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Surface Mechanical Properties and Micro-Structure Evolution of 7075 Aluminum Alloy Sheet for 2-Dimension Ellipse Ultrasonic Vibration Incremental Forming: A Pretreatment for Laser Shock Peening

Coatings 2022, 12(12), 1914; https://doi.org/10.3390/coatings12121914

by Yuan Lv^*, Mengen Dong, Xixiang Pan, Cong Yi and Jiaqi Su

Reviewer 1: Anonymous

Reviewer 2:

Jaykumar Vora

Reviewer 3:

Ali Arman

Coatings 2022, 12(12), 1914; https://doi.org/10.3390/coatings12121914

Submission received: 5 November 2022 / Revised: 28 November 2022 / Accepted: 4 December 2022 / Published: 7 December 2022

(This article belongs to the Special Issue Laser-Assisted Coating Techniques and Surface Modifications)

Round 1

Reviewer 1 Report

Dear author(s), the manuscript ‘Surface Mechanical Properties and Micro-structure Evolution of 7075 Aluminum Alloy Sheet for 2Dimension Ultrasonic Vibration Incremental Forming: A Pretreatment for Laser Shock Peening’, Manuscript ID: coatings-2046723, has some serious weaknesses that makes it difficult to be further processed, if even allowed.

Firstly, the ‘Abstract’ section is too long. Looks like author(s) moved the scrucial part of the ‘Introduction’ section to the Abstract. The justification of the studies proposed should be reduced. Very long explnanation of the analysis presented does not fit well to the scientific article.

Comparing to the ‘Abstract’ section, the ‘introduction’ is poor. It is difficult to separate proposed nowelty to the current state of knowledge. Usually, author(s) should present the lack of knowledge and from that point of view motivate its studies. Writing the whole section in one part is diffuclt to follow for, even regular, reader(s).

Furhter, the area of studies was not presented appropriately, the number of cited items is too small, the significance of the analysis should be highlighted. In its current form it looks more like a short review. Critical part of the literature review not exist. From that matter, why the author(s) nowelty is required?

In section 2.3., especially subsection 2.3.1., the nowelty is also not precisely separated from the current state of knowledge. In fact, the whole manuscript is not appropriately constructed. Looks like one direction without any discussion or doubts.

A huge number of shortcuts and abbreviations without a special section is another weakness of the manuscript. Reader, not only a regular one, can feel lost following the manuscript in the current form.

However, the nightmare comes with the ‘Conclusion’ section, where its longth and plenty of information makes understanding of the studies provided extremely difficult to met and, respectively, what are the author(s) trying to convey.

Generally, the proposed title is interesting but, respectively, feel sorry but cannot be accepted in the presented form. Some issues make understanding the paper difficult and the reader totally confused. It must be improved significantly before any further re-submission in future and, correspondingly, any further processing for publication in a quality journal as the Coatings is.

Author Response

Dear Editors and reviewers,

On behalf of my co-authors, we thank you very much for giving us an opportunity to revise our manuscript, we appreciate editors and reviewers very much for their positive and constructive comments and suggestions on our manuscript entitled “Surface Mechanical Properties and Micro-structure Evolution of 7075 Aluminum Alloy Sheet for 2Dimension Ellipse Ultrasonic Vibration Incremental Forming: A Pretreatment for Laser Shock Peening”(ID: coatings-2046723).

We have studied reviewer’s comments carefully and have made revision which marked in red in the paper. We have tried our best to revise our manuscript according to the comments. The revised parts are list as follows.

Comment 1: “Firstly, the ‘Abstract’ section is too long. Looks like author(s) moved the scrucial part of the ‘Introduction’ section to the Abstract. The justification of the studies proposed should be reduced. Very long explnanation of the analysis presented does not fit well to the scientific article.”

Answer: The “Abstract” section has been rewrite. The long explanation part was deleted. The aims, method and results are present in brief. The new abstract is list.

