Search results for "residual stress"
showing 10 items of 119 documents
Investigating the effect of residual stress on hydrogen cracking in multi-pass robotic welding through process compatible non-destructive testing
2021
Abstract In this paper, the effect of Welding Residual Stress (WRS) on the size and morphology of hydrogen-induced cracks (HIC) is studied. Four samples were manufactured using a 6-axis welding robot and in two separate batches. The difference between the two batches was the clamping system used, which resulted in different amounts of welding deformation and WRS. The hydrogen cracks were intentionally manufactured in the samples using a localised water-quenching method, where water was sprayed over a specific weld pass in a predetermined position. The Phased-Array Ultrasonic Testing (PAUT) system was implemented during the welding process (high-temperature in-process method), to detect the …
In situ and postradiation analysis of mechanical stress in Al2O3:Cr induced by swift heavy-ion irradiation
2010
Abstract Optical spectroscopy and TEM techniques have been applied to study the radiation damage and correlated mechanical stresses in Al2O3 and Al2O3:Cr single crystals induced by (1–3) MeV/amu Kr, Xe and Bi ion irradiation. Mechanical stresses were evaluated in situ using a piezospectroscopic effect through the shift of the respective lines in ionoluminescence spectra. It was found that dose dependence of the stress level for Xe and Bi ions, when ionization energy loss exceeds the threshold of damage formation via electronic excitations, exhibits several alternate stages showing the build-up and relaxation of stresses. The beginning of relaxation stages is observed at fluences associated …
Measurement of edge residual stresses in glass by the phase-shifting method
2011
Abstract Control and measurement of residual stress in glass is of great importance in the industrial field. Since glass is a birefringent material, the residual stress analysis is based mainly on the photoelastic method. This paper considers two methods of automated analysis of membrane residual stress in glass sheets, based on the phase-shifting concept in monochromatic light. In particular these methods are the automated versions of goniometric compensation methods of Tardy and Senarmont. The proposed methods can effectively replace manual methods of compensation (goniometric compensation of Tardy and Senarmont, Babinet and Babinet–Soleil compensators) provided by current standards on th…
Photoelastic Analysis of Edge Residual Stresses in Glass by Automated “Test Fringes” Methods
2011
Since the glass is a birefringent material, the analysis of residual stress in glass is usually carried out by means of photoelastic methods. This paper considers the automation of the “test fringes” method which is based on the use of a Babinet compensator or of a beam subjected to bending. In particular, two automated methods are proposed: the first one is based on the use of the centre fringe method in monochromatic light and the second one is based on the use of RGB photoelasticity in white light. The proposed methods have been applied to the analysis of membranal residual stresses in some tempered glasses, showing that they can effectively replace manual methods of photoelastic analysi…
RGB photoelasticity applied to the analysis of membrane residual stress in glass
2011
The measurement of residual stresses is of great relevance in the glass industry. The analysis of residual stress in glass is usually made by photoelastic methods because glass is a photoelastic material. This paper considers the determination of membrane residual stresses in glass plates by automatic digital photoelasticity in white light (RGB photoelasticity). The proposed method is applied to the analysis of membrane residual stresses in some tempered glass. The proposed method can effectively replace manual methods based on the use of white light, which are currently provided by some technical standards.
A critical assessment of automatic photoelastic methods for the analysis of edge residual stresses in glass
2014
The measurement of residual stresses is of great importance in the glass industry. The analysis of residual stresses in the glass is usually carried out by photoelastic methods since the glass is a photoelastic material. This article considers the determination of membrane residual stresses of glass plates by digital photoelasticity. In particular, it presents a critical assessment concerning the automated methods based on gray-field polariscope, spectral content analysis, phase shifting, RGB photoelasticity, “test fringes” methods and “tint plate” method. These methods can effectively automate manual methods currently specified in some standards.
Photoelastic Analysis of Edge Residual Stresses in Glass by the Automated Tint Plate Method
2013
The analysis of residual stress in glass is usually carried out by means of photoelastic methods. This article considers the automation of the white light photoelastic method based on the use of a full-wave plate placed behind the glass plate. In particular, the method in based on the use of RGB photoelasticity in white light in conjunction with a full wave plate. The proposed method have been applied to the analysis of membrane residual stresses in tempered glass, showing that it can effectively replace manual methods of photoelastic analysis of residual stresses in glass when a low photoelastic retardation is present.
Automated Stress Separation Along Stress Trajectories
2007
A procedure for the separation of principal stresses in automated photoelasticity is presented. It is based on the integration of indefinite equations of equilibrium along stress trajectories, also known as Lame-Maxwell equations. A new algorithm for precise and reliable stress trajectory calculation, which is an essential feature of the procedure, has also been developed. Automated stress separation is carried out along stress trajectories starting from free boundaries. Experimental tests were performed on a disc in diametral compression and on a ring with internally applied pressure. Full-field principal stress values were obtained and results were compared with those from the theory of e…
Influence of the Residual Stresses Induced by Shot-Peening on the Oxidation of Zr Plates
2014
The present study evaluates the influence of the residual stress on the oxidation rate of Zr at 650°C. It is shown that the oxidation rate can be substantially decreased by shot-peening. A systematic instigation of the various factors (such as the residual stress, the surface pollution and the chemical composition of the oxidation atmosphere) is realized to separate their influence on the oxidation. The influence of an annealing made after the shot-peening is also considered. One show that the pollution of the surface during the shot-peening process is not responsible for the oxidation rate decrease.
On the thermo-mechanical loads and the resultant residual stresses in friction stir processing operations
2008
In friction stir welding and processing both a thermal flux and a mechanical action are exerted on the material determining metallurgical evolutions, changes in the mechanical behaviour and a complex residual stress state. In the paper, the metallurgical changes are examined through numerical simulation and experiments to highlight and distinguish the effects of thermal and mechanical loadings. A particular focus is made on the residual stresses generated during the stir processing of AA7075-T6 aluminium blanks. The predictions of FE model are validated by experimental measurements. Lastly, this paper presents an in-process quenching of the processed blanks for improved mechanical propertie…