No abstract

No abstract

No abstract

A method for estimating the residual stresses in the weld joint material is described. The results of acoustic examination of the samples made from structural plate steels 15, 20, 08ps, 15G2SF, and 09G2S are presented. A linear relationship between the Poisson ratios of the studied orthotropic materials is found when no residual mechanical stresses are present. Using the example of a weld joint of a pipe element made from steel 15G2SF, it is shown that the linear relationship between the Poisson ratios is violated in the presence of residual stresses. An algorithm for monitoring the residual mechanical stresses in the depressed zero acoustic tensometry regime based on the deviation of the Poisson ratio of the material from the linear relationship is proposed. The results of measurements of the principal stress difference in a weld joint of a pipe made from steel 09G2S are detailed.

Nondestructive evaluation methods provide additional information about the material fatigue behavior and enhance the comprehension of damage evolution thanks to relationship between microstructure and physical properties. This paper deals with optical and ultrasonic investigations of structural steel specimens tested for low-cycle fatigue. The development of persistent slip bands observed on the surface with an optical microscope was quantified using a previously trained neural network and fractal analysis. A surface damage parameter was defined as the ratio of total area of detected slip bands to the area of observed surface. Relationships between the rate of change and critical value of the damage parameter, the strain range, and the fatigue life were established. A single square relationship between relative number of cycles and ratio of the surface damage parameter to its critical value was obtained.Acoustic birefringence was measured by the echo method. The effect of the strain range on the rate of change in acoustic birefringence was investigated. A single linear relationship between relative number of cycles and change in acoustic birefringence was established. An algorithm for predicting the material remaining life, combining optical and ultrasonic data, was proposed.