“In this paper, a composite technique of ultrasonic incremental forming and laser shock peeing is proposed. The former process is mainly used for manufacturing of complex-shaped sheet and strengthening coating which is prepared for subsequent laser treatment. The latter one is applied for secondary surface reinforcement with ultra-high energy. This work focuses on the novel ultrasonic incremental forming method and its effects on surface mechanical properties and micro-structure of 7075 aluminium alloy. Firstly, one kind of 2 dimension ellipse ultrasonic vibration incremental forming process and the unique double-mechanism method of sectionalized cooperative control of plastic deformation and mechanical performance are designed. Secondly, the single-point incremental forming, the longitudinal ultrasonic vibration incremental forming and the 2 dimension ellipse ultrasonic vibration incremental forming were performed for manufacturing conical components of 7075 aluminum alloy. Thirdly, the Vickers micro-hardness testing results and images of fracture morphology of the machined part for the novel technique confirm that softening mechanisms become dominant inside of metals sheet. Besides, a strengthening coating of excellent mechanical properties and a residual compressive stress field were created on its surface simultaneously. In a word, the research shows potential values of the proposed technique for manufacturing of aircraft panels of complex shape and excellent surface properties.”

Comment 2: “Comparing to the ‘Abstract’ section, the ‘introduction’ is poor. It is difficult to separate proposed nowelty to the current state of knowledge. Usually, author(s) should present the lack of knowledge and from that point of view motivate its studies. Writing the whole section in one part is diffuclt to follow for, even regular, reader(s).Furhter, the area of studies was not presented appropriately, the number of cited items is too small, the significance of the analysis should be highlighted. In its current form it looks more like a short review. Critical part of the literature review not exist. From that matter, why the author(s) nowelty is required?”

Answer: The introduction part has been rewrite. (1) Research status about the traditional single-point incremental forming and the one-way ultrasonic incremental forming are given. Critical conclusion about the shortage of current research is described. Such as”However, it still has some weaknesses such as severe sheet thinning, long processing cycle and fracture. Those problems impede the application of SPIF process in industrial practice” “However, the modified model only considering softening effect is insufficient and provides limited improvement of prediction accuracy.” “All of current published research mainly pay attentions to ultrasonic effect and technical optimization based on unidirectional ultrasonic vibration incremental forming process. The one-way vibration device only provides inadequate ultrasonic energy and single high-frequency impact for processing high-strength alloys. Ultrasonic softening effect is limited to reduce forming force and improve formability of high-strength metals.” and so on. (2) The introduction has been divided into 3 parts, which respectively describe the traditional single-point incremental forming, the one-way ultrasonic incremental forming and the 2D ellipse ultrasonic incremental forming. (3) The number of cited items are increased to 25 papers related to the proposed research. (4) The reason for new study and its innovation are also highlighted. “The existing forming technology could not meet the strict and paradoxical manufacturing requirements of excellent formability, good flexibility and valid surface-strengthening simultaneously. To satisfy the increasingly common and challenging needs, a composite technique of 2 dimension ultrasonic incremental forming and laser shock peeing is proposed in this paper. The former method is suitable for manufacturing of complex-shaped sheet and strengthening coating which is prepared for subsequent laser treatment. The latter one is applied for secondary surface reinforcement with ultra-high energy. This work focuses on design of one kind of 2 dimension ultrasonic vibration incremental forming method and its effects on surface mechanical property and micro-structure of 7075 aluminium alloy.”

The new introduction is list.

“In the aviation industry, great attention has been paid to high-strength aluminum alloy and thin-walled integral panels which is a crucial component of large aircraft. So, forming technology of key panels is one of the critical issues[1]. At present, several kinds of developing technology are suitable for manufacturing essential board, such as stretch forming, shot-peening, incremental forming, creep age forming and laser forming[2]. Single-point incremental forming (SPIF) is a sheet metal forming method which has gained considerable interest in the research field due to its good formability, high flexibility and low cost. Researchers mainly study on deformation mechanism, process optimization and FEM simulation to resolve forming accuracy and qualities problems. Malhotra[3] used a new fracture model combined with finite element analyses to predict the occurrence of fracture in SPIF process. Aerens[4] established practical formulae to predict forming forces based on a large set of systematic experiments. Vanhove and Pereira[5,6] studied on the the influence of an increasing feed rate on forming forces, temperature and formability. Azevedo[7] evaluated the influence of the type of lubricant on the surface quality of incremental forming parts of aluminum 1050 and DP780 steel sheets. Trzepieciński[8] analyzed the interactions between the SPIF process parameters and the main roughness parameters of stiffened ribs fabricated in aluminium alloy panels. In Bansal’s work, a modified model was given to accurately predict formed component thickness, contact area and forming forces during single and multi-stage incremental forming[9]. In addition, a great number of research also facilitated the rapid development of SPIF technique. However, it still has some weaknesses such as severe sheet thinning, long processing cycle and fracture. Those problems impede the application of SPIF process in industrial practice[10].

