CAD learning in mechanical engineering at universities

In this study, we attempt to compile all the CAD-related concepts, contents and working methods that students of mechanical engineering should learn at universities. To do so, we first study the background to CAD-related methodologies. In second place, we compile the results of surveys administered over the past three years to our students of CAD studying mechanical engineering at our university. In third place, different publications in the literature relating to the need for CAD in industry are studied to understand the sort of CAD training that is needed in industry. In fourth place, an exploratory analysis is performed of the CAD-related contents taught at the 50 universities that top the QS (Quacquarelli Symonds) ranking. In fifth place, a survey of possible CAD-related contents is administered to teachers, instructors, and experts in CAD from those 50 leading universities in the QS ranking. The basic pillars of modeling in 3D are: methodologies of modeling, solid modeling, assemblies, and the design of technical drawings. The use of 3D printers in CAD learning means that thinking, designing, and manufacturing any object is easy at university. Knowledge of top-down/bottom-up/in-context methodologies has to be widened both for industry and for students. Design intent must be introduced in CAD from the very beginning so that all the models are flexible and robust. The students expressed a preference to learn the concepts through a set of good practice exercises and to be evaluated by completing a final course assignment of their choice

Validation of a tolerance analysis simulation procedure in assemblies

A simulation of tolerance analysis in assemblies using Sigmund Computer Aided Tolerancing (CAT) software is validated through the example of an automobile locking device. Simulation with CAT, applying criteria on both the statistical distribution and the rivet pin position in the hole used in the example, will allow us to predict the functional dimension tolerances in these assemblies with greater accuracy in the preliminary design phase. These tolerances will subsequently define the manufacturing specifications. The statistical distribution, in the example, that best fits the overall set of tolerances, is the triangular distribution followed by the normal distribution; the position of the rivet pin axis in its hole is off-centre by 53 % with regard to its maximum value

Assessment of 3D viewers for the display of interactive documents in the learning of graphic engineering

The purpose of this study is to determine which 3D viewers should be used for the display of interactive graphic engineering documents, so that the visualization and manipulation of 3D models provide useful support to students of industrial engineering (mechanical, organizational, electronic engineering, etc). The technical features of 26 3D visualization software programmes (viewers, publishers, 3D output formats) are examined, to select the three visualization configurations that best meet our needs at the Graphic Expression Department of the University of Burgos (Solidworks plus Solidworks eDrawings; Catia plus Catia eDrawings and 3DXML; several Computer-Aided Design software programmes plus Adobe Acrobat Pro Extended). These are compared using the Quality Function Deployment tool known as House of Quality. The House of Quality has enabled us to identify and quantify the importance attached by engineering teachers to each of their requirements for 3D viewers, and to identify and quantify the technical importance of each of the measurable features of these viewers

The importance of adaptive expertise in CAD learning: maintaining design intent

In CAD modelling, there is no one general standardised teaching-learning methodology. We use the strategic-learning methodology, maintaining design intent, fully aware that it is necessary to modify CAD models for their reuse. Questions concerning the thought processes of students when modelling with CAD and the strategies that they choose that best maintain design intent arise in the course of using the 3D modelling programmes. Our aim here is to determine the importance of adaptive expertise in the results of CAD models and, particularly, in one of its constructs: design intent. To do so, CAD-based experimentation took place over two years with 78 third-year students in the first year and with 53 third-year students in the second year from the subject module of Graphic Engineering, on the Degree in Mechanical Engineering of the University of Burgos (Spain). At the start of the year, the students conducted a survey to measure adaptive expertise. Subsequently, in the first year of experimentation, the students prepared various CAD models and the design intent was evaluated in one of them (a connecting rod or conrod), broken down into the skeleton, the structure, the modifications and the constraints. In the conrod exercise, the students also completed a questionnaire both before and after designing their models, which were analysed to detect the thought processes and the strategies that they had applied. In the second year of experimentation, design intent was incorporated in various exercises at the beginning of the year, in addition to the conrod. The main conclusion is that the correct division of the part into its pieces and adaptive expertise improved the results in relation to design intent in the CAD. KEYWORDS: CAD learning, design intent (DI), adaptive expertise (AE), modification of CAD

Spatial visualization learning in engineering: traditional methods vs. a web-based tool

This study compares an interactive learning manager for graphic engineering to develop spatial vision (ILMAGE_SV) to traditional methods. ILMAGE_SV is an asynchronous web-based learning tool that allows the manipulation of objects with a 3D viewer, self-evaluation, and continuous assessment. In addition, student learning may be monitored, which saves a significant amount of time for the teacher, as both correction and grading are automatically performed. Our aim in this study is to establish whether the application is an effective tool for learning spatial visualization. Students of engineering graphics following an industrial engineering degree course at the University of Burgos (Spain) participated in a pilot project over two academic years. The students were separated into two groups: an experimental group that studied with the ILMAGE_SV web application and a control group taught with traditional methods. Our study demonstrates that the results of both methods, with regard to the development of spatial vision, are in general equal. Nevertheless, ILMAGE_SV is more efficient for students who experience greater difficulties with spatial vision and for students with no prior knowledge of technical drawing

Effectiveness of a hypermedia tool in the innovative teaching of pneumatic engineering design drawing

This article presents research undertaken to determine the quality, effectiveness, and efficiency of the “pneumatic engineering design drawing” hypermedia. Among our reasons for carrying out this research are the implementation of the European Credit Transfer System (ECTS), the inexistence on the market of a similar product, and an increasing daily need for asynchronous teaching methods. Its objectives sought to evaluate the application and its impact on the teaching–learning of pneumatics. Two sources of documentation were used as research strategies: opinion polls and experimentation. Three groups of equal size were formed at random, based on traditional teaching (T), self-study using multimedia (M), and traditional teaching reinforced by the use of the hypermedia (A). The following rank among some of the more noteworthy conclusions. The hypermedia application has been positively rated. In the group with prior knowledge of the subject, the results of the post-test are strongly related to those of the pre-test in pneumatics. There is no empirical evidence to support the affirmation that students in group A achieved better results that those in group M or group T. In group M, academic performance is not directly dependent on the intellectual abilities of the student. The minimum time saving in group M was 42% in comparison with the other two groups

Experimentación de un gestor web interactivo de aprendizaje en ingeniería gráfica para el desarrollo de la visualización espacial

Ponencia presentada en: VI Jornadas de Innovación Docente de la UBU, Burgos, 23 y 24 de febrero de 2012, organizadas por el Instituto de Formación e Innovación Educativa-IFIE de la Universidad de Burgo

A tolerance analysis and optimization methodology: the combined use of 3D CAT, a dimensional hierarchization matrix and an optimization algorithm

We propose a methodology in this study for the analysis and the optimization of assembly tolerances. A combination of three components, it involves the use of 3D CAT software, a table referred to as a “dimensional hierarchization matrix” and a tolerance optimization algorithm. The Antolin Group, a Spanish multinational in the automobile components sector, employs this system to optimize tolerance values and to reduce manufacturing costs. The matrix was designed to enable easy identification, in a single table, of all requirements that fail to meet the specifications in the different approximations, prior to the definition of the dimensional and the geometric tolerances that comply with the functional requirements, and to identify which tolerances contribute most to variations in all of the functional conditions of the mechanism. Through its different iterations, this matrix allows us to see which of the tolerances should first be modified to optimize the design requirement specifications. A tolerance optimization algorithm was also defined, which functions with the data from the dimensional hierarchization matrix

Learning CAD at university through summaries of the rules of design intent

The ease with which 3D CAD models may be modified and reused are two key aspects that improve the design-intent variable and that can significantly shorten the development timelines of a product. A set of rules are gathered from various authors that take different 3D modelling strategies into account. These rules are then applied to CAD strategic-knowledge learning methodology and included in 3D CAD modelling exercises for students following the degree in mechanical engineering at the University of Burgos (Spain). The experiment was conducted in two groups with a total of 75 students. The design-intent rules were introduced in the different exercises that the teacher explained in both the theoretical and the practical classes. In addition, a summary of the different design rules in each of the practical exercises was explained in the practical classes in only one of the groups. The experimental results, reported in this paper, tested the influence of these summaries on overall improvements in 3D modelling and on the design-intent variable, which is subdivided into four sections: skeleton, structures, alterations and constraints. The use of the summaries of the design intent rules led to statistically significant improvements in 3D modelling in the experimental group, in comparison with the group of students to whom those summaries were not explained

Aprendizaje innovador en la visualización de piezas y dispositivos, en la formación de Dibujo Técnico mediante aplicación Hipermedia

El objeto ha sido realizar una aplicación hipermedia interactiva que sirva de iniciación al aprendizaje de visualización espacial dentro de la expresión gráfica y ajustándonos a los principios generales de representación en dibujo técnico recogidos en la norma UNE 1032-82 o ISO 128-82. Se ha elaborado un material innovador didáctico multimedia interactivo que facilita a los alumnos el aprendizaje de la visualización espacial. Este material es especialmente adecuado para aquellos alumnos que llegan a las carreras técnicas de Ingeniería y Arquitectura de la universidad y que no tienen desarrolladas suficientemente las habilidades y destrezas de visualización e interpretación de piezas. La aplicación se divide en dos partes diferenciadas: en primer lugar, se explican los conceptos de visualización por medio de animaciones, con narración incorporada con ficheros tipo avi; en segundo lugar, se plantean ejercicios interactivos de dificultad creciente en los distintos niveles de aprendizaje de: identificación, comprensión, aplicación, análisis y evaluación. En cada tipo de ejercicio se resuelve un ejemplo para guiar el aprendizaje. Se ha experimentado la aplicación con un grupo reducido de alumnos, detectando los errores de forma y fondo y los puntos de mejora. Por último, se han corregido los distintos errores detectados y se ha colgado la aplicación en la red de la Universidad de Burgos para que pueda ser utilizada por todos aquellos alumnos de ésta y de otras universidades, en la dirección http://www2.ubu.es/expgraf/expgrain/visualización3d.Junta de Castilla y León. Consejería de Educación y CulturaCastilla y LeónES