QUICK-RETURN MECHANISM REVISITED

Abstract

In this paper, the teaching and learning experiences of the author with two summer interns at one of the educational institutions in India and other students at Kettering University in Flint, MI are presented. The students in India were the senior mechanical engineering students from two different engineering colleges who spent nearly two months at the Indian institute where the author spent a 3-month sabbatical as a visiting faculty member. Although these two students took the “Theory of Machines” course at their college, a complete understanding of kinematic and dynamic analyses of mechanisms such as a quick-return linkage seemed to be not fully realized by them, due to the limitation of laboratory and CAE facilities at their parent colleges. The other mechanical engineering students at Kettering University took a basic course on Dynamics of Rigid Bodies, but they too had no hands on laboratory or CAE tools used for this course. Therefore, they took the Design and Analysis of Mechanical Systems and Assemblies course which is offered as a mezzanine level directed study course. Previously recorded lecture material was sent to distance learning students, while the recorded lectures helped the on campus students as supplementary material. The students modeled the linkages using the motion simulation application that is commonly available in any CAE tool such as Catia, UG-NX, NX I-DEAS, or SolidWorks. Other math tools such as MatLab Simulink, Excel, MapleSim, etc., are also used to to perform calculations and to draw plots of the various characteristics. All student participants were taught the basics of loop-closure equations pertaining to the kinematic and dynamic analysis of planar mechanisms with an example of quick-return, which is the topic of the paper presented here. For the quick return mechanism, plots such as variation of quick return ratio as a function of the critical link lengths, and kinematic and dynamic characteristics of the linkage have been studied and validated by CAE tools. Studies related to partial balancing of the system are also under way, mostly using a CAE tool. Finally, the students in India used the available laboratory experimental apparatus to verify some of the theoretical calculations. The performance metric is a final report that included the learning outcomes and recommendations for further work.