1992

Marquis, Gary

Automated crack length measuring methods have largely replaced manual techniques in many applications. They require little operator time and have the additional feature of being able to collect large amounts of data. A method for compressing a large number of crack length observations into a smaller number of crack length estimates suitable for calculating the fatigue crack growth rate is described and verified using a simulation technique. With this method, the effective crack length measuring precision is improved and the amount of crack growth rate data obtainable from a single specimen is increased. Test times for threshold testing can also be potentially decreased. This method has been incorporated into a computer program, SÄRMÄ, currently in use in VTT Metals Laboratory.