The Experts below are selected from a list of 294 Experts worldwide ranked by ideXlab platform
Hiroyuki Sasahara - One of the best experts on this subject based on the ideXlab platform.
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effect of dynamic response and displacement Stress Amplitude on ultrasonic vibration cutting
Journal of Materials Processing Technology, 2009Co-Authors: Kei Harada, Hiroyuki SasaharaAbstract:Abstract In this report, the behavior of the cutting force measured through the dynamic response of tool–work piece system in ultrasonic vibration cutting was discussed first. Measured cutting force mainly depends on the ratio of net cutting time to a vibration cycle in vibration cutting (tc/T) because the tool–work piece system has much lower natural frequency comparing with the ultrasonic vibration cycle. It was confirmed by the newly proposed cutting experiment using resonated-horn-type work piece, displacement Amplitude and Stress Amplitude at the cutting point vary continuously in this device. It was shown that the measured cutting force varies corresponding to the displacement Amplitude. It was also indicated that the measured cutting force does not decrease when the cutting point is on the node of the resonated-horn-type work piece, where the Stress Amplitude is the maximum but there is no displacement Amplitude. It means that there should be the relative intermittent displacement between the tool and the chip in order to decrease the measured cutting force. In addition, the deformation resistance of the work piece material itself does not decrease with ultrasonic vibration of the Stress field. Secondly, the significance of the elastic deformation of the tool–work piece system of several microns in ultrasonic intermittent cutting was also indicated from an analytical and experimental point of view. The effect of the elastic behavior on the cutting force becomes relatively large as tc/T becomes small. The above-mentioned characteristics will be helpful to utilize the ultrasonic vibration cutting system more efficiently.
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Effect of dynamic response and displacement/Stress Amplitude on ultrasonic vibration cutting
Journal of Materials Processing Technology, 2009Co-Authors: Kei Harada, Hiroyuki SasaharaAbstract:Abstract In this report, the behavior of the cutting force measured through the dynamic response of tool–work piece system in ultrasonic vibration cutting was discussed first. Measured cutting force mainly depends on the ratio of net cutting time to a vibration cycle in vibration cutting (tc/T) because the tool–work piece system has much lower natural frequency comparing with the ultrasonic vibration cycle. It was confirmed by the newly proposed cutting experiment using resonated-horn-type work piece, displacement Amplitude and Stress Amplitude at the cutting point vary continuously in this device. It was shown that the measured cutting force varies corresponding to the displacement Amplitude. It was also indicated that the measured cutting force does not decrease when the cutting point is on the node of the resonated-horn-type work piece, where the Stress Amplitude is the maximum but there is no displacement Amplitude. It means that there should be the relative intermittent displacement between the tool and the chip in order to decrease the measured cutting force. In addition, the deformation resistance of the work piece material itself does not decrease with ultrasonic vibration of the Stress field. Secondly, the significance of the elastic deformation of the tool–work piece system of several microns in ultrasonic intermittent cutting was also indicated from an analytical and experimental point of view. The effect of the elastic behavior on the cutting force becomes relatively large as tc/T becomes small. The above-mentioned characteristics will be helpful to utilize the ultrasonic vibration cutting system more efficiently.
Kei Harada - One of the best experts on this subject based on the ideXlab platform.
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effect of dynamic response and displacement Stress Amplitude on ultrasonic vibration cutting
Journal of Materials Processing Technology, 2009Co-Authors: Kei Harada, Hiroyuki SasaharaAbstract:Abstract In this report, the behavior of the cutting force measured through the dynamic response of tool–work piece system in ultrasonic vibration cutting was discussed first. Measured cutting force mainly depends on the ratio of net cutting time to a vibration cycle in vibration cutting (tc/T) because the tool–work piece system has much lower natural frequency comparing with the ultrasonic vibration cycle. It was confirmed by the newly proposed cutting experiment using resonated-horn-type work piece, displacement Amplitude and Stress Amplitude at the cutting point vary continuously in this device. It was shown that the measured cutting force varies corresponding to the displacement Amplitude. It was also indicated that the measured cutting force does not decrease when the cutting point is on the node of the resonated-horn-type work piece, where the Stress Amplitude is the maximum but there is no displacement Amplitude. It means that there should be the relative intermittent displacement between the tool and the chip in order to decrease the measured cutting force. In addition, the deformation resistance of the work piece material itself does not decrease with ultrasonic vibration of the Stress field. Secondly, the significance of the elastic deformation of the tool–work piece system of several microns in ultrasonic intermittent cutting was also indicated from an analytical and experimental point of view. The effect of the elastic behavior on the cutting force becomes relatively large as tc/T becomes small. The above-mentioned characteristics will be helpful to utilize the ultrasonic vibration cutting system more efficiently.
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Effect of dynamic response and displacement/Stress Amplitude on ultrasonic vibration cutting
Journal of Materials Processing Technology, 2009Co-Authors: Kei Harada, Hiroyuki SasaharaAbstract:Abstract In this report, the behavior of the cutting force measured through the dynamic response of tool–work piece system in ultrasonic vibration cutting was discussed first. Measured cutting force mainly depends on the ratio of net cutting time to a vibration cycle in vibration cutting (tc/T) because the tool–work piece system has much lower natural frequency comparing with the ultrasonic vibration cycle. It was confirmed by the newly proposed cutting experiment using resonated-horn-type work piece, displacement Amplitude and Stress Amplitude at the cutting point vary continuously in this device. It was shown that the measured cutting force varies corresponding to the displacement Amplitude. It was also indicated that the measured cutting force does not decrease when the cutting point is on the node of the resonated-horn-type work piece, where the Stress Amplitude is the maximum but there is no displacement Amplitude. It means that there should be the relative intermittent displacement between the tool and the chip in order to decrease the measured cutting force. In addition, the deformation resistance of the work piece material itself does not decrease with ultrasonic vibration of the Stress field. Secondly, the significance of the elastic deformation of the tool–work piece system of several microns in ultrasonic intermittent cutting was also indicated from an analytical and experimental point of view. The effect of the elastic behavior on the cutting force becomes relatively large as tc/T becomes small. The above-mentioned characteristics will be helpful to utilize the ultrasonic vibration cutting system more efficiently.
Andrea Bernasconi - One of the best experts on this subject based on the ideXlab platform.
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Efficiency of algorithms for shear Stress Amplitude calculation in critical plane class fatigue criteria
Computational Materials Science, 2005Co-Authors: Andrea Bernasconi, I V PapadopoulosAbstract:Fatigue criteria that belong to the critical plane class necessitate unambiguous definitions of the Amplitude and mean value of the shear Stress acting on a material plane. This is achieved through the construction of the minimum circle circumscribing the path described by the tip of the shear Stress vector on each plane. By definition, the centre and the radius of this circle provide the mean shear Stress and the shear Stress Amplitude, respectively. The search of the minimum enclosing circle is an optimisation problem for which efficient numerical solution schemes are required. Several algorithms exist for similar situations; however these are not necessarily related to the fatigue strength of metals. In this paper some algorithms are studied to assess their computational efficiency within the engineering framework of the application of fatigue criteria of the critical plane type.
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Efficient algorithms for calculation of shear Stress Amplitude and Amplitude of the second invariant of the Stress deviator in fatigue criteria applications
International Journal of Fatigue, 2002Co-Authors: Andrea BernasconiAbstract:Criteria based on both critical plane and Stress invariant approaches require routines for the calculation of the Amplitude of critical Stress quantities. The definition of the shear Stress Amplitude on a material plane as well as the evaluation of the Amplitude of the second invariant of the Stress deviator can be led back to an optimization problem which can be quickly solved with already existing routines. In this paper a new method is presented and results are compared with those obtained with other previously proposed algorithms.
J.a. Araújo - One of the best experts on this subject based on the ideXlab platform.
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combined resolved shear Stresses as an alternative to enclosing geometrical objects as a measure of shear Stress Amplitude in critical plane approaches
International Journal of Fatigue, 2014Co-Authors: F C Castro, J.a. Araújo, E N Mamiya, P A PinheiroAbstract:Abstract A measure of shear Stress Amplitude based on a combination of resolved shear Stress Amplitudes on two perpendicular directions of a material plane is investigated in this paper. This measure is very fast to calculate. Hence, it turns unnecessary numerical schemes to accelerate the critical plane search, as well as it enables to significantly reduce the processing time of finite element based fatigue calculations, even when small angle increments are used. Findley’s relationship with the proposed shear Stress Amplitude provided estimates within a ±15% error interval for published fatigue limits obtained under proportional and non-proportional multiaxial loadings. The accuracy and computational cost of the approach are compared with those obtained with other measures of shear Stress Amplitude available in the literature.
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an alternative definition of the shear Stress Amplitude based on the maximum rectangular hull method and application to the c s carpinteri spagnoli criterion
Fatigue & Fracture of Engineering Materials & Structures, 2014Co-Authors: J.a. Araújo, Andrea Carpinteri, Camilla Ronchei, Andrea Spagnoli, Sabrina VantadoriAbstract:In the present paper, the fatigue strength estimation capabilities of the modified C-S (Carpinteri-Spagnoli) criterion are improved by employing the Maximum Rectangular Hull (MRH) method proposed by the first author. The C–S criterion is a multiaxial high-cycle fatigue criterion based on the critical plane approach and takes into account both shear Stress (Mode II) and normal Stress (Mode I) mechanisms to evaluate the orientation of the critical plane. The fatigue damage parameter used is given by a nonlinear combination of the equivalent normal Stress Amplitude, Na,eq, and the shear Stress Amplitude, Ca, acting on the critical plane. In the present paper, the shear Stress Amplitude is evaluated through the MRH method. Some experimental data available in the literature are compared with the theoretical estimations, concluding that the multiaxial fatigue strength evaluations provided by the C–S criterion are improved when Ca is computed applying the MRH method instead of the Minimum Bounding Circle (MBC) method.
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An alternative measure for the shear Stress Amplitude in critical plane based multiaxial fatigue models
2013Co-Authors: A.p. Dantas, J.a. Araújo, F.c. Comes, E N Mamiya, J.l.a. FerreriaAbstract:The goal of this work is to propose and to assess an alternative measure for the shear Stress Amplitude in critical plane based multiaxial fatigue criteria. Usually such Amplitude is characterized by the radius of the minimum circle circumscribing the shear Stress history in a material plane. Here, an alternative measure which considers the maximum circumscribed rectangle (MCR) in terms of its Frobenius norm is considered. The computation of the shear Stress Amplitude by the minimum circle and by the maximum rectangle was conducted for a number of experimental data available in the literature involving proportional and nonproportional Stress paths. Then a critical plane criterion was invoked to estimate the fatigue endurance based on such values. It is shown that the multiaxial fatigue estimates were improved for most data evaluated when the shear Stress Amplitude was computed in terms of the maximum box. Some critical assessment concerning the classical definition of the critical plane was also addressed in this work.
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on the characterization of the critical plane with a simple and fast alternative measure of the shear Stress Amplitude in multiaxial fatigue
International Journal of Fatigue, 2011Co-Authors: J.a. Araújo, A.p. Dantas, E N Mamiya, F C Castro, J L A FerreiraAbstract:The goal of this work is not only to characterize the critical plane determination as a well-posed problem, but also to propose an alternative measure for the shear Stress Amplitude. Usually such an Amplitude is characterized by the radius of the Minimum Circumscribed Circle (MCC) to the shear Stress vector history in a material plane. In the present paper, a measure which considers a Maximum Rectangular Hull (MRH) is discussed. Available experimental data involving proportional and nonproportional Stress paths and a critical plane criterion are invoked to compare the fatigue strength estimates based on both methods (MCC and MRH). It is shown that the multiaxial fatigue estimates are improved for most data evaluated when the equivalent shear Stress Amplitude is computed in terms of the MRH.
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multiaxial fatigue life estimation based on a piecewise ruled s n surface
International Journal of Fatigue, 2011Co-Authors: E N Mamiya, F C Castro, R D Algarte, J.a. AraújoAbstract:Abstract A multiaxial model for fatigue life estimation, formulated in terms of a piecewise ruled S–N surface, is proposed. The first ruled surface considers the sum of a deviatoric Stress Amplitude and the maximum hydrostatic Stress as an exponential function of the number of cycles to failure. For small magnitudes of the hydrostatic Stress, another surface is defined by considering only the effect of the deviatoric Stress Amplitude upon the expected fatigue life. The deviatoric Stress Amplitude was computed by the maximum prismatic hull concept. The model proved successful when compared with other multiaxial criteria for available data.
Philippe Bompard - One of the best experts on this subject based on the ideXlab platform.
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The effects of variable Stress Amplitude on cyclic plasticity and microcrack initiation in austenitic steel 304L
Computational Materials Science, 2012Co-Authors: Véronique Aubin, Colette Rey, Philippe BompardAbstract:Abstract In this paper, recent results of the numerical simulation and experimental investigation of variable Stress Amplitude effects on cyclic plasticity and microcrack initiation in 304L steel are presented. A volume of the material corresponding to a realistic microstructure, containing about 150 grains, has been modeled on the basis of crystal plasticity theory. This model takes account of dislocation densities on the 12 slip systems, isotropic and kinematic hardening, grain sizes, crystal orientations and elastic anisotropy. In order to investigate the effects of variable Stress Amplitude on cyclic plasticity, the fatigue tests were conducted under Stress Amplitude of 220–320 (overload) −220 MPa. Four loading paths were considered, which only differ in signs of the beginning and end of the overload block but not in level of Amplitude. The fields of local Stress and strain, maximum shear strain Amplitude of 12 slip systems and the normal Stress on the critical plane of maximum shear strain Amplitude were simulated before, during and after overload. The numerical studies performed on a realistic polycrystalline aggregate of 304L have demonstrated that overload effects on cyclic plasticity and microcrack initiation are significant in all these four loading paths. By comparison with experimental results, local Stress and maximum shear strain Amplitude may be the good indicators for prediction of crack initiation under variable Stress Amplitude.
