Construction of a true compaction curve: critical review of the closed die compaction test for powdered materials

This job came of an investigation about a new model called Energy Split Hypothesis (onwards ESH), which is proposed and experimentally tested for the closed die compaction test based on a statement of energy conservation. It was motivated by the observed data scattering in constructing the compaction curve, making use of the well-known Method of Differential Slices (onwards MDS). As part of this was addressed the problem of uniform fill-den-sity before compaction, when using specimens of different size. As with testing the validity of the ESH, the methodology is based on a statistical analysis of the observed data scattering upon experi-ment repetition. The friction between the die wall and the powder specimen is considered the cause of data scattering, and it is shown as a reduc-tion in the friction force, which makes the magnitude of this being equal for ESH and MDS approaches to the compaction curve. This is considered a proof of the physical validity of the ESH as a model of the Closed Die Compaction Test (at least to the extent the MDS is). The study of this test from the standpoint of data scattering analysis, provided a method for computing a so-called True Com-paction Curve, in a probabilistic sense and from a physically valid model of the process. The ESH, as an energy-based interpretation of the compaction test, allowed a proposal for the computation of die wall-powder friction coefficient, using optimisation principles. In addition, a re-formulation of the MDS by considering an empirically defined parameter is also put forward. These last two items were subject to experimental validation, and thus, set out as future work.

• Autores: Barrera Cárdenas, Helver Mauricio
• Tipo de recurso: Book
• Fecha de publicación: 2017
• Institución: Universidad Autónoma de Occidente
• Repositorio: RED: Repositorio Educativo Digital UAO
• Idioma: eng
• OAI Identifier: oai:red.uao.edu.co:10614/13934
• Acceso en línea: https://hdl.handle.net/10614/13934; https://red.uao.edu.co/
• Palabra clave: Metalurgia de polvos; Materiales - Propiedades mecánicas; Mecánica; Material - Mechanical properties; Powder metallurgy; Mechanics
• Rights: openAccess
• License: Derechos reservados - Universidad Autónoma de Occidente, 2017