Arnaud Delamézière

Optimization of the blankholder force distribution with application to the stamping of a car front door panel (Numisheet’99)

New materials such as dual phase steel or aluminium and complex geometries of industrial parts increase the difficulties to obtain a defect free part by stamping. One way of solution is a better regulation of the blankholder pressures. Our work is based on an original idea of Siegert, Haussermann and Haller. The goal is to control the movement of the blank under the blankholder. Thanks to a deformable flexible blankholder, it is possible to create some independent zones. In each zone, a blankholder force can be applied on the sheet, so that a strong force can hold the blank in a zone, and a smaller one can let it move in another zone. The methodology is presented as well as some results dealing with the optimization of the blankholder force considering the drawing of a front door panel (Numisheet’99 benchmark test). The numerical simulations are performed using ABAQUS Explicit. The parameters of the finite element model (mesh density, speed of punch) are set to achieve a good prediction with a minimum sim...

Optimization Of The Blankholder Force With Application To The Numisheet’02 Deep Drawing Benchmark Test B1

The increasing use of new materials such as dual phase steel or aluminium alloys leads to some difficulties to overcome regarding their formability. One way to obtain good parts in deep drawing operations is to modify the process parameters to achieve a better control of the strains in the sheet. Our work is based on an original idea of Siegert, Haussermann and Haller. The goal is to control the movement of the blank under the blankholder by varying locally the blankholder force. This is achieved by a deformable blankholder and by different pressures in the pins (in time and space). In this paper, we present the methodology and some results dealing with the optimization in time of the blankholder force considering the drawing of a cylindrical cup (Numisheet’02 benchmark test). The numerical simulations are performed using Abaqus Explicit. The parameters of the finite element model (mesh dimension, speed, contact algorithms) are set to achieve a good prediction. The objective function is to minimize the wo...

Numerical Simulation of Incremental Sheet Forming by Simplified Approach

The Incremental Sheet Forming (ISF) is a process, which can transform a flat metal sheet in a 3D complex part using a hemispherical tool. The final geometry of the product is obtained by the relative movement between this tool and the blank. The main advantage of that process is that the cost of the tool is very low compared to deep drawing with rigid tools. The main disadvantage is the very low velocity of the tool and thus the large amount of time to form the part. Classical contact algorithms give good agreement with experimental results, but are time consuming. A Simplified Approach for the contact management between the tool and the blank in ISF is presented here. The general principle of this approach is to imposed displacement of the nodes in contact with the tool at a given position. On a benchmark part, the CPU time of the present Simplified Approach is significantly reduced compared with a classical simulation performed with Abaqus implicit.

Contrôle des défauts d’emboutissage par optimisation des efforts serre-flan

Ce travail concerne l’optimisation des efforts serre-flan en emboutissage, le serreflan étant constitué de zones indépendantes. Les forces optimales appliquées sur ces zones sont calculées pour éviter les défauts d’emboutissage (striction et plissement de la tôle). Dans le cadre de ces travaux, un critère de striction a été formulé. La procédure d’optimisation utilise une surface de réponse basée sur une approximation par moindres carrés pondérés. La méthode est appliquée à un panneau de porte, cas-test de la conférence Numisheet’99.

Optimisation des efforts serre-flan pour l’emboutissage d’une boîte carrée: Contrôle de la striction et du plissement sous serre-flan

L’objectif de la simulation numérique en emboutissage est principalement l’amélioration de la qualité de la pièce finale obtenue par le contrôle et l’optimisation de paramètres du procédé. Pour éviter la rupture, un critère de striction localisée a été formulé et validé sur un godet cylindrique et un test de Nakazima, sur lesquels des ruptures ont été observées expérimentalement. La deuxième partie de ce travail est consacrée à l’optimisation des efforts serre-flan d’une boîte carrée afin d’améliorer sa formabilité.