1,446 research outputs found
Che cosa significa scrivere?
No full textA partire dalla sovversione cartesiana, la soggettivazione passa per la scrittura, la visione, l'immagin
ANOVA OF 3D VARIATIONAL MODELS FOR COMPUTER AIDED TOLERANCING WITH RESPECT TO THE MODELING FACTORS
No full textSheet metal assemblies are subjected to errors as deformations due to material, thickness, geometries and process variations. Advanced simulations enable the optimization of product features, GD&T scheme and assembly process. The 3D error propagation due to the different contributors can be studied with Variational Models of the product and assembly system. However, the practical application of these methods is limited by the high number of factors in the models, which makes the operator experience fundamental to achieve their trustworthiness. Guidelines for modeling the sheet metal assemblies are needed. The present work aims at analysing the variations in the model with a Design of Computer Experiments (DoCE) plan. A case study on an automotive fender is discussed. The results demonstrate that the modeling strategy of clamping operation have the major effects, while the modeling of locators scheme, spot joints and FEM meshing are less important
Il sovrano alla prova delle passioni. Prudenza, ira, dissimulazione nelle tragedie italiane tra Cinque e Seicento
No full textIl saggio legge la produzione tragica controriformistica attraverso la lente di quelle prerogative simulatorie/dissimulatorie tipiche del sovrano. Questa lettura diacronica e insieme legata ad un genere così connotato politicamente costituisce la novità del contributo. Le vicende rappresentate dal teatro tardo cinquecentesco e secentesco (di solito storiche o mitologiche) sfociano nella tragedia proprio nel momento in cui il sovrano cede alle passioni, senza attuare le necessarie tattiche di “velamento” dei propri sentimenti o dei propri impulsi in grado di garantire un retto esercizio del potere. In questo senso il genere tragico sembra far tesoro, dissimulandone (questa volta sì!) la portata, della lezione di accorto pragmatismo del Principe machiavelliano. L’unica tragedia che sembra adombrare il nome del quondam Segretario è l’Asdrubale di Iacopo Castellini (1562): per il resto, ovviamente, il nome di Machiavelli non può che essere taciuto. Alcune tragedie presentano scene che discutono il comportamento del sovrano in maniera quasi argomentativa, segnalando quale deve essere il comportamento corretto da tenere (per es. l’Acripanda di Antonio Decio). Mano a mano che si procede nel Seicento, infine, l’ipoteca moralista diviene via via sempre più invadente e la discussione sul comportamento del sovrano un’opzione quasi retorica: lo rivelano per esempio le tragedie di Emanuele Tesauro
Integrated design method for optimal tolerance stack evaluation for top class automotive chassis. In Advances on Mechanics, Design Engineering and Manufacturing (pp. 1013-1022). Springer International Publishing.
No full textThe tolerances of welded chassis are usually defined and adjusted in very expensive trials and errors on the shop floor. Computer Aided Tolerancing (CAT) tools are capable to optimize the tolerances of given product and process. However, the optimization is limited since the manufacturing process is already mostly defined by the early choices of product design. Therefore, we propose an integrated design method that considers the assembly operations before the detail design of the chassis and the concept design of the fixture system. The method consists in four phases, namely functional analysis in the CAD environment, assembly sequence modelling in the CAT tool, Design Of Simulation Experiment on the stack of the tolerance ranges and finally optimization of the tolerances. A case study on a car chassis demonstrates the effectiveness of the method. The method enables to selectively assign tight tolerances only on the main contributors in the stack, while generally requiring cheaper assembly operations. Moreover, a virtual fixture system is the input for the assembly equipment design as on optimized set of specifications, thus potentially reducing the number of trials and errors on the shop floor
Robust Parameter Analysis of Compliant Part Models for Computer Aided Tolerancing
No full textSheet metal parts are widely used in automotive, aerospace, ship and consumer goods industries. The final dimensions of a sheet metal assembly result from the parts deformation, which in turn is affected by many variations in material, thickness and single parts dimensions. The tolerance analysis on sheet metal assemblies improve the knowledge about the process. Advanced simulations enable the optimization of product features, GD&T scheme and assembly process. Moreover, Variational Models of both the product and the assembly system enable to assess the sources of 3D error propagation from the different contributors. However, the simulation results are very affected by the modelling approach of critical components, such as the Fixture Systems. The present paper firstly introduces a strategy to model the Fixture System and the assembly process for compliant parts. Then, a robust analysis of the variations in the model with respect to the modelling factors is performed by a Design of Experiments. A case study on an automotive fender is discussed. The results
demonstrate that the modelling strategy of the clamping operation have the main effects, while the modelling of locators scheme, spot joints and FEM meshing
are less important
Design of fixture systems in automotive manufacturing and assembly
No full textFixture systems have a great importance in modern manufacturing and assembly because of the high number of scenarios in which they are used. Fixture design is a complex task since the system effectiveness depends both on position and type of locators. Several authors deal with the problem of determine the most suitable design for fixture systems but their investigation is commonly limited to the evaluation of the effects due to the locators’ position. In the present work a design method is proposed to evaluate the fixture systems considering also the locators’ type. Since it is possible to model the fixtures as multi-performance systems, the comparison is performed by introducing appropriate sensitivity indexes. The effectiveness of the design method is proved through the application to an automotive case study
David Audretsch: A Source of Inspiration, a Co-author, and a Friend
No full textIn this chapter, Enrico Santarelli discusses the profound impact that David had on his career. Beginning with a conference in Budapest, Santarelli and David bocame close friends and colleagues. They went on to collaborate on many papers and projects, several of which Santarelli highlights below
Dialogo con Enrico Palandri
No full textA conversation with Enrico Palandri aimed at contextualizing his work as an author
Genetic algorithm optimization and robustness analysis for the computer aided design of fixture systems in automotive manufacturing
No full textFixture Systems (FSs) have great importance in machining, welding, assembly, measuring, testing and other manufacturing processes. One of the most critical issue in FS design is the choice of both the type of fixing devices such as clamps, locators, and support points, (configuration), and their arrangement with respect to workpieces (layout). Several authors deal with the problem of determine the most suitable solution for FSs, often investigating their layout without considering the change of the type of locators. A computer aided design method is proposed to compare and evaluate different configurations for a FS, optimizing the locator type and analysing the roboustness of the solution. A multi-objective optimization based on a genetic algorithm is presented and the selection of the most suitable configuration is performed through the definition of robustness indexes. The effectiveness of the design method is demonstrated for an automotive case study
Numerical Simulation and Experimental Validation of MIG Welding of T-Joints of Thin Aluminum Plates for Top Class Vehicles
No full textThe integration of experiments with numerical simulations can efficiently support a quick evaluation of the welded joint. In this work, the MIG welding operation on aluminum T-joint thin plate has been studied by the integration of both simulation and experiments. The aim of the paper is to enlarge the global database, to promote the use of thin aluminum sheets in automotive body industries and to provide new data. Since the welding of aluminum thin plates is difficult to control due to high speed of the heat source and high heat flows during heating and cooling, a simulation model could be considered an effective design tool to predict the real phenomena. This integrated approach enables new evaluation possibilities on MIG-welded thin aluminum T-joints, as correspondence between the extension of the microstructural zones and the simulation parameters, material hardness, transient 3D temperature distribution on the surface and inside the material, stresses, strains, and deformations. The results of the mechanical simulations are comparable with the experimental measurements along the welding path, especially considering the variability of the process. The results could well predict the welding-induced distortion, which together with local heating during welding must be anticipated and subsequently minimized and counterbalance
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