Philippe Picart

A New Modelling of Blanking for Thin Sheet in Copper Alloys with Dynamic Recrystallization

Precision blanking process is widely used by electronic and micromechanical industries to produce small and thin components in large quantities. To take account of the influence of strain rate and temperature on precision blanking of thin sheet in copper alloys, we have proposed a thermo‐elasto‐visco‐plastic modelling. In addition, dynamic recrystallization takes place in Cual copper alloy during the blanking process of thin sheet. A new modelling of dynamic recrystallization based on the thermodynamics of irreversible processes is presented. Blanking simulations of Cual copper sheet are carried out in order to analyze the softening effect induced by dynamic recrystallization.

Numerical Design Of Experiments to Analyse the Contact Conditions in Microforming

In microforming, the so‐called size effects can be observed in the material flow behaviour as well as in the frictional behaviour. In order to study the frictional behaviour a preliminary numerical characterization of the surface tribology has been carried out. A numerical design of experiments (DOE) is based on cylinder upsetting tests to define the influence of surface geometric properties on the resultant force. The simulations have been performed with the finite element software LS‐Dyna by using an axisymmetric model. The mechanical behaviour of the cylinder specimen was described by an elastic‐plastic material law, whereas the upsetting plates were assumed to be rigid. The workpiece is considered to be a copper alloy (CuZn10). The average roughness Ra and the average mean spacing Sm have been chosen to describe surface roughness properties. The tool and workpiece surfaces have been modelled using a sinusoidal profile. The five input parameters of the DOE are the amplitude and the period of the two si...

A New Modelling of Dynamic Recrystallization — Application to Blanking Process of Thin Sheet in Copper Alloy

Blanking process is widely used by electronic and micromechanical industries to produce small and thin components in large quantities. To take into consideration the influence of strain rate and temperature on precision blanking of thin sheet in copper alloy, a thermo‐elasto‐visco‐plastic modelling has been developed in [1]. Furthermore the blanking of thin sheet in Cual copper presents dynamic recrystallization. A new modelling of dynamic recrystallization based on the thermodynamics of irreversible processes is proposed. Blanking simulations of Cual copper sheet are performed to analyze the softening effect induced by dynamic recrystallization.

Micromechanical nonlocal damage modeling

Publisher Summary This chapter presents a micromechanical nonlocal damage model to predict the damage evolution in metal forming processes, especially in the cold forging of small components. The modeling considered in this chapter is based on a Gurson model modified by Bennani, where the nonlocal damage has been defined in the same manner as Pijaudier-Cabot and Bazant. A nonlocal damage modeling based on Gursons model has been implemented in the large strain finite element framework of POLYFORM code for quasi-static loading conditions. The first results show that nonlocal damage could reduce the problem of mesh dependency. Future works consist in testing this nonlocal formulation on classical tensile tests with axisymmetric notched specimens and then to apply it on metal forming processes—such as blanking or cold forging.