Journal articles on the topic 'Very High Cycle Fatigue, VHCF, ultrasonic testing, size effect'
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1
Tridello, Andrea, Davide Salvatore Paolino, and Massimo Rossetto. "Ultrasonic VHCF Tests on Very Large Specimens with Risk-Volume Up to 5000 mm3." Applied Sciences 10, no. 7 (March 25, 2020): 2210. http://dx.doi.org/10.3390/app10072210.
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The research on the size-effects in Very-High-Cycle Fatigue (VHCF) has recently drawn the attention of several scholars. The fatigue cracks in VHCF originate from the largest defect present within the loaded material volume (risk-volume) and the larger the risk-volume, the larger the probability of critical defects affecting the VHCF response (size-effect). Many models have been proposed in the literature to deal with size-effects in VHCF. However, the proposed models cannot be validated on full-scale components, since VHCF tests are typically carried out with ultrasonic fatigue testing machines. The authors have proposed a specimen geometry, the so-called Gaussian specimens, to enlarge as much as possible the risk-volume in ultrasonic VHCF tests. In this study, fully reversed tension–compression ultrasonic VHCF tests up to 109 cycles were carried out on AISI H13 steel Gaussian specimens with a risk-volume of 5000 mm3, two times larger than the largest tested in the literature. The stress distribution and the absence of bending loads were verified with strain gages, proving that VHCF tests on risk-volumes of 5000 mm3 can be reliably carried out. Ultrasonic VHCF tests were also carried out on small hourglass specimens, confirming that larger risk-volumes allow for a more reliable design against VHCF failures.
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Tridello, A., D. S. Paolino, G. Chiandussi, and Massimo Rossetto. "Gaussian Specimens for Gigacycle Fatigue Tests: Evaluation of Temperature Increment." Key Engineering Materials 627 (September 2014): 85–88. http://dx.doi.org/10.4028/www.scientific.net/kem.627.85.
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Experimental tests investigating very-high-cycle fatigue (VHCF) properties of materials are commonly performed with ultrasonic testing machines, which allow for a significant reduction of testing time. In order to evaluate the effect of tested material volume (size-effect) on VHCF properties, the Authors recently proposed to adopt Gaussian specimens for VHCF tests. Investigation of size-effect with Gaussian specimen induces large mechanical power dissipation and temperature increment that must be taken into account. The present paper proposes an analytical model, which allows to approximately predict the dissipated mechanical power and the temperature increment in Gaussian specimens. The analytical model is also numerically verified through a Finite Element Analysis.
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Ghadimi, Hamed, Arash P. Jirandehi, Saber Nemati, Huan Ding, Abdelrahman Garbie, Jonathan Raush, Congyuan Zeng, and Shengmin Guo. "Effects of Printing Layer Orientation on the High-Frequency Bending-Fatigue Life and Tensile Strength of Additively Manufactured 17-4 PH Stainless Steel." Materials 16, no. 2 (January 4, 2023): 469. http://dx.doi.org/10.3390/ma16020469.
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In this paper, small blocks of 17-4 PH stainless steel were manufactured via extrusion-based bound powder extrusion (BPE)/atomic diffusion additive manufacturing (ADAM) technology in two different orientations. Ultrasonic bending-fatigue and uniaxial tensile tests were carried out on the test specimens prepared from the AM blocks. Specifically, a recently-introduced small-size specimen design is employed to carry out time-efficient fatigue tests. Based on the results of the testing, the stress–life (S-N) curves were created in the very high-cycle fatigue (VHCF) regime. The effects of the printing orientation on the fatigue life and tensile strength were discussed, supported by fractography taken from the specimens’ fracture surfaces. The findings of the tensile test and the fatigue test revealed that vertically-oriented test specimens had lower ductility and a shorter fatigue life than their horizontally-oriented counterparts. The resulting S-N curves were also compared against existing data in the open literature. It is concluded that the large-sized pores (which originated from the extrusion process) along the track boundaries strongly affect the fatigue life and elongation of the AM parts.
