Thomas Heckel

BAM · company speakers →

Imaging, Sizing and POD with ultrasound – challenges which have to be overcome. Abstract: Each inspection task poses its own specific challenges to imaging, sizing and classification of indications and well as probability of detection (POD) estimation. This statement is valid in particular for the ultrasonic inspection of components with complex geometries or components made of complex materials or even both. Fiber reinforced plastic (FRP) is one of the most common examples of complex materials inspected by non-destructive testing methods. Applications of FRP composites in modern industries are increasing due to their considerable advantages such as light weight and excellent mechanical properties. Defects in FRP structures may be introduced during the processing and fabrication of composite components and can initiate or grow in-service. In order for a particular NDE technique to achieve broad acceptance by industry, it is desirable for the technique to be able to detect a range of defect types with a high level of confidence. For ultrasonic inspections of these parts standard techniques, phased array techniques and air coupled techniques are available and solutions will be presented and compared against each other. Methods for data analysis will be discussed. A good example of an inspection of parts with complex geometry is the inspection of railway axles. These axles are safety relevant parts and therefore have to be inspected regularly. For in-service inspections on hollow wheelset axles, manual or mechanized ultrasonic inspection systems with a rotating ultrasonic probe are used to inspect the outer surface for flaws. The surfaces of these flaws are typically positioned in the radial-radial plane perpendicular to the axis of the axle. The inspection is performed with a helix like movement of the beam along the testing zones. At DGZfP training centre Wittenberge/Germany round robin tests with the trainees have been carried out on three hollow axels featuring three flaws with different depth and positions each to statistically evaluate the overall performance of the inspection. The evaluation was focused on the determination of position and size/amplitude of the flaws at different locations of the complex geometry of the axle to obtain information about the probability of detection (POD). Results of this study will be presented. A reliability analysis, or any analysis of the capability of NDT to achieve its purpose—whether it’s to detect, characterize or classify flaws—is incomplete without the consideration of human factors. Whereas POD provides information about the system’s capability under controlled laboratory conditions, studying human factors provides an insight into the reliability and likelihood of failure in the field. How the knowledge of human factors, i.e. various factors affecting NDT inspectors in the field, can be used to optimize NDT reliability, productivity, inspection process and personnel training will be demonstrated.

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