Papers by Author: Dirk Vandepitte

Paper TitlePage

Authors: Dirk Vandepitte, David Moens
Abstract: Development of a complicated technical problem encompasses different successive decisions that are based on techical analysis and engineering judgment. In each of these steps, somedegree of non-determinism is inevitable. The paper discusses different types of non-deterministic parameters that may be relevant in different stages of engineering analysis. The entire cycle of development of a product is considered, and it is shown that the relevance of methods isdifferent in different stages of the development cycle. A classification of different types of non-deterministic properties is presented. Based on the nature of these different classes of model properties, it is discussed to what degree each of these fits in the framework of either a probabilistic or a non-probabilistic concept.The availability of realistic data in an appropriate format is another issue that should be taken into account. A validated probabilistic representation is usually only possible after an extensive campaign of data acquisition has been conducted, or at least after suffcient data have been collected to allow for a reliable estimation of a statistical model. A study of scientific literature shows that validated information is not always available. A general conclusion is that probabilistic methods are applicable in later stages of development, when a suffciently large database of product data has been gathered. Probabilistic approaches are perfectly suited for conditions when the product is already in service. Possibilistic analysis on the other hand is best suited for application in cases when the data set about the product at hand is still incomplete.
23
Authors: Vitalii Vorkov, Richard Aerens, Dirk Vandepitte, Joost R. Duflou
Abstract: Bump bending or step bending is a forming technique that allows making large radius bends in a sheet metal part by means of a series of bends performed close to each other. The bump bending process has been studied by means of both an experimental campaign and finite element analysis. High-strength steel Weldox 1300 and a punch of radius 30 mm have been used. The finite element calculations have been performed with Abaqus using the solid formulation and Implicit/Explicit solvers. The results of the finite element analysis have been validated experimentally by monitoring the bending process using a camera system aligned with the bending line. Experiments were performed on a press-brake with a capacity of 50 metric tons. Deflections of a sheet during and after bending have been measured using the images recorded by the camera. In order to investigate the influence of a new bend on a previously formed bend, experiments have been performed with different distances between two consecutive bends. Based on the experiments, the size of the affected zone for the bend has been measured. The dependence of the distance between two consecutive bends on the resulting global bending angle has been studied. Moreover the influence of the bump distance on the springback has been investigated.
1090
Authors: Vitalii Vorkov, Richard Aerens, Dirk Vandepitte, Joost R. Duflou
Abstract: Large radius air bending has a different loading diagram than conventional bending, which affects the material behavior during the bending process. In order to establish a correct loading diagram, the position of the contact points between the plate and the punch is determinant. The position of the contact points is depending on the evolution of the bending process and the influence of the material is unknown. In this work, the determination of the position of the contact points in large radius air bending has been studied by means of both an experimental campaign and finite element analysis. Experiments were performed on a press-brake with a capacity of 50 metric tons. High-strength steel Weldox 1300 and aluminum alloy AlMg3, and punches of radii 30, 35 and 40 mm have been used. During the bending process, the punch movement has been monitored and the bending angle has been measured by means of images recorded by a camera system. Based on the obtained results, the relation between the bending angle and the position of the contact points is discussed.
155
Authors: Vitalii Vorkov, Richard Aerens, Dirk Vandepitte, Joost R. Duflou
Abstract: In this work, the multi-breakage effect has been studied by means of an experimental campaign and finite element analysis. We suggest that large radius bending (XL-bending) consists of three phases that are distinguishable according to the type of contact of the plate with the tool: 1-point, surface and 2-points. In the experimental investigation the high-strength steel Weldox 1300 and a 40 mm radius punch were used. The authors created a camera setup to film the multi-breakage effect. Additionally, finite-element calculations were performed to confirm the hypothesis of the three phases of the bending process. For the springback and the bending force evaluation, the difference in the moment distribution for each phase has been calculated in the case of a beam. It shows that the multi-breakage effect must be taken into account to obtain a good accuracy for the springback and the bending force calculation.
1047
Showing 1 to 4 of 4 Paper Titles