Piezoelectric fatigue testing machines and devices

Bathìas, Claude

doi:10.1016/j.ijfatigue.2005.09.020

Cited by 210 publications

(138 citation statements)

References 3 publications

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“…The Primary Setup also offers the possibility of setting the displacement value at the tip of the specimen. During measurement, a closed-loop feedback system adjusts the exciter's power so that the average displacement per block is constant; (2) Trigger Setup menu (Fig. 8) -The trigger setup offers the possibility to test the performance of the configuration set on the primary setup.…”

Section: Data Acquisition Processing and Control Systemmentioning

confidence: 99%

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Automation in Strain and Temperature Control on VHCF with an Ultrasonic Testing Facility

Lage

Ribeiro

Montalvão

et al. 2014

Application of Automation Technology in Fatigue and Fracture Testing and Analysis

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Increased safety and reliability in mechanical components became a subject of prime importance over the past recent years. Therefore, a proper understanding of damage and fracture mechanics in materials and components designed to withstand Very High Cycle Fatigue (VHCF) loadings is extremely important nowadays. However, conventional machines used for fatigue testing are very time-consuming and costly in order to perform VHCF tests. Ultrasonic machines have been introduced as a way to increase the number of cycles in fatigue testing up to 1E 8 to 1E 10 cycles within a considerably reduced amount of time. Nevertheless, the accurate measurement of the parameters that influence fatigue life at ultrasonic frequencies (e.g., stress, displacement, strain-rate, temperature and frequency) is still a matter of concern and on-going development. Due to the high frequencies involved in VHCF testing, a huge amount of heat is generated over the specimen, which greatly affects the variables determining the fatigue behavior. This paper describes the design and instrumentation of an ultrasonic fatigue testing machine that operates at 20 kHz working frequency. Among other features, it incorporates automated strain and temperature control. In order to run automated tests, a closed loop monitoring and control system was developed based on the measured temperature and displacement amplitudes. Temperature readings are made with a pyrometer and thermography camera and displacement is monitored at the free end of the specimen with a high resolution laser. The machine's power output is continuously adjusted from the displacement readings, so that the stress variations within the specimen are as flat as possible. When temperature increases above a certain set value, a cooling function is triggered and the test is interrupted until the specimen is cooled down. Data is acquired, managed and processed with a data acquisition device working at 400 kHz sampling frequency.The advantages and limitations of metal fatigue testing at very high frequencies are discussed in this paper, with special emphasis on the strain and temperature control issues. Comparison of tests carried out with and without both displacement and temperature control are made on two metallic alloys, copper 99% and carbon steel, with the determination of S-N curves.

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Section: Data Acquisition Processing and Control Systemmentioning

confidence: 99%

“…Latest developments in the ultrasonic technique are presented by Bathias et al [1][2][3][4][5]. An extensive review of the fundamentals on VHCF fatigue using ultrasonic methods, including considerations on the machine development, its performance and applications, can be found in these works.…”

Section: Introductionmentioning

confidence: 99%

Automation in Strain and Temperature Control on VHCF with an Ultrasonic Testing Facility

Lage

Ribeiro

Montalvão

et al. 2014

Application of Automation Technology in Fatigue and Fracture Testing and Analysis

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“…This interaction which can be charac terized by a certain correlation scale, above which the interaction proceeds to a scale that determines the subsequent increment in the length of the propagating crack (size of the "process zone"). This assumption concerning the critical conditions for the aforemen tioned transition was used in interpretation of the experimental data so as to explain the self similar sce nario of fatigue crack propagation in a steel sample under conditions of gigacycle loading.The samples of R4 high strength steel (with a room temperature fatigue limit of 600 MPa for 10 6 cycles at 10 Hz) were tested under fatigue loading conditions with symmetric tension-compression cycling at 20 kHz (gigacycle loading regime) on an original setup [5]. The testing machine consisted of the following main parts: (i) generator, which con verted 50 Hz oscillations into an ultrasonic electric sinusoidal signal with a frequency of 20 kHz;…”

mentioning

confidence: 99%

“…The samples of R4 high strength steel (with a room temperature fatigue limit of 600 MPa for 10 6 cycles at 10 Hz) were tested under fatigue loading conditions with symmetric tension-compression cycling at 20 kHz (gigacycle loading regime) on an original setup [5]. The testing machine consisted of the following main parts: (i) generator, which con verted 50 Hz oscillations into an ultrasonic electric sinusoidal signal with a frequency of 20 kHz;…”

mentioning

confidence: 99%

Scaling invariance of fatigue crack growth in gigacycle loading regime

et al. 2010

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is an open access repository that collects the work of Arts et Métiers ParisTech researchers and makes it freely available over the web where possible.This is an author-deposited version published in: http://sam.ensam.eu Handle ID: .http://hdl.handle.net/10985/10516To cite this version :V. OBORIN, M. BANNIKOV, O. NAIMARK, Thierry PALIN-LUC -Scaling invariance of fatigue crack growth in gigacycle loading regime -Tech. Phys. Lett. -Vol. 36, n°11, p.1061-1063 -2010 Any correspondence concerning this service should be sent to the repository Administrator : archiveouverte@ensam.euThe task of assessing the working resource of important structures, in particular, those for aircraft engines, poses qualitatively new basic problem related to evaluation of the reliability of materials under con ditions of cyclic loading in excess of 10 6 -10 10 cycles, which refer to the field of so called gigacycle fatigue. This interest is related to the fact that the resource of loading for many important parts operating under conditions of cyclic loading exceeds the so called multicycle range. the behavior of materials in the range of gigacycle fatigue reveals some qualitative changes in the laws governing both the nucleation of cracks (in the bulk of a sample) and their propagation, which are related to changes in the mechanisms of fatigue crack nucleation and propagation. In the range of gigacycle loading, the fatigue curve exhibits discon tinuities and the behavior shows evidence of a signifi cant increase in the role of environment, so that the problem acquires an interdisciplinary character.The stages of material fracture in the range of giga cycle loading are classified based on the structural signs of damage related to a broad spectrum of spatial scales, including persistent slip bands (PSBs), fatigue striations, microcracks (formed as a result of PSB crossing), and grain boundary defects. The main damage refers to the defect scales within 0.1 μm-1 mm, which are significantly smaller than those detected by the standard methods of nondestructive testing used for the conventional monitoring of reli ability, in particular, during the exploitation of build ings.An effective method for investigating the role of initial structural heterogeneity, monitoring the accu mulation of defects on various scales (dislocation ensembles, micropores, microcracks), and determin ing critical conditions for the transition from dispersed to macroscopic fracture is offered by the quantitative fractography. This technique reveals the characteristic stages of fracture (crack nucleation and propagation), thus providing a base for evaluating the temporal resource of materials and structures under conditions of gigacycle loading.The approach to characterization of the fracture surface morphology in terms of spatiotemporal invari ants was originally proposed by Mandelbrot [1]. This method is based on an analysis of the relief of a frac ture surface, which exhibits the property of self affin ity as manifested by the invariant characteristics of the surrace re...

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“…Fretting corrosion, torsion and three-point bending fatigue experiments are also possible. [1] These experiments can also be run on variable amplitudes, which makes it possible to create arrest marks that make it possible to calculate the crack growth rate from the fracture surface. [10] …”

Section: Introductionmentioning

confidence: 99%