Digital Image Analysis System for Monitoring Crack Growth at Elevated Temperature

摘要

The objective of the research work reported here was to develop a new concept, based on Digital Image Analysis, for monitoring the crack-tip position at elevated temperatures. The proposed system includes: a) Charge Coupled Device camera observing the crack-tip. b) PC-based frame grabber, capturing a 512 x 512 pixel frame. c) Digital Image Analysis software developed to locate and digitize the position of the crack-tip, on the observed image area. d) Step-motor driven stage, permitting the image-transmitting penetrator to follow-up the tip as it advances. e) A penetrator (fiber-optic or lenses) transmitting the magnified image from the vicinity of the crack-tip to the camera. The system was designed, assembled, and tested. Also, a program was developed for digitizing the crack-tip position. To evaluate the feasibility of the concept, its potential accuracy, resolution, temperature limitation and usefulness the system was tested at room and elevated temperature. The results of the testing and evaluation prove that the proposed concept is feasible, practical, and capable of performing at temperatures exceeding our initial objectives. (AW)