Identification of non-linear Kinematic Hardening with Bend-reverse Bend Experiments in Anisotropic Sheet-metals
An inverse identification technique is proposed based on bending-unbending
experiments on anisotropic sheet-metal strips. The initial anisotropy theory of plasticity is
extended to include the concept of combined isotropic and non-linear kinematic hardening.
This theory is adopted to characterise the anisotropic hardening due to loading-unloading
which occurs in sheet-metals forming processes. To this end, a specific bending-unbending
apparatus has been built to provide experimental moment-curvature curves. The constant
bending moment applied over the length of the specimen allows to determined numerically the
strain-stress behaviour without Finite Element Analysis. Four constitutive parameters have
been identified by an inverse approach performed simultaneously on the bending and tensile
tests. Our results show that bending-unbending tests are suitable to model quite accurately
the constitutive behaviour of sheet metals under complex loading paths. As an example, a F.E.
spring-back analysis of a U-shape deep-drawn sheet strip shows the influence of the non
linear kinematic hardening.
Michel BRUNET, Fabrice MORESTIN, Francis SABOURIN, Stéphane GODEREAUX
Reçu le 1 juillet 2001.
Accepté le 25 octobre 2001.
Sheet-metals, anisotropy, kinematic-hardening, inverse-method, bending-unbending, spring-back.