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Title: Powder compaction, finite element modelling and experimental validation
Author: Mohd Ihsan, A. K. A.
Awarding Body: University College of Swansea
Current Institution: Swansea University
Date of Award: 1995
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In the modelling of powder compaction, the behaviour of powders is assumed to be rate-independent elastoplastic, and the process may be described by a large displacement based finite element formulation. Three constitutive relationships to describe the mechanical behaviour of the powders were examined, namely a Mohr-Coulomb yield surface, an elliptical cap yield surface and a combined yield surface model. Of all the models tested, an elliptical cap was shown to be the most appropriate for the compaction phase. An incremental elastoplastic material model was used to simulate the relaxation phase and a plasticity theory for friction was employed in the treatment of the powder-tooling interface for the ejection phase. The model was extended to provide a decoupled thermal solution where the plastic and friction work during the compaction process was considered as sources of energy and the consequent temperature fields were calculated. In parallel, a series of experimental studies were carried out in the laboratory and factory for a plain bush and multi-level component. The parameters which were measured were force, displacement and density. The friction coefficient was derived from the plain bush compaction and shear yield tests were conducted to establish the shear behaviour of the powders. The powders tested are typical of those used in industrial applications. The results detailed information concerning the behaviour of the powders in terms of their material parameters for modelling and in validation of the numerical simulation work. Finally the numerical simulation results were validated against the experimental data to gain confidence in the model developed. The comparisons showed good agreement. The versatility of the simulation allows the complete representation of the green compact generation cycle.
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available