In recent years, numerous studies have indicated that the input of auxiliary energy is helpful for improvement of forming limit and qualities and reduction of forming force. Then, powerful energy such as electricity, magnetism and ultrasonic wave has been widely applied to plastic forming field and machining field[11-14]. Ultrasonic vibration incremental forming has been the one of the most promising technologies. To study its unique forming mechanism, ultrasonic volume effect containing multi-mechanisms of stress superposition, acoustic softening and dynamic impact has been investigated[15-18]. Li[19] explored the influence of the superposition of ultrasonic vibration on the contact behavior and material deformation mechanism during forming process. Zhai[20] conducted a series of experiments to explore the impacts of the step-down size, the sheet thickness and the rotation speed on the ultrasonic soften effect. Based on the conversion of ultrasonic vibration to heat, Sakhtemanian[21] established a new theoretical model to investigate material behavior in the finite element simulation of ultrasonic assisted SPIF process. In fact, complicated ultrasonic effect involves a multi-coupling action of ultrasonic softening effect, ultrasonic hardening effect, work hardening, heat softening and stress superposition. The simple heat-conversion theory is insufficient to completely explore the ultrasonic forming mechanism and satisfactorily explain the ultrasonic-induced material behaviors. In addition to these mechanism studies, technique rules and parameter optimization also became the research focuses. Sun[22] established a series of experiments to explore the influence of ultrasonic vibration on the surface property and springback effect of symmetrical aluminum alloy sheet. Li[23] investigated the effect of the ultrasonic vibration on the material flow characteristics and the plastic deformation mechanism during the forming of straight groove. Amini[24] analyzed the impacts of process parameters including the sheet material, ultrasonic power, feeding speed and tool diameter on force reduction and temperature increment. Li and Cheng[25] built a theoretical model describing the relationship between the stress and strain during the ultrasonic-assisted incremental sheet forming to facilitate the accurate prediction. However, the modified model only considering softening effect is insufficient and provides limited improvement of prediction accuracy.

References

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Wang D, Xu F. Brief introduction and recent development on the manufacture of aluminium alloy integral panels in aerospace applications. Int. J. Mater. Struct. Integr. 2021: 299-318. https://doi.org/10.1504/IJMSI.2021.125814

Malhotra R, Xue L. Mechanics of fracture in single point incremental forming. J. Mater. Process. Technol. 2012: 1573-1590. https://doi.org/10.1016/j.jmatprotec.2012.02.021

Aerens R, Eyckens P. Force prediction for single point incremental forming deduced from experimental and FEM observations. Int. J. Adv. Manuf. Technol. 2010: 969-982. https://doi.org/10.1007/s00170-009-2160-2

Vanhove H, Mohammadi A. High-speed single point incremental forming of an automotive aluminium alloy. Key. Eng. Mater. 2014: 433-439. https://doi.org/10.4028/www.scientific.net/KEM.622-623.433

Pereira Bastos R N, Alves de Sousa R J. Enhancing time efficiency on single point incremental forming processes. Int. J. Mater. Form. 2016: 653-662. https://doi.org/10.1007/s12289-015-1251-x

Azevedo N G, Farias J S. Lubrication aspects during single point incremental forming for steel and aluminum materials. Int. J. Precis. Eng. Manuf. 2015: 589-595. https://doi.org/10.1007/s12541-015-0079-0

Trzepieciński T, Kubit A. Surface finish analysis in single point incremental sheet forming of rib-stiffened 2024-T3 and 7075-T6 alclad aluminium alloy panels. Materials. 2021: 1640. https://doi.org/10.3390/ma14071640

