摘要
人类对能源的需求越来越大,对于海洋油气资源的探测和开发也随之越来越广泛和深入。其中,又以自升式平台的应用最为广泛。自升式平台上的悬臂梁,能有效地提高平台的作业范围和能力。因此,自升式平台悬臂梁连接形式的研究和设计,在当前来说是极具实际意义和经济价值的。而悬臂梁与甲板的连接部件与滑轨之间的接触分析,可以给研究和设计提供具体、详细的计算数据,从而进一步优化悬臂梁结构的连接形式。
在工程实际中校核悬臂梁强度时,对于连接结构之间的接触面,较为普遍的做法是使用梁单元和杆单元来简化模拟接触行为,或者直接不考虑接触。但是,接触是一个非常复杂的非线性行为,忽略接触的影响,会使计算结果与实际情况相差较大。
针对上述问题,本文介绍了接触分析的有限元计算的原理和方法,并以400英尺自升式平台为例,使用有限元计算软件ABAQUS6.8.1对悬臂梁与其支撑结构的接触行为进行数值仿真研究。先利用MSC. Patran2005建立悬臂梁、主甲板及其连接机构的有限元模型。然后利用Patran中与ABAQUS的接口,生成中间命令流文件。再将命令流导入ABAQUS中进行模型的装配和修改,对接触分析的关键参数进行设置,使用Standard分析模块进行计算。最后,将其计算结果与不考虑接触影响的线性有限元方法的计算结果进行对比,分析悬臂梁及其支撑结构的应力分布、整个系统的能量耗散以及接触面之间的接触力和摩擦力。由此发现,对悬臂梁进行非线性接触分析可以有效模拟接触位置的应力、变形以及系统的能量耗散,可以给研究和设计提供更准确、详细的计算数据。
Human demand for energy is growing. Exploration and exploitation of offshore oil and gas resources also will be more extensive and in-depth. Among them, the jack-up platform has been the most widely used. The cantilever on the jack-up platform can effectively improve the operating range and capabilities of the platform. Therefore, the t research and design of the connection form of the cantilever on the jack-up platform is of great practical significance and economic value. The contact analysis between the connecting structures of the cantilever and the main deck, could provide specific details of the calculation data to the research and design in order to optimize the connection form of cantilever.
When the strength of the cantilever is checked in engineering practice, on the contact surfaces between the connecting structures, the more common practice is to use the beam and bar elements to simplify the simulation of contact behavior, or directly to not consider contact behavior. However, the contact is a very complex nonlinear behavior. And ignoring the effects of the contact will make the calculation results quite different with the real one.
In response to the problem, this article describes the principles and methods of the finite element contact analysis. And with an example of a400feet jack-up platform, a study for numerical simulation of the contact behavior of the cantilever and its support structure has been done, using finite element software of ABAQUS6.8.1.
First, this article builds the finite element models of the cantilever, the main deck and connected institutions with MSC. Patran2005. And then,"inp" files are generated by the using of the interface of Patran and ABAQUS. After that, this article assembles and modifies the model which is input into ABAQUS with "inp" files, sets the key parameters of the contact analysis, and calculates with the Standard analysis module of ABAQUS. Finally, the calculation results are compared with the results by linear finite element method without considering the effects of the contact. This article analyzes the stress distribution of the cantilever and its supporting structure, the energy dissipation of the whole system as well as the contact surface between the contact force and friction force. Then, this article comes to a conclusion that the nonlinear finite element method for the contact analysis can effectively simulate the contact position of stress, deformation, and system energy dissipation, and is able to provide more accurate and detailed study and design calculations.
引文
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