PRELIMINARY RESULTS OF THE IMPLEMENTATION OF CAD/CAE SYSTEMS IN MECHANICS LECTURES

J. Andres, M. Mora

Universitat Jaume I (SPAIN)
In the subject of Mechanics, a well known maxim is that individuals should not think formulas, but keep in mind the course of reasoning by understanding how a mechanism works. Consequently, concepts of Kinematics should be treated progressively, in sequence, with mathematical manipulations initially kept to a minimum.
Particularly in this field, classroom materials are traditionally based on static resources (pictures and drawings). In many cases they do not help to visualize the problems to be analyzed. The students fail to understand how an assembled mechanism moves since their thought remains in the picture. For example, they find it difficult to think in propagation of linear velocities at the instant to which the picture refers. Similarly, they find it difficult to recognize the kinematic invariants of a solid body (SB) as they are unable to visualize each one moving separately from the rest of the assembly.
New technologies have provided tools to make engineering education more efficient. Several Computer Aided Design / Engineering (CAD / CAE) systems may be helpful in the subjects of Kinematics, i.e. Working Model® and SolidWorks Motion®. Both of them are available at the Universitat Jaume I (UJI). The first is well known in the teaching of Kinematics, but is inappropriate for the three-dimensional analysis. The second is a powerful CAD tool in engineering design. Solid and assembly design (by assigning kinematic pairs among SBs) are beyond the scope of the Kinematics subject (as it is challenging for students to learn). However, it is feasible to have assemblies made prior to each lecture to tackle the motion analysis.
Using CAD/CAE technologies, faculty planed new instruction materials to teach in novel ways. For example, by showing an assembly animation, a CAE system can enable students to improve their ability to visualize and analyze SBs’ behaviour.
For the present research on the subject of kinematic analysis, the set of on-blackboard exercises was considered. Each one was solved with Working Model® (flat solids in 2D motion) and SolidWorks Motion® (solid bodies in 3D motion). In both cases, videos were saved to show:
- the mechanism’s motion
- the total motion of each link solely (by hiding the remaining SBs)
- drag and relative motions, in case of problems solved by relative motion analysis.
The evaluation of the convenience of these new tools for teaching was evaluated among the students of the Mechanical / Electrical / Industrial Technology Engineering Degree at the UJI. This is a total amount of 141 students in 2011-12 and 261 in 2012-13.

On-line tests are performed periodically on those subjects, in the context of what is named Continuous Evaluation. The test-questions are multiple-choice questions that assess student reasoning and understanding of basic concepts, and which require little or no analysis. [Figure 1 shows an example of test question after being modified]. It guarantees that those students will face the final exam after having understood these basic concepts.

References:
[1] Beer, F.P.; Johnston, E.R. Mecánica vectorial para ingenieros. Dinámica. McGraw-Hill. 2010.
[2] http://help.solidworks.com/2012/English/SolidWorks/motionstudies/COSMOSMotion_Overview.htm (Accesed on November 2012)
keywords: cad, cae, kinematics.