Computed Tomography (CT) Is an Asset to Ensure the Quality and Reliability of Parts in Aerospace Applications

Abstract

AbstractThe quality of parts, before they are used in space applications, is to be essentially certified for its dimensional correctness and freedom from defects to reliably ensure its intended in-flight operation. This is achieved through extensive dimensional inspection and defect detection/analysis by non-destructive evaluation. But traditional evaluation techniques have limitations that are widely known. In metrology, measurement of inaccessible inner features with surfaces that are deformable and highly reflecting by tactile and optical methods are either impossible or extremely challenging. In NDE, two-dimensional X-ray radiographic testing lacks depth information of defects and is restricted by film and source placement. Computed tomography (CT) combines the best of both worlds to overcome such limitations with the unique capability of performing simultaneous NDE and non-contact metrology in a single scan. Its superlative imaging capability allows for one-to-one reconstruction of the scanned object into a 3D model from which dimensional details of any external/internal feature including information of defects; its location and severity can be extracted. Through CT, the quality of inspection data available for interpretation can be improved substantially, thereby increasing the reliability of existing inspection activities. Unlike radiography, a reconstructed CT model can be viewed across any desired virtual plane which further facilitates faster decision making and validation. This paper describes the novel inspection activities performed with the aid of CT on launch vehicle parts and components at ISRO. Five cases of NDE, followed by two unique cases where CT was used for failure analysis (FA) of assembled components and few cases of dimensional inspection are discussed. The merits of using CT in aerospace industry are also summarized.KeywordsNDECTISROFailure analysisLaunch vehiclesDimensional metrology