Proceedings of The IRES 25th International Conference, Istanbul, Turkey, 24th January 2016, ISBN: 978-81-925751-3-1

47

ANALYSIS BY NUMERICAL SIMULATION OFTHE TEAR SHEET OF WHEELBARROWS DURING DEEP DRAWING

1FAOUZI HAMZA, 2OUZINEBOUSSAID, 3KAMELTADJINE

1,2,3aboratory of industrial risks Research,Deptof Mechanical Engineering,University ofAnnaba

E-mail: 1faouzi-hamza@hotmail.fr, 2oboussaid@yahoo.fr, 3kameltadjine@rocketmail.com

Abstract- This study is based on cases of the sheet metal rupture in the deep drawn, recorded inworkshop of the wheelbarrows manufacturing company. The process simulations for obtaining the wheelbarrow are conducted on the Abaqus/caefinite element code, in order to visualize the deformation process and the material mechanical behavior at deep drawing. Areas with high local thinning before a tear have been highlighted from the representation of the thickness configuration and the deformation at the end operation. This allows to predicting the areas of necking which caused of rupture at certain drawn of the company, such as the wheelbarrow reported to the laboratory for analysis of material and of the tear of sheet at the end of operation. The results are summarized in the curves of stresses and strains distribution during the deep drawing, the localization of areas at risk of tears and the determination of parameters causing the tearing of sheet. Index Terms- Deep drawing, simulation, strain,stress, tear. I. INTRODUCTION The deep drawing is one of the forming processes of thin sheets which transform a sheet in one part, more or less hollow to non- developed surface. The parts obtained a complex geometry leads the material to be uncontrollable deformation paths. This geometric diversity on the drawing part serves to satisfy the current industry's progress which requires a careful study of deep drawing tools, and the material to be drawn, that enriching the results of the forming processes,which gives rise to several searches in the field, that allowed to understand the influence of the different parameters of this process on the material behavior, the material drawability by determining of the forming limit curve FLC[1], The limit drawing ratio LDR [2], and the materials characterization [3]-[4]. The material mechanic behavior modeling and the deep drawing simulation have been performed to different drawing geometry in order to analyze the interactions tools-sheet according the metal forming parameters, as cylindrical cup drawing [5],deep drawing of the hemispherical cups [6] and a square cup deep drawing [7]. The stress and strain distributiontaken the extent in the study of this process.Other studies regarding the necking and thinning during the forming have been performed [8]. The numerical simulation, allowing realizing virtually the forming operation, occupies a very broad space in current scientific research, allowing replacing the mechanical tests at lower cost. The present study aims to explore the tearing sheet problem during the deep drawing of the wheelbarrows within a company,by numerical analysis of the elasto-plastic material behavior during the deformation, using the finite element code ABAQUS/explicit, to follow up and evaluate the stress and strain distribution,allowing to locate areas

which represented a plastic material instability and predicting of the thinning appearance, leading to tearing of the sheet. II. THE PROBLEM DESCRIPTION The encountered problem is the presence of necking and tear on the sheet during the metal forming, on the wheelbarrow at the end of the deep drawing operation.

(a) (b)

Fig.1 The appearance of necking and the tear of wheelbarrow.

Atear problemduring the deep drawing of the sheet metal leading to us investigates the origin of this problem. The simulation of Process is possible with the software ABAQUS/cae. III. SIMULATION Description of simulation steps:

Fig.2Simulationsteps[9].

Analysis By Numerical Simulation Of the Tear Sheet Of Wheelbarrows During Deep Drawing

Proceedings of The IRES 25th International Conference, Istanbul, Turkey, 24th January 2016, ISBN: 978-81-925751-3-1

48

IV. IMPLEMENTATION OF THE SIMULATION We executed the wheelbarrow forming operation with the finite element code software ABAQUS/CAE by a 3D simulation.The Model design starts with the creation of the deep drawing operation tools such as the die, Blank holder and the punch in shell forms,and the blank is deformable solid-extrusion with a thickness T= 1mmthen introduced the material mechanical properties. The sheet rheology considered isotropic elasto-plastic. The mechanical properties of material answer to European standard EN 10130.

Table.IMechanical properties of the DC04 steel.

V. RESULTS The obtained results according to deep drawing parameters, such as the blank holder force, the die and the punch radius, the blank thickness and the friction coefficient are represented below:

Fig.3Assembly in Initial and final position (Sectional

representation).

Fig.4Representation of the stress and strains distribution.

VI. EXPLOITATION OF RESULTS Once the results are obtained, one follows the penetration of punch into the die for determining the

evolution of stresses and strains distribution during the wheelbarrow formingunder the action of punch. Thepenetration course of punch duringthe wheelbarrow forming is subdivided into 20 equal parts according to step/frame. So one can save the results of maximum strain and stress for each penetration of the punch of 1.25mm a drawing depth of 25 mm. In determining according Abaqus/CAE the curves that allow us to visualize the stress and strain distribution,we choose the line of nodes located on the first contact of the punch with blank.

Fig.5The series of nodes located on the line of the first contact

punch-blank.

The contact conditions and blank deformation are varied under the punch, sheet thins by expansion while sliding bit on the tool [10]. The plastic deformation with reduction of the blank thickness is called thinning deformation.

Fig.6Principal strains during the forming of sheet metal by

plastic deformation.

