Model-based Rotor Shaft Crack Identification In Time Domain

The large rotating machinery is widely used in modern industrial construction, which needs high quality equipments and devices to ensure safe and stable operations. Fatigue crack is one of the most important fault which may cause catastrophic failure if they was not detected in time.This paper proposes a very method to be used in the on-line crack’s identification and detection, named as model-based crack identification method in time domain. It is applied to the following process:for the precondition a FE model of crack rotary is utilized, which was used in the last decade by scholars. And a mathematical description of dynamics equation should be created as research foundation. Base on the modal expansion theory to acquire all the DOFs from only parts of them (e.g.4DOFs or8DOFs). This step which decides the success rate is the core the total complete theory system. Then theoretical fault models are introduced and least-square fitting in the time domain is involved to identify the right ones by comparing the theoretical ones with the measured ones. Finally the position and depth can be find out through this theory. At last an experiment was carried out to prove the results.