A pre-processing method for digital image correlation on rotating structures

Inter-frame structural motions are required to be small for classic Digital Image Correlation (DIC) algorithms, which severely limits the application of technique in large rotation cases. To solve problem, multiple methods obtain initial guesses deformation parameters have been introduced over recent years. However, success rate is still limited by angles and efficiency low due extra calculations with these methods. further develop DIC cases, Phase Mapping Method (PMM) this paper. The principle proposed method rearrange obtained images sorted rotating phases, previously mapped into range 0 2?. As a result, an image set n frames, average inter-frame angle reduced 2?n-1, original transferred equivalent semi-static one PMM. Additionally, fast phase-detection approach automate PMM cases that speeds unknown. By performing tests, it proved PMM, as pre-processing method, can significantly improve DIC, whether used alone or concurrently other algorithms. first natural frequencies mode shapes beam under different extracted through vibration test, from hardening effect observed.