ADVANCED LEARNING IN ELASTICITY THEORY BY PHOTOELASTICITY-BASED EXPERIMENTAL TECHNIQUES

In the new degree in Industrial Technology Engineering arising from the Bologna Process the education system takes a new approach placing the student in the centre of teaching-learning process. For that purpose, the lecturers have to innovate and improve their functions explaining the concepts in a more visual way turning the learning process attractive. Moreover, it is important to enhance the independent learning, focused on creation of the opportunities and experiences necessary for students to become capable, self-reliant, self-motivated and life-long learners.
In this context, we have focused our attention on the basical subject called “Elasticity and Strength of Materials” given in third course. This topic provides the fundamental knowledge to deal with important fields in Mechanical Engineering such as Structural Analysis and Machine Design. Throughout the course, students become familiar with fundamental concepts of Structural Engineering and Mechanics, such as stress, strain, strength, stiffness and stability. The subject is divided into two parts. The first one discusses the theoretical foundations of the Theory of Elasticity, studying the stress and strain fields in an elastic solid subjected to a load system. In the second part the study is made for simplified models through the Strength of Materials.
Over the years of teaching it has been noticed that students have more difficulties to understand and learn the first part, which is more abstract and less intuitive. In order to enhance the curriculum development of students and complement the theoretical basis explained in the lectures, we will use a photoelasticity device which is available to the students during the workshop practices of “Elasticity and Strength of Materials”. Photoelasticity is an experimental non-destructive technique that evaluates stresses and strains in an elastic solid through the optical refraction appearing in a particular material subjected to mechanical loads. This technique requieres very few resources, making it very suitable for teaching in small labs.
In those teaching practices, the students are invited to reproduce physically some of the problems analytically raised and solved in class, and they can see the stress and strain results for different points of the particular solid through different colours, which is more visual and attractive. Furthermore, this practice is conceived as a multidisciplinary task since it is offered the students the opportunity to resolve the problem by Finite Element Analysis, which is addressed in subsequent courses.
The students are divided in different groups to solve analytically and experimentally different case problems and they gain new skills and abilities in the field of Mechanical Engineering, improving problem-solving competences and promoting the teamwork and the cooperativity among students. In that way, productive and enriching discussion is encouraged through the comparison between theoretical results and experimental reality, improving the reasoning and the critical spirit of the students.