The competitiveness of conventional press & sinter technology mainly depends on the ability to obtain tight tolerance on sintered products. In order to maintain this strategic advantage in spite of the rapid global market changes, a continuous improvement in the dimensional accuracy of the products has to be pursued. One of the major limits in the dimensional precision of sintered products regards the anisotropic dimensional change occurring on sintering. Despite this problem is well known, an effective design procedure accounting for the anisotropic behavior of dimensional variations is far to be reached. The main reasons concern the multiphysical mechanisms involved and the effect of material, geometry and process condition on the final results. This work aims at developing a design methodology accounting for the anisotropy of dimensional changes on sintering. This study has been performed considering both the fundamental principles and the industrial application, aiming at proposing: - a solid theory considering the mechanisms which determine the anisotropic dimensional changes; - a practical and effective design tool for the industrial application. The role of uniaxial compaction on the origin of anisotropic dimensional change was firstly investigated. AISI 316L ring shaped samples were compacted at different geometries, and four different particle sizes. During single action compaction, forces acting on the tooling and powder column, and related displacements, were recorded by the press in order to derive the compaction mechanics of the powder mixes. Further, the dimensions of the samples were measured before and after sintering. A linear trend was observed correlating the deviatoric stresses occurring in compaction to the anisotropic dimensional variations on sintering. This result offers a new perspective in the prediction of the anisotropic dimensional change, and could lay the foundation of a solid model. Aiming at developing an effective design tool to predict dimensional change on sintering, the analytical design procedure previously developed by the research group at the University of Trento was validated on real parts. A Club Project was promoted by EPMA, collecting the University of Trento and five qualified industrial partners. These companies provided five different real parts characterized by different materials and geometries, whose dimensions were measured before and after sintering. The comparison of the measured and the predicted sintered dimensions demonstrated that this design approach can be an effective tool for designers. Further work could implement the promising results obtained investigating the compaction mechanics in the design procedure, aiming at defining a powerful tool to design PM parts accounting for anisotropic dimensional changes.

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This research examined whether or not an auditory stimulus would affect rates of change blindness. Change blindness occurs when there is a failure to detect an obvious change to a visual scene. For this experiment 40 participants were asked to determine if a change occurred between two pictures. This involved an original picture shown for 1 second, a neutral screen shown for 50 milliseconds and then either a modified version of the original image or the same image for 1 second and then repeated. Participants then determined whether a change occurred in the visual display. For some participants a familiar song played on repeat during the visual task. My goal was to determine if music would affect rates of change blindness and how quickly changes would be detected if present. I found that participants in both the music and non-music conditions were more accurate when there was no change to a scene. Participants in the music condition also took longer to respond as opposed to the control group. When examining reaction times of only correct responses, both conditions responded in a similar amount of time for pictures with changes. In trials with no changes the participants in the music condition took longer to respond than the control group. Overall, it appears that music had a negative effect on reaction times when a change was present. Participants were also more accurate in detecting pictures with no changes as opposed to pictures with changes.

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