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Gao, Tao, Zhidan Sun, Hongqian Xue, and Delphine Retraint. "Effect of Surface Mechanical Attrition Treatment on the very high cycle fatigue behavior of TC11." MATEC Web of Conferences 165 (2018): 09001. http://dx.doi.org/10.1051/matecconf/201816509001.
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As an important engine component material, TC11 (Ti-6.5Al-3.5Mo-1.5Zr-0.3Si) titanium alloy is subjected to high frequency cyclic loading and its failure occurs beyond 109 cycles. It is thus essential to investigate the very high cycle fatigue (VHCF) behavior of this alloy. Surface Mechanical Attrition Treatment (SMAT) is a promising surface treatment technique to improve fatigue strength by modifying the surface microstructure. Therefore, it is important to understand the fatigue damage and failure process of SMATed titanium alloy in the VHCF regime. In this work, VHCF tests of TC11 before and after SMAT under fully reversed loading were conducted at room temperature by using an ultrasonic fatigue testing machine at a frequency of 20 kHz. The preliminary results seem to indicate that SMAT can reduce fatigue strength and fatigue life of TC11. Fracture surface analysis of the specimens before and after SMAT was performed using scanning electron microscope (SEM) to investigate the mechanisms of crack initiation and propagation. Particular attention was paid to fatigue crack initiation sites. The effect of SMAT on damage mechanism of SMATed TC11 in the VHCF regime was discussed.
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Xiong, Zhihong, Takashi Naoe, and Masatoshi Futakawa. "Effect of Artificial Defects on the Very High Cycle Fatigue Behavior of 316L Stainless Steel." Metals 9, no. 4 (April 4, 2019): 412. http://dx.doi.org/10.3390/met9040412.
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Widely used for structural materials in nuclear engineering, 316L austenitic stainless steel undergoes very high cycle fatigue (VHCF) throughout its service life. Since defects caused by service conditions are unavoidable in many engineering components during service life, the effects should be properly understood. In the present study, the effect of surface defects on the VHCF behavior were investigated on solution annealed (SA) and cold-worked (CW) 316L. Surface defects were artificially created using indentation. The VHCF test was conducted using an ultrasonic fatigue testing system. The results showed that the fatigue crack initiation was independent of the indent with the applied range of depth in this research. Furthermore, the critical depth of the indent was evaluated based on an empirical formula (Murakami’s model). In the case of SA 316L, the VHCF strength was not affected when the indent depth was less than 40 μm, which is consistent with the value obtained from the empirical formula. In the case of 20% CW 316L, the VHCF strength was not affected when the indent depth was less than 80 μm. The experimental results, i.e., the critical depth of the indent, were much larger than the results obtained from the empirical formula, and might have been caused by the plastic deformation, residual stress, and probable deformation-induced martensite transition around the indent.
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Gao, Tao, Zhidan Sun, Hongqian Xue, Emin Bayraktar, Zhi Qin, Bin Li, and Han Zhang. "Effect of Turning on the Surface Integrity and Fatigue Life of a TC11 Alloy in Very High Cycle Fatigue Regime." Metals 10, no. 11 (November 12, 2020): 1507. http://dx.doi.org/10.3390/met10111507.
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In this work, the effect of a turning process on fatigue performance of a Ti-6.5Al-3.5Mo-1.5Zr-0.3Si (TC11) titanium alloy is studied in the high cycle fatigue (HCF) and very high cycle fatigue (VHCF) regimes. For this purpose, the surface characteristics including surface morphology, surface roughness and residual stress were investigated. Moreover, axial fatigue tests were conducted with an ultrasonic fatigue testing system working at a frequency of 20 kHz. The results show that the turning process deteriorated the fatigue properties in both HCF and VHCF regimes. The fatigue strength at 1 × 108 cycles of turned samples is approximately 6% lower than that of electropolished ones. Fracture surface observations indicate that turning marks play a crucial role in the fatigue damage process, especially in the crack initiation stage. It was observed that the crack of all the turned samples originated from turning marks. In addition, the compressive residual stress induced by the turning process played a more effective role in resisting crack propagation in the VHCF regime than in the HCF regime.
7
Bülbül, Fatih, Tina Kirsten, Marcel Wicke, Martina Zimmermann, Angelika Brückner-Foit, and Hans-Jürgen Christ. "Crack growth behaviour of aluminium wrought alloys in the Very High Cycle Fatigue regime." MATEC Web of Conferences 165 (2018): 20007. http://dx.doi.org/10.1051/matecconf/2018165020007.
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Investigations have shown that in the regime of Very High Cycle Fatigue (VHCF) “natural” crack initiation often takes place underneath the material surface leading to crack propagation without contact to atmospheric components. In order to elucidate the environmental damage contribution and its effect on the VHCF long crack propagation, fatigue experiments with alternating environment (vacuum and laboratory air) were performed. An ultrasonic fatigue testing system (USFT) equipped with a small vacuum chamber was applied that enables the in-situ examination of the long fatigue crack propagation at a resonance frequency of about 20 kHz by using a long distance microscope. By means of the Focused-Ion-Beam technique, micro-notches were prepared in the USFT specimens. The tests were carried out on the aluminium alloys EN-AW 6082 and 5083 in different conditions. It has been found that the atmosphere has a significant influence on the VHCF long crack propagation which manifests itself in the crack path as well as in the crack growth rates. Because of pronounced single sliding in vacuum, shear-stress-controlled crack propagation was detected whereas in laboratory air normal-stress-controlled crack propagation occurred. Furthermore, it has been proven that the secondary precipitation state of the aluminium alloy significantly influences the VHCF long crack propagation in vacuum.
8
Bülbül, Fatih, Tina Kirsten, Marcel Wicke, Martina Zimmermann, Angelika Brückner-Foit, and Hans-Jürgen Christ. "Crack growth behaviour of aluminium wrought alloys in the Very High Cycle Fatigue regime." MATEC Web of Conferences 165 (2018): 20007. http://dx.doi.org/10.1051/matecconf/201816520007.
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Investigations have shown that in the regime of Very High Cycle Fatigue (VHCF) “natural” crack initiation often takes place underneath the material surface leading to crack propagation without contact to atmospheric components. In order to elucidate the environmental damage contribution and its effect on the VHCF long crack propagation, fatigue experiments with alternating environment (vacuum and laboratory air) were performed. An ultrasonic fatigue testing system (USFT) equipped with a small vacuum chamber was applied that enables the in-situ examination of the long fatigue crack propagation at a resonance frequency of about 20 kHz by using a long distance microscope. By means of the Focused-Ion-Beam technique, micro-notches were prepared in the USFT specimens. The tests were carried out on the aluminium alloys EN-AW 6082 and 5083 in different conditions. It has been found that the atmosphere has a significant influence on the VHCF long crack propagation which manifests itself in the crack path as well as in the crack growth rates. Because of pronounced single sliding in vacuum, shear-stress-controlled crack propagation was detected whereas in laboratory air normal-stress-controlled crack propagation occurred. Furthermore, it has been proven that the secondary precipitation state of the aluminium alloy significantly influences the VHCF long crack propagation in vacuum.
9
Schneider, Norbert, Brita Pyttel, Christina Berger, and Matthias Oechsner. "Influence of Frequency and Testing Technique on the Fatigue Behaviour of Quenched and Tempered Steel in the VHCF-Regime." Advanced Materials Research 891-892 (March 2014): 1430–35. http://dx.doi.org/10.4028/www.scientific.net/amr.891-892.1430.
