{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,10,5]],"date-time":"2026-10-05T21:20:15Z","timestamp":1791235215107,"version":"4.1.0"},"reference-count":46,"publisher":"MDPI AG","issue":"4","license":[{"start":{"date-parts":[[2022,2,12]],"date-time":"2022-02-12T00:00:00Z","timestamp":1644624000000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Materials"],"abstract":"<jats:p>A better understanding of material deformation behaviours with changes in size is crucial to the design and operation of metal microforming processes. In order to facilitate the investigation of size effects, material deformation behaviours needed to be determined directly from material characterizations. This study was aimed at the design and manufacture of a compact universal testing machine (UTM) compatible with a 3D laser-confocal microscope to observe the deformation behaviour of materials in real-time. In this study, uniaxial micro tensile testing was conducted on three different thin (0.05 mm, 0.1 mm, and 0.3 mm) copper specimens with characteristic dimensions at micro scales. Micro tensile experimental runs were carried out on copper specimens with varying grain sizes on the newly developed apparatus under a 3D laser-confocal microscope. Microscale experiments under 3D laser-confocal microscope provided not only a method to observe the microstructure of materials, but also a novel way to observe the early stages of fracture mechanisms. From real-time examination using the newly developed compact testing apparatus, we discovered that fracture behaviour was mostly brought about by the concave surface formed by free surface roughening. Findings with high stability were discovered while moving with the sample grasped along the drive screw in the graphical plot of a crosshead\u2019s displacement against time. Our results also showed very low mechanical noise (detected during the displacement of the crosshead), which indicated that there were no additional effects on the machine, such as vibrations or shifts in speed that could influence performance. The engineering stress-strain plots of the pure copper-tests with various thicknesses or samples depicted a level of stress necessary to initiate plastic flowing inside the material. From these results, we observed that strength and ductility declined with decreasing thickness. The influence of thickness on fracture-strain, observed during tensile testing, made it clear that the elongation-at-break of the pure-copper foils intensely decreased with decreases in thickness. The relative average surface-roughness Ra was evaluated, which showed us that the surface-roughness escalated with the increasing trend of plasticity deformation (plastic strain) \u03b5. For better understanding of the effects of plastic strain on surface roughness prior to material fractures, micro tensile tests were performed on the newly developed machine under a 3D laser-confocal-microscope. We observed that homogeneous surface roughness was caused by plastic strain, which further formed the concave surface that led to the fracture points. Finally, we concluded that surface roughness was one of the crucial factors influencing the fracture behaviour of metallic sheet-strips in metal microforming. We found that this type of testing apparatus could be designed and manufactured within a manageable budget.<\/jats:p>","DOI":"10.3390\/ma15041368","type":"journal-article","created":{"date-parts":[[2022,2,13]],"date-time":"2022-02-13T20:34:45Z","timestamp":1644784485000},"page":"1368","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":25,"title":["In Situ Micro-Observation of Surface Roughness and Fracture Mechanism in Metal Microforming of Thin Copper Sheets with Newly Developed Compact Testing Apparatus"],"prefix":"10.3390","volume":"15","author":[{"ORCID":"https:\/\/orcid.org\/0000-0003-1085-3704","authenticated-orcid":false,"given":"Mandeep","family":"Singh","sequence":"first","affiliation":[{"name":"School of Mechanical and Mechatronic Engineering, University of Technology Sydney, Ultimo, NSW 2007, Australia"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0001-9446-8074","authenticated-orcid":false,"given":"Shubham","family":"Sharma","sequence":"additional","affiliation":[{"name":"Department of Mechanical Engineering, Main Campus-Kapurthala, IK Gujral Punjab Technical University, Jalandhar 144603, Punjab, India"},{"name":"Department of Mechanical Engineering, University Centre for Research and Development, Chandigarh University, Kolkata 140413, Punjab, India"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Appusamy","family":"Muniappan","sequence":"additional","affiliation":[{"name":"Department of Automobile Engineering, Saveetha School of Engineering, Saveetha Institute of Medical and Technical Sciences, Chennai 600124, Tamil Nadu, India"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-5568-8928","authenticated-orcid":false,"given":"Danil Yurievich","family":"Pimenov","sequence":"additional","affiliation":[{"name":"Department of Automated Mechanical Engineering, South Ural State University, Lenin Prosp. 76, 454080 Chelyabinsk, Russia"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-3380-4588","authenticated-orcid":false,"given":"Szymon","family":"Wojciechowski","sequence":"additional","affiliation":[{"name":"Faculty of Mechanical Engineering and Management, Poznan University of Technology, 60-965 Poznan, Poland"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Kanishka","family":"Jha","sequence":"additional","affiliation":[{"name":"Department of Mechanical Engineering, Lovely Professional University, Delhi 144001, Punjab, India"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Shashi Prakash","family":"Dwivedi","sequence":"additional","affiliation":[{"name":"G.L. Bajaj Institute of Technology and Management, Greater Noida, Gautam Buddha Nagar, Greater Noida 201310, Uttar Pradesh, India"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0003-4409-956X","authenticated-orcid":false,"given":"Changhe","family":"Li","sequence":"additional","affiliation":[{"name":"School of Mechanical and Automotive Engineering, Qingdao University of Technology, Qingdao 266520, China"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Jolanta B.","family":"Kr\u00f3lczyk","sequence":"additional","affiliation":[{"name":"Department of Manufacturing and Materials Engineering, Faculty of Mechanical Engineering, Opole University of Technology, Mikolajczyka 5, 45-271 Opole, Poland"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0003-2679-7575","authenticated-orcid":false,"given":"Dominik","family":"Walczak","sequence":"additional","affiliation":[{"name":"Department of Manufacturing and Materials Engineering, Faculty of Mechanical Engineering, Opole University of Technology, Mikolajczyka 5, 45-271 Opole, Poland"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Tien V. T.","family":"Nguyen","sequence":"additional","affiliation":[{"name":"Department of Industrial Engineering, Industrial University of Ho Chi Minh City, Ho Chi Minh City 70000, Vietnam"}],"role":[{"vocabulary":"crossref","role":"author"}]}],"member":"1968","published-online":{"date-parts":[[2022,2,12]]},"reference":[{"key":"ref_1","doi-asserted-by":"crossref","first-page":"3858","DOI":"10.1016\/j.matpr.2020.06.230","article-title":"Investigating the EDM parameter effects on aluminium based metal matrix composite for high MRR","volume":"33","author":"Singh","year":"2020","journal-title":"Mater. Today Proc."},{"key":"ref_2","unstructured":"Patnaik, A. (2021). Experimental Investigation of Tool Wear Rate (TWR) During the EDM of Hybrid Aluminum Metal Matrix Composite Reinforced with SiCp and Grp. 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