Abstract. This paper presents experimental and numerical results of butt friction stir welding of high density polyethylene. The FSW designed tool insulates the welded samples and preserves the heat gained from friction thus avoiding the appearance of blisters and splits after welding. The experimental tests, conducted according to combinations of process factors such as rotation speed, welding speed, pin diameter and hold time at beginning welding, were carried out according the Taguchi orthogonal table L 27 in randomized way. Temperatures in the joint during the welding operation and flow stresses from the tensile tests of welded samples were measured and variances were analyzed. Identified models were used to simulate, by finite elements, the tensile tests performed on specimens having a weld cordon in their active area. The results show coherence between the numerical predictions and experimental observations in different cases of weld cordon mechanical behaviour.
The workers’ performance in the mechanical manufacturing sector is the main factor for the improvement of productivity and quality. At present, it seems that the available information on the ergonomics and the working environment of the mechanical manufacturing actors is scarce. This study deals with the relationship between the working method and the workstation in injection mold manufacturing. An original methodology, based on the survey of operators using participatory ergonomic tools, is proposed in order to evaluate the ergonomic performance of 3 workstations: milling, turning, and drilling. The surveys concerned 3 operators. Obtained results showed that ergonomics play a key role in improving mechanical manufacturing. The results obtained from the analysis showed that ergonomics has a key role in the quality of the various tasks performed by operators. Using the Rapid Entire Body Assessment (RULA) and Rapid Entire Body Assessment (REBA) investigation tools, the examination of the workstations revealed 4 machining operations and 12 operator postures that have a direct influence on the performance of all machining stations. In addition, data from the analysis conducted on injection mold manufacturing revealed that neither the workstations were ergonomic nor the operators complied with the ergonomic rules. Based on the results obtained, a new standardized score is proposed for the RULA and REBA calculations. This score was applied and validated through another study conducted in a leaf spring manufacturing plant. The results of these studies were concretized by proposing the digital factory where CATIA software was used for the virtual design of the ergonomic workstations and their environments.
This paper provides the experimental protocol, of the process of a single point incremental sheet forming "SPIF", allowing predicting the efforts of forming. To speak about parameters of a single point incremental sheet forming (SPIF), we should find the good parameter for judgement. A prediction of the forming force during the SPIF process is selected to ensure the safe use of the tooling and machinery, in particular when using a robot or a milling machine not designed for the process. During the incremental forming process, considerable forces can occur depending on the studied material, the thickness of the sheet, the tool steps. In this work, the influence of several parameters on the evolution of the axial forming force during the incremental forming of a truncated cone is studied. A set of experiments is carried out using steel and aluminium sheets. The results on the most influent process parameters can be used to optimize the process. The results obtained are compared with those found by finite element simulations.
Dans cetteétude, on présente une contributionà la modélisation expérimentale et numérique du comportementélastoplastique endommageable anisotrope de tôles destinéesà la mise en forme. L'accent est mis sur la localisation des instabilités plastiques induites par l'anisotropie plastique et l'endommagement. La procédure d'identification des paramètres matériau du modèle de comportement est basée sur une approche inverse d'optimisation s'appuyant sur des essais de traction orientés, associéeà des simulations numériques (Abaqus/Standard et Matlab). La validation de la procédure proposée a puêtre menée grâcè a une confrontation entre simulations numériques et résultats expérimentaux obtenus sur deséprouvettes caractéristiques des tôles minces texturées en acier doux. L'application est ensuite faiteà la simulation de procédés de gonflement hydraulique de ces tôles avec prévision de l'endommagement ductile. Plusieurs cas en expansion libre (matrices circulaires et elliptiques) et en expansion dans des cavités de matrice seront présentés et des comparaisons avec les résultats expérimentaux seront réalisées.
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