Begin by asking students how they would break the stick? Most, if not all, students will break the popsicle stick in weak-axis, three-point bending. Note that students have an understanding of stresses without even realizing it! Let’s do the math! Why is this the best configuration for failure? Assume the normal stress limit of the […]

 Determine failure surface using Mohr’s Circle by giving students two pieced of chalk to break: one in bending and one in torsion. General note you may need to share with you students: brittle materials (like chalk) tend to fail under high tensile stresses. We need to find peak tensile stresses in a material. Let’s find […]