Bansal A, Lingam R. Prediction of forming forces in single point incremental forming. J. Manuf. Process. 2017: 486-493. https://doi.org/10.1016/j.jmapro.2017.04.016

Zhang H, Lu B. Thickness control in a new flexible hybrid incremental sheet forming process. P. I. Mech. Eng. B-J Eng. 2017: 779-791. https://doi.org/10.1177/0954405417694061

Liu S, Shan X. Experimental study on titanium wire drawing with ultrasonic vibration. Ultrasonics. 2018: 60–67. https://doi.org/10.1016/j.ultras.2017.08.003

Zhou H, Cui H. Influence of ultrasonic vibration on the plasticity of metals during compression process. J Mater Process Tech. 2018. 146–159. https://doi.org/10.1016/j.jmatprotec.2017.08.021

Tao G, Ma C. Feed-direction ultrasonic vibration− assisted milling surface texture formation. Mater. Manuf. Process. 2017: 193-198. https://doi.org/10.1080/10426914.2016.1198029

Sun S Y, Tang J Y. Research on the matching relationship between ultrasonic-assisted grinding parameters and workpiece surface roughness. INT J ADV MANUF TECH. 2019, 102: 487-496. https://doi.org/10.1007/s00170-018-3195-z

Hu J, Shimizu T. Investigation on ultrasonic volume effects: stress superposition, acoustic softening and dynamic impact. Ultrason Sonochem. 2018. 240–248. https://doi.org/10.1016/j.ultsonch.2018.05.039

Siddiq A, El Sayed T. Ultrasonic-assisted manufacturing processes: variational model and numerical simulations. Ultrasonics. 2012: 521-529. https://doi.org/10.1016/j.ultras.2011.11.004

Deshpande A, Hsu K. Acoustic energy enabled dynamic recovery in aluminium and its effects on stress evolution and post-deformation microstructure. Mater. Sci. Eng. A 2018: 62-68. https://doi.org/10.1016/j.msea.2017.11.015

Hu J, Shimizu T. Ultrasonic dynamic impact effect on deformation of aluminum during micro-compression tests. J MATER PROCESS TECH. 2018: 144-154. https://doi.org/10.1016/j.jmatprotec.2018.03.021

Li Y, Chen X. Effects of ultrasonic vibration on deformation mechanism of incremental point-forming process. Procedia Engineering. 2017. 777–782, https://doi.org/10.1016/j.proeng.2017.10.828

Zhai W, Li Y. Investigation on the forming force and surface quality during ultrasonic-assisted incremental sheet forming process. Int J Adv Manuf Tech. 2020, 106(7): 2703-2719. https://doi.org/10.1007/s00170-019-04870-0

Sakhtemanian M R, Honarpisheh M. A novel material modeling technique in the single-point incremental forming assisted by the ultrasonic vibration of low carbon steel/commercially pure titanium bimetal sheet. Int J Adv Manuf Tech. 2019, 102(1): 473-486. https://doi.org/10.1007/s00170-018-3148-6

Sun Y, Lu Z. Study on the springback effect and surface property for ultrasonic-assisted incremental sheet forming of aluminum alloy. Symmetry. 2021: 1217. https://doi.org/10.3390/sym13071217

Li Y, Zhai W. Investigation on the material flow and deformation behavior during ultrasonic-assisted incremental forming of straight grooves. J. Mater. Res. Technol. 2020: 433-454. https://doi.org/10.1016/j.jmrt.2019.10.072

Amini S, Hosseinpour Gollo A. An Investigation of conventional and ultrasonic-assisted incremental forming of annealed AA1050 sheet. Int j adv manuf tech. 2016. https://doi.org/10.1007/s00170-016-9458-7

Li Y L, Cheng Z N. Constitutive modeling and deformation analysis for the ultrasonic-assisted incremental forming process. INT J ADV MANUF TECH. 2019: 2287-2299. https://doi.org/10.1007/s00170-019-04031-3

Comment 3: “In section 2.3., especially subsection 2.3.1., the nowelty is also not precisely separated from the current state of knowledge. In fact, the whole manuscript is not appropriately constructed. Looks like one direction without any discussion or doubts.”

Answer: The subsection 2.3.1 has been rewrite. The advantages and shortages of the single point incremental forming and one-way ultrasonic incremental forming have been analyzed. The innovation for new method is also discussed.

