https://sam.ensam.eu:443 The DSpace digital repository system captures, stores, indexes, preserves, and distributes digital research material. Tue, 09 Jun 2026 18:59:54 GMT 2026-06-09T18:59:54Z http://hdl.handle.net/10985/10079 Ultrasonic fatigue tests at high temperature on an austenitic steel WAGNER, D; CAVALIERI, F.J; BATHIAS, Claude; RANC, Nicolas The objective of this paper is to study the gigacycle fatigue behavior of an austenitic steel at temperatures of 600 °C and 700 °C under fully reverse loading (R=−1). Numerical simulation by finite element method (FEM) was used to design the specimens and to analyze the effects of the variation in the dynamic Young modulus with temperature from measurements of the ultrasonic resonance frequency. Finally, new stress-life curves for this material are presented for a lifetime range from 105 to 109 cycles at room temperature, 600 °C and 700 °C. Sun, 01 Jan 2012 00:00:00 GMT http://hdl.handle.net/10985/10079 2012-01-01T00:00:00Z WAGNER, D CAVALIERI, F.J BATHIAS, Claude RANC, Nicolas The objective of this paper is to study the gigacycle fatigue behavior of an austenitic steel at temperatures of 600 °C and 700 °C under fully reverse loading (R=−1). Numerical simulation by finite element method (FEM) was used to design the specimens and to analyze the effects of the variation in the dynamic Young modulus with temperature from measurements of the ultrasonic resonance frequency. Finally, new stress-life curves for this material are presented for a lifetime range from 105 to 109 cycles at room temperature, 600 °C and 700 °C. http://hdl.handle.net/10985/9281 Very high cycle fatigue of a high strength steel under sea water corrosion: A strong corrosion and mechanical damage coupling PEREZ MORA, Ruben; PALIN-LUC, Thierry; BATHIAS, Claude; PARIS, Paul Croce This paper is focused on the effect of sea water corrosion on the gigacycle fatigue strength of a martensitic–bainitic hot rolled steel R5 used for manufacturing off-shore mooring chains for petroleum platforms in the North Sea. Crack initiation fatigue tests in the regime of 106 to 1010 cycles were carried out on smooth specimens under three different environment conditions: (i) without any corrosion (virgin state) in air, (ii) in air after pre-corrosion, and (iii) in-situ corrosion-fatigue under artificial sea water flow. A drastic effect of sea water corrosion was found: the median fatigue strength beyond 108 cycles is divided by 5 compared to virgin state specimens. The crack initiation sites were corrosion pits caused by pre- corrosion or created during corrosion-fatigue under sea water flow. Furthermore some sub-surface and internal crack initiations were observed on specimens without any corrosion (virgin state). Crack propagation curves were obtained in mode I in air and under sea water flow. Calculation of the stress intensity factor at the tip of cracks emanating from hemispherical surface pits combined with the Paris–Hertzberg–Mc Clintock crack growth rate model showed that fatigue crack initiation period represents most of the fatigue life in the VHCF regime. Additional original experiments have shown physical evidences that the fatigue strength in the gigacycle regime under sea water flow is mainly governed by the corrosion process with a strong coupling between cyclic loading and corrosion. Thu, 01 Jan 2015 00:00:00 GMT http://hdl.handle.net/10985/9281 2015-01-01T00:00:00Z PEREZ MORA, Ruben PALIN-LUC, Thierry BATHIAS, Claude PARIS, Paul Croce This paper is focused on the effect of sea water corrosion on the gigacycle fatigue strength of a martensitic–bainitic hot rolled steel R5 used for manufacturing off-shore mooring chains for petroleum platforms in the North Sea. Crack initiation fatigue tests in the regime of 106 to 1010 cycles were carried out on smooth specimens under three different environment conditions: (i) without any corrosion (virgin state) in air, (ii) in air after pre-corrosion, and (iii) in-situ corrosion-fatigue under artificial sea water flow. A drastic effect of sea water corrosion was found: the median fatigue strength beyond 108 cycles is divided by 5 compared to virgin state specimens. The crack initiation sites were corrosion pits caused by pre- corrosion or created during corrosion-fatigue under sea water flow. Furthermore some sub-surface and internal crack