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F. Finite element and experimental investigations of the multipoint flexible hydroforming process. Naceur Selmi, Hedi Belhadjsalah . Mechanical Engineering Laboratory , National Engineering School of Monastir. University of Monastir, Tunisia. Contents.

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slide1

F

Finite element and experimental investigations of

the multipoint flexible hydroforming process.

Naceur Selmi, Hedi Belhadjsalah.

Mechanical Engineering Laboratory, National Engineering School of Monastir.

University of Monastir, Tunisia.

ESAFORM 2013

contents
Contents
  • Object of works: The flexibility.
  • Introduction to (the flexible processes).
  • Stepof Numerical analysis design.
  • Experimental implementation system.
  • Experimental investigations.
  • Validation works (simulation confronted with the experimental).
  • Conclusions and prospects in sight.

N.Selmi,H.Belhadjsalah: LGM/ENIM/University of Monastir/TUNISIA ESAFORM 2013

object of works the flexibility
Object of works: The flexibility
  • Metal forming industries field:
  • The flexibility:

- Produce many shapes with the same tooling:

- Polymorphism of tooling state

- Reconfigurable system setting or set up.

- Ability to be converted in other form.

- Easier way or facility to produce different shapes.

N.Selmi,H.Belhadjsalah: LGM/ENIM/University of Monastir/TUNISIA ESAFORM 2013

introduction 1
Introduction (1)
  • The hydroforming process:
  • One of the tools (punch or die) is replaced by the fluid pressure.
  • More flexibility, only one tool rigid is necessary and sufficient to define the final shape of the product.

N.Selmi,H.Belhadjsalah: LGM/ENIM/University of Monastir/TUNISIA ESAFORM 2013

introduction 2
Introduction(2)
  • Flexible forming :

Two basic alternatives : Flexible forming

- Two complementary opposed matrices of punch elements .

- A matrix of punch elements as lower die completed and opposed elastomeric stack.

N.Selmi,H.Belhadjsalah: LGM/ENIM/University of Monastir/TUNISIA ESAFORM 2013

the multipoint flexible hydroforming mpfh

The multipoint flexible hydroforming (MPFH)

N.Selmi,H.Belhadjsalah: LGM/ENIM/University of Monastir/TUNISIA ESAFORM 2013

presentation of the process
Presentation of the process
  • The multipoint flexible hydroforming (MPFH),
  • combining the hydroforming and the multipoint forming.
  • Obtaining a synergy of the advantages of both processes.
  • Using uniquely one multipoint die to perform completely the final part shape.
  • It allows flexibility of the basic multipoint flexible forming (with two multipoint discrete dies).

N.Selmi,H.Belhadjsalah: LGM/ENIM/University of Monastir/TUNISIA ESAFORM 2013

slide8
Multipoint flexible hydroforming process.

Multipointdie set up for (MPFH).

N.Selmi,H.Belhadjsalah: LGM/ENIM/University of Monastir/TUNISIA ESAFORM 2013

step of numerical analysis design
Stepof Numerical analysis design.
  • To show the capacity of the new process to produce complex three-dimensional forms.
  • To compare the new process (flexible Hydro-processing) with a relatively recent and existing flexible processes (MPSF).

ABAQUS/Explicit was used for Finite element analysis model

of the multipoint flexible hydroforming process.

Doubly curved part shape to be formed:

Written in Cartesian coordinate system as follows:

Such as: Z (x, y) = a1.x2 + b1.y2(1) Saddle form: a1.b1 < 0, parabolic form: a1.b1 > 0. Or in cylindrical coordinates for the forms of revolution: Z (R) = have sin (2 p .i.f.r/R) (2)

N.Selmi,H.Belhadjsalah: LGM/ENIM/University of Monastir/TUNISIA ESAFORM 2013

step of numerical analysis design1
Stepof Numerical analysis design
  • The discrete die size was 100 mm x 100 mm.
  • punch elements density of setting (11x11 and 21x21),
  • many cases of blank and interpolator sheet thicknesses was used for analysis.
  • The Mooney–Rivlin hyperelastic model for elastomeric.
  • Dynamic/explicit method was used for the simulation.

N.Selmi,H.Belhadjsalah: LGM/ENIM/University of Monastir/TUNISIA ESAFORM 2013

step of numerical analysis design parameters effect
Stepof Numerical analysis design(parameters effect)
  • 3.1.1 Effect of the sheet thicknesses
  • The effect of blank thickness can be observed from the simulation results, for lower thickness, all surface of final part is severely dimpled and the increase of thickness reduces dimpling and improves the profile regularity and the surface quality.

N.Selmi,H.Belhadjsalah: LGM/ENIM/University of Monastir/TUNISIA ESAFORM 2013

effect of the sheet thicknesses
Effect of the sheet thicknesses.

N.Selmi,H.Belhadjsalah: LGM/ENIM/University of Monastir/TUNISIA ESAFORM 2013

experimental analysis 1
Experimental analysis (1)
  • Effect of the sheet thickness

This effect is confirmed by experimental way.

By producing many doubly curved parabolic.

(shape part eq.(2))

For aluminum alloy sheet part produced:

Severe dimpling effect was observed for thin sheet (0.5 mm) with irregular profile and buckled edges.

N.Selmi,H.Belhadjsalah: LGM/ENIM/University of Monastir/TUNISIA ESAFORM 2013

experimental analysis 2
Experimental analysis (2)
  • for relatively thicker sheet (2mm):

Successful sheet part was obtained with more regular profile and with no significant dimples.

N.Selmi,H.Belhadjsalah: LGM/ENIM/University of Monastir/TUNISIA ESAFORM 2013

interest of the metallic die sheet
Interest of the metallic die sheet
  • In this configuration,

we will insert a metallic thick die sheet instead of the elastomeric interpolator conventionally inserted between multipoint die and blank side, the combination of both methods can be considered also.

N.Selmi,H.Belhadjsalah: LGM/ENIM/University of Monastir/TUNISIA ESAFORM 2013

interest of the metallic die sheet 2 aluminum alloy products
Interest of the metallic die sheet (2)Aluminum alloy products:

Elastomeric interpolator Metallic media.

N.Selmi,H.Belhadjsalah: LGM/ENIM/University of Monastir/TUNISIA ESAFORM 2013

interest of the metallic die sheet 3 stainless steel products
Interest of the metallic die sheet (3)Stainless steel products:

Elastomeric interpolator Metallic media.

N.Selmi,H.Belhadjsalah: LGM/ENIM/University of Monastir/TUNISIA ESAFORM 2013

interest of the metallic die sheet 4
Interest of the metallic die sheet (4)

N.Selmi,H.Belhadjsalah: LGM/ENIM/University of Monastir/TUNISIA ESAFORM 2013

interest of the metallic die sheet 5
Interest of the metallic die sheet (5)

N.Selmi,H.Belhadjsalah: LGM/ENIM/University of Monastir/TUNISIA ESAFORM 2013

interest of the metallic die sheet 6
Interest of the metallic die sheet (6)
  • Instead of request of costly increased number of punches for relatively thinner blank usual , the use of metallic sheet media is more relevant and efficient way to eliminate significantly dimpling and edge buckling with reasonable density of punch elements.

N.Selmi,H.Belhadjsalah: LGM/ENIM/University of Monastir/TUNISIA ESAFORM 2013

conclusions
Conclusions

The multipoint flexible hydroforming (MPFH) is a relevant way to obtain flexibility by combining adequately two emergent processes :

The hydroforming and multipoint flexible forming.

  • The feasibility of the process is validated by the prototype designed and recently realized.
  • Successful doubly curved shell products was obtained by implemented prototype of this process.
  • the results of preliminary experimental works are in good agreement with previous numerical analysis .
  • This process is an accurate and low cost technology with great saving in time manufacturing especially in the field of fast prototyping, small batch or single production.
  • Using of metallic sheet media is more efficient way to eliminate dimpling and edge buckling and to extend flexible multipoint hydroforming quality for thin sheet products with reasonable density of punch elements, the result is resourceful process with reduced number of components.
  • For extended experiments, larger scale prototype is under progress.

N.Selmi,H.Belhadjsalah: LGM/ENIM/University of Monastir/TUNISIA ESAFORM 2013

thank you for your attention
Thankyou for your attention

N.Selmi,H.Belhadjsalah: LGM/ENIM/University of Monastir/TUNISIA ESAFORM 2013