Fundamental Research On Doformation Of Welded Hollow Spherical Joint By Using Acoustic Emission Method

Deformation computation and monitoring of welded hollow spherical joints are important task to ensure large steel structural safety. As fast developing of the span of the structure in the recent years, construction and deformation monitoring of large welded hollow spherical joints in service have become hot technical point in this field. Under the support of fundation of 863 hightech young of offshore platform's damge identifying online and model updating (Number:2001AA616110), national postdoctoral foundation of offshore platform's parameters extracting under excited by the ambient and the method of identification (Number:2004035532), and national nation foundation of measured point selection based on the vibration based on ambient input and it's demonstrated system(Number:50508012). Plastic deformation computation and AE monitoring sensor measured point selection of large diameter welded hollow spherical joints are studyed primarily. The main research included as following:1. Based on elasto-plastic yield criterion, three-dimensional mechanical models are established for welded spheres, the stress-strain processes of spherical joints under material and geometry nonlinearity are analyzed detailedly with arc-length iterative method, Load deformation curve, distribution and development of plastic deformation are obtained.2. Based on the simulative computation and the modal of the random faults, the modals of welded hollow spherical joints are simulated, the change of the bearing capacity and plastic deformation in random fault modal are analyzed and computed.3. Based on the analysis above, the plastic deformation aera under ultimate bearing capacity is analyzed and computed. With the transmitting mechanism of the point sound source's sound field, longitudinal wave transmiting law in the faulty aera is analyzed by analogy method, which provides qualitative and quantitive theoretical foundation for sensor location and amplification of the surface wave.4. Based on the computation of the the stress intensity factor of welded hollow spherical joints, the relation between AE counts and stress intensity factor...