Measurement of the stressed state of welded joints in the NPP process components and circulation pipelines based on acoustoelasticity theory
The results of the theoretical study and experimental research of the measurement method of the stressed state of welded joints of technological equipment and the circulating piping of NPPs based on the theory of acoustoelasticity, and ways of their technical implementation.
Depending on the speed and attenuation of ultrasonic waves in a material by its composition, structure and preferred orientation of the grains determine uprugosti and strength characteristics. Measurement of the velocity of longitudinal and shear waves in polycrystalline materials allows to obtain the numerical values of the elastic modulus and singlecrystal constants elastic anisotropy. The device for measuring the stress state of welded joints of technological equipment and the circulating piping of NPPs, based on the theory of acoustoelasticity, allow us to measure the residual stresses along the height of the welded connection, to find places of formation of cracks. The use of such devices will allow for early diagnostics of welded joints, which will enhance the safety of NPP operation.
Acoustic tenzometric based on registration of change of the velocity of propagation of elastic waves under the influence of stresses in the test object. It is known that the change of speed is proportional to the magnitude of stress or strain in the test object. An important advantage of acoustic tensometry – control stress not only on the surface but also inside the object. It is established that the amplitude of the signal decreases as the tensile stress and increases with compressive stresses, i.e. there is a dependence of the amplitude on the magnitude and sign of the stresses. At the Obninsk Institute for Nuclear Power Engineering designed and manufactured automated device of measurement of the stressed state of welded joints of technological equipment and the circulating piping of NPPs based on acoustoelasticity theory.
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