Catálogo de publicaciones - libros

The paper is an attempt to recall the principal events during the first ten years of the ESAFORM association. Nuphymat, a European network on material forming, was a first trial to coordinate research in the field and was soon followed by the creation of the ESAFORM association. The main “philosophical principles” and general scientific goals of the association are briefly recalled. Some examples of achievements are listed and their impact is discussed.

In recent years new and advanced numerical strategies have opened new possibilities in the simulation of forming processes. Multiscale descriptions, meshless methods and enhanced finite element approaches are some techniques that have contributed to the enhancement of forming process simulations. These approaches will be revisited in this chapter.

The paper first presents the experimental set-ups designed to produce flow-induced crystallization and the techniques used to analyze structure development. Then, the general effects of flow are discussed in terms of crystallization thermodynamics (nucleation, growth, overall kinetics), with the consequences on morphologies (from spherulites to shish-kebab morphologies). Finally, some open questions are presented, which shows that many things are not yet explained, especially the nucleation event.

Polymer processing modelling offers new opportunities for die or mould optimization.

We first present a short state of the art of polymer processing technology, followed by a discussion on how to develop reasonable processing models, some illustrations being given. We then deal with the question of constitutive equations in polymer processing modelling, both for classical thermoplastics and for more sophisticated (fibre reinforced) polymer systems. Finally, we revise flow instabilities that limit processability both in confined flows and in free surface extensional flows.

The strong development of composite materials in particular in aeronautics leads to a demand for knowledge and simulation codes concerning composites forming. The mini-symposia developed on this theme within the ESAFORM conference are a privileged framework for the researchers in this field to communicate and to exchange ideas. This paper gives a progress report on the advancements achieved during these ten last years and on the research prospects in the various fields of composite material forming.

Semi-solid processing involves forming metallic alloys between the solidus and the liquidus. The microstructure must consist of solid spheroids in the liquid matrix, rather than dendrites, for the process to operate. The material then behaves thixotropically i.e. it flows when it is sheared but thickens again when allowed to stand. The behaviour was first discovered by Flemings and coworkers in the 1970s and is utilized in a family of processes, some now applied commercially. Here the current status of semi-solid processing, both technologically and from a research point of view, will be reviewed.

Micro technology and nano materials are gaining increasing interest in the metal forming community. This can be explained by a large number of new applications and products pushed to market in the past, yielding smaller geometrical dimensions of the final products and thus demanding for smallest components to be manufactured in large quantities. Up to now, most of these parts are being manufactured by machining technology well suited for the production of small series. The analysis of the current market situation shows, that the steadily increasing trend towards smallest products is continuing in the future and thus requesting for new manufacturing technologies for large quantity production. Forming technology seems to be well suited due to its high production output and high accuracy. The aim of this chapter is to give an overview on current research activities related to microforming and nanomaterials technology showing the capabilities and problems. The analysis of the current state will give a hint on existing gaps in knowledge and will finally describe the future demands.

This paper presents a review of the main families of multiscale models. A first group of models is interested in an accurate modelling of the texture induced anisotropy of the material during numerical simulations. The differences between the proposed models are mainly due to different choices concerning the necessary compromise between the importance of the microscopic roots of the model and the maximum admissible computation time. The length scale of the investigated process is also an important parameter. The second group of micro-macro models is based on an analysis of the dislocation densities linked to the plastic deformations. A discussion concerning the past evolution, the recent achievements and the future trends concerning multiscale models is also provided.

The chapter presents synthetically the most recent models of the anisotropic plastic behavior. The first section gives an overview of the classical models, In the next step, the discussion is focused on the anisotropic formulations developed on the basis of the theories of linear transformations and tensor representations, respectively. Those models are applied to different types of materials: body centered, faced centered and hexagonal-close packed metals. A brief review of the experimental methods used for observing and modeling the anisotropic plastic behavior of metallic sheets and tubes under biaxial loading is presented together with the models and methods developed for predicting and establishing the limit strains. The capabilities of some commercial programs specially designed for the computation of forming limit curves (FLC) are also analyzed.

Sheet metal forming represents an extensive research area involving numerous topics such as finite element techniques and modeling, material models, material characterization, formability, component and full-scale test methods as well as a variety of industrial processes and technologies. In the present overview, however, attempts have been made to mainly concentrate on recent technology development and innovative sheet metal forming methods, representing a summary of works presented at ESAFORM conferences during the past decade. The first objective is to demonstrate advances in sheet metal forming by specific examples with different degree of industrial readiness—from new process ideas to fully industrialized processes. The second objective is to give a brief discussion on marked and industrial trends, forming the basis and direction for future technology development and associated research within more basic fields in sheet metal forming.