Structure Design And Experimental Research Of Magnetic Memory Testing Device For Submarine Pipeline Defects

With the development of the global economic integration process,the demand of power resources has increased fiercely in recent years.In order to meet the huge domestic demand for oil and gas resources,the development and construction of oil and gas resources in China has gradually extended from land to sea.As the key carrier of transportation process for offshore oil and gas gathering,submarine pipeline has many effects,such as processing factors,mechanical damage and complex external loads,which threaten the safe operation of the submarine pipeline.Currently,the common damage detection methods of submarine pipeline have some limitations,that is,only macro cracks can be known.The external detection method needs coupling agent,and the internal detection method is prone to block the pipeline.As a modern green non-destructive testing technology,magnetic memory testing technology can not only detect macro cracks,but also find early stress concentration and hidden damage of materials by using the mechanism of magnetic memory effect in the geomagnetic environment,which makes it have great development potential in the field of submarine pipeline testing.In view of the difficulties in the detection of early defects and hidden damage about submarine pipeline,virtual reality technology is used to explore submarine pipeline defect detection device,which is based on magnetic memory technology.Firstly,according to the test object and working environment,the virtual prototype technology is used to complete the structural design and material selection of the test device prototype model.Meanwhile,the mechanical balance equation of the device structure is analyzed and solved,which are based on the virtual prototype model and combined with the external loads,such as gravity,buoyancy and current force.Furthermore,the static and modal analysis of the basal body and the clamping mechanism of model are carried out respectively,which is based on the virtual prototype model.On this basis,a transient dynamic simulation model is established to simulate the operation process of the magnetic memory testing device for submarine pipeline defects,and its variable condition is current force.Finally,the physical prototype is built and tested according to the research parameters of virtual prototype.At the same time,the finite element model of the pipeline with the same test variables is established,which is taking a single defect as the research object.And the feasibility of the detection device for submarine pipeline is verified by comparing the measured magnetic memory signal and simulation signal.According to the analysis of the submarine pipeline detection device,the maximum deviation distance is 16.742 mm and the maximum deviation angle is 0.044 °,which is observed of the action characteristics and running track of the device prototype.And the device can complete the attitude correction process in the first 3.625 s and reach a stable state,which conforms to the actual working conditions.By comparing the test signal and simulation signal under the condition of te same variable,it is found that the curve change rule of the two defect characteristic parameters is the same.This shows that the designed magnetic memory testing device can be applied to the detection of pipeline defects in the seabed environment.And it provides a new method and idea for the engineering application of magnetic memory testing technology of submarine pipeline.