Preenchimento de cavidades provenientes de remoção de trinca em turbinas hidráulicas por meio do processo GMAW-P

Dissertação (mestrado)—Universidade de Brasília, Faculdade de Tecnologia, Departamento de Engenharia Mecânica, 2016.

Modelling and simulations of ductile iron solidification-induced variations in mechanical behaviour on component and microstructural level

The mechanical behaviour and performance of a ductile iron component is highly dependent on the local variations in solidification conditions during the casting process. Here we show a framework which combine a previously developed closed chain of simulations for cast components with a micro-scale Finite Element Method (FEM) simulation of the behaviour and performance of the microstructure. A casting process simulation, including modelling of solidification and mechanical material characterization, provides the basis for a macro-scale FEM analysis of the component. A critical region is identified to which the micro-scale FEM simulation of a representative microstructure, generated using X-ray tomography, is applied. The mechanical behaviour of the different microstructural phases are determined using a surrogate model based optimisation routine and experimental data. It is discussed that the approach enables a link between solidification- and microstructure-models and simulations of as well component as microstructural behaviour, and can contribute with new understanding regarding the behaviour and performance of different microstructural phases and morphologies in industrial ductile iron components in service.

Early stage assessment of the inspectability of welded components : A case from the aerospace industry

This paper proposes a method to indicate potential problems when planning dye penetrant and x-ray inspection of welded components. Inspection has been found to be an important part of the manufacturability evaluation made in a large CAD-based parametric environment for making multidisciplinary design simulations in early stages of design at an aircraft component manufacturer. The paper explains how the proposed method is to be included in the design platform at the company. It predicts the expected probability of detection of cracks (POD) in situations where the geometry of the parts is unfavourable for inspection so that potential problems can be discovered and solved in early stages. It is based on automatically extracting information from CAD-models and making a rule-based evaluation. It also provides a scale for how favourable the geometry is for inspection. In the paper it is also shown that the manufacturability evaluation need to take into consideration the expected stresses in the structures, highlighting the importance of multi-disciplinary simulations.