Eventos Anais de eventos
COBEM 2021
26th International Congress of Mechanical Engineering
A new approach of a mobility analysis in mechanism design
Submission Author:
Thiago Hoeltgebaum , SC , Brazil
Co-Authors:
Daniel Martins, Thiago Hoeltgebaum, Luan Meneghini, Henrique Simas
Presenter: Luan Meneghini
doi://10.26678/ABCM.COBEM2021.COB2021-1180
Abstract
The mobility analysis of mechanisms has been a relevant topic throughout mechanism science history. Since the end of the 19th century, researchers around the globe have proposed methods to evaluate mobility. Finding an efficient and universal method for determining mobility has been a relevant subject in the field of mechanics. This paper brings a literature review of such methods and equations to investigate the current state of the art of mobility evaluation. As mechanism theory became more complex, the same happened in mobility analysis. In a mechanism, it is possible to find three types of mobilities: actuated, passive and dangerous. It is common among the researchers to evaluate the mobilities just considering the actuated mobilities. In fact, actuated mobilities are previously known, both for analysis and synthesis. In mechanism analysis, a simple count of the number of actuators shows the actuated mobility. In mechanism synthesis, the actuated mobility is desired and it will be a design input. However, passive and dangerous mobilities have an important role in mechanism design and they are often neglected. Passive mobilities can occur intentionally to promote self-alignment. On the other hand, dangerous mobilities can yield a failure of the mechanism. They are possible threats to the users and environmental safety. This paper proposes a new method for mobility evaluation considering the effect of passive and dangerous mobilities, using: screw theory, Davies’s Method, and redundant constraints knowledge. The redundant constraints are responsible for residual stresses, assembling problems, premature wear in mechanisms, among other issues. With the proposed method the presence and effects of all types of mobility will be highlighted to the reader. By applying this new method, this paper discusses through some case studies a new point of view in mechanism mobility analysis, which in the future could lead to new synthesis methods.
Keywords
Mobility, analysis, Method, Mechanisms
