Numerical Simulation and Experiment on Magnetic Flux Leakage Inspection of Cracks in Steels
The magnetic flux leakage inspection method is widely use d in the detection of pipelines, storage tanks and other steel materials. Especially in c orrosion pits detection, it has become a matured technology. As cracks may exist in the steels which may lead to big hazards, its detection becomes very important. Meanwhile, the cracks evaluation by MFL inspection can be determined by many parameters, it has much difficulty t o implement due to its weaker signals compared with pits. In this research, the finit e element model for cracks’ MFL is established and corresponding method are carried out. Furthe rmore, parameters such as depth, width, angle of cracks and scanning direction are analyzed. Also, the experiments are done which show great reliability comparing with numerical s imulations. The results show that the cracks can not be detected when the scanning direction para llels with it. So the cross-scanning method is recommended for MFL inspection on cracks.
A comparative study of 3D and axisymmetric magnetizer assemblies used in magnetic flux leakage inspection of pipelines
Axisymmetric numerical codes are often used in modeling non-destructive testing phenomena, to approximate geometries and defects which are not truly axisymmetric in nature. This is especially true in cases where large computational resources are needed to model the exact geometry. However, there has been no study to confirm the nature and extent of errors introduced by an axisymmetric approximation. The gas pipeline industry makes use of bath axisymmetric and non-axisymmetric magnetizers for the magnetic flux leakage inspection of pipelines. The authors utilize this platform to perform a comparative analysis of axisymmetric and non-axisymmetric magnetizers from a design perspective and also study the differences in respective electromagnetic behavior.
"Flying Triangulation" - a new optical 3D sensor enabling the acquisition of surfaces by freehand motion
In order to obtain complete 3D surface information of an object it is often necessary to acquire many partial 3D views. For this purpose, the sensor has to be moved (e.g. for the acquisition of sculptures or rooms). Further, in many cases a motion of the object relative to the sensor is unintended but inevitable (e.g. for medical applications such as intraoral measurements of teeth). Nearly all existing optical 3D sensors either lack an easy handling or require a standstill during the acquisition of a single partial 3D view, since usually multiple camera shots have to be taken for this purpose. This makes such measurements elaborate or even impossible.