“As known, the most remarkable characteristic of the single-point incremental forming is that the metal sheet is extruded by the rolling tool point by point according to the layered forming paths which are a series of contour lines of the designed production. In Fig.2(a), as the principle image of the single-point incremental forming shows, regional materials that contact to the half-spherical head of the forming tool deforms permanently as the tool feeds horizontally or vertically. Compared to the traditional stamping process, this unique processing mode reduces forming force and improves manufacturing flexibility tremendously. At the same time, it causes heterogeneous deformation and flow of materials. The severe problem of thinning rate of forming sheet hampers the application of the traditional incremental forming in manufacturing fields. Besides, it is difficult to utilize this technique for manufacturing of high-strength alloys. Rupture phenomenons always happened on the metal sheets as deformation beyond their forming limit. To conquer these challenging difficulties, ultrasonic energy is used for softening the difficult-to-deformation materials. In resent years, the longitudinal ultrasonic vibration incremental forming has became a research hot spot for some advantages. As Fig.2(b) shows, the sheet driven by a one-way ultrasonic device vertically vibrates relative to the forming tool. Then, the feeding and rolling tool impacts the sheet surface while it extrudes the deformed sheet. The half-spherical affected field caused by the impact actions marked as shadow is present in Fig.2(b). The longitudinal ultrasonic vibration incremental forming process features with a special phenomenon of high frequency periodic contact-detach conditions of the sheet and the tool. This working mechanism which causes a coupling action of ultrasonic effect, work hardening, heat softening and stress superposition has been investigated. Moreover, the periodic extrusion ameliorates the intense friction condition between the sheet and the tool. This is beneficial to improvement of surface qualities of the forming sheet. However, the unidirectional ultrasonic vibration design only provides limited energy for material softening. Manufacturing of complex thin-walled panels of high-strength alloys is still a challenging engineering problems. In addition, current technologies can not fill industry’s need for surface strengthening and fatigue resistance of thin-walled parts. The bidirectional ultrasonic vibration device which was successfully applied to other manufacturing fields has never been used for incremental forming. In this work, a unique 2 dimension ellipse ultrasonic vibration method and device were designed. As Fig.2(c) shows, the forming sheet driven by the designed 2 dimension ellipse ultrasonic device vibrates in an ellipse path relative to the forming tool. Compare to the second process, it dramatically increases the contact areas between the sheet and the tool. This affected area marked as ellipsoid shadow in Fig.2(c) is divided into two parts. One part is located in the processing region. Materials in this area deform and flow under the extrusion action and ultrasonic effect of the rolling and vibrating tool. A coupling action of ultrasonic softening effect, ultrasonic hardening effect, thermal softening effect, work hardening, refined crystalline strengthening and stress superposition affects the micro-structure evolution and the mechanical behaviors of metal materials. It is deduced that the reinforced softening effects dominate in this process, which tremendously improves the forming limit of difficult-to-deformation materials such as 7075 aluminium alloy. The other part of the affected area is located in the adjacent processed region on the side wall of the sheet. Materials restricted by the supporting mould in this area can not flow. This process similar to shot-peening creates a huge number of impact craters and a layer of strengthening coating with residual compressive stress field. Obviously, hardening effects play a leading role in this area. In a word, the most outstanding innovation of this work is that the proposed 2 dimension ellipse ultrasonic vibration incremental forming process and the unique double-mechanism method of sectionalized cooperative control of forming deformation and mechanical performance including a internal softening mechanism which promotes deformation of materials and a surface strengthening mechanism which improves superficial mechanical properties of sheet. Therefore, this new technique could meet the challenging demands on aircraft panels of complex shape and strengthening surface. Micro-hardness tests, SEM tests of micro-structure and residual stress tests were performed to prove above assumptions.”

Comment 4: “A huge number of shortcuts and abbreviations without a special section is another weakness of the manuscript. Reader, not only a regular one, can feel lost following the manuscript in the current form.”

