Research on Calculation and Location of Defects in Derrick Tower

Abstract

Having suffered from the serious environment for ages leads to a decline in the carrying capacity of the derrick as a result of different types of defects. Aiming at a certain derrick tower, finite element analysis software ANSYS was used to calculate and analyze the mode difference of curvature of derrick before and after the damage based on the theory of damage identification from changes in curvature mode shape. Then the conclusion is confirmed by experiments. It shows that local corrosion and bending will cause the change of first two order curvature mode of derrick, and the more is the local damage, the bigger is the mode difference of curvature.