Analytical Model of the Anisotropic Dimensional Change on Sintering of Ferrous PM Parts

Abstract This work proposes an analytical model developed from experimental data to describe the anisotropic dimensional change on sintering. Axial-symmetric iron parts differing for geometry and sintering conditions have been investigated, aiming at highlighting the influence of geometry. The specimens were measured in the green and sintered state by a coordinate measuring machine (CMM). The dimensional changes of height, external diameter and internal diameter were derived from measurement results. The anisotropy of the dimensional variations has been studied with reference to the isotropic dimensional change derived from the change in volume of the parts. The influence of geometry and sintering temperature was highlighted. To properly describe the dimensional variations in the compaction plane, the dimensional change of the external diameter versus the dimensional change of the internal one has been analysed. By means of the experimental data, a reliable analytical relationship has been found, dependent on the parts geometry. An anisotropy parameter has been identified, which allows relating the dimensional change in the compaction plane and in the axial direction to the isotropic dimensional change. This parameter depends both on geometry and on sintering conditions. By means of the anisotropy parameter an analytical model for the anisotropic behaviour has been developed

Surface Hardening Vs. Surface Embrittlement in Carburizing of Porous Steels

Abstract Carburizing increases the contact fatigue resistance of sintered steels, but the surface hardening may result the formation of surface brittle cracks due to the combined effect of high hardness and porosity. The effect of carburizing on the embrittlement of the case of a 7.3 g/cm3 1.5%Mo - 0.25%C sintered steel was studied. The phenomenon was analyzed theoretically and verified by experiments. The resistance of the carburized steel to surface brittle cracking increases with the load bearing surface and the decrease of the maximum pore size, of the surface microhardness and the friction coefficient. The theoretical analysis was implemented in a design procedure for parts subject to contact stresses

DETC2006-99113 HOW RAPID PROTOTYPING PROCESS PARAMETERS COULD AFFECT THE PRODUCT DESIGN PHASE: A KBS APPROACH

ABSTRACT Considering the whole product life-cycle, product model is usually defined during the design phase, given a set of requirements and constraints belonging to the same domain. The use of different manufacturing and verification technologies may, however, profoundly affect the characteristics of the product, so that a re-design phase is often necessary. In previous work, a Knowledge Based System named Design GuideLines (DGLs) was developed, aiming to help the designers make the product model compatible with the requirements and constraints of the specific manufacturing and verification domains. During the DGLs development, the possibility emerged to exploit them in order to identify possible relations among product features. This aspect seems very important, further helping the designer to better understand the consequences of the modifications suggested by the DGLs and applied to the product model during the re-design phase. The present work aims to identify these relations among product features. The result of DGLs exploitation has been critically analyzed to highlight the link between manufacturing characteristics and product features, and, further, among features themselves. Unpredictable relations among the product features, given a particular Rapid Prototyping technology as manufacturing technology, have been discovered and exploited

The Design Guidelines Collaborative Framework: A Design for Multi-X Method for Product Development

The Design Guidelines Collaborative Framework describes a knowledge-based 'design for multi-X' method, aimed at improving and assisting the work of designers, manufacturers, and inspectors in the areas of product redesign and process reconfiguration. Designers are not necessarily experts in manufacturing and verification processes; likewise, manufacturers and inspectors may not be experts in design. For this reason, the Design Guidelines Collaborative Framework (DGLs-CF) constitutes a meeting point for all three parties, where their knowledge is formalized, expanded upon, and put at the designers' disposal, thereby maximizing the user-friendliness of the results. The DGLs-CF is characterized by the homogeneous union of different algorithms, clear interfaces among the modules that implement them, and clear roles assigned to the different actors. These elements, together with a strong adherence to the ISO GPS standards, make the DGLs-CF the perfect environment for researchers, experts in different fields, and industrial partners to formalize their knowledge, and develop and implement their own algorithms and procedures. The Design Guidelines Collaborative Framework uses the simple IDEF0 formalism to describe the DGLs-CF framework in a top-down way, in order to facilitate readers' comprehension, and their adoption and development of the framework. Several case studies on the application of the DGLs-CF in industrial environments show the framework's effectiveness and robustness. Industrial and academic researchers will find this book a useful guide to the DGLs-CF and mechanical engineers will be quick to appreciate the streamlined approach it describes. \ua9 Springer-Verlag London Limited 2010

Working on Cognitive Functions in a Fully Digitalized Multisensory Interactive Room: A New Approach for Intervention in Autism Spectrum Disorders

The feasibility of working on cognitive functions with children and adults with Autism Spectrum Disorders (ASD) inside Multisensory Interactive Rooms (MIRs) has been poorly investigated, even if sensory atypicalities are common in ASD and usual intervention rooms could represent a challenging sensory setting for patients with ASD. We hypothesized that the possibility to calibrate the sensory stimulation offered by this type of environment, able to promote a positive emotional state in patients with ASD, can consequently favor the interaction with the therapist and the motivation towards activities targeting cognitive functions. High- and low-functioning children and low-functioning adolescents/adults underwent five sessions in a fully digitalized MIR, working on sustained attention, selective attention, association, single inhibition, receptive communication, verbalization, and turn. We developed specific protocols calibrated for sensory stimulation and difficulty level based on the characteristics of the participants. We found statistically significant improvements in all functions, except association, in the children’s group. Therefore, a fully digitalized MIR seems suitable for intervention on cognitive functions in ASDs, but further investigations are needed to better address possible differences related to age and functioning level