The paper presents an overview of methods for determining residual stresses. Methods such as splitting and segmentation, layer-by-layer removal, slitting (cutting, pliability), profiling, drilling holes (including a «deep» hole) are considered. The description of the methods for mea-suring the deformation used in the determination of residual stresses is given. The most common contact method using strain gauges, as well as non-contact methods: polarization-optical (photo-elasticity), optical speckle interferometry, digital image correlation.
The crystallographic alignment of various permanent magnets has been investigated by X-ray pole figure analysis. Attempts have been made to measure the degree of alignment of these sintered magnets using the (105) reflection. It has been shown that the (105) pole figure can be used only to verify small differences in texture in magnets high degree of crystallographic alignment. A comparison between the measured and the calculated L105 index showed good agreement.
Four North American pipeline operators and a pipeline inspection company have been working together on a research project assessing the feasibility of using an electromagnetic non-contacting strain measurement tool capable of being deployed during ILI inspection to measure axial strain in pipelines. The axial strain sensor is the TSC StressProbe. It is an electromagnetic technique which makes use of the fact that when a steel structure is loaded, its electromagnetic properties change. Monitoring the changes in magnetic properties allows one to measure changes in strain.
The use of in-line inspection high resolution inertial survey tool data in the determination of bending strain in operating pipelines is well developed and understood. The missing component in determining the total strain in the pipeline is to understand the component of axial strain that the pipeline is experiencing without the need to expose the pipeline for the installation of surficial pipe monitoring (primarily strain gauges) or destructive testing (such as cut-outs). Many current methods of stress/strain measurement including the installation of strain gauges only allows for the determination of change in strain going forward from the date of install; whereas, the StressProbe responds to total strain at the time of inspection.
This paper will present the technology implementation, inspection feasibility and discuss preliminary results from case studies in determining the ability of the in-line inspection axial strain measurement to correlate with known changes in strain in pipelines being influenced by ground movements.
Experimental determination of the Townsend coefficient for Argon–CO2 gas mixtures at high fields