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MACHMINI Résumé de rapport

Project ID: G1RD-CT-2001-00657
Financé au titre de: FP5-GROWTH
Pays: France

Self-consistent method for miniature materials

The description of the elasto-viscoplastic behaviour of miniature materials and components the minimum size of which is that of a grain, has to rely on the phenomenological or macroscopic approach. Microscopic constitutive laws, based on the dislocation theory, are used to predict the behaviour of elementary volumes of the material of the scale of 5×5×5mm require the use of powerful computers. The approach developed in the MACHMINI project, for use at meso-scale, is appropriate for the quantification of miniature materials and components.

The developed UMAT subroutine is based on a single crystal elasto-viscoplastic constitutive law. Preliminary requirements are to experimentally identify the five significant material parameters with sufficient accuracy to ensure reliability of the FE simulation results. The mini-press was developed in order to conduct this parameter identification task.

All components/products that require the simulation of component behaviour, either during the forming operation or in subsequent use, would require test data of the accuracy possible with the use of the mini-press. Commonly, the electronics, sensor, instrumentation, biomedical and control industries require such quantification.
UMAT subroutine version V17 was successfully implemented into ABAQUS software. Its capability to reproduce mini component forming processes has been demonstrated.

Numerous microstructural data are available from simulation obtained using this program, such as:
- Crystallographic texture evolution,
- Set of active slip systems,
- Density dislocation on all slip systems for every grain,
- Intragranular stress state.

Usual global information are also accessible with increased accuracy:
- Force-displacement characteristic,
- Elastic spring-back,
- Anisotropy induced by plastic strain, etc.

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