In this paper, by using adequate stress-strain relationship, mesh elements, boundary conditions and loading conditions, the finite element ANSYS analysis on the behavior of circular tubes subjected to symmetrical cycl...In this paper, by using adequate stress-strain relationship, mesh elements, boundary conditions and loading conditions, the finite element ANSYS analysis on the behavior of circular tubes subjected to symmetrical cyclic bending with or without external pressure is discussed. The behavior includes the moment-curvature and ovalization-curvature relationships. In addition, the calculated ovalizations at two different sections, middle and right cross-sections, are also included. Experimental data for 6061-T6 aluminum alloy tubes subjected to cyclic bending with or without external pressure were compared with the ANSYS analysis. It has been shown that the analysis of the elastoplatic moment-curvature relationship and the symmetrical, ratcheting and increasing ovalization-curvature relationship is in good agreement with the experimental data.展开更多
Because various reasons, the tubing near wellhead was collapsed during well testing in high pressure and high temperature deep well when the outer pressure was less than collapsing strength. To find the reasons in the...Because various reasons, the tubing near wellhead was collapsed during well testing in high pressure and high temperature deep well when the outer pressure was less than collapsing strength. To find the reasons in the abnormally collapse and countermeasures, first the quality of the tubing was checked. It was founded that the collapse was not resulted from the defect of the tubing. Then, force and stress exerted in the tubing was analyzed taking XS2 well as an example. The analysis results were concluded as follows. The collapsing strength of tubing decreased due to the axial tensile, which is seriously at the upper tubing especially. During injecting, the additional axial force that was caused by the temperature effect increased the tubing near wellhead to suffer axial tensile and further reduced the collapsing strength of tubing near wellhead. Reinforcing defect, prohibiting defect tubing to trip in hole, according to the calculation to impose appropriate annular pressure, selecting size nozzle to reverse pumping and controlling the reverse pumping speed and pressure, prohibiting to be opened flow and reducing or releasing the annular pressure can prevent the well testing tubing down-hole being collapsed at the wellhead.展开更多
The international US executive in foreign assignments faces more obstacles than his counterpart for domestic assignments. He has to pursue better coping skills for： cultural, communication and language, self-capabili...The international US executive in foreign assignments faces more obstacles than his counterpart for domestic assignments. He has to pursue better coping skills for： cultural, communication and language, self-capability, stress management, and adjustment issues in the foreign settings. Premature return can be obviated through improved pre-departure training and post-arrival mentoring. US expatriates who are selected for foreign assignments in culturally distant and operationally different countries have an especially important need for their development and training. The challenge to adapt and become functional and fluent in the local surroundings in a very short time is very difficult for the expatriate. The expatriate＇s strange and difficult-to-fathom foreign environment causes him to be anxious as he works hard to adjust and be effective. The obstacles of dealing with the different business customs, social etiquette, and language differences make it difficult for communication, operating environments, and building professional relationships in an appropriate manner. He has to deal with the strangeness and unfamiliarity during the initial period after his arrival in the foreign country. This is further compounded by the pressing need for him to show good performance and produce results in his foreign assignment. He struggles to adjust and to perform the technical aspects of his task.展开更多
文摘In this paper, by using adequate stress-strain relationship, mesh elements, boundary conditions and loading conditions, the finite element ANSYS analysis on the behavior of circular tubes subjected to symmetrical cyclic bending with or without external pressure is discussed. The behavior includes the moment-curvature and ovalization-curvature relationships. In addition, the calculated ovalizations at two different sections, middle and right cross-sections, are also included. Experimental data for 6061-T6 aluminum alloy tubes subjected to cyclic bending with or without external pressure were compared with the ANSYS analysis. It has been shown that the analysis of the elastoplatic moment-curvature relationship and the symmetrical, ratcheting and increasing ovalization-curvature relationship is in good agreement with the experimental data.
文摘Because various reasons, the tubing near wellhead was collapsed during well testing in high pressure and high temperature deep well when the outer pressure was less than collapsing strength. To find the reasons in the abnormally collapse and countermeasures, first the quality of the tubing was checked. It was founded that the collapse was not resulted from the defect of the tubing. Then, force and stress exerted in the tubing was analyzed taking XS2 well as an example. The analysis results were concluded as follows. The collapsing strength of tubing decreased due to the axial tensile, which is seriously at the upper tubing especially. During injecting, the additional axial force that was caused by the temperature effect increased the tubing near wellhead to suffer axial tensile and further reduced the collapsing strength of tubing near wellhead. Reinforcing defect, prohibiting defect tubing to trip in hole, according to the calculation to impose appropriate annular pressure, selecting size nozzle to reverse pumping and controlling the reverse pumping speed and pressure, prohibiting to be opened flow and reducing or releasing the annular pressure can prevent the well testing tubing down-hole being collapsed at the wellhead.
文摘The international US executive in foreign assignments faces more obstacles than his counterpart for domestic assignments. He has to pursue better coping skills for： cultural, communication and language, self-capability, stress management, and adjustment issues in the foreign settings. Premature return can be obviated through improved pre-departure training and post-arrival mentoring. US expatriates who are selected for foreign assignments in culturally distant and operationally different countries have an especially important need for their development and training. The challenge to adapt and become functional and fluent in the local surroundings in a very short time is very difficult for the expatriate. The expatriate＇s strange and difficult-to-fathom foreign environment causes him to be anxious as he works hard to adjust and be effective. The obstacles of dealing with the different business customs, social etiquette, and language differences make it difficult for communication, operating environments, and building professional relationships in an appropriate manner. He has to deal with the strangeness and unfamiliarity during the initial period after his arrival in the foreign country. This is further compounded by the pressing need for him to show good performance and produce results in his foreign assignment. He struggles to adjust and to perform the technical aspects of his task.
