Introductory Material Science: A Solid Modeling Approach Gerald Sullivan Department of Mechanical Engineering, Virginia Military Institute Abstract As a means to enhance students’ abilities to visualize the three dimensional structure of materials, solid model based exercises have been integrated into the introductory materials science curriculum at the Virginia Military Institute. The exercises included exploration oriented tasks, where students used the viewing functions of the solid modeling environment to examine models of materials, as well as problems where students constructed their own models of materials. The intent of the exercises was to allow students to obtain a deeper understanding of the three dimensional structure of materials, while at the same time reinforcing their solid modeling skills. This paper reviews the exercises developed to complement the materials curriculum, and describes the lessons learned in this first attempt at applying solid modeling as a visualization tool for material science education. 1. Introduction Material science is an extremely diverse body of knowledge, comprised of concepts ranging from quantum level interactions between atoms, to explanations of the effects of industrial processes on material properties. Central to the understanding of these concepts is the ability to visualize and reason about the somewhat abstract three-dimensional arrangements of atoms that make up the structure of materials, (e.g. crystal solids, amorphous solids and polymer chains). In many cases students taking their first material science course do not have adequate 3-D visualization skills [1], and are unable to develop a deep understanding of the principles responsible for the behavior of engineering materials. As a means to supplant weak visualization skills and improve comprehension of material science concepts, the mechanical engineering department at the Virginia Military Institute has incorporated solid modeling exercises into the material science curriculum. The intent of these solid modeling exercises is to help students interactively explore the crystal structures that make up metallic substances, in an environment that amplifies the students’ abilities to operate in an abstract 3 dimensional landscape. In addition to supporting the material science curriculum, the inclusion of solid modeling exercises in the materials science class also supports the equally important goal of improving students’ long-term retention of solid modeling skills. In the paper that follows, a description of the current material science program at VMI is given, along with a summary of characteristic problem areas for student comprehension in material science. Goals for the incorporation of solid modeling tools with the materials science course are reviewed, and descriptions of solid modeling exercises are detailed. Lastly, student reactions to the new teaching approach are discussed, as well as future plans for using solid modeling in the materials course. 10.836.1 Page 2. Background and Goals Currently the mechanical engineering dept. at the Virginia Military Institute offers an introductory material science course for their second year students, during the fall semester. The course begins with an over view of material properties and introduces elastic and plastic deformation, as well as brittle fracture. This first section of the course emphasizes the characterization of material behavior via material properties, and is backed up with extensive laboratory experimentation, (e.g. tensile tests, torsion tests, charpy impact tests). The next section of the course goes beyond characterizations of material behavior and investigates the mechanisms responsible for the observed behavior of materials. During this part of the course the links between macroscopic properties of materials and features of the materials microstructure, crystalline structure and atomic structure, are presented. The goal is to provide students with the ability not only to describe material behavior but also to predict behavior based on information about the structure of the material on microscopic and atomic scales. Finally in the last section of the course, students are given a basis for manipulating material properties through an understanding of equilibrium and non-equilibrium phase transformations, as well as an introduction to industrial heat-treating practices. By far the most difficult concepts for students to grasp in this course are those involving the relation of macroscopic material properties to the microscopic and atomic scale features of a material. In large part, the problems can be traced to students’ difficulty in visualizing the three dimensional structure of materials at the atomic level. Key material science concepts that are directly related to the 3-D crystalline structure of metals include anisotropy/isotropy, elasticity, and plasticity. The inability to visualize and manipulate the 3-D crystalline geometries associated with structure of metals, prevents students from gaining a true appreciation and understanding of these concepts. Recognizing this issue, authors and publishers of textbooks, now include software with their textbooks to help students probe the structure of unit cells for a variety of materials, [2]. Students gain some improvement in their understanding of the structure of materials, but the limited scope of the software bundled with texts, does not provide all of the features and tools that allow truly interactive study of material structures. Particularly useful features that are not available in the software that accompanies textbooks include: • modeling primitives that allow students to generate new geometries • advanced viewing features that allow students to generate sectional views of structures at any point and orientation in space within a crystal structure • A full complement of measurement tools that permit students to find distance, area, and volume measurements within a crystal structure As an alternative to these relatively simplistic software aids, some universities are now using sophisticated 3-D visualization environments to allow students to probe the inner structure of materials [3],[4]. At Valparaiso University, the Visbox virtual reality environment is used as part of the materials curriculum to view crystal structures of 10.836.2 Page metals and ceramics, as well as the structure of polymer chains, [5]. The resolution of this tool is so powerful that it may even be used by students to examine the details of the orbital structures within the atoms of a material. This option does provide almost limitless potential for interactive study of material structures, however, has the disadvantage that dedicated equipment must be purchased, and lab space provided in order to implement the technology. To justify this approach, multiple courses would have to incorporate the visualization environment in their curricula requiring extensive coordination and expenditure of time by faculty. In the materials science course at the Virginia Military Institute, an attempt has been made to provide interactive visualization tools for the materials course by leveraging our existing investment in solid modeling software, (Autodesk Inventor), and workstations. Students at VMI, as well as in many other engineering programs nationwide are first exposed to solid modeling technology during their first year in the engineering curriculum. At VMI, the introductory materials science course follows the solid modeling course during the first semester of students’ second year in the mechanical engineering program. It was felt that since the materials science course followed immediately after the solid modeling course, students would still retain enough knowledge of solid modeling to use it effectively in the materials course. Pedagogically, this sequence has the advantage that material science concepts are strengthened, while at the same time solid modeling skills are rehearsed and refreshed, aiding in their long term retention. This type of longitudinal incorporation of concepts across the curriculum has been gaining popularity at universities in the US, and is the basis for the “Spiral” engineering curricula now being pioneered at University of New Haven, [6]. Educators at the University of New Haven have found that by moving to course sequence that constantly revisits multiple sets of skills and concepts, students do demonstrate better retention and additionally are better able to operate in multidisciplinary teams. Incorporating solid modeling into the materials course at VMI represents just a single case of networking two courses together, however, with a small incremental effort, the approach could be adopted for other visualization intense courses, (statics, design, strength of materials). In the materials science course at VMI, the primary expectations for the use of solid model based exercises were as follows: 1. Allow students to use solid models of crystal structures in an explorative mode, panning, rotating and zooming in on important features of the crystal structures. 2. Allow students to generate views of crystal structures on arbitrary planes and point in space. 3. Use distance, area, and volume measurement tools available in the solid modeling environment to analyze the geometry of crystal structures and planes. 4. Allow students to model crystal structures on their own, using the geometrical construction features and mating primitives available in the solid modeling environment. 10.836.3 Page It was felt