When Is A Truss Not A Truss: A ‘Do Say’ Pedagogical Laboratory Exercise

Contrary to common perception, engineering mechanics in undergraduate education does not need reform. Basic aspects of mechanics (strength of materials, mechanical behavior of materials, experimental mechanics, etc) are still necessary components of any Mechanical Engineering program. However, the delivery system and the tools used by students and faculty in learning and teaching engineering mechanics does need reform. In this paper, an example of such a change in the delivery system and learning tools is highlighted. The course which contains this example is an experiential learning “do and say” environment entitled “Mechanics of Materials Laboratory”. The highlighted example is a strain gauged bicycle frame. The premise of the laboratory exercise is that although the bicycle frame appears to be a truss, it is not. This is because many of the assumptions inherent in a truss analysis are violated. Students must prove that the bicycle frame is not a truss by triangulating on proof of their hypothesis (i.e., that the bicycle frame is not a truss) using analytical, experimental and numerical methods. Student surveys and course evaluations indicate that this laboratory exercise is one of their favorites in the course. In addition, students indicate that the exercise is particularly good at helping them “put the pieces together” so as to really understand the subject.