initiations were observed on specimens without any corrosion (virgin state). Crack propagation curves were obtained in mode I in air and under sea water flow. Calculation of the stress intensity factor at the tip of cracks emanating from hemispherical surface pits combined with the Paris–Hertzberg–Mc Clintock crack growth rate model showed that fatigue crack initiation period represents most of the fatigue life in the VHCF regime. Additional original experiments have shown physical evidences that the fatigue strength in the gigacycle regime under sea water flow is mainly governed by the corrosion process with a strong coupling between cyclic loading and corrosion. http://hdl.handle.net/10985/14800 Very high cycle fatigue for single phase ductile materials: Comparison between α-iron, copper and α-brass polycrystals BLANCHE, Antoine; WANG, Chong; PHUNG, Ngoclam; WAGNER, Daniele; BATHIAS, Claude; CHRYSOCHOOS, André; MUGHRABI, Haeel; RANC, Nicolas; FAVIER, Véronique In this paper, the main results obtained in the framework of a National French Agency project called DISFAT, standing for “Dissipation in Fatigue”, are presented. The project was dedicated to the microplastic mechanisms leading to crack initiation in the case of ductile metals loaded in very high cycle fatigue. Fatigue tests were carried out at 20 kHz using an ultrasonic facility. In order to investigate the microplastic mechanisms, slip markings at the surface of the specimens were observed and the self-heating of the specimen during the tests was measured by thermography to deduce the dissipated energy. Polycrystalline copper, α-brass and α-iron were investigated. A good correlation was found between persistent slip bands and dissipated energy. The dissipated energy for the three materials was of the same order of magnitude but while α-iron reached a stable dissipative state, the dissipated energy in the case of copper and α-brass was found to continue to increase gradually with increasing numbers of cycles. That change in dissipated energy during cycling was consistent with the development of persistent slip bands. Both were discussed with regard to the materials. Fri, 01 Jan 2016 00:00:00 GMT http://hdl.handle.net/10985/14800 2016-01-01T00:00:00Z BLANCHE, Antoine WANG, Chong PHUNG, Ngoclam WAGNER, Daniele BATHIAS, Claude CHRYSOCHOOS, André MUGHRABI, Haeel RANC, Nicolas FAVIER, Véronique In this paper, the main results obtained in the framework of a National French Agency project called DISFAT, standing for “Dissipation in Fatigue”, are presented. The project was dedicated to the microplastic mechanisms leading to crack initiation in the case of ductile metals loaded in very high cycle fatigue. Fatigue tests were carried out at 20 kHz using an ultrasonic facility. In order to investigate the microplastic mechanisms, slip markings at the surface of the specimens were observed and the self-heating of the specimen during the tests was measured by thermography to deduce the dissipated energy. Polycrystalline copper, α-brass and α-iron were investigated. A good correlation was found between persistent slip bands and dissipated energy. The dissipated energy for the three materials was of the same order of magnitude but while α-iron reached a stable dissipative state, the dissipated energy in the case of copper and α-brass was found to continue to increase gradually with increasing numbers of cycles. That change in dissipated energy during cycling was consistent with the development of persistent slip bands. Both were discussed with regard to the materials. http://hdl.handle.net/10985/17324 Crack path in aeronautical titanium alloy under ultrasonic torsion loading NIKITIN, Alexander; BATHIAS, Claude; PALIN-LUC, Thierry; SHANYAVSKIY, Andrey This paper discusses features of fatigue crack initiation and growth in aeronautical VT3-1 titanium alloy under pure torsion loading in gigacycle regime. Two materials: extruded and forged VT3-1 titanium alloys were studied. Torsion fatigue tests were performed up to fatigue life of 109 cycles. The results of the torsion tests were compared with previously obtained results under fully reversed axial loading on the same alloys. It has been shown that independently on production process as surface as well subsurface crack initiation may appear under ultrasonic torsion loading despite the maximum