Detection Technique Of Threaded Drill Pipe Compound Loads Based On Fiber Bragg Grating

In recent years,the threaded drill pipe is widely used in mining engineering.In the drilling process,the compound loads of threaded drill pipe.are axial force,bending moment and torque.The compound loads are too large to cause threaded drill pipe to be deformed or even broken.Therefore,it is necessary to select the appropriate sensor and detection methods for compound loads separation and online detection.The traditional electrical sensor detection results are susceptible to ambient temperature,electromagnetic fields and moist air,and the signal transmission line is complicated,which is not suitable for the detection of compound loads of threaded drill pipe in the drilling process.Fiber Bragg grating(FBG)sensor has many advantages,such as small volume,anti-electromagnetic interference,easily multiplexing networks,etc,which overcome the disadvantages of electrical sensor.It is more and more widely applied in the practical engineering.It is very important to ensure the safe and efficient operation of the mechanical system by FBG sensor online detecting compound loads of the thread drill pipe.The compound loads of the threaded drill pipe are simulated and analyzed based on ANSYS finite element simulation,and they are detected in the drilling process.The main works of this paper include the following aspects:1.The development and application of fiber grating sensing technology are analyzed systematically.The present situation of detection of compound loads are analyzed.2.The sensing principle of FBG is analyzed,and the temperature compensation scheme of FBG strain sensor is proposed.The separation principle and correction method of compound loads of threaded drill pipe are introduced.In the end,the sensing system of detection is briefly introduced.3.In the ANYSY software,the stress distribution of the threaded drill pipe,the correction value(?)of the axial stress and the correction coefficient(k)of the shear stress are obtained by the mechanical simulation analysis of the threaded drill pipe in compound loads.The detection points location in the threaded drill pipe are determined according to the simulation results.4.Combined with the sensing principle of FBG,the principle of temperature compensation and the separation principle of compound loads of threaded drill pipe,two plug-in are programmed by using LabVIEW software,which can be used for single-node measurement of compound loads of threaded drill pipe and three-nodeonline detection of compound loads of threaded drill pipe.5.The single-node measurement of compound loads of threaded drill pipe,which shows the feasibility of the detection method.And the compound loads of the thread drill pipe are detected online in the drilling process,which are compared with applied compound loads(axial force and torque)by drilling rig.The front end of threaded drill pipe(close to drill bit)is greatly influenced by external force and friction of workpiece being drilled.Transfer losses of drilling rig applied pressure and torque increase in the front end of threaded drill pipe.So the front end of threaded drill pipe is susceptible to wear and damage.In the drilling process,the middle end and terminal end of threaded drill pipe are greatly influenced by bending moment.The middle end and terminal end of threaded drill pipe drill into workpiece being drilled with less time,which lead to low transfer losses.The detection technology provides technical support for material selection of drill pipe,optimization of drilling mechanism and selection of drilling parameters,which provides a new and feasible method for monitoring simultaneously of mechanical parameters at the engineering site.