Answer: Abuse problem of abbreviations has been corrected. Few abbreviations are used for images with notes. Such as “Figure.4 Micro-hardness tests of samples for various forming techniques (a) Hardness testing points; (b) Hardness curves; (c) Micro-hardness test images (from upper left to lower right: 7075 aluminum alloy raw material, incremental forming sample, vertical vibrating ultrasonic incremental forming sample, and elliptic vibrating ultrasonic incremental forming sample. Notes: 2D-EUVIF is the abbreviation for 2D ellipse ultrasonic vibration incremental forming; LUVIF is the abbreviation for longitudinal ultrasonic vibration incremental forming; SPIF is the abbreviation for single-point incremental forming)”

Comment 5: “However, the nightmare comes with the ‘Conclusion’ section, where its longth and plenty of information makes understanding of the studies provided extremely difficult to met and, respectively, what are the author(s) trying to convey.”

Answer: “Conclusion” section has been rewrite. The research results are described in brief words. And the limitation of the novel method and further improvement are discussed.

“1. In this work, one kind of 2 dimension ellipse ultrasonic vibration incremental forming process and its unique double-mechanism method of sectionalized cooperative control of forming deformation and mechanical performance including the internal softening mechanism which promotes deformation of materials and the surface strengthening mechanism which improves superficial mechanical properties of sheet are designed. This innovative technique aims to meet the challenging industry demands on manufacturing of thin-walled aircraft panels of high-strength aluminium alloy with complex shape and surface strengthening coating.

2. Experimental results showed that the mean value of surface micro-hardness of the conical sheets processed by single-point incremental forming, longitudinal ultrasonic vibration incremental forming and 2D ellipse ultrasonic vibration incremental forming were increased accordingly by 17.67%, 38.2% and 50.13% compared to that of the raw materials of 7075 aluminium ally. However, the mean value of cross-sectional micro-hardness of 2D ellipse ultrasonic vibration incremental forming sheet increased by 6.87% only. Experimental results manifested that mechanical properties of core materials of the part were nearly the same as or even lower than that of the raw materials. SEM images of fracture surface of the sheet for the novel forming technique showed distinct features of the surface strengthening coating of about 200 micrometers fibrous-structure thickness and ductile fracture with a great number of dimples induced by softening effects. Testing results totally confirm the double-mechanism assumption of internal softening and surface strengthening. In addition, a residual compressive stress field located on surface of the sheet for the novel forming method could improve its fatigue resistance.

3. SEM images of fracture surface of the sheet for the novel technique showed that ductile feature of isometric dimples decreased along the depth and more quasi-cleavage planes appeared far from the source of ultrasonic vibration. Obviously, these phenomenons are closely related to the affecting range of ultrasonic vibration. Although the double-mechanism method is proved feasible, conditions for motivating softening effects or hardening effects to play a leading role are still unknown. Precise quantification of ultrasonic softening, ultrasonic hardening, thermal softening, work hardening, refined crystalline strengthening and stress superposition is challenging but vital for application of the 2D ellipse ultrasonic vibration incremental forming process and the double-mechanism method in industry.”

In addition, other problems are also corrected. The revised manuscript is seen in the attachment.

We would like to express our great appreciation to you and reviewers for comments on our paper. Looking forward to hearing from you.

Thank you and best regards.

Yours sincerely,

Corresponding author:

Name: Yuan Lv

E-mail: [email protected]

Mobile Phone: 86+13572199684

Author Response File: Author Response.pdf

Reviewer 2 Report

The presented manuscript “Surface Mechanical Properties and Micro-structure Evolution of 7075 Aluminum Alloy Sheet for 2Dimension Ultrasonic Vibration Incremental Forming: A Pre-treatment for Laser Shock Peening” contains some key findings. However, the manuscript requires major improvements in following areas before taken into the considerations for publication:

· Abstract is written very well. It contains key findings in terms of qualitative and quantitative results.

· Introduction section is very weak. I didn’t any literature work which can justify the research gap. Authors must add it. In the last paragraph of introduction, write the novelty of your work and selected conditions for experiments.

· Compare the obtained results and justify the findings with proper technical reasons in results and discussion section.

· Conclusion section is too large. It seems more discussion that conclusion. Revise it

· Mention the limitations and further scope of improvement in last section.

Author Response

Dear Editors and reviewers,

Comment 1: “Abstract is written very well. It contains key findings in terms of qualitative and quantitative results.”

