Using the Total Focusing Method (TFM) to accurately size flaws for probability of detection (POD) purposes

Hydro-Québec has found that welding flaws induced during the manufacturing of hydraulic turbine runners are prone to fatigue damage. To avoid catastrophic failure, they developed a life estimation model that relies on flaw detection and sizing through non-destructive testing (NDT) inspection procedures. Probability of detection (POD) gives the probability or likelihood that a flaw of a given size will be detected in a part by an inspection procedure; it is used as an indicator of its reliability. POD value is computed through the statistical analysis of inspection data obtained on qualifying coupons. These coupons contain known flaws with a designed size distribution. However, even intentionally fabricated flaws are often not the size and location that the manufacturer intended or documented them to be. On the other hand, recent developments in ultrasonic phased array signal processing indicate that Total Focusing Method (TFM) is a powerful NDT method that can provide accurate flaw sizing information. The current proposal, therefore, aims to validate the use of TFM to accurately size the flaws present in qualifying coupons. In fact, TFM sizing tolerance will be assessed by X-ray micro-tomography and destructive salami slicing.

Faculty Supervisor:

Martin Viens

Student:

Partner:

Institut de Recherche Hydro-Québec

Discipline:

Engineering

Sector:

Professional, scientific and technical services; Utilities

University:

École de technologie supérieure

Program: