基于应力和当量损伤系数的石油井架损伤识别

Damage identification of oil derrick based on stress and equivalent damage coefficients

损伤是影响石油井架承载性能最重要的因素,为了准确诊断石油井架的损伤,提出了基于应力和当量损伤系数的识别法。首先,应用当量损伤系数作为判别损伤是否存在与程度大小的综合评价指标,建立了损伤刚度矩阵;其次,确定了应力与当量损伤系数之间的函数关系,推导了应力残差矩阵对当量损伤系数的灵敏度表达式;然后,构造了基于应力的目标函数,提出应用正算过程和优化方法反演识别当量损伤系数;最后,用该方法对某石油井架进行了损伤识别。结果表明:该方法能够准确地识别单损伤、两损伤和对称位置损伤。相对其他静力识别方法,计算工作量小,识别效率高。

Damage is the most important factor that influences the load - carrying capacity of oil derricks. To correctly diagnose the damage, a novel identification approach to oil derricks is proposed based on two indices, stress and equivalent damage coefficient. Firstly, equivalent damage coefficient is taken as the synthetical index to identify the existence and degree of damage, based on which, the damaged stiffness matrix is established. Secondly, the functional relationship between stress and equivalent damage coefficients is determined, and the sensitivity expression of stress residual matrix to equivalent damage coefficients is built. After that, the objective function based on stress is constructed, the direct derivation and optimization method are applied to identify the equivalent damage coefficients. Finally, the method is demonstrated with some oil derrick. Results show that single, two - damage and symmetry damage can be identified accurately. Compared with other static identification methods, it is more efficient and needs less working capacity.