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A study on the mechanical properties and springback of 3D aluminum sheets

  • Seok-Hwan Oh
  • Dae-Cheol Ahn
  • Young-Suk Kim
Article

Abstract

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.

Keywords

3D sheet Embossing pattern Tensile test Springback 

Nomenclature

R1

the radius of the upper punch for the V-bending test

R2

the radius of the lower die for the V-bending test

L1

the distance between the upper die and the lower die for the V-bending test

θi

the initial angle of the specimen after the V-bending test

θf

the final angle of the specimen after the V-bending test

Δθ

the difference in the angle between the initial and final angles of the specimen after V-bending

R3

the radius of the upper punch for the U-draw bending test

R4

the radius of the lower die for the U-draw bending test

P1

the length of the punch for the U-draw bending test

L2

the clearance of the die on the U-draw bending test

θ1

the angle of the specimen on the upper punch shoulder

θ2

the angle of the specimen on the lower die shoulder

σY

yield strength

σTS

tensile strength

E

Young’s modulus

n

strain hardening exponent

K

strength coefficient

R

plastic anisotropic coefficient

width, dεthickness

the plastic strain in the direction of the width and thickness, respectively

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Copyright information

© Korean Society for Precision Engineering and Springer-Verlag Berlin Heidelberg 2016

Authors and Affiliations

  1. 1.School of Mechanical EngineeringKyungpook National UniversityDaeguSouth Korea

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