Ultrasonic-assisted manufacturing processes: Variational model and numerical simulations

Siddiq, M.; Sayed, Tamer El

doi:10.1016/j.ultras.2011.11.004

Cited by 116 publications

(36 citation statements)

References 27 publications

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“…This phenomenon is the so-called the Blaha effect. The same phenomena have been confirmed in many metals (e.g., [33][34][35]) and have been widely made to apply to the plastic working technique for industrial purpose such as wire drawing, deep drawing, rolling, and another metal forming techniques, since this phenomenon has an industrial significance (e.g., [36][37][38][39][40][41][42][43][44]). The Blaha effect has been explained by a temperature rise of materials [45], an abrupt increase in mobile dislocation density [46], a reduction in internal stress [47][48][49], or a stress superposition mechanism [50][51][52][53][54][55] so far.…”

Section: Introductionmentioning

confidence: 72%

Study on Dislocation-Dopant Ions Interaction in Ionic Crystals by the Strain-Rate Cycling Test during the Blaha Effect

Kohzuki

2018

Crystals

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Abstract:The interaction between a dislocation and impurities has been investigated by measurements of yield stress and proof stress, micro-hardness tests, direct observations of dislocation, internal friction measurements, or stress relaxation tests so far. A large number of investigations has been carried out by the separation of the flow stress into effective and internal stresses on the basis of the temperature dependence of yield stress, the strain rate dependence of flow stress, and stress relaxation. Nevertheless, it is difficult to investigate the interaction between a dislocation and obstacles during plastic deformation by the mentioned methods. As for the original method which combines strain-rate cycling tests with the Blaha effect measurement, the original method is different from above-mentioned ones and would be possible to clear it up. The strain-rate cycling test during the Blaha effect measurement has successively provided the information on the dislocation motion breaking away from the strain fields around dopant ions with the help of thermal activation, and seems to separate the contributions arising from the interaction between dislocation and the point defects and those from dislocations themselves during plastic deformation of ionic crystals. Such information on dislocation motion in bulk material cannot be obtained by the widely known methods so far. Furthermore, the various deformation characteristics derived from the original method are sensitive to a change in the state of dopant ions in a specimen by heat treatment, e.g., the Gibbs free energy (G 0 ) for overcoming of the strain field around the dopant by a dislocation at absolute zero becomes small for the annealed KCl:Sr 2+ single crystal (G 0 = 0.26 eV) in comparison with that for the quenched one (G 0 = 0.39 eV).

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Section: Introductionmentioning

confidence: 72%

Study on Dislocation-Dopant Ions Interaction in Ionic Crystals by the Strain-Rate Cycling Test during the Blaha Effect

Kohzuki

2018

Crystals

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“…These in-process heating characteristics of hammer forging reduce surface chilling and improve mechanical properties of the workpiece. Many works [9][10][11] have studied the effects of applying ultrasonic vibrations during metal forming processes. They found that the application of ultrasonic vibrations causes a reduction of the forming load and a beneficial effect on metal characteristics.…”

Section: Matec Web Of Conferencesmentioning

confidence: 99%

Effect of rotational speed in rotary hammer forging process

Hamdy

2015

MATEC Web of Conferences

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Abstract.Rotary press forging (RPF) has been used in the last century, but it produces many defects in the forgings. The author has invented the rotary hammer forging (RHF) process to reduce such defects. RHF is a multi-axes compression process where the material is partially and incrementally deformed by the action of several repeated hammering blows, while the produced deformation region is swept through the whole area of the workpiece. The aim of the present work is to study the effects of rotational speed on the forgings produced by RPF and RHF to compare between the two processes. It has been found that as the rotational speed increases the mushroom effect is constant in RHF while it is greater and increases in RPF. As the rotational speed increases, the twist angle increases in both RHF and RPF, but it is bigger in RPF. These results demonstrate the benefits of using RHF instead of RPF.

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“…In addition, they involve high wire breakage ratio, large contact or friction force, and poor surface quality [7]. Ultrasonic-vibration drawing, which applies ultrasonic vibration to the die axially or radially, contributes to the improvement of lubricant conditions, the softening of metals and the reduction of drawing force [8][9][10]. Therefore, it is promising to superimpose ultrasonic vibration in the process of titanium wire drawing.…”

Section: Introductionmentioning

confidence: 99%

Research on a Composite Power-Superimposed Ultrasonic Vibrator for Wire Drawing

et al. 2016

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Vibration power and amplitude are essential factors in ultrasonic drawing processes, especially for difficult-to-draw materials like titanium and its alloys. This paper presents a new composite power-superimposed ultrasonic vibrator for wire drawing which was driven by three separate ultrasonic transducers. The transducers were uniformly distributed around the circular cross section of the vibrator, with their axes along the radial direction and pointing to the center. The vibrator can concentrate the vibrational energy of multiple transducers and transform the radial vibration into a longitudinal vibrator because of the Poisson effect and therefore output larger vibration power and amplitude. In the paper, the four-terminal network method was used to establish the vibration equations of the vibrator. The FE model was established in ANSYS to investigate its characteristics under various excitation conditions. A prototype was manufactured and measurements were performed to verify the validation of FEA results. The results matched well with the theoretical results. It was found that the composite vibrator achieved an amplitude of about 40 µm when driven by square wave signals with 120˝in phase difference, which implies a potential way of applying ultrasonic vibration to the processing of difficult-to-draw materials.

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Ultrasonic-assisted manufacturing processes: Variational model and numerical simulations

Cited by 116 publications

References 27 publications

Study on Dislocation-Dopant Ions Interaction in Ionic Crystals by the Strain-Rate Cycling Test during the Blaha Effect

Study on Dislocation-Dopant Ions Interaction in Ionic Crystals by the Strain-Rate Cycling Test during the Blaha Effect

Effect of rotational speed in rotary hammer forging process

Research on a Composite Power-Superimposed Ultrasonic Vibrator for Wire Drawing

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