Gemala Hapsari : "'Identification of inelastic cyclic behaviour of thin metal sheets under very large strain from instrumented micro forming process

PhD works of Gemala Hapsari : "Identification of inelastic cyclic behaviour of thin metal sheets under very large strain from instrumented micro forming process"

Abstract : The success of micro product’s industrialization depends on the conception, design and manufacturing process. A crucial step is characterization of material used in numerical simulations. Although it gives some mechanical properties of material, tensile test is far from representing the complete deformation produced in material. Therefore another test, Micro Incremental Deformation (Micro InDef) test which has non homogeneous deformation and rich in characterization data is developped, based on Micro Single Point Incremental Forming (μSPIF).To modelise the limit of formability (especially the damage of materials), Lemaitre’s constitutive model is chosen due to its possibility to define the material behaviour by using continuum mechanics and thermodynamics of irreversible processes. Within this study, Micro InDef as material characterization test is validated. Moreover,using an identifiability method, the material parameters identified are proven to be physical parameters, instead of only mathematical fitting. Once Lemaitre’s model is identified, experimental tests and finite element simulations are performed on tensile tests, shearing tests, forming limit tests and out-of-plane tests, to verify the reliability and adaptability of our identification. This study is applied in an industrial project within the connector domain, which use copper alloys.

Evaluation committee :

• PASCALE BALLAND, Reporting Jury, university Professor at University of Savoie Mont Blanc
• ARNAUD DELAMAIZIERE, Reporting Jury, university Professor at University of Lorraine
• PIERRE-YVES MANACH, Examiner, university Professor at University of Bretagne Sud
• KARL DEBRAY, Examiner, university Professor at University of Reims
• YU NING, Examiner, R&D Director of Axon Cable
• SEBASTIEN THIBAUD, Thesis Director, university Professor of ENSMM
• FABRICE RICHARD, Thesis Co-Directeur, Associate Professor (HDR) at University of Franche Comté

Localization :  Jules HAAG Auditorium at ENSMM - 26, Rue de l'Epitaphe  - Besançon