基于周期系统反共振敏感性的架空长输管线法兰联接状态辨识方法研究

The project is intended to investigate the detection of loosening in bolted flange joints for supported long-distance pipeline, which is considered as a multi-coupled periodically-supported structure system connected by a large number of flange connections. The simplified dynamic model for the whole pipeline structure is developed including the nonlinear effects of flange joints. The change of connection status induced by the loosening in bolted flange joints is considered as the local disorder of the periodic pipeline structure, and the dynamic parametric identification model for the periodically-supported pipeline is developed by considering such disorder effects. Based on the developed multi-coupled periodic dynamic model for pipeline structure, the characteristic equation of driving-point antiresonance frequencies together with the sensitivity-based identification equations for antiresonance frequencies from multiple set of measurements is developed. In addition, by considering the uncertainties associated with the unknown parameters for assessing the connection status, a trade-off between the complexity of the parametric identification model and that of its corresponding information-theoretic interpretation is achieved by utilizing the information theory, in order to obtain a relatively simple parameterization scheme for keeping the similar model-data matching and avoiding the over-fitting problem arisen from excessive modeling parameters. Moreover, the applicability and feasibility of proposed detection methodology for assessing the connection status of bolted flange joints of multi-coupled periodically-supported pipeline structure are fully validated by conducting theoretical analysis, numerical simulations as well as laboratory experiments. It’s expected to provide new ideas for the research areas of nondestructive testing and structural health monitoring of long distance pipelines during service period.

本项目以架空直线敷设长输管线螺栓法兰联接状态辨识方法为研究对象，将架空管线视作由众多法兰联接的多耦合周期支撑结构系统，建立考虑螺栓法兰联接刚度非线性的长输管线混合动力学周期结构模型；再将法兰螺栓松动引起的接头联接状态改变视为管线周期结构的局部失谐，建立考虑此失谐因素的多耦合周期支撑管线法兰联接状态的参数化动力学辨识模型。基于该周期管线整体辨识模型，进一步建立其驱动点反共振频率特征方程及法兰联接状态表征参数的反共振频率敏感性识别方程组；再考虑待定联接状态参数不确定性，基于信息理论权衡管线局部失谐辨识模型的参数化复杂度与其信息论表述复杂度，获得参数化程度相对简化的辨识模型以避免参数过多导致的模型过拟合引起辨识结果失真。经理论分析、数值模拟及实验室模型试验研究，探讨基于周期结构系统反共振频率敏感性分析的架空长输管线法兰螺栓联接状态辨识方法的可行性，为长输工业管线无损检测及健康监测领域提供新思路。

随着工业管道运行年限的增加，由管道腐蚀、裂纹、疲劳破坏等损伤引起的管道泄漏、爆炸等事故频发，不仅造成经济上巨大损失、人员伤亡，而且严重污染生态环境。鉴于螺栓法兰联接在工业管道中的广泛应用，研究有效的法兰螺栓联接状态动力检测技术，具有重要的理论意义与实用价值。本项目充分考虑法兰联接架空长输管线沿纵向呈周期性的特点，将其模拟为周期支撑结构系统以简化整体动力分析过程，同时将法兰联接刚度损失视作周期结构的局部失谐，并以此为基础开展长输管线整体动力特性研究，并进一步发展基于动力测试数据的法兰联接状态辨识方法。针对螺栓法兰连接周期支撑管道的具体结构形式，将周期系统的Bloch定理、高精度谱有限元法以及传递矩阵法相结合，进行超长周期支撑管线整体动力学建模，使周期结构整体模型动力分析计算量与单个周期胞元相当，极大提升了大型周期结构动力分析的计算效率，为基于动力测量数据的超长周期结构状态监测提供理论模型基础。分别提出了基于敏感性分析、贝叶斯理论以及粒子滤波的概率损伤辨识方法，同时发展了一种结构模型参数化复杂度的定量控制手段，提出了一种有限元模型缩聚主自由度的优化选择策略，并建立了一种高维参数空间中模型参数的有效辨识理论框架，为超长周期结构损伤表征参数辨识的有效分组与模型复杂度的合理控制，以及高维参数的有效反演提供可行的技术支撑。深入开展理论探究、数值仿真以及实验室模型实验等相关研究，使本项目所提出的理论、模型以及方法等获得验证。本项目研究成果可为长输工业管线无损检测及健康监测领域提供新思路及相关理论支撑与实验依据。