The development of a truly hands-on torsional strength of materials testing lab

Abstract

Traditionally, strength of materials labs include tensile testing of prepared metal samples. This is normally achieved through the use of an automated tensile testing machine with data acquisition system (hardware and software). Even though students may need to load the part into the fixture manually, during the pulling process, students are mostly reduced to the role of a passive observer. This is simply due to the fact that it is impossible for human hands to pull apart a metal piece. Some education technology providers such as PASCO, Inc. sell a hand-cranked tensile testing machine that would give students some "feel" of the strength of different materials4. But the equipment is not suitable for torsional testing, and the "hands-on" experience it offered is still limited. In this paper, a "quick and dirty" low-budget torsional strength testing lab has been developed that would give students maximum exposure to hands-on material testing. There is no need for special fixtures - the required equipment/tools for this lab can normally be found in any machine shop. Students will have a chance to learn some basic skills using shop tools such as a lathe, a grinder, a vise, a Vernier caliper, etc. Simple torsional load calculation is required for this lab. It can also lead to a study of industrial fasteners which normally is only briefly covered in a machine component design class in the senior year. Weakness of this lab is that a needle-type mechanical torque wrench is not very accurate. The reading of measurements of torque and twist angles would all require some "eye-balling." But overall, the educational experience gained through this lab is well worth it for students. It facilitates student learning of various shop tools. Some assessment data is presented at the end of the paper. A poster presentation of part of this work was previously made at the 2016 ASEE North Central regional conference10.