An ultrasound method for the acoustoelastic evaluation of simple bending stresses

• Published in: NDT & E international : independent nondestructive testing and evaluation Vol. 34; no. 8; pp. 521 - 529
• Main Authors: Si-Chaib, M.O., Menad, S., Djelouah, H., Bocquet, M.
• Format: Journal Article
• Language: English
• Published: Oxford Elsevier Ltd 01.12.2001; Elsevier Science
• Subjects: Acoustical measurements and instrumentation; Acoustics; Analysing. Testing. Standards; Applied sciences; Bending loads; Correlation technique; Cross-disciplinary physics: materials science; rheology; Elastic deformation; Exact sciences and technology; Fundamental areas of phenomenology (including applications); Materials science; Materials testing; Measurement and testing methods; Measurement methods and techniques in continuum mechanics of solids; Metals. Metallurgy; Nondestructive testing; Nondestructive testing: ultrasonic testing, photoacoustic testing; Normal bending stresses; Physics; Solid mechanics; Structural and continuum mechanics; Testing for defects; Ultrasound velocities; Ultrasound velocities; Normal bending stresses; Elastic deformation; Bending loads; Correlation technique; Deformation measurement; Acoustic measurement; Ultrasonic control; Testing equipment; Bending stress; Experimental study; Non destructive test; Modeling; Stress measurement
• ISSN: 0963-8695; 1879-1174
• DOI: 10.1016/S0963-8695(01)00012-3

Ultrasonic waves constitute a privileged tool for investigation in the analysis and characterisation of mechanical stress states. Ultrasonic wave velocities depend on many physical properties of the propagation medium such as the second-, third- and higher-order elastic constants, the volume density and the strain. They also depend on whether the wave is longitudinal or transversal. In this last case, they also depend on the wave polarisation direction. The present paper deals with the classical acoustoelasticity in stressed and elastically deformed media when they are submitted to bending stresses. A numerical and an experimental evaluation of the resulting change in the ultrasound velocities as a function of bending loads are described. Some results have been obtained on the variation of propagation velocities of the longitudinal and transversal polarised waves as a function of mechanical bending loads applied on samples made of S 185 steel. The acoustoelastic evaluations have been achieved in three zones under bending stress (compressed, central and extended fibres) in the case where the path of probing, longitudinal and linearly polarised shear waves are parallel to the sample axis. As additional investigation on acoustoelastic behaviour on bending load, we propose some acoustoelastic responses simulated numerically on materials of known macroscopic properties. The experimental study was achieved by means of a measurement set-up composed of an ultrasound bench and a mechanical test machine. In order to measure the variations of the propagation velocity, a correlation technique has been used to obtain an accurate estimation of the propagation time. The velocity measurements have taken into account the elastic deformation of the samples made of carbon steel (C 35).