C. Bernal

Analytical Procedure for Geometrical Evaluation of Flat Surfaces Formed by Multiple Indentation Processes

Elementary indentation processes are relatively simple compression processes and they are quite extended in many fields of the industry. Nevertheless, the concatenation of these processes is a new approach and has interest from a technological point of view. In this work the geometry of multiple indentation processes is analyzed on flat surfaces. The state of the formed surface by several types of tools is studied and a model has been developed in order to quantify by means of shape parameters the quality of the theoretical surface depending on the technological and geometrical characteristics of the process.

Accuracy Analysis of Fringe Projection Systems Based on Blue Light Technology

Some manufacturers of 3D digitizing systems are developing and market more accurate, fastest and affordable systems of fringe projection based on blue light technology. The aim of the present work is the determination of the quality and accuracy of the data provided by the LED structured light scanner Comet L3D (Steinbichler). The quality and accuracy of the cloud of points produced by the scanner is determined by measuring a number of gauge blocks of different sizes. The accuracy range of the scanner has been established through multiple digitizations showing the dependence on different factors such as the characteristics of the object and scanning procedure. Although many factors influence, accuracies announced by manufacturer have been achieved under optimal conditions and it has been noted that the quality of the point clouds (density, noise, dispersion of points) provided by this system is higher than that obtained with laser technology devices.

Manufacturing Engineering Education: Study of the Continuous Evaluation Activities on UNED

In this study, the continuous assessment activities are analyzed on the learning results. The subjects chosen belong to the field of Manufacturing Engineering. The subjects analyzed are taught in Bachelor´s Degree in College of Industrial Engineering. The continuous assessment activities were designed to propose in both obligatory and elective subjects. The number of the students in obligatory subjects is usually higher than in the other type. In this paper, the data were extracted from the last three academic courses. From the analysis of the results it can be affirmed that, in general, students who carried out assessment activities, improved their academic results.

Implicit and explicit techniques for localised–incremental forging processes analysis by computer aided engineering

Two finite element simulation techniques are applied for the analysis of a basic operation in LIF processes. Implicit and explicit numerical methodologies are used by Abaqus/standard and Abaqus/explicit solvers, respectively. The most suitable mesh and geometry of the punch have been chosen among different ones according to the computation time, accuracy of results and forming capability. Once the mesh and the geometry of the punch are chosen, a single operation is simulated by means of both implicit and explicit FE models. Experimental tests were also conducted. Forces and geometrical profiles were compared among those obtained by experiments and simulations and the results show good correspondence. The explicit FE model looks robust enough to use the same modelling parameters in further studies, where explicit methodology is expected to be mandatory due to multiple–strokes operations.

Observations on the Use of Friction Factor Maps in Metal Forming

In metal forming simulation the right definition of friction conditions at the tool-workpiece interface is a key matter, in order to obtain reliable results. The aim of the present work is the determination of friction factor maps by using the RCT with different alloys which are commonly used in the metal forming practice; and the subsequent comparison of the curves to probe if there are important deviations among different materials, which will lead to prevent the use of a unique and general map of friction curves for all materials. Results confirm the necessity of using a friction calibration map for each material. Furthermore the differences and similarities in the behaviour observed are evaluated for all materials.

Finite Element analysis of the combined effect of strain hardening and friction in elementary processes of forging

Forging processes have been studied since years. However, recently these studies are gaining in importance because of the increasing emergence of non conventional forging processes such as LIF processes, in order to improve their efficiency and to fit the production requirements. In this work elementary forging processes are studied under plane strain conditions in order to evaluate the combined effect of strain hardening and friction in forces and contact pressure distributions by a FE analysis. For this purpose, different base to height ratios (b/h) of the workpiece have been considered, with different friction conditions. All cases have been solved for both a rigid perfectly plastic material and a strain hardened one. It is observed that the effect of the strain hardening on the forces and contact pressures is higher when the friction conditions become more extreme. The results do not depend on the base to height ratios when frictionless conditions are assumed.