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Evaluation of the Plastic Yield Locus for Embossed Sheet Using Biaxial Tensile Tests
Young-Suk Kim,Seok-Hwan Oh,Van-Cuong Do,Bong-Hyun Lee 대한금속·재료학회 2016 METALS AND MATERIALS International Vol.22 No.6
3D-structured (embossed) aluminium sheets have been used as heat insulation materials in automotive exhaustparts because the embossments on the sheets increase the surface area and reinforce the stiffness of exhaustcomponents. Unlike the press-forming process for flat (non-embossed) sheets, however, that for embossedaluminium sheets is constrained by many restrictions given the distinct mechanical properties and geometric3D shape of the latter. In designing sheet-stamping tools, manufacturers have recently used CAE technologiesbased on finite element analysis. Guaranteeing the effectiveness of CAE technologies necessitatesinformation about the plastic yield criterion, which is determined primarily by performing a biaxial tensile teston cruciform-shaped specimens. We measured the yield locus of an embossed aluminium 3004-P sheet byusing the camera vision method instead of strain gauge measurement because of the difficulty in attachinga strain gauge to the central region of the aluminium body. The measured yield locus of the studied sheet showsthat its yield stress in equi-biaxial stress is smaller than the flat sheet yield locus measured by the strain gaugemethod. The shape of the yield locus of the embossed aluminium sheet also adequately corresponds withLogan-Hosford anisotropic yield function.
KSPE and Springer 2016 A Study on the Mechanical Properties and Springback of 3D Aluminum Sheets
오석환,안대철,김영석 한국정밀공학회 2016 International Journal of Precision Engineering and Vol.17 No.5
Three-dimensional (3D), cone-shape embossed aluminum sheets are used in automotive exhaust systems to increase their heat dissipation efficiency by increasing the surface area. However, the manufacturing process has various restrictions because wrinkling occurs easily during the press forming process. In this study, A tensile test and a bending test were performed to investigate the mechanical properties and springback characteristics of 3D aluminum sheets. We clarified how the direction in which the specimen is cut affects the tensile properties. The results of the tensile test showed that the characteristics of the parallel and diagonal direction specimens differed from each other and those of the as-received flat sheet. The 3D aluminum sheets had a smaller Young’s modulus and smaller flow stress than the as-received flat sheets in the small plastic range due to the flattening effect of the embossed cone shapes. However, as the plastic strain increased, the flow stress followed the as-received flat specimen’s flow stress curve because the cone-shape was flattened according to increases in the plastic strain. The yield stress increased in the diagonal-direction specimen and decreased in the parallel-direction specimen. The change in Young’s modulus in the 3D sheets affected the amount of springback.
Mechanical Behavior of Embossed AA1050-O Sheets Subjected to Tension and Forming
사비르므졸리,Carl Labergere,Marion Martiny,Mohamad Jrad,Guillaume Robin,김흥수,Francois Choquart 한국정밀공학회 2018 International Journal of Precision Engineering and Vol.19 No.10
In this paper, experimental characterization of embossed aluminum sheets is performed using extensive mechanical tests. Rotary embossing is performed on these sheets in order to obtain a periodic hill-and-valley structure. The experimental program consists of realizing mechanical tests such as tension, deep drawing, and hydraulic bulge tests using embossed samples in order to build a database that can be used for future finite element modeling tasks. The tensile tests are performed using digital images correlation (DIC) for total displacement measurements and for detailed strain maps. The hydraulic bulge and deep drawing tests are conducted on embossed circular samples to study their formability. A comparison was made with the plane (non-embossed) sheets to explain the contribution of the embossed structure either in both cases of uniaxial and multiaxial loadings.
