Statics Analysis Of Oil Drilling Rig Derricks

Derrick is an important part of oil drilling rig,its forces and load cases are very complicated.All along,the safety and reliability of the derrick structure are the focus of people’s attention.Therefore,using the finite element analysis software to carry on the static analysis of the derrick structure,and check the strength,rigidity and stability of the derrick have become an important part in the design process.In this paper,a newly developed product derrick,with the finite element software ANSYS focuses on the static mechanical properties,the main contents are as follows:Firstly,based on the simplified basic principles of derrick structure,according to the technical parameters of K43 type derrick,beam188 element in ANSYS software is used to establish the simplified derrick finite element model,and through keyword set each rod discrete as an independent beam element,under the condition that the calculation accuracy,greatly reduced computing and storage space,which can improve the computational efficiency.Secondly,the load of derrick static analysis is studied in detail,including: constant load,natural load,working load and lifting load.According to the actual situation of derrick type and derrick load,combined with the environment of oil drilling derrick,refer to the API Spec 4F "Specification for Drilling and Well Servicing Structures",identified six kinds of static load combinations.Then,according to different conditions,the strain and stress cloud of derrick structure is obtained,and the maximum equivalent stress is displayed through the program list.Among them,no hook load,full setback,with wind speed as 70 knots from the sides,its safety factor is 1.89,it is recommended to optimize the design;rated hook load,full setback,with wind speed as 16 knots from the sides,its safety factor is 4.28,there is a large margin of safety,it is recommended to optimize the design;when the lifting angle is 4 degrees,the maximum lifting stress of the derrick is 145.2Mpa,the safety factor is 2.38,so the derrick meets the requirement of safety strength in lifting condition.Finally,the traditional theory of translation method to the overall stability of the derrick structure is analyzed,the overall stability of derrick stress is 115.7MPa,less than 345 MPa,the overall stability of derrick is good.At the same time,ANSYS software is used to verify the calculation results obtained by the theoretical calculation method,so as to determine the overall stability of the derrick structure is safe and reliable,and it does not occur instability phenomenon.