stress amplitude located at the specimen surface. In the case of surface crack initiation, a scenario of crack initiation and growth is similar to HCF regime except an additional possibility for internal crack branching. In the case of subsurface crack, the initiation site is located below the specimen surface (about 200 μm) and is not clearly related to any material flaw. Internal crack initiation is produced by shear stress in maximum shear plane and early crack growth is in Mode II. Crack branching is limited in the case of internal crack initiation compared to surface one. A typical ‘fish-eye’ crack can be observed at the torsion fracture surface, but mechanism of crack initiation seems not to be the same than under axial fatigue loading. Thu, 01 Jan 2015 00:00:00 GMT http://hdl.handle.net/10985/17324 2015-01-01T00:00:00Z NIKITIN, Alexander BATHIAS, Claude PALIN-LUC, Thierry SHANYAVSKIY, Andrey This paper discusses features of fatigue crack initiation and growth in aeronautical VT3-1 titanium alloy under pure torsion loading in gigacycle regime. Two materials: extruded and forged VT3-1 titanium alloys were studied. Torsion fatigue tests were performed up to fatigue life of 109 cycles. The results of the torsion tests were compared with previously obtained results under fully reversed axial loading on the same alloys. It has been shown that independently on production process as surface as well subsurface crack initiation may appear under ultrasonic torsion loading despite the maximum stress amplitude located at the specimen surface. In the case of surface crack initiation, a scenario of crack initiation and growth is similar to HCF regime except an additional possibility for internal crack branching. In the case of subsurface crack, the initiation site is located below the specimen surface (about 200 μm) and is not clearly related to any material flaw. Internal crack initiation is produced by shear stress in maximum shear plane and early crack growth is in Mode II. Crack branching is limited in the case of internal crack initiation compared to surface one. A typical ‘fish-eye’ crack can be observed at the torsion fracture surface, but mechanism of crack initiation seems not to be the same than under axial fatigue loading. http://hdl.handle.net/10985/17322 Very high cycle fatigue strength and crack growth of thin steel sheets OUARABI, Mohand; PEREZ MORA, Ruben; BATHIAS, Claude; PALIN-LUC, Thierry For basic observations or for industrial applications it is of interest to use flat specimens at very high frequency in the gigacycle regime. In this work, thin flat sheet, with 1.2 mm thickness of a complex phase ferrite-martensitic steels were considered for carrying out fatigue tests at high frequency (20 kHz) up to the gigacycle regime (>109 cycles). The crack initiation tests were carried out with water cooling, while the crack growth test were carried out in laboratory air at room temperature. All the tests were carried out under loading ratio R=-1. To do that, special designs of specimens were made and computed using FEM for defining the stress amplitude for endurance tests. Special attachments for specimens to the ultrasonic system’s horn were enhanced. A particular FEM computing of the stress intensity range on crack growth specimens was carried out for determining the specimen dimensions and an equation that defines the stress intensity range as a function of the harmonic displacement amplitude, dynamic Young’s modulus, material density and crack length. Detailed procedures and fatigue results are presented in this paper. Fri, 01 Jan 2016 00:00:00 GMT http://hdl.handle.net/10985/17322 2016-01-01T00:00:00Z OUARABI, Mohand PEREZ MORA, Ruben BATHIAS, Claude PALIN-LUC, Thierry For basic observations or for industrial applications it is of interest to use flat specimens at very high frequency in the gigacycle regime. In this work, thin flat sheet, with 1.2 mm thickness of a complex phase ferrite-martensitic steels were considered for carrying out fatigue tests at high frequency (20 kHz) up to the gigacycle regime (>109 cycles). The crack initiation tests were carried out with water cooling, while the crack growth test were carried out in laboratory air at room temperature. All the tests were carried out under loading ratio R=-1. To do that, special designs of specimens were made and