이광석(K.S. Lee),김상우(S.W. Kim),신민철(M.C. Shin),이정환(J.H. Lee) 한국소성가공학회 2009 한국소성가공학회 학술대회 논문집 Vol.2009 No.5
When the metal sheet is subjected to the housing surface for fitting and insulating from harsh surroundings like fluid ingression or hot steam, both strength and formability have to be equally considered. In this regard, the main aim of this study is to design an apparatus of cost-effectively producing flexible fluted band with increasing the formability of embossed stainless steel sheet, which is utilized as a thermal insulation metal for housing ship engine exhauster. Designed to fabricate a maximum sheet width of 700 mm. this new apparatus consists of upper roll made of hard urethane and the female-etched lower roll made of SKD11, have a producing capacity up to 1-meter homogeneously embossed sheet for just 60 seconds. This machine is devised for the maximum operating efficiency from original sheet handling to machine setting. The embossing properties are characterized by 3-D PROFILING. After embossing plain metal sheet, both yield strength and elongation properties are improved simultaneously, indicating the effectiveness of the newly designed apparatus.
Heat Shields Fused with Embossed and Press Formed Al Alloy Sheets for Automobiles
Dong Hwan Park,Hyuk Hong Kwon,Jun Hyuk Seo 한국생산제조학회 2020 한국생산제조학회지 Vol.29 No.4
Heat shields are used on most engines to protect components and bodywork from heat damage. With regular driving conditions, heat shields need to protect parts from nearby heat sources with surface temperatures up to 650°C. Aluminum heat shields are able to protect against quite high temperatures. Aluminized steel sheets are required for heat shielding in the highest temperature range. Lightweight materials such as aluminum alloys are used to realize low fuel consumption for automobiles. The influence of embossing for heat shield parts in the press forming of Al alloy sheet after embossing was examined. This paper is to develop heat shield parts using aluminum alloy sheet for automobiles to improve the formability and reduce the wrinkling.
Incremental Forming of 3D Structured Aluminum Sheet
Van-Cuong Do,Duc-Toan Nguyen,조준행,김영석 한국정밀공학회 2016 International Journal of Precision Engineering and Vol.17 No.2
In this paper we investigated the deformation characteristic of embossed aluminum sheet in the incremental sheet forming process which has frequently used in the design verification and the trial manufacturing of sheet products. The single point incremental forming (SPIF) experiments for the rectangular cone forming using the CNC machine with a chemical wood-machined die and a circular tool shape showed that the formability of the embossed sheet are better than that of the flat sheet in view of the maximum angle of cone forming. This comes from the fact that the embossed sheet between the tool and the elastic die wall is plastically compressed and the flatted area contributes to increase the plastic deformation. Also the tool path along the outward movement from the center showed a better formability than that of the inward movement from the edge. However the surface quality for the tool path along the outward movement evaluated from the surface deflection is inferior than that of the tool path along the inward movement. The experimental results and detail forming mechanism of the 3D structured sheet in incremental forming were reviewed with a finite element simulation using ABAQUS software.
Experimental investigations on composite slabs to evaluate longitudinal shear strength
Saravanan, M.,Marimuthu, V,Prabha, P.,Arul Jayachandran, S.,Datta, D. 국제구조공학회 2012 Steel and Composite Structures, An International J Vol.13 No.5
Cold-formed steel profile sheets acting as decks have been popularly used in composite slab systems in steel structural works, since it acts as a working platform as well as formwork for concreting during construction stage and also as tension reinforcement for the concrete slab during service. In developing countries like India, this system of flooring is being increasingly used due to the innate advantage of these systems. Three modes of failure have been identified in composite slab such as flexural, vertical shear and longitudinal shear failure. Longitudinal shear failure is the one which is difficult to predict theoretically and therefore experimental methods suggested by Eurocode 4 (EC 4) of four point bending test is in practice throughout world. This paper presents such an experimental investigation on embossed profile sheet acting as a composite deck where in the longitudinal shear bond characteristics values are evaluated. Two stages, brittle and ductile phases were observed during the tests. The cyclic load appears to less effect on the ultimate shear strength of the composite slab.