A comprehensive survey of the analytical, numerical and experimental methodologies for dynamics of multibody mechanical systems with clearance or imperfect joints

"Available online 19 December 2017"A comprehensive survey of the literature of the most relevant analytical, numerical, and experimental approaches for the kinematic and dynamic analyses of multibody mechanical systems with clearance joints is presented in this review. Both dry and lubricated clearance joints are addressed here, and an effort is made to include a large number of research works in this particular field, which have been published since the 1960′s. First, the most frequently utilized methods for modeling planar and spatial multibody mechanical systems with clearance joints are analyzed, and compared. Other important phenomena commonly associated with clearance joint models, such as wear, non-smooth behavior, optimization and control, chaos, and uncertainty and links’ flexibility, are then discussed. The main assumptions procedures and conclusions for the different methodologies are also examined and compared. Finally, future developments and new applications of clearance joint modeling and analysis are highlighted.This research was supported in part by the China 111 Project (B16003) and the National Natural Science Foundation of China under Grants 11290151, 11472042 and 11221202. The work was also supported by the Portuguese Foundation for Science and Technology with the reference project UID/EEA/04436/2013, by FEDER funds through the COMPETE 2020 – Programa Operacional Competitividade e Internacionalização (POCI) with the reference project POCI-01-0145-FEDER-006941.info:eu-repo/semantics/publishedVersio

Stress distribution and strength condition of two rolling cylinders pressed together

Cover title.Prepared as part of an investigation conducted by the Engineering Experiment Station, University of Illinois at Urbana-Champaign

Dynamic Behavior of Gear Systems and Variation of Coefficient of Friction and Efficiency During the Engagement Cycle

In this work, the instantaneous and average efficiency and coefficient of friction of gear drives operating at low, medium, and moderately high speeds were experimentally and analytically investigated. First, using the gear testing machine specially designed for this type of investigation, the frictional losses in gearing during the engagement period were obtained experimentally. Based upon the obtained data, the values of efficiency and coefficient of friction were evaluated. A mathematical model simulating the gear testing machine was then developed and employed for the analysis of the dynamic behavior of the gear train system and analytical evaluation of gear system efficiency. The results obtained from this model were compared to those obtained directly from experiments, and a close correlation was achieved. The influence of such factors as diametral pitch, contact ratio, magnitude of transmitted load, and speed upon the efficiency of gear drives and the coefficient of friction in gearing was investigated. This investigation showed that the suggested method may be used to predict the dynamic behavior and efficiency of gear systems if a coefficient of friction is known or assumed. This investigation also gives some promise for power gear transmission design with improved capacity when scoring is the limiting criterion for capacity.</jats:p

A Multi-Purpose Planetary Gear Testing Machine for Studies of Gear Drive Dynamics, Efficiency, and Lubrication

Feasibility of a multi-purpose testing machine for research studies in gearing has been demonstrated with construction of a unique gear testing machine with a differential planetary gear drive. This machine was used in such interdependent studies as determination of instantaneous gear tooth engagement loads, minimum film thicknesses, and gear efficiencies. With minimal structural and mechanical modifications, this gear research machine can be used for studies of surface durability, thermal distribution in gear meshing zones, and effects of variable torques and torsional oscillations on performance of gearing. Most of these studies could be conducted simultaneously. Upon selection of appropriate gear ratios, this machine was operated either with one or two stationary gears. Presence of stationary gears simplified greatly the measurement techniques and increased the reliability of tests. This machine can accommodate spur, helical or any special type of gearing. Design and operational characteristics of this machine, as well as a short summary of research projects performed on this machine, are presented in this paper.</jats:p

The Synthesis of Tooth Profile Shapes and Spur Gears of High Load Capacity

In this work a method is presented for the synthesis of high capacity noninvolute spur gears and tooth profiles. Two gear capacity criteria are used in the synthesis: (1) the capacity based on maximum allowable Hertz stress and (2) the capacity based on the bending strength of the tooth. These capacity criteria are related to a generalized noninvolute gear geometry which includes the factors number of teeth and contact ratio. It was found that there are certain optimal relationships which exist among the noninvolute parameters which lead to a solution, for a maximum capacity noninvolute gear pair. For a speed ratio of one to five it was found that a significant capacity advantage exists for the synthesized noninvolute gear pair (compared to a 20-deg involute spur gear pair) for moderate as well as high hardness values. For a speed ratio of one to one a capacity advantage was found for moderate hardness but the advantage decreased significantly for high hardness.</jats:p