Dynamic 3D optical measurement system for the characterisation of the behaviour of a pipe in a resonant bending test rig

In this paper the dynamic behaviour of a pipe in a resonant bending fatigue test rig is investigated. This kind of test rig is used for full scale testing of pipeline joints such as girth welds and threaded connections. In order to optimize the test conditions in such a test rig, accurate knowledge of its dynamic behaviour is necessary. This dynamic behaviour is first evaluated theoretically using a semi-analytical model to study the effects of pipe dimensions and test rig properties. Afterwards, the validity of this model is illustrated by experimental test results. To measure the bending deflection of the pipe during a test, a dynamic 3D optical measurement system is used. Using the measurements it is shown that the dynamic behaviour of a pipe in the resonant bending test rig can be accurately predicted by the theoretical model. For a given pipe diameter and wall thickness size, the model prescribes the required pipe length, the necessity to fill the pipe with water, the necessary mass of the endweights, the systems natural frequency and the position of the test rig supports.