A stereovision measurement for large deformation of light structures

Abstract The vibration characterized by large deformation of light structures is important in aerospace engineering, while it is very difficult to be obtained. The traditional contact method is not available because of unwanted mass-loading. In this paper, a non-contact stereovision method is proposed for measuring large deformation vibration of light structures. The vibration responses are measured by the modified 3D point stereovision method. But the stereovision measurement is difficult to gain excitation information, which results in the modal identification method based on transfer function is not applicable. Thus the modal identification without excitation information is required for the development of the vibration stereovision measurement. The time domain modal identification method based on mathematical model is adopted. As comparison, the contact sensor method is also carried out and the transfer function modal identification method is employed for this method. The cantilever-beam experimental results show that the modal parameters using this proposed method agree with the theoretical analysis results much better than contact sensor method. In addition, the 3D point stereovision measurement can provide more information about mode shapes than the traditional sensor method for large deformation of light structures.