RESEARCH ON PANORAMIC SURFACE DEFORMATION MEASUREMENT AND ANALYSIS METHOD FOR SPHERE STRUCTURE

Spherical structures play a crucial role in key fields such as aerospace, precision manufacturing, and civil engineering due to their excellent mechanical properties and spatial geometric characteristics. However, the geometric characteristics of spheres determine that their surface measurements have the characteristics of large curvature, full circumference, and full field. The existing research on high-precision three-dimensional measurement of spherical deformation is still relatively scarce, which cannot meet the urgent needs of practical engineering applications and scientific research. To address this, this paper proposes an innovative multi-camera digital image correlation (DIC) system architecture tailored for spherical surface measurement. The paper first analyzed and optimized the effective measurement field of view and accuracy under different camera angles, and determined that the optimal observation angle of the camera in the subsystem under spherical measurement conditions was 20°, which achieved the optimal balance between in-plane and out of plane deformation measurement accuracy. Based on the optimization scheme, a simplified, stable and high-precision "1-6-1" multi-camera DIC system was developed. The panoramic calibration method based on icosahedral calibration objects was used to unify the global coordinate system of the multi camera system. The relative measurement error of the system was less than 1%, and the stitching error was within 0.05% of the field of view. The system was applied to the pressure deformation measurement of bamboo Cuju and polymer flexible inflatable balls, successfully achieving high-precision deformation measurement of the entire circumference and field of the spherical structure surface. Based on the deformation data representation method in spherical coordinate system, the evolution law and mechanical response mechanism of the deformation field on the surface of Cuju and flexible inflatable balls were further analyzed, effectively verifying the feasibility of the "1-6-1" multi camera DIC measurement system in the full field deformation measurement and mechanical research of spherical surfaces.