Analysis Of Sheet Metal Bending By Using Finite Element Method

International Journal of Engineering Research & Technology (IJERT)ISSN: 2278-0181Vol. 2 Issue 1, January- 2013Analysis of sheet metal bending by using Finite Element MethodKalyani AbhinavSchool of Mechanical & Building sciencesVIT UniversityChennai, IndiaProf. K. AnnamalaiSchool of Mechanical & Building sciencesVIT UniversityChennai, IndiaAbstract-Out of all the traditional manufacturingprocesses like casting, forming, cutting, joining, sheetmetal forming, deep drawing etc., sheet metal formingis a special case of deformation process in which sheetmetals of less than 6 mm are formed. It is the process ofconverting a flat sheet of metal into a part of desiredshape without fracture or excessive localized thinning.Hence the formability assessment of the different metalsi.e., Type 303 Stainless steel, mild steel and Aluminum isdone. Theparameters such as normal stress, totaldeformation, maximum principal stress, equivalentstress (Von Mises) and maximum principal elasticstrainare analyzed using ANSYS ERRTTKeywords- Sheet metal,deformation, formability.processes can be successfully operated only when theforming properties of the work material are withinnarrow range.Certain factors which influence onoverall operation of forming processes are stretching,elongation, anisotropy, grain size etc. Anotherimportant factor which influences sheet metalforming is Anisotropy or directionality of sheetmetal. Anisotropy is acquired during the thermomechanical processing of the sheet.In other worlds,the same sheet metal can have good or badformability depending upon the components of theforming system. It is interesting to contrast this to atypical mechanical property of sheet metal which isdependent on the sheet metal only rather than on thesystem conditions such as sheet thickness, processconditions, surface finish, sheet metal properties etc.A large variety of metallic parts are produced bydeformation process. In fact, there are more than1000 registered types of steels; each of these wasoriginally designated for some specific use.Forming process involve shaping material in the solidstate whether the material is a continuous solid orpowder. It is the essential property when the materialis subjected to deformation .This process requires lotof energy depending on the type of metal,expenditure and capital investment to be formeddiffers.In sheet metal working operations, the crosssection of the work piece remains same and thematerial is subjected to shape changes. Theseoperations are performed on thin sheets ( 6 mm) bymeans of a set of tools called punch and die. Formingcan be done based on type of sheet, punch and die.Sheet metal forming involves bending, punching,drawing, stretching and some other processes. Out ofvarious bending operations, V-die bending is chosenfor the sheet metal to be formed. The commonfailures encountered during sheet metal forming,wrinkling, puckering, and shape distortion factors.They are generally characterized by a high ratio ofsurface area to thickness. Sheet metal formingoperations are so diverse in type, extent and rate thatno single test provides an accurate indication of theformability of a material in all situations. SomeSo many researchers have done the formability andanalysis of sheet metals of different materials. [1]Misklos Tisza, Zoltan peter kovacs showed variousaspects of damage limitations like fracture, neckingetc. and studied as limits of formability. [2]V.Taylon, R.H.Wagoner and J.K.Lee investigated theformability of austenitic and ferritic stainless amdesigned new test and evaluatedseveral coated and uncoated sheet materials whichproduces more stable and repeatable plain-strainstates near fracture location. [4] M.Kleiber, J.Rojek,R.Stocki revealed that the reliability analysis does notrequire any change for sheet forming process. [5]Mehmet Firat, BilginKaftanoglu, OrhanEser showedthat stamping simulations and FE analysis givessimilar predictions in terms of formability andthickness distribution. [6] Thomas B.Stoughton,JeongWhan Yoon predicted fracture polygon fromstress based FLC and analytical equation with thefunction of local fracture strain. [7] KjellMattiasson,Mats Sigvant presented yield criteria and evaluatedwith respect to their suitability and concluded thatthey both are ideally suited for sheet metal formingprocesses. [8] OzgurTekaslan, NedimGerger,UlviSeker supported that spring back variesaccording to functions of both material and die. [9]W.M.Chan, H.I.Chew, H.P.Lee, B.T.Cheok studiedspring back angles of work piece by varying punchwww.ijert.org1

International Journal of Engineering Research & Technology (IJERT)ISSN: 2278-0181Vol. 2 Issue 1, January- 2013angle, punch radius and die radius.[10]K.M.Zhao,J.K.Lee obtained stress-strain curves after theparameters in combined hardening model areidentified. [11] Li-Ping Lei, Sang-Moon Hwang,Beon-Soo Kang analysed free bending & square cupdeep drawing. [12] Jong-Jin park, Yung-Ho Kimindicated about positive and negative formingmethods. [13] Nader Asnafi studied modes offracture in the sheet metals.A.Aluminum:Aluminum, being lowest densest metal which isrelatively ductile and appears as silver gray. Thoughit is difficult to extract form ores, it forms strongbonds and their strength is very high. This propertyenhances Al to be used widely in various sectors.Analysis of aluminum type of sheet metal is done andthe parameters are calculated after applying certainforce of 115 N on the sheet. The sheet metal of240X65X1 mm dimension is used for formingprocess.In this, the arrangement the die is provided with fixedsupport so that it will not change the location if theforces are applied on the sheet metal. Similarly, thedifferent sheet metals of 240X65X1 mm dimensionsare set on the die and different forces are applied onthe punch. These forces are calculated using UTM.The type of die used to for the sheet metal to form isof V-type. Other type of dies such as U-die, rollertype can also be used for the sheet metal to be formed.This enhances differences in calculating parameterssuch as normal stress, total deformation, maximumprincipal stress, and maximum principal elastic strain.These parameters are analyzed later.III. FINITE ELEMENT ANALYSISThe setup of die, punch and sheet metal is drawn inthe solid works software which is shown infigure1This arrangement is meshed and refined whichis shown in fig.2 so that one can have a clear pictureof the deformed part. After the setup is arranged inrequired format, different sheet metals are placed andforces are applied accordingly. The sheet metal is benton 70oV-die and the required parameters arecalculated. Each type of sheet metal is deformed andforces are calculated using UTM. Static analysis isdone using ANSYS V12 software for calculating theparameters.IIJJEERRTTB.Mild steel:Mild steel is most common form of steel whichexhibits low-tensile strength. Static analysis is doneon mild steel by applying force of 105 N on the sheetmetal and parameters are calculated. This formingprocess has the sheet metal of same dimensionswhich are considered before.II. EXPERIMENTAL PROCEDUREC.Stainless Steel of Type 303:Stainless steel, also known as inox steel which differsfrom carbon steel by amount of chromium present isused. The sheet of type 303 is formed by applying aforce of 260 N and the parameters are analyzed.The properties of three different sheet metals areindicated in the table I.Figure1.Showing solid model of the arrangementTable I. Properties of Sheet metalsTypePropertyDensity (g/cc)UltimateTensileStrength (Mpa)Yield TensileStrength sSteel8AluminumMild 0Figure 2. Showing mesh structure of the arrangementAfter applying the fixed support for the base of thedie and the force on the punch, which acts verticallydownwards on the sheet metal and is deformed. Bywww.ijert.org2

International Journal of Engineering Research & Technology (IJERT)ISSN: 2278-0181Vol. 2 Issue 1, January- 2013this we can analyze the required parameters. Thefigures below indicate parameters like normal stress,total deformation, maximum principal elastic strain,equivalent stress and maximum principal stress ofdifferent sheet metals like aluminum, stainless steelof type 303 and mild steel.Figure 6. Showing Equivalent stress in mild steelFigure 3. Showing normal stress for AluminumIIJJEERRTTFigure 7. Showing maximum principal stress instainless steelIV. RESULTS AND DISCUSSIONSAfter analysis of certain parameters by applyingdifferent loads and conditions on three different sheetmetals, results are obtained. Here we consider all themaximum values which are obtained and graphs areplotted accordingly. Table 2 depicts all themaximumvalues of the different parameters like maximumnormal stress, total deformation, maximum principalelastic strain, equivalent stress and principal stress.Figure 4. Showing Total deformation in AluminumTABLE 2.Parameters obtained of three different sheet metalsTypeParametersMax. normal stress(Mpa)Figure 5. Showing Max principal elastic strain in AlTotal deformation(mm)Max.principalelastic strain (m/m)Equivalent(Mpa)Stainlesssteeltype ssMax.principal stress(Mpa)www.ijert.orgAlumin-um3

International Journal of Engineering Research & Technology (IJERT)ISSN: 2278-0181Vol. 2 Issue 1, January- 2013From the analysis of three different sheet metals ofdifferent materials, we obtain the required parametersand the graphs are plotted accordingly. The resultsare formulated as:Max principal elasticstrain(m/m)1.210.80.61. Maximum normal stress for the stainless steel isvery high when compared to aluminum and mildsteel which is shown in figure 8.0.40.22. Total deformation taking place is much higher inthe case of aluminum whereas lower in mild steel dueto its physical properties which is shown in figure 9.0Aluminum Stainless Mild steelSteelTypes of sheet metals3. Maximum principal elastic strain is much higher inaluminum and lower in mild steel which isrepresented in the figure 10.Figure10. Types of sheet metal Vs Max principal elastic strainEquivalent stress(Mpa)4. Equivalent stress in mild steel reached altitudewhen compared to aluminum and mild steel and isrepresented in the figure 11.IIJJEERRTTstildTypes of sheet metalsFigure 11. Types of sheet metal Vs Equivalent Maximum normalstress(Mpa)5. Maximum principal stress is higher in mild steeland lower in stainless steel which is shown in thefigure12.10009008007006005004003002001000Types of sheet metalsMax principal stress(Mpa)Total deformation (mm)Figure 8.Types of sheet metal VS max. Normal 3002001000Aluminum Stainless Mild steelsteelTypes of sheet metalsFigure 12.Types of sheet metals Vs Max principal stressAluminum Stainless Mild steelSteelV. CONCLUSIONSTypes of sheet metalsFigure9. Types of sheet metal VS total deformationIn this paper,different sheet metals are consideredand different loads are applied and parameters areobtained. From all the graphs, we can conclude thatnormal stress is maximum onlyin the case ofwww.ijert.org4