This paper analyses the natural frequencies and modes of ‘A’ form derricks. Using the random perturbative finite element methods, the first-order and second-order sensitivities are calculated when several structural...This paper analyses the natural frequencies and modes of ‘A’ form derricks. Using the random perturbative finite element methods, the first-order and second-order sensitivities are calculated when several structural parameters of elements are changed randomly. The expressions of the random structural eigenvalues of ‘A’ form derricks are given. The results and conclusions are valuable for designing new oilfield derricks in the future.展开更多
This paper presents a dynamic evaluation method to calculate the buckling strength of oilfield derricks. First, the linear relationship between the basic frequency and the ultimate strength of the cantilever structure...This paper presents a dynamic evaluation method to calculate the buckling strength of oilfield derricks. First, the linear relationship between the basic frequency and the ultimate strength of the cantilever structure with axial load is determined using the dynamic eigenvalue equations of the structure. Then, the basic frequency, ω 2 1i , corresponding to the load, N i, can be calculated or measured, and the linear relationship of ω 2 1i ～N i is plotted using the data mentioned above. The axial force corresponding to ω 2 1i =0 is the required buckling strength of the oilfield derrick. The suggested method can evaluate the buckling strength of oilfield derricks combining nondestructive testing with calculating. It is a convenient and practical method to estimate the carrying capacity of any steel structure.展开更多
This paper puts forward a new method of PCNN （pulse-coupled neural networks ） image segmentation, in which the binary matrix of the ignition frequency matrix is employed, for the first time, to act as the final resu...This paper puts forward a new method of PCNN （pulse-coupled neural networks ） image segmentation, in which the binary matrix of the ignition frequency matrix is employed, for the first time, to act as the final result of image segmentation. It gives the principles of PCNN parameter selection under the guidance of this process. The new method reduces the dependence of PCNN on parameters, improves the effect of image segmentation, and produces good results after being applied to image recognition of weld seam of oil derrick welded by arc welding robot.展开更多
In this paper, the finite element analysis software (ANSYS) is applied to the modal analysis of a ZJ30/1700CZ's drilling machine derrick under a natural condition and a loaded condition, respectively. The precedin...In this paper, the finite element analysis software (ANSYS) is applied to the modal analysis of a ZJ30/1700CZ's drilling machine derrick under a natural condition and a loaded condition, respectively. The preceding nine step natural frequencies and the corresponding mode shapes of the derrick are calculated. By means of the comparison of the natural frequency of the derrick with the design work frequency of the drilling machine and the analysis of the step mode shape of the derrick, the drilling machine derrick structure design is proved to be correct.展开更多
The fiber Bragg grating （FBG） strain sensor is used in the oil and gas derricks for the health monitoring. The system consisted of the FBG strain sensors, optical interrogator and monitoring software. 64 sensors wer...The fiber Bragg grating （FBG） strain sensor is used in the oil and gas derricks for the health monitoring. The system consisted of the FBG strain sensors, optical interrogator and monitoring software. 64 sensors were installed on a derrick for loading and unloading tests. The results showed that the monitoring system had the advantages of the high accuracy, good repeatability, large capacity and real-time monitoring ability.展开更多
文摘This paper analyses the natural frequencies and modes of ‘A’ form derricks. Using the random perturbative finite element methods, the first-order and second-order sensitivities are calculated when several structural parameters of elements are changed randomly. The expressions of the random structural eigenvalues of ‘A’ form derricks are given. The results and conclusions are valuable for designing new oilfield derricks in the future.
文摘This paper presents a dynamic evaluation method to calculate the buckling strength of oilfield derricks. First, the linear relationship between the basic frequency and the ultimate strength of the cantilever structure with axial load is determined using the dynamic eigenvalue equations of the structure. Then, the basic frequency, ω 2 1i , corresponding to the load, N i, can be calculated or measured, and the linear relationship of ω 2 1i ～N i is plotted using the data mentioned above. The axial force corresponding to ω 2 1i =0 is the required buckling strength of the oilfield derrick. The suggested method can evaluate the buckling strength of oilfield derricks combining nondestructive testing with calculating. It is a convenient and practical method to estimate the carrying capacity of any steel structure.
文摘This paper puts forward a new method of PCNN （pulse-coupled neural networks ） image segmentation, in which the binary matrix of the ignition frequency matrix is employed, for the first time, to act as the final result of image segmentation. It gives the principles of PCNN parameter selection under the guidance of this process. The new method reduces the dependence of PCNN on parameters, improves the effect of image segmentation, and produces good results after being applied to image recognition of weld seam of oil derrick welded by arc welding robot.
文摘In this paper, the finite element analysis software (ANSYS) is applied to the modal analysis of a ZJ30/1700CZ's drilling machine derrick under a natural condition and a loaded condition, respectively. The preceding nine step natural frequencies and the corresponding mode shapes of the derrick are calculated. By means of the comparison of the natural frequency of the derrick with the design work frequency of the drilling machine and the analysis of the step mode shape of the derrick, the drilling machine derrick structure design is proved to be correct.
文摘The fiber Bragg grating （FBG） strain sensor is used in the oil and gas derricks for the health monitoring. The system consisted of the FBG strain sensors, optical interrogator and monitoring software. 64 sensors were installed on a derrick for loading and unloading tests. The results showed that the monitoring system had the advantages of the high accuracy, good repeatability, large capacity and real-time monitoring ability.
