【作者】 严谨； 张娟；

【Author】 Yan Jin,Zhang Juan (Engineering College,Guangdong Ocean University,Zhanjiang 524088,China)

【机构】 广东海洋大学工程学院；

【摘要】 管道振动会产生令人烦躁的噪声,有时还可能由于振动疲劳导致结构失效,从而造成严重的经济和环境事故。因此,通过测量对管道动态应力应变进行实时监控,对于预估管道的安全状态是非常重要的。但是在实际工业生产中,如能源生产和海洋油气储运装置中,管线长度常常达到数十公里。很明显,在这种情况下不可能在每个点安装应变仪来检测管道的最大应力应变。一般更实际的做法是,在选定的几个点用轻便的加速度计和分析设备测量管道的振幅。根据结构振动速度和应变的关系,单元体内折应变大致和结构材料内的膨胀(声)速度成比例,因此可以通过速度测量得到结构应变。在考虑振动能量的基础上,发展了这种速度测量方法。根据理论,一个点上应力应变的最大值与横截面上的应变能量密度平均值密切相关,即与平均动能相关,也就是和管道的平均振动速度相关。因此,可以通过几个测量点得到空间平均速度,进而预测结构应变的极值点。相比于寻找最大振幅,这种基于速度测量的能量方法在实际中更易于实施,物理概念也更加简明,这也有助于工程实际中对结构振动疲劳寿命的评估。更多还原

【Abstract】 Pipe vibrations cause annoying noise,sometimes even cause failure due to fatigue,possibly resulting in economical and environmental disasters.It is important to access the safety state of pipelines by online monitoring the dynamic stress and strain based on measurements.But in practice industry,such as energy production and on off-shore oil and gas installations,there are often many kilometers of pipes.Clearly,it is impossible to install strain gauges instrument at every point to find maximum strain or stress.A more practical cause of action would instead be to measure vibration amplitudes at selected positions using portable accelerometer and analyzer equipment.According to the relations between vibration velocity and strain,the strain within an element is approximately proportional to the ratio of the vibration velocity to the dilatational(sound) velocity in the element’s material,so strain can be obtained by velocity measurements.This work develops a velocity measurements method based on considerations of vibration energy.The maximum strain and stress,at a point is related to the cross-sectional average of strain energy density.This gives a foundation that the maximum strain,being related to the strain energy and hence the average kinetic energy,relates to the average vibration velocity in the pipe.Hence,prediction of peak strain can be made from estimates of spatial average velocity obtained from a few monitoring positions.Relative to find the maximum vibration amplitude,the energy approach based on velocity measurements is easier to carried on and conceptually simpler,and it may become useful in engineering practice for assessments of fatigue life.更多还原