Using additive manufacturing and finite element analysis in a design-analyze-build-test project

Abstract

Additive manufacturing (AM), also called rapid prototyping or 3-D printing, has become increasingly available to engineering programs over the last two decades. This paper discusses a design-analyze-build-test project that uses AM to supplement instruction in finite element analysis. Variations of the project have been used with both high school and upper-division undergraduate students. The project involves the redesign of a bracket. The students follow step-by-step instructions to model a baseline design with SolidWorks software. They then use the SolidWorks Simulation Professional Finite Element Analysis (FEA) program to apply boundary conditions and loads, mesh and run the static (linear) analysis, and view the stress and deflection results. A baseline bracket fabricated by additive manufacturing is then tested for deflection under a specific load and then loaded to failure. Based on the analysis and test results, students are tasked to redesign the bracket, with the goal of producing the lightest design that meets deflection and strength requirements subjected to several geometric constraints. With high school students, the students are advised to remove material where the stresses are low and to add material where the stresses are high. After allowing the students to work individually on the bracket redesign, groups of two or three students are formed and allowed time to discuss their ideas and produce a design to be built and tested. The testing of the brackets provides a fun competition to conclude the project, and afterwards the results are discussed, with focus on both the usefulness and the limitations of the analysis. Student survey results show that the exercise enhances the students' understanding of the engineering design process, particularly the role of analysis as a design tool. The bracket project has also been adapted for use in a one-credit elective course for upper-division undergraduate students. The project serves as an introduction to nonlinear analysis, as the ultimate failure load is much higher than the load for which yield is first predicted with linear analysis. Results from mechanical property tests of the AM material (ABS plastic) are used to define the non-linear properties. Another important lesson of the project is that idealized boundary conditions do not always adequately simulate actual displacements. This project is an example of how additive manufacturing can be used to supplement instruction in finite element analysis. While verification of FEA results by comparison with closed-form solutions is valuable, physical testing of the articles being analyzed highlights effects such as nonlinear (both material and geometric) behavior and inconsistent boundary conditions that are not apparent in the closed-form solutions. Although the bracket appears to be a simple component, accurately simulating its nonlinear behavior under loading is a challenging problem even for upper-division undergraduate engineering students.