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Today in many cases ultrasonic testing machines with a frequency of f ≈ 20 kHz are used for investigations of the fatigue behaviour up to the very high cycle regime (VHCF-regime). A question that arises is if the results of these high frequency fatigue tests are comparable to conventional fatigue tests. This paper compares the fatigue behaviour of a quenched and tempered steel 50CrMo4 in two different tempered conditions investigated at low frequencies (f ≤ 400 Hz) on a servohydraulic testing machine and at a high frequency (f ≈ 20 kHz) on an ultrasonic fatigue testing machine. Effects which can occur because of the different testing techniques and testing frequencies are investigated. A concept is derived to describe the frequency effect caused by the strain rate. The estimations are compared with results of the fatigue tests.
10
Paolino, Davide S., Andrea Tridello, Jacopo Fiocchi, Carlo A. Biffi, Giorgio Chiandussi, Massimo Rossetto, and Ausonio Tuissi. "VHCF Response up to 109 Cycles of SLM AlSi10Mg Specimens Built in a Vertical Direction." Applied Sciences 9, no. 15 (July 24, 2019): 2954. http://dx.doi.org/10.3390/app9152954.
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It is well-known that many manufacturing parameters affect the quasi-static and the fatigue response of additive manufacturing (AM) parts. In particular, due to the layer-by-layer production, the load orientation, with respect to the building direction, plays a fundamental role for the fatigue response. This paper investigates the fatigue response up to 109 cycles (very high cycle fatigue (VHCF)) of selective laser melting (SLM) AlSi10Mg specimens built in a vertical direction. Ultrasonic tension-compression tests (stress ratio of –1) are carried out on as-built Gaussian specimens with a large loaded volume (2300 mm3). Fracture surfaces are investigated with the scanning electron microscope to analyze the defects originating the VHCF failure. Probabilistic S-N curves are estimated and analyzed. Experimental results confirm that the defect size controls the VHCF response, thus highlighting the importance of testing large risk volumes for a reliable assessment of VHCF behavior. The average value of the VHCF strength is close to that of the hourglass specimen tested in the literature. The variability of the VHCF strength is instead significantly larger, due to the scattered size distribution of the defects located near the specimen surface, which is the most critical region for crack initiation.
11
Wen-jie, PENG, XUE Huan, GE rui, and PENG zhou. "The influential factors on very high cycle fatigue testing results." MATEC Web of Conferences 165 (2018): 20002. http://dx.doi.org/10.1051/matecconf/201816520002.
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When the fatigue cycle is extended from high cycle (105~107) to very high cycle (107~109), the fatigue testing results will be more sensitive to the influential factors such as specimen size, specimen surface roughness and the inclusion size. The influential factors on the very high cycle fatigue testing results are investigated in the present paper. Firstly, the design and control method for ultrasonic fatigue test were introduced for several specimen shapes. The effect of the shape, size and the surface roughness of specimen on the ultrasonic fatigue test results are investigated. Meanwhile, the effect of test frequency and the size of the inclusion on the fatigue test results are also investigated. It is concluded that: 1. the test results of specimen with different shape and size differ with each other, due to the risk volume is different. 2. There is a critical roughness for the specimen, depending on the hardness of tested metallic material. A larger roughness than the critical one will lead to a premature fracture. 3. The frequency effect is obvious for the low strength steel, however, is prone to vanish for the very high strength steel. 4. The very high cycle fatigue will be more sensitive to the inclusion size as the strength increases and the S/N curve character is strongly related to the size of the inclusion.
12
Khatibi, Golta, Ali Mazloum-Nejadari, Martin Lederer, Mitra Delshadmanesh, and Bernhard Czerny. "Fatigue life time modelling of Cu and Au fine wires." MATEC Web of Conferences 165 (2018): 06002. http://dx.doi.org/10.1051/matecconf/201816506002.
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In this study, the influence of microstructure on the cyclic behaviour and lifetime of Cu and Au wires with diameters of 25μm in the low and high cycle fatigue regimes was investigated. Low cycle fatigue (LCF) tests were conducted with a load ratio of 0.1 and a strain rate of ~2e-4. An ultrasonic resonance fatigue testing system working at 20 kHz was used to obtain lifetime curves under symmetrical loading conditions up to very high cycle regime (VHCF). In order to obtain a total fatigue life model covering the low to high cycle regime of the thin wires by considering the effects of mean stress, a four parameter lifetime model is proposed. The effect of testing frequency on high cycle fatigue data of Cu is discussed based on analysis of strain rate dependency of the tensile properties with the help of the material model proposed by Johnson and Cook.
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Jebieshia, T. R., Jong Min Kim, Jung Woo Kang, Seok Woo Son, and Heuy Dong Kim. "Microstructural and Very High Cycle Fatigue (VHCF) Behavior of Ti6Al4V—A Comparative Study." Materials 13, no. 8 (April 21, 2020): 1948. http://dx.doi.org/10.3390/ma13081948.
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In this study, an investigation is carried out to evaluate and compare the material and physical properties of Grade 5 Titanium alloy (Ti6Al4V G5) samples of three different impeller manufacturers. The study aims to identify the efficient impeller core material from different Ti6Al4V G5 manufacturers. Ultrasonic fatigue test for Ti6Al4V samples of 100 horsepower (hp) centrifugal compressor impeller parts is performed before and after heat treatment. The effect of microstructure on Very High Cycle Fatigue (VHCF) behavior of Ti6Al4V is also analyzed and discussed in detail. Optical Microscopy (OM) and Scanning Electron Microscopy (SEM) observation are carried out to investigate the microstructure of different Ti6Al4V material samples. The dynamic elastic properties are measured by the Impulse Excitation Technique (IET) at room temperature. The fracture behavior of the tensile specimens is analyzed by SEM. Post-heat-treatment analysis of Ti6Al4V is also carried out and presented which affects the grain size of the material sample and thus considerable effect in the mechanical properties. Chemical composition investigation of Ti6Al4V using SEM and Energy Dispersive X-ray Spectroscopy (EDS) also included in this study.
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Beck, Tilmann, Stephan A. Kovacs, and Fabian Ritz. "VHCF Behavior and Word Hardening of a Ferritic-Martensitic Steel at High Mean Stresses." Key Engineering Materials 664 (September 2015): 246–54. http://dx.doi.org/10.4028/www.scientific.net/kem.664.246.
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Low-pressure steam turbine blades undergo VHCF-loadings induced by inhomogenous flow behind the vanes resulting in excitation frequencies of ≈ 2 kHz for rotational speeds of 50 Hz and a typical number of stator vanes of ≈ 60. The VHCF loading is superimposed by considerable mean stresses caused by centrifugal forces. In the present study, the VHCF-behavior of the ferritic-martensitic turbine blade steel X10CrNiMoV12-2-2 is investigated using an ultrasonic fatigue testing system up to cycle numbers of 5∙109 at stress ratios from R = -1 up to 0.7, i.e. up to very high mean stresses. Generally, crack initiation changes from the surface to internal inclusions at fatigue lives around 4∙107. The transition between fatigue failure and run-outs is shifted to higher lifetime with increasing R, and fine grained areas (FGAs) at the crack initiation sites only occur at R < -0.1. However, the fracture mechanics approach proposed by Murakami consistently describes the lifetime behavior for all load ratios over 4 decades of lifetime. At R up from 0.5 considerable cyclic creep occurs, even for lifetimes above 108 cycles, resulting in cyclic hardening which was proved by microhardness measurements at longitudinal sections. This effect at least partially explains the high maximum stresses close to the tensile strength of the material occurring in the VHCF regime at load ratios ≥ 0.5.
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Peng, Wen Jie, Yue Wang, Huan Xue, and Jia He. "On the Research and Application of Ultrasonic Fatigue Testing Technology." Key Engineering Materials 664 (September 2015): 62–67. http://dx.doi.org/10.4028/www.scientific.net/kem.664.62.
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In the present paper, the characteristic and the application of ultrasonic fatigue testing technology is illuminated. The main problems i.e. the size effect, the thermal effect and frequency effect due to the high frequency are discussed. The results show that: 1. As there is a size effect, a uniform specimen size should be adopted in the very-high cycle fatigue standard and for special designed specimen the designed size should be noted along with the fatigue test results; 2.the heat generation attributes mainly to the low yield strength and the high applied stress, as a result, ultrasonic fatigue testing technology can be mainly applied to the ultra-high cycle fatigue test of high-strength steel; 3.the frequency effect is related to the crystal structure of metallic materials, however, ultrasonic fatigue testing technology can be applied to conduct the comparison of the fatigue properties of the same steel grade before and after the smelting process.
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Lee, Byung-Hoon, Sung-Woo Park, Soong-Keun Hyun, In-Sik Cho, and Kyung-Taek Kim. "Mechanical Properties and Very High Cycle Fatigue Behavior of Peak-Aged AA7021 Alloy." Metals 8, no. 12 (December 5, 2018): 1023. http://dx.doi.org/10.3390/met8121023.
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The effect of heat treatment condition on non-Cu AA7021 alloy was investigated with respect to mechanical properties and very high cycle fatigue behavior. With a focus on the influence of heat treatment, AA7021 alloy was solution heat-treated at 470 °C for 4 h and aged at 124 °C. Comparing the results of solution-treated and peak-aged AA7021 alloy shows a significant increase in Vickers hardness and tensile strength. The hardness of AA7021 alloy was increased by 65% after aging treatment, and both tensile strength and yield strength were increased by 50~80 MPa in each case. In particular, this paper investigated the very high cycle fatigue behavior of AA7021 alloy with the ultrasonic fatigue testing method using a resonance frequency of 20 kHz. The fatigue results showed that the stress amplitude of peak-aged AA7021 alloy was about 50 MPa higher than the solution-treated alloy at the same fatigue cycles. Furthermore, it was confirmed that the size of the crack initiation site was larger after peak aging than after solution treatment.
17
Celli, Dino, Onome Scott-Emuakpor, Justin Warner, and Tommy George. "Investigation of Self-Heating During Ultrasonic Fatigue Testing and Effect On Very High Cycle Fatigue Behavior of Titanium 6Al-4V." Journal of Engineering for Gas Turbines and Power, September 22, 2022. http://dx.doi.org/10.1115/1.4055726.
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Abstract Very high cycle fatigue (VHCF) data and experiments, 10^7-10^9 cycles to failure, has traditionally been both a cumbersome and costly task to perform. However, characterizing VHCF behavior of material systems are critical for the design and sustainability of turbine engines as outlined in the turbine engine structural integrity program (ENSIP). With recent advancements, ultrasonic fatigue test systems have become increasingly available to generate VHCF fatigue data. A primary consideration for ultrasonic fatigue testing is the frequency of loading, the resulting thermal evolution, and its effect on fatigue life. To mitigate the heat generation within the specimen during experiments, cooling air is directed to the specimen and cyclic loading is performed by selecting an appropriate test frequency or defining a duty cycle rather than continuously subjected to fatigue. However, standardization of experimental test procedures remains ongoing and continues to be developed. In this study a Shimadzu USF-1000A ultrasonic fatigue test system is used to characterized VHCF behavior of Ti 6Al-4V to understand the effect of duty cycle and thermal evolution on fatigue life for ultrasonic fatigue testing. Titanium 6Al-4V test specimens are subjected to fully reversed axial fatigue at 20kHz exciting resonance in an axial mode to better characterize the experimental process. Heat generation is monitored in-situ via a single-point optical pyrometer and in-situ mechanical and thermal data is collected and compared to standardized servo-hydraulic fatigue test data performed in this study as well as from data found in the literature.