the last years, great efforts have been made to improve different parts of the inspection systems. The results have been satisfactory for simple inspections, but not for inspections of elements with complex shapes is still proving a major challenge.