computed using FEM for defining the stress amplitude for endurance tests. Special attachments for specimens to the ultrasonic system’s horn were enhanced. A particular FEM computing of the stress intensity range on crack growth specimens was carried out for determining the specimen dimensions and an equation that defines the stress intensity range as a function of the harmonic displacement amplitude, dynamic Young’s modulus, material density and crack length. Detailed procedures and fatigue results are presented in this paper. http://hdl.handle.net/10985/15976 Fatigue crack initiation detection by an infrared thermography method WAGNER, D.; BATHIAS, Claude; PARIS, Paul C.; RANC, Nicolas In this paper, the study of the temperature variation during fatigue tests was carried out on different materials (steels and aluminium alloys). Tests were performed at ambient temperature using a piezoelectric fatigue system (20 kHz). The temperature field was measured on the surface of the specimen, by means of an infrared camera. Just at the beginning of the test, it was observed that the temperature increased, followed by a stabilization which corresponds to the balance between dissipated energy associated with microplasticity and the energy lost by convection and radiation at the specimen surface and by conduction inside the specimen. At the crack initiation, the surface temperature suddenly increases (whatever the localization of the initiation), which allows the determination of the number of cycles at the crack initiation and the number of cycles devoted to the fatigue crack propagation. In the gigacycle fatigue domain, more than 92% of the total life is devoted to the initiation of the crack. So, the study of the thermal dissipation during the test appears a promising method to improve the understanding of the damage and failure mechanism in fatigue and to determine the number of cycles at initiation. Fri, 01 Jan 2010 00:00:00 GMT http://hdl.handle.net/10985/15976 2010-01-01T00:00:00Z WAGNER, D. BATHIAS, Claude PARIS, Paul C. RANC, Nicolas In this paper, the study of the temperature variation during fatigue tests was carried out on different materials (steels and aluminium alloys). Tests were performed at ambient temperature using a piezoelectric fatigue system (20 kHz). The temperature field was measured on the surface of the specimen, by means of an infrared camera. Just at the beginning of the test, it was observed that the temperature increased, followed by a stabilization which corresponds to the balance between dissipated energy associated with microplasticity and the energy lost by convection and radiation at the specimen surface and by conduction inside the specimen. At the crack initiation, the surface temperature suddenly increases (whatever the localization of the initiation), which allows the determination of the number of cycles at the crack initiation and the number of cycles devoted to the fatigue crack propagation. In the gigacycle fatigue domain, more than 92% of the total life is devoted to the initiation of the crack. So, the study of the thermal dissipation during the test appears a promising method to improve the understanding of the damage and failure mechanism in fatigue and to determine the number of cycles at initiation. http://hdl.handle.net/10985/9676 Dispositif d'essai de fatigue d'une éprouvette BLANC, Michel; OSMOND, Pierre; PALIN-LUC, Thierry; BATHIAS, Claude L'invention porte sur un dispositif d'essai de fatigue d'une éprouvette comprenant un châssis pourvu d'au moins une matrice de réception de l'éprouvette. Le dispositif d'essai de fatigue comprend un système de délivrance à l'éprouvette de sollicitations à fréquence ultrasonoer comprise entre 10 kHz et 70 kHz. Thu, 01 Jan 2015 00:00:00 GMT http://hdl.handle.net/10985/9676 2015-01-01T00:00:00Z BLANC, Michel OSMOND, Pierre PALIN-LUC, Thierry BATHIAS, Claude L'invention porte sur un dispositif d'essai de fatigue d'une éprouvette comprenant un châssis pourvu d'au moins une matrice de réception de l'éprouvette. Le dispositif d'essai de fatigue comprend un système de délivrance à l'éprouvette de sollicitations à fréquence ultrasonoer comprise entre 10 kHz et 70 kHz. http://hdl.handle.net/10985/10017 A new piezoelectric fatigue testing machine in pure torsion for ultrasonic gigacycle fatigue tests: application to forged and extruded titanium alloys NIKITIN, Alexander; BATHIAS, Claude; PALIN-LUC, Thierry This article briefly discusses the history of the development of ultrasonic fatigue testing methods, with respect to industrial needs. The development of ultrasonic techniques and the progress made in the computer industry have led to improvements in ultrasonic testing techniques. It has been shown, that existing ultrasonic testing systems have limitations that lead to the need for a new ultrasonic fatigue testing machine operating in pure torsion. This paper introduces the development of a new piezoelectric machine working in the continuous regime (i.e. without pulse-pause). This machine has been used to investigate the Very High Cycle Fatigue (VHCF) properties of the VT3-1 alpha beta aeronautical titanium alloy (which is similar to Ti–6Al–4V) produced by two manufacturing processes: forging and extrusion. The extruded titanium alloy has a higher VHCF strength in torsion compared to the forged one. Despite the maximum shear stress occurring at the specimen surface under torsion loading, internal fatigue crack initiation can be observed in both the forged and extruded alloys. Thu, 01 Jan 2015 00:00:00 GMT http://hdl.handle.net/10985/10017 2015-01-01T00:00:00Z NIKITIN, Alexander BATHIAS, Claude PALIN-LUC, Thierry This article briefly discusses the history of the development of ultrasonic fatigue testing methods, with respect to industrial needs. The development of ultrasonic techniques and the progress made in the computer industry have led to improvements in ultrasonic testing techniques. It has been shown, that existing ultrasonic testing systems have limitations that lead to the need for a new ultrasonic fatigue testing machine operating in pure torsion. This paper introduces the development of a new piezoelectric machine working in the continuous regime (i.e. without pulse-pause). This machine has been used to investigate the Very High Cycle Fatigue (VHCF) properties of the VT3-1 alpha beta aeronautical titanium alloy (which is similar to Ti–6Al–4V) produced by two manufacturing processes: forging and extrusion. The extruded titanium alloy has a higher VHCF strength in torsion compared to the forged one. Despite the maximum shear stress occurring at the specimen surface under torsion loading, internal fatigue crack initiation can be observed in both the forged and extruded alloys. http://hdl.handle.net/10985/8815 Fatigue crack initiation and growth on a steel in the very high cycle regime with sea water corrosion PALIN-LUC, Thierry; PÉREZ-MORA, Ruben; BATHIAS, Claude; DOMINGUEZ, Gonzalo; PARIS, Paul Croce; ARANA, Jose Luis This paper is devoted to the effect of corrosion on the gigacycle fatigue strength of a martensitic–bainitic hot rolled steel used for manufacturing offshore mooring chains for petroleum platforms. Smooth specimens were tested under fully reversed tension between 1E6 and 1E10 cycles in three testing conditions and environments: (i) in air, (ii) in air after precorrosion and (iii) in air under real time artificial sea water flow. The fatigue strength at greater than 108 cycles is reduced by a factor more than five compared with non-corroded specimens. Fatigue cracks initiate at corrosion pits due to pre-corrosion, if any, or pits resulting from corrosion in real time during the cyclic loading. It is shown that under sea water flow, the fatigue life in the gigacycle regime is mainly governed by the corrosion process. Furthermore, the calculation of the mode I stress intensity factor at hemispherical surface defects (pits) combined with the Paris–Hertzberg–Mc Clintock crack growth rate model shows that fatigue crack initiation regime represents most of the fatigue life. The authors acknowledge Arts et Métiers ParisTech and Foundation Arts et Métiers for the financial support of P.C. Paris’ stay at LAMEFIP. They acknowledge Vicinay Cadenas S.A. for its financial support, and both the PCP France-Mexique and the CONACYT for their financial support too. Fri, 01 Jan 2010 00:00:00 GMT http://hdl.handle.net/10985/8815 2010-01-01T00:00:00Z PALIN-LUC, Thierry PÉREZ-MORA, Ruben BATHIAS, Claude DOMINGUEZ, Gonzalo PARIS, Paul Croce ARANA, Jose Luis This paper is devoted to the effect of corrosion on the gigacycle fatigue strength of a martensitic–bainitic hot rolled steel used for manufacturing offshore mooring chains for petroleum platforms. Smooth specimens were tested under fully reversed tension between 1E6 and 1E10 cycles in three testing conditions and environments: (i) in air, (ii) in air after precorrosion and (iii) in air under real time artificial sea water flow. The fatigue strength at greater than 108 cycles is reduced by a factor more than five compared with non-corroded specimens. Fatigue cracks initiate at corrosion pits due to pre-corrosion, if any, or pits resulting from corrosion in real time during the cyclic loading. It is shown that under sea water flow, the fatigue life in the gigacycle regime is mainly governed by the corrosion process. Furthermore, the calculation of the mode I stress intensity factor at hemispherical surface defects (pits) combined with the Paris–Hertzberg–Mc Clintock crack growth rate model shows that fatigue crack initiation regime represents most of the fatigue life. http://hdl.handle.net/10985/11223 Comparison of crack paths in a forged and extruded aeronautical titanium alloy loaded in torsion in the gigacycle fatigue regime NIKITIN, Alexander; PALIN-LUC, Thierry; SHANYAVSKIY, Andrey; BATHIAS, Claude This paper discusses features of fatigue crack initiation and growth in an extruded and forged VT3-1 titanium alloy loaded in pure torsion in the gigacycle regime. Torsion fatigue tests were performed at 20 kHz up to a fatigue life of 109 cycles. It has been shown that regardless of the manufacturing process both surface and subsurface crack initiation may appear under ultrasonic torsion loads despite the fact that the maximum shear stress amplitude is located at the specimen surface. In the two cases cracks initiate on planes of maximum shear stress amplitude (mode II). After reaching a certain length the cracks turn and propagate in mode I. Surface crack initiation and growth mechanisms in VHCF regime are similar to HCF ones. Subsurface crack forms a typical ‘‘fish-eye” pattern on fracture surface with three different zones: (1) small crack growth in the plane of maximum shear stress, (2) crack growth on the plane of maximum normal stress with the formation of a quasi-flat failure surface covered by fretting debris, (3) crack branching under mixed mode loading conditions (I + II + III) with the formation of several secondary cracks. Subsurface crack initiation sites are located below the specimen surface (at a depth of approximately 200 lm) for both the forged and the extruded materials. Subsurface crack growth is observed on the failure surface as being less rough. The mechanisms of subsurface crack initiation seems to be similar to these observed under fully reversed tensile loads. Fri, 01 Jan 2016 00:00:00 GMT http://hdl.handle.net/10985/11223 2016-01-01T00:00:00Z NIKITIN, Alexander PALIN-LUC, Thierry SHANYAVSKIY, Andrey BATHIAS, Claude This paper discusses features of fatigue crack initiation and growth in an extruded and forged VT3-1 titanium alloy loaded in pure torsion in the gigacycle regime. Torsion fatigue tests were performed at 20 kHz up to a fatigue life of 109 cycles. It has been shown that regardless of the manufacturing process both surface and subsurface crack initiation may appear under ultrasonic torsion loads despite the fact that the maximum shear stress amplitude is located at the specimen surface. In the two cases cracks initiate on planes of maximum shear stress amplitude (mode II). After reaching a certain length the cracks turn and propagate in mode I. Surface crack initiation and growth mechanisms in VHCF regime are similar to HCF ones. Subsurface crack forms a typical ‘‘fish-eye” pattern on fracture surface with three different zones: (1) small crack growth in the plane of maximum shear stress, (2) crack growth on the plane of maximum normal stress with the formation of a quasi-flat failure surface covered by fretting debris, (3) crack branching under mixed mode loading conditions (I + II + III) with the formation of several secondary cracks. Subsurface crack initiation sites are located below the specimen surface (at a depth of approximately 200 lm) for both the forged and the extruded materials. Subsurface crack growth is observed on the failure surface as being less rough. The mechanisms of subsurface crack initiation seems to be similar to these observed under fully reversed tensile loads.