The principle of volume conservation translates in terms of deformation: (1+e maj). (1+ e min). (1+e thickness)= 1 (1) Where εmaj+ εmin+ εthickness=0(2) The principle of mass conservation allows to measure two deformations and to deduce the third.The deformation in the thickness of sheet etwhere the thinning deformation,will be: According to (1) : e = ( )

(3) Where ε = − ε + ε (4) εmaj, emaj : majordeformation. εmin, emin : minordeformation. Theories of rupturebased on some numerous criteria. Among the most known is the von mises criterion, it

Analysis By Numerical Simulation Of the Tear Sheet Of Wheelbarrows During Deep Drawing

Proceedings of The IRES 25th International Conference, Istanbul, Turkey, 24th January 2016, ISBN: 978-81-925751-3-1

49

is based directly on the terms of the stress matrix:

Γ =σ τ ττ σ ττ τ σ

(5)

determined for the reference axes M0xyz. This criterion takes into account the intermediate stress σ2. The stress state (σ1, σ2 and σ3) is characterized by equivalent stress σeq,its value is obviously a function of the rupture criterion [11]. σ =

√

(σ −σ ) + (σ −σ ) +(σ −σ ) + 6(τ + τ + τ )

(6) VII. ANALYSIS OF RESULTS The collected results are in the form of curves of the stresses and strains which show that the evolution of transition is most often the deformation of blank under the action of the punch.

Fig.7Stress- strains curve during the penetration of the punch.

This curve shows that depth of deep drawing of 11,25 mm the registered stress was 400 MPa with a strain of 34.4%,indicating that the onset of necking is just after the punch penetration of 1.25 mm where the strain reached 45.2% can lead to tearing of metal. This interpretation is confirmed in the below figure.

Fig.8Evolution of strain PE22 depending the deep drawing depth.

The deformation in direction eps22 takes very small values and almost equal until the depth 8.75 mm and begin to increase uniformly. When the punch exceeds 12.5 mm, the strain reaches 37.7%, up there the thickness is thinned and from the depth of 20 mm, she stabilized at 77.2%, which indicates the tearing of the sheet.

Fig. 9The stresses variation following the line of selected nodes.

Fig. 10The strain variation following the line of selected nodes.

The representation of the stress S and strain PE in the second direction,allows us to evaluate the variation of the sheet thickness. The curves above indicate the tearing zone of the sheet, by the sudden fall of the stress and strain in the area of application of the punch nose on the blank. This drop is in the middle of each of the two curves. CONCLUSION The simulation of mode for obtaining of the wheelbarrow has allowed us to visualize the deformation process and the material mechanical behavior to deep drawing. Areas with high local thinning before a tearhave been highlighted from the representation of the thickness configuration and the deformation at the end operation. Areas with necking causing ruptures of the company's wheelbarrowswere localized. The results are summed up in representation curves of distribution of the stresses and strains during the deep drawing, identifying areas at risk the tearing of sheet and determination of the

Analysis By Numerical Simulation Of the Tear Sheet Of Wheelbarrows During Deep Drawing

Proceedings of The IRES 25th International Conference, Istanbul, Turkey, 24th January 2016, ISBN: 978-81-925751-3-1

50

parameters to the origin of this tear. REFERENCES [1] W. Frącz, F. Stachowicz, T. Trzepieciński, and T.

Pieja,“Forming Limit Diagram Of The Ams 5599 Sheet Metal,” Archives of metallurgyand materials, Vol. 58, pp. 1213-1217, 2013.

[2] S.Magar, M.Ghanegaonkar, P.M.Khire, and M.Y.Kachare, “Studies on Deep Drawing of Steel Cups for the Variation of Yield Strength and Drawing Ratio Using FEA,” International Journal of Mechanical Engineering, Vol. 3, pp. 1–5,jan2013.

[3] Y.LEDOUX, “Optimisation des procédés d’emboutissage par caractérisation géométrique et essais numériques,” Thèse de Doctorat : Université de SAVOIE lméca, December2005.

[4] P. MANACH, “Lois de comportement et mise en forme des matériaux métalliques,” Thèse de doctorat : Université De Bretagne Sud,October 2004.

[5] B. Rao, R. Ravindra, M. Chandra, and M. Krishna, “Optimization of Blank Holding Force in Deep Drawing of Cylindrical Cups Using Taguchi Approach,”International Journal of Engineering and Innovative Technology (IJEIT), Vol 2, pp. 143-148, September 2012.

[6] E. GAO, L. Hong-wei, and K.Hong-chao,“Influences of material parameters on deep drawing of thin-walled

hemispheric surface part,” Transactions of nonferrous Metals Society of China,Vol. 19, pp.433−437,April 2009.

[7] F. Ayari,b.E. Bayraktar, “Parametric Finite Element Analysis for a square cup deep drawing process,” Journal of Achievements in Materials and Manufacturing Engineering,Vol. 48, pp. 64-86,September 2011.

[8] R. Ravindra, S. Rao, G. Chandra, P. Radhakrishna, and G.Krishna, “Parametric Studies on Wrinkling and Fracture Limits in Deep Drawing of Cylindrical Cup,” International Journal of Emerging Technology and Advanced Engineering, Vol. 2, pp. 218- 222,Jun2012

[9] J.Detraux, M. Jameux, R. Horkay, F.(Renault),R.Oustau, F (PSA). Marchand, J-L (Sollac), “Simulation numérique de l'emboutissage de tôles minces en acier extra doux,” Recherche technique acier Propriétés et comportement en service,Commission des Communautés européennes,1991.

[10] G. Payen, E.Felder, “Analyse mécanique des conditions de contact entre la tôle et le serre-flan en emboutissage profond,” 19ème Congrès Français de Mécanique. Marseille, 24-28 août, August2009.

[11] V.Songmene, “Mise En Forme Par Déformation Plastique,” Techniques avancées de mise en forme,Le génie pour l’industrie.