Effect of stress on ultrasonic response in detection and sizing of cracks

Jorma Pitkänen*, Anssi Laukkanen, Mika Kemppainen, Iikka Virkkunen

*Corresponding author for this work

Research output: Contribution to journalArticleScientificpeer-review


In different NOT techniques huge developments have been achieved during the last few years with regard to crack detection and sizing. In a large range of materials, cracks are one of the most dangerous defect types. A crack is a planar reflector, which is sometimes extremely difficult to detect and to be sized. A crack can be totally open, partly closed or even totally closed because of compressive stresses. The effects of stresses cause problems, for instance, in inservice inspections of nuclear power plants in detection and sizing of closed cracks. This phenomenon causes similar effects in all kinds of plants and components. In this study some experimental inspections have been carried out as well as some FEM calculations of stress field around the crack and compared to corresponding measurements in literature. Materials used for this study are austenitic and ferritic piping steel. The dynamic load applied to the cracks was in form of different thermal cycles. The maximum temperature variations were from 20°C to 600°C depending on each dynamic loading cycle. Different types of ultrasonic methods were used in the measurements. The effect of closure on the response of normal ultrasonic practical probes was recorded. Dynamic loading during ultrasonic measurement gives clear evidence on the effect of the crack closure as well as on the amplitude variation limits in ultrasonic testing.

Original languageEnglish
Pages (from-to)299-309
Number of pages11
Issue number6
Publication statusPublished - 2007
MoE publication typeA1 Journal article-refereed

Fingerprint Dive into the research topics of 'Effect of stress on ultrasonic response in detection and sizing of cracks'. Together they form a unique fingerprint.

Cite this