Dislocation density based constitutive model for ultrasonic assisted deformation

Prabhakar, Abhishek; Verma, Girish Chandra; Krishnasamy, Hariharan N; Pandey, Pulak M.; Lee, Myoung‐Gyu; Suwas, Satyam

doi:10.1016/j.mechrescom.2017.08.003

Cited by 40 publications

(8 citation statements)

References 18 publications

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“…In the literature, there are various studies, investigated ultrasonic application and thermal activation effect on flow stress during a tensile test, and deformation to understand the underlying mechanism. [29,[44][45][46][47][48] During the deformation process, thermal activation enables dislocation movements and decreases the flow stress. [29,[44][45][46][47][48] The decrease in the flow stress increases the ductility and formability of the material.…”

Section: Discussionmentioning

confidence: 99%

“…[29,[44][45][46][47][48] During the deformation process, thermal activation enables dislocation movements and decreases the flow stress. [29,[44][45][46][47][48] The decrease in the flow stress increases the ductility and formability of the material. Under the effect of thermal activation, the mechanism enables movements of short-range dislocations, more homogenous grain size distribution, and decreased hardness in UI-ECAPed samples, and it is grounded to this thermal activation mechanism besides decreased friction.…”

Section: Discussionmentioning

confidence: 99%

“…This effect has combined strengthening sources, such as friction effect, thermal activation, stress superposition, etc. [44][45][46][47][48] These sources grouped under the symbol of the σ u difference of coarse-grained AA 6063 yield strength with the initial state of this current cold extruded, T6 heat-treated sample was taken to determine cold profile extrusion and T6 heat treatment strengthening. The coarse-grained AA 6063 yield strength is used as 90 MPa.…”

Section: Discussionmentioning

confidence: 99%

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Ultrasonic Assisted Incremental Equal Angular Channel Pressing Process of AA 6063

Bulutsuz

2020

Adv Eng Mater

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Recent technological developments need lightweight materials with high mechanical properties, especially in energy, automotive, and aerospace industries. [1,2] New chemical compositions have been developed with the increased demand for Al and their alloys. Moreover, to increase their mechanical properties, thermomechanical processes, such as extrusion, upsetting, and wire drawing, have widely been used for industrial applications of Al and its alloys. Severe plastic deformation (SPD) is one of the thermomechanical processes, which increases dislocation density. This increase results in finer grain sizes and increased mechanical properties, which render SPD techniques an attractive method. [3,4] Conventional methods, such as extrusion or upset forging, are able to deform, generally, external parts of materials. However, SPD methods, such as equal channel angular pressing (ECAP), can produce more homogenous strain distribution along the cross section of the material due to homogenous severe deformation. SPD methods are capable of doubling the mechanical strength while manufacturing ultrafine grain structures with mean grain sizes smaller than 400 nm. [4-6] Despite improved material properties' results of SPD techniques, most of them are still being used at the laboratory scale due to their manufacturing costs and usage difficulties. Materials size and length are the usage difficulties, which is generally restricted by die sizes. According to the literature, the ECAP is more convenient for producing longer specimens than other SPD methods for producing longer size ultrafine-grained materials. [7,8] However, this technique restricts the specimen length with its die size and plunger length, which is a significant limitation. High friction rate between the die walls and the specimen is another restriction for specimen size. Movable side walls during ECAP are developed as a solution to friction. However, the specimen length is limited to the die size. [9] Conform methods adapt continuous material feeding to SPD processes, which allow manufacturing fine-grained longer products. The conform SPD application was developed by Raab et al. in 2004 [10] for deformation of pure Al with ECAP. Various materials were used in conform methods, such as Ti G4, [11] TiNi, [12] Al6061, [13] and Al6101. [14] The most significant limitation of this method is the high friction rate between die and material. Especially, materials with low melting temperatures are effected from friction heat and result with a grain recovery that also decreases process efficiency. In the incremental ECAP (I-ECAP) process, which was first described in 2007, the material is fed step by step, and a punch deforms material between these steps; there are two separated synchronous movements of punch (deformation) and feeding system. [15] Thus, there is not a load on the specimen during feeding, which also eliminates high friction rates between die and specimen in contrast with traditional ECAP. Because of the continuous feeding of materials in the I-ECAP method, the ...

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Section: Discussionmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

See 1 more Smart Citation

Ultrasonic Assisted Incremental Equal Angular Channel Pressing Process of AA 6063

Bulutsuz

2020

Adv Eng Mater

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“…Prabhakar et al [66] proposed a constitutive model based on the dislocation density. The K-M model was used as the basic model framework, and parameters α and n were modified to reflect the influence of UV.…”

Section: Models Based On Physical Mechanismmentioning

confidence: 99%

“…Good agreement was found between the predictions and experimental results through the reasonable selection of parameters in the model. In addition, Prabhakar et al [66] modified the parameters α and n in their established dislocation density-based model. The acoustic softening effect and residual effect during the tensile tests can be accurately described by varying the parameters β (1-9) .…”

Section: Comparison Of Different Modelsmentioning

confidence: 99%

A Review on Ultrasonic-Assisted Forming: Mechanism, Model, and Process

Shao

Zhan

2021

Chin. J. Mech. Eng.

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Compared with conventional forming processes, ultrasonic-assisted forming technology with a high frequency and small amplitude can significantly improve the forming quality of materials. Owing to the advantages of reduced forming force, improved surface quality, avoidance of forming defects, and strengthened surface structure, ultrasonic-assisted forming technology has been applied to increasingly advanced forming processes, such as incremental forming, spinning, and micro-forming. However, in the ultrasonic-assisted forming process, there are multiple ultrasonic mechanisms, such as the volume effect and surface effect. The explanation of the effect of ultrasonic vibration (UV) on plastic deformation remains controversial, hindering the development of related technologies. Recently, many researchers have proposed many new theories and technologies for ultrasonic-assisted forming. To summarize these developments, systematic discussions on mechanisms, theoretical models, and forming performances are provided in this review. On this basis, the limitations of the current study are discussed. In addition, an outlook for ultrasonic-assisted forming is proposed: efficient and stable UV systems, difficulty forming components with complex geometry, explanation of the in-depth mechanism, a systematic theoretical prediction model, and multi-field-coupling energy-assisted forming are considered to be hot spots in future studies. The present review enhances existing knowledge of ultrasonic-assisted forming, and facilitates a fast reference for related researchers.

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Process Fundamentals of Ultrasonic Additive Manufacturing

Ward

2024

Solid‐State Metal Additive Manufacturing

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Dislocation density based constitutive model for ultrasonic assisted deformation

Cited by 40 publications

References 18 publications

Ultrasonic Assisted Incremental Equal Angular Channel Pressing Process of AA 6063

Ultrasonic Assisted Incremental Equal Angular Channel Pressing Process of AA 6063

A Review on Ultrasonic-Assisted Forming: Mechanism, Model, and Process

Process Fundamentals of Ultrasonic Additive Manufacturing

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