1,721,024 research outputs found
A Review of FEM Codes Accuracy for Reliable Extrusion Process Analysis: ICEB Extrusion Benchmark Conference
No full textThe paper presents an overview on the 2015 and 2017 editions of the ICEB
benchmark conferences, with a focus on experimental trials results and on the comparison of the accuracy of the different finite element method (FEM) codes in predicting critical process outputs. Indeed, benchmark experiments are designed with the aim to focus the attention on a particular phenomenon and to check the ability of FEM codes for its prediction. Profile lengths, process load, die deflections, die and profile temperatures were accurately recorded during the extrusion trials (conducted in laboratory or industrial environment) and were used as benchmarking parameters for FEM comparison. On the profiles, locations of seam and charge
welds and grain size distribution were metallurgically analyzed and required as benchmarking parameters as well. Moreover, computational times, simulation set-up times, as well as information on the required hardware were compared for the proposed case studies. A detailed discussion of all the output parameters is realized, in order to illustrate the evolution of the potentialities, and limits, of each code in the recent year
Modeling of Nitrogen Cooling in the Extrusion of Aluminum Alloys
No full textThe extrusion process with liquid nitrogen cooled dies is widely adopted in
industrial practice. Cooling channels are usually realized on the backer face in contact with the die and their design is mainly based on die maker experience. However, many parameters can be included in a die optimization, such as the number and the position of inlets/outlets, as well as the nitrogen channel position, shape, and dimensions. Trial-and-error approach is time and cost consuming, thus suggesting a great interest in numerical simulations to be carried out at the die
design stage. In the present work, a model for the simulation of the nitrogen-cooled extrusion process is innovatively presented and validated. A simplified 1D model of the channel is integrated in a 3D Finite Element (FE) simulation of the extrusion process by means of COMSOL code. Two experimental campaigns specifically carried out to monitor the efficiency of nitrogen cooling in industrial plants have been simulated and results compared in terms of die and profile temperatures, as well as in terms of extrusion load, in cooled and uncooled conditions
ICEB2017-Benchmark Settings
No full textAim of the benchmark at ICEB conference is to examine FEM codes capabilities and users’ knowledge in
the simulation of extrusion trials which were carried out and monitored by conference organizers. The comparison of the
“blind” simulations by the participants with the experimental results allows users to check if their simulation settings are
generally adequate to replicate the problem and software house to verify the sensitivity of their solving methods. It is very
important for us to remind that, due to the complexity of this matter, it would be useless to consider the benchmark as a
contest: it is, instead, an opportunity to fix some points about the everyday simulation practice, each participant with his
own particular interest. In this direction no winner will be awarded at the end of the conference because a clear
comparison of code’s capabilities will visibly emerge.
.Also for the 2017 edition, at the end of the benchmark session, a comparison of all codes outputs
with experimental results will be performed by the conference organizers. During such presentation
the results of all the participants will be compared over experimental trials on the basis of results
submitted at beginning June2017.
Comparing Hot-Work Tool Steels for Extrusion Die Performance
No full textHot-work tool steels are usually the selected materials for high-load and high-
temperature applications such as forging, casting and extrusion dies. In this framework, each cast/forged part or each extruded billet represents for the tool a mechanical load cycle, thus leading to the fatigue-working regime. In addition, the high thermal loads are also involved for the creep phenomenon that synergistically and detrimentally act with fatigue, reducing the tool lifetime. In the present work, three hot-work tool steels commonly used to manufacture extrusion dies have
been selected and compared in terms of dynamic performance under the creep-fatigue regime. An innovative experimental setup was used to test the steels by means of specimens that replicate the mandrel of a porthole die on a small scale. The H11 and the H13 have been compared at different levels of temperature and load by evaluating the specimen deflection over time, clearly highlighting the relative optimal working windows. An analytical model developed by the authors was also used to predict the H11 specimen lifetime at further load/temperature levels in order to perform a comparison with previous performed experiments on the super clean hot-work tool steel TQ1
A novel SLM H13 cooling insert for extrusion dies: experimental and numerical investigations
No full textThe additive manufacturing technology (AM) is considered to be the forth-industrial revolution allowing to produce «near net» components almost without geometrical constraints. This made the process perfectly fits with the requirement of extrusion dies since usually a maximum of two dies are required and the lack of design constraints allows to easily produce inserts with variable internal cooling channels. In the present work, a multi-die is proposed in which the expensive AM part, the insert with conformal cooling channels, is integrated into a conventional machined steel housing. Two AM inserts have been manufactured with SLM technology with different cooling channels diameters. Complex Finite Element (FE) simulations of the extrusion process have been performed by means of different FE codes in order to properly predict the thermal field gradient, the die stresses under the process thermomechanical loads and the multistate fluid dynamics. Preliminary results of the experimental trials of the insert are also presented in the present work
Back-End and Front-End Scrap in Direct Extrusion; an Estimation by Means of Finite Elements Analysis
No full textFinite elements analyses are offering to extrusions a big opportunity: to estimate accurately not only the charge weld extension but also the billet skin contamination. The present work examined the dynamics of the back-end and front-end defect in the direct extrusion of a solid profile through the use of FE analyses. Numerical results have been compared with industrial experiments with the aim to understand the effect of the chosen boundary conditions on the accuracy of the predictions
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Variations on the Author
Full text link“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
Appropriate Similarity Measures for Author Cocitation Analysis
Full text linkWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
- …
