Material Property Variation in an Additive Manufacturing Lab

Traditional structural design is typically covered in statics and strengths of materials. New additive manufacturing (AM) techniques allow us to design structures free of prismatic constraints, using 'freeform' design that results in better performance. But AM structures also exhibit significant variation in material properties that must be taken into account. Using 'best practice' in engineering analyses is a student outcome that is part of our senior design course. One lab was modified in this course to improve student performance on this outcome. Originally the machine design 'lever' lab was a theoretical exercise. Several years ago, this was improved to an applied lab. The student design was printed (AM) and then failed. Recently, the machine design 'lever' lab was modified to include a transition from prismatic to freeform design through the creation of a simple lever. The lab consists of five sequential activities. The first three are: a traditional prismatic analysis, then a non-prismatic analysis, then an optimization to success criteria analysis, with AM fabrication and test feedback. The last two activities involve applying 'light-weighting' techniques and further optimization, with another round of AM fabrication and test feedback. Throughout the lever lab activities, students are evaluated on analysis performance. A part of the new modifications was an evaluation of tolerancing and predictions. Since AM processes have directional and other inputs causing material property variation, this was an aspect of lever performance prediction that was modified and specified for evaluation. Student performance in this outcome improved and is now used as part of our continued assessment.