A simple lab project integrating theoretical, numerical, and experimental stress analysis

Abstract

Learning is enhanced when students consider problems from different perspectives. Unfortunately, in stress analysis courses, the depth of the mathematical analysis and limited time and resources often restricts the focus to traditional closed-form solutions occasionally supplemented with simple demonstrations. In order to enhance student engagement and understanding, a lab mini-project was developed for teaching Castigliano's method for structural analysis in a stress analysis course. The mini-project consists of a design evaluation task which is investigated using three different methods: closed-form analysis, finite element analysis, and simple model build and test. The task is to select the better of two alternative support structures for a heavy-duty material-handling conveyor belt. Acceptance criteria in the form of maximum deflection and stress are provided. The closed-form analysis is conducted using Castigliano's method. Beam and shell finite element models are built and analyzed in Abaqus CAE. Structural prototypes are constructed with PASCO Structures System components and tested with simple weights and scales. The strengths of this combined approach are that the students (a) gain experience with the three different methods of stress/deflection analysis, (b) compare the different methods on a single problem, and (c) check or confirm their own results. By using existing finite element software licenses and available PASCO components, the project took no additional lab time and no additional cost to implement. Since the first use of this lab project was with in a small class, no direct measures were used to capture improvements in student learning. Instead, Indirect measures (instructor observations, student comments) were used to evaluate the lab's effectiveness. During the build and test phase of the project, students were much more engaged (discussing, changing approach) than in prior years when only the closed-form analysis was included. Student closed-form analysis results were also more complete, with fewer (20% versus 40%) of the student groups forgetting to include parts of the structure in their Castigliano's analysis. On end-of-course evaluation forms, students commented that they enjoyed comparing results between the three methods, and appreciated having something physical to test rather than just performing calculations. © 2011 American Society for Engineering Education.