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Students commonly exhibit serious spatial comprehension difficulties when they come to learning crystal systems. To solve this problem, an active methodology based on the use of a Didactic Virtual Tool (DVT)-developed by the authors-is presented in this paper. The students' opinion was obtained from a survey carried out on 40 mechanical engineering students. The analysis of the obtained results reveals that, by using this DVT, students achieve a better understanding of the contents where spatial difficulties often arise during conventional teaching. Several DVT features were highly valued by the students, e.g., didactic use was rated 9.5 out of 10 and the methodology using the DVT in the classroom was rated 8.5 out of 10. In addition, the results revealed two factors that the students considered essential for using a DVT, both related to the tool design: (i) the modern aspect, i.e., it is necessary to keep a DVT updated to avoid obsolescence; and (ii) the DVT must be appealing in order to attract the students' attention.

Abstract:In this paper a study is presented of the tensile fracture behavior of progressively-drawn pearlitic steels obtained from five different cold-drawing chains, including each drawing step from the initial hot-rolled bar (not cold-drawn at all) to the final commercial product (pre-stressing steel wire). To this end, samples of the different wires were tested up to fracture by means of standard tension tests, and later, all of the fracture surfaces were analyzed by scanning electron microscopy (SEM). Micro-fracture maps (MFMs) were assembled to characterize the different fractographic modes and to study their evolution with the level of cumulative plastic strain during cold drawing.

The present work is based on previous research on the one-dimensional (1D) analysis of the hydrogen diffusion process, and proposes a numerical approach of the same phenomenon in two-dimensional (2D) situations, e.g. notches. The weighted residual method was used to solve numerically the differential equations set out when the geometry was discretized through the application of the finite element method. Three-node triangular elements were used in the discretization, due to its simplicity, and a numerical algorithm was numerically implemented to obtain the hydrogen concentration distribution in the material at different time increments. The model is a powerful tool to analyze hydrogen embrittlement phenomena in structural materials.

Laboratory practices in technical degrees are usually crowed, what makes that many students waste the opportunity of putting into practice the knowledge acquired in theoretical classes. Taking this into account, an interactive virtual platform (IVP) is presented in this paper for enhancing students´ self-learning of one of the most commonly material tests used in engineering: the compression test for concrete samples. In order to carry out such innovative teaching approach, a computational modeling of a virtual materials laboratory was developed by authors including an interactive compression test machine. This way, by using this IVP, students can freely interact with the virtual compression machine during out of class study time. According to this approach, the aim of this computational application is essentially didactic, since (i) this tool allows students to get familiar with concrete compression test and, in this way, (ii) the knowledge acquired by means of such tool can be really useful to improve the performance in students´ learning during their later pressential laboratory practices.