Answer: The “Abstract” section has been rewrite. The long explanation part was deleted. The aims, method and results are present in brief. The new abstract is list.

Comment 2: “Introduction section is very weak. I didn’t any literature work which can justify the research gap. Authors must add it. In the last paragraph of introduction, write the novelty of your work and selected conditions for experiments.”

Answer: The introduction part has been rewrite. (1) Research status about the traditional single-point incremental forming and the one-way ultrasonic incremental forming are given. Critical conclusion about the shortage of current research is described. Such as”However, it still has some weaknesses such as severe sheet thinning, long processing cycle and fracture. Those problems impede the application of SPIF process in industrial practice” “However, the modified model only considering softening effect is insufficient and provides limited improvement of prediction accuracy.” “All of current published research mainly pay attentions to ultrasonic effect and technical optimization based on unidirectional ultrasonic vibration incremental forming process. The one-way vibration device only provides inadequate ultrasonic energy and single high-frequency impact for processing high-strength alloys. Ultrasonic softening effect is limited to reduce forming force and improve formability of high-strength metals.” and so on. (2) The introduction has been divided into 3 parts, which respectively describe the traditional single-point incremental forming, the one-way ultrasonic incremental forming and the 2D ellipse ultrasonic incremental forming. (3) The number of cited items are increased to 25 papers related to the proposed research. (4) The reason for new study and its innovation are also highlighted. The selected conditions for experiments are also given. “The existing forming technology could not meet the strict and paradoxical manufacturing requirements of excellent formability, good flexibility and valid surface-strengthening simultaneously. To satisfy the increasingly common and challenging needs, a composite technique of 2 dimension ultrasonic incremental forming and laser shock peeing is proposed in this paper. The former method is suitable for manufacturing of complex-shaped sheet and strengthening coating which is prepared for subsequent laser treatment. The latter one is applied for secondary surface reinforcement with ultra-high energy. This work focuses on design of one kind of 2 dimension ultrasonic vibration incremental forming method and its effects on surface mechanical property and micro-structure of 7075 aluminium alloy. The traditional single-point incremental forming tests, the longitudinal ultrasonic vibration incremental forming tests and 2D ellipse ultrasonic vibration incremental forming tests were conducted on the designed special ultrasonic incremental forming equipment. Classic conical sheets of 7075 aluminium alloy were manufactured with above techniques to verified the effectiveness of the novel method and to study its influence on the mechanical properties and micro structure evolution of high strength alloys.”

The new introduction is list.

All of current published research mainly pay attentions to ultrasonic effect and technical optimization based on unidirectional ultrasonic vibration incremental forming process. The one-way vibration device only provides inadequate ultrasonic energy and single high-frequency impact for processing high-strength alloys. Ultrasonic softening effect is limited to reduce forming force and improve formability of high-strength metals. Besides, it is well known that a series of aircraft disasters were induced by fatigue failures of the airplane panels because of vibration, aerodynamic noise, corrosion environment and high temperature. This demands aircraft panels of complex and accurate shape, outstanding superficial mechanical properties and remarkable anti-fatigue performance. The existing forming technology could not meet the strict and paradoxical manufacturing requirements of excellent formability, good flexibility and valid surface-strengthening simultaneously. To satisfy the increasingly common and challenging needs, a composite technique of 2 dimension ultrasonic incremental forming and laser shock peeing is proposed in this paper. The former method is suitable for manufacturing of complex-shaped sheet and strengthening coating which is prepared for subsequent laser treatment. The latter one is applied for secondary surface reinforcement with ultra-high energy. This work focuses on design of one kind of 2 dimension ultrasonic vibration incremental forming method and its effects on surface mechanical property and micro-structure of 7075 aluminium alloy. The traditional single-point incremental forming tests, the longitudinal ultrasonic vibration incremental forming tests and 2D ellipse ultrasonic vibration incremental forming tests were conducted on the designed special ultrasonic incremental forming equipment. Classic conical sheets of 7075 aluminium alloy were manufactured with above techniques to verified the effectiveness of the novel method and to study its influence on the mechanical properties and micro structure evolution of high strength alloys.”