Development of an ultrasonic method of determining residual stresses in solids with initial property anisotropy

Predicting residual stresses arising from the thermal and mechanical loading history during engineering processes including welding would be a viable tool to reach the optimum process parameters. In the present article, an elasto-thermo-visco-plastic model has been employed to estimate the residual stress caused by the underwater friction stir welding, which are resulted by large thermo-mechanical deformations on one hand and rapid cooling arising from the enormous non-uniform boiling heat convention of water on the other hand. Finally, the numerical results are compared with experimental data acquired by the ultrasonic method to evaluate the accuracy of the simulation process. Regarding the low temperature during underwater friction stir welding, the employed constitutive equations result in acceptable residual stress fields, while for in-air case, the amount of error increases significantly due to experience of high temperatures and intensification in hardening precipitation phenomena.

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Ultrasonic Stress Measurement in Welded Component by Using Lcr Waves: Analysis of the Microstructure Effect

Recent Advances in Nondestructive Evaluation Techniques for Material Science and Industries ◽

10.1115/pvp2004-2829 ◽

2004 ◽

Cited By ~ 2

Author(s):

H. Walaszek ◽

J. Hoblos ◽

G. Bourse ◽

C. Robin ◽

P. Bouteille ◽

...

Keyword(s):

Residual Stresses ◽

Stress Measurement ◽

Ultrasonic Method ◽

Life Time ◽

Ultrasonic Waves ◽

Engineering Industry ◽

Hole Drilling ◽

Ultrasonic Methods ◽

Melted Zone ◽

Microstructure Effect

Welding, which is a largely used process in the mechanical manufacturing, is one of the causes of high-level residual stresses. The level of residual stresses has a great importance for the life time of welded components used in mechanical engineering industry. The ultrasonic technique may be used to determine the residual stresses. The technique is based on the acoustoelastic effect, which refers to the change in the velocity of ultrasonic waves propagating in strained solids. Previous studies were carried out to evaluate residual stresses by using ultrasonic methods, but they do not enable to exactly determine the stress values in the heat-affected zone (HAZ) and the melted zone (MZ). This paper describes the experimental procedure of ultrasonic stress measurements applied to welded manufactured joints for different steel grades such high elastic limit material. It is noticeable that, to take into account of microstructure influence on ultrasonic behavior of the weld, the measurement were calibrated on samples machined in the melted zone and in parent metal. The results obtained by the ultrasonic Lcr waves technique were compared with those obtained by “reference” techniques such as hole-drilling. This work confirms the possibility of evaluating the residual stresses induced by welding using the ultrasonic method, and shows improvements obtained in taking into account of metal microstructure for evaluating stresses in the welds.

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Ultrasonic Stress Measurement in Welded Component by Using Lcr Waves: Analysis of the Microstructure Effect

Materials Science Forum ◽

10.4028/www.scientific.net/msf.524-525.453 ◽

2006 ◽

Vol 524-525 ◽

pp. 453-458 ◽

Cited By ~ 6

Author(s):

H. Qozam ◽

J. Hoblos ◽

G. Bourse ◽

C. Robin ◽

Henri Walaszek ◽

...

Keyword(s):

Residual Stresses ◽

Acoustic Waves ◽

Stress Measurement ◽

Ultrasonic Method ◽

Engineering Industry ◽

Hole Drilling ◽

Melted Zone ◽

Wave Technique ◽

High Level ◽

Microstructure Effect

Welding, which is a largely used process in the mechanical manufacturing, well known to induce high-level residual stresses. The level of residual stresses is of great importance for the lifetime of welded components used in mechanical engineering industry. The use of the ultrasonic method for the evaluation of the residual stresses is based on the acoustoelastic effect, which refers to the change in velocity of the acoustic waves propagating in a strained solid. In the case of welding, the microstructure modifications observed in the heat affected zone (HAZ) and the melted zone (MZ) also induce variations of the velocity of the acoustic waves. The superposition of the two effects, stresses and microstructure, results in over-estimating the levels of stresses. This work which was completed in collaboration with CETIM is a contribution to this problem. The experimental study was carried out on P460HLE and P265 steels welded sheets. The results obtained by the ultrasonic Lcr wave technique were compared with those obtained by the hole drilling technique. This work confirms the possibility of evaluating the residual stresses induced by welding using the ultrasonic method.

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Non-destructive measurements of residual stresses in structural details of bridges

Zavarivanje i zavarene konstrukcije ◽

10.5937/zzk2002065k ◽

2020 ◽

Vol 65 (2) ◽

pp. 65-74

Author(s):

Jacob Kleimana ◽

Yuri Kudryavtsevb

Keyword(s):

Residual Stress ◽

Stress Distribution ◽

Residual Stresses ◽

Fatigue Cracks ◽

Ultrasonic Transducer ◽

Ultrasonic Method ◽

Ultrasonic Waves ◽

Actual Measurement ◽

Maintenance And Repair ◽

Structural Details

Bridges are vital in our society for uninterrupted transportation of goods and people on roads and railways and timely maintenance and repair of bridges are of outmost importance. The residual stresses have a significant effect on the process of the initiation and propagation of the fatigue cracks in welded elements and are responsible for many bridge failures.Knowledge of residual stresses, their distribution and their nature is, therefore, of paramount importance in all stages of bridge's design, building and maintenance. Among nondestructive methods for residual stress measurements the use of ultrasonic waves is gaining popularity and acceptance. A portable instrument, UltraMARS that is capable of measuring residual stresses in materials either averaged through thickness or in surface and subsurface layers using ultrasonic waves of different frequencies and displaying the results in a form of a continuous curve on the screen of the instrument was developed and used successfully in many investigations [1, 2]. The main principles of operation and used methodology are briefly discussed, with actual measurement examples using the bulk, the surface and the subsurface presented. A new transducer for measurement of surface and subsurface stresses with a variable base between the ultrasonic wave sender and receiver was designed and manufactured recently. By changing the distance between the sender and receiver it is possible to obtain nondestructively information on residual stress distribution through a certain range of thicknesses of the interrogated materials and structures. Results of calibration of the new variable base ultrasonic transducer (VBUT) for a number of selected materials will be presented. The results of residual stresses measured in structural details of a bridge that was damaged as well as in a number of welded bridges before and after application of improvement treatment used to beneficially redistribute the residual stresses are also presented. The obtained data on residuals stress distribution had proven that the nondestructive ultrasonic method for measurement of residual stresses is a practical and useful tool in maintenance and repair of bridges.

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Evaluation of 7050 Aluminum Plates Joined by Friction Stir Welding Using Acoustoelastic

Volume 2: Advanced Manufacturing ◽

10.1115/imece2017-71668 ◽

2017 ◽

Author(s):

Shirley Alexandra García Ruano ◽

Felipe Bertelli ◽

Auteliano Antunes dos Santos

Keyword(s):

Aluminum Alloy ◽

Friction Stir Welding ◽

Residual Stresses ◽

Ultrasonic Method ◽

Welding Process ◽

Longitudinal Direction ◽

Structural Components ◽

Friction Stir ◽

Low Weight ◽

Aluminum Plates

The 7050-T7451 aluminum alloy has been widely used in the aerospace industry. Due to its chemical composition, this alloy has high levels of mechanical properties that allow the production of low-weight aircraft structural components. However, these alloys are thermally treatable and are not able to bear manufacturing processes involving heat. Because of the importance of their applications, studies based on the development of solid state welding process would be desirable aiming to find an alternative to generate welded joints for this kind of components. In this work, an investigation concerning the behavior of the 7050-T7451 aluminum alloy during Friction Stir Welding (FSW) was carried out. The profile of longitudinal residual stresses of plates welded by the FSW process was obtained using the ultrasonic method through critically refracted longitudinal waves (LCR). Two different frequencies were employed, 3.5 MHz and 5 MHz. The measurements were performed in the longitudinal direction of the welded joint at different distances from the center line of the weld. The magnitude and distribution of residual stresses found with this method are consistent with literature review, reaching 150MPa on the center of the weld.

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