Abstract
Reflectance Transformation Imaging (RTI) is a technique which can be used to record the surface appearance of objects. It can capture a surface's interaction with incident light from different directions and it enables estimation of the surface normal vector. 3D surface profile information can be estimated from RTI datasets using photometric stereo methods. RTI currently has applications in archaeometry and cultural heritage studies but here we discuss the use of RTI in an engineering context: as a tool for failure analysis and particularly for examining failure surfaces in structural materials and components. We demonstrate that RTI can be a practical and low-cost technique for failure analysis, complementing other surface analysis and 3D scanning methods.
Highlights
Failure analysis and Reflectance Transformation Imaging (RTI)Macroscopic optical examination is a key step in any failure analysis of a broken structural component or material test specimen [1]
We examine the use of Reflectance Transformation Imaging (RTI) for failure analysis and show that it can be used to aid the macroscopic observation of topographical features on failure surfaces in engineering and materials science
Reflectance Transformation Imaging can be used to characterise the visual appearance of surfaces for engineering failure analysis
Summary
Macroscopic optical examination is a key step in any failure analysis of a broken structural component or material test specimen [1]. When performing an initial examination of a failed component, the analyst unconsciously synthesises these different aspects of their visual perception: multiple visual cues are used to differentiate between a failure surface formed by cleavage fracture and one formed by ductile tearing, for example. After a set of RTI images of a subject have been taken, PTM, HSH or DMD basis coefficients for each pixel are calculated by leastsquares fitting of the texture model to the image set. Using this model which relates the lighting direction to the appearance of the subject, subtle surface features can be appreciated better than with a single image [9]. We examine the use of RTI for failure analysis and show that it can be used to aid the macroscopic observation of topographical features on failure surfaces in engineering and materials science
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
