Clearances in imperfect joints are unavoidable due to assemblage, manufacturing errors and wear. When clearance is introduced to real mechanism, it will lead to poor dynamic performances and undesirable vibrations due to impact forces in clearance joint. Modern spacecraft usually has large deployment structure, which consisting of plenty of joints could produce undesirable dynamic responses when considering clearances in joints and driving input fluctuation. However, in the dynamic performance analysis of space deployment mechanism, the clearances and input fluctuation are always