| One of the most significant components of drilling rigs is the mast, which bears the weight of tripping, casing, etc. In this thesis three-dimensional (3D) finite element model is built according to the actual structure of model30/1700DBT-drilling rig mast. ANSYS is applied to static and dynamic characteristic study of mast. Seven sorts of loads are respectively exerted on the finite model and reliable results are obtained in the course of static analysis. The computation result shows that the mast can work safely and reliably with these seven sorts of loads. By the model analysis of mast, the preceding9steps modal frequency and the corresponding vibration modes are calculated and analyzed. The computation result shows that the rigidity and mass distribution of the mast are balanced, and there are no obviously week or excess section, all of these are benefit to the dynamic performance of the mast. The computation result shows that the preceding9steps model frequency are very important to guiding the actual operation. It is suggested to examine the speed of rotary table and draw works to avoid the rotation speed close to or overlap the natural vibration frequency of mast or make it rapidly exceed inherent vibration frequency of derrick while operating drilling rigs, avoiding sympathetic vibration in the course of drilling. The affect of guy wire forces on the structure of derrick is mainly analyzed in this thesis, the result shows that raising the guy wire forces of the mast can add the base frequency of the mast shaking, and then the rigidity of the mast can also increase. At the same time, according to the actual structure feature of the mast which slops forwards3degree, there are two results about the dynamic character of the mast which caused by forwards or backwards guy wire. Therefore, in the actual operations we can adjust proper guy wire or force to change the base frequency of the mast, and then we can avoid sympathetic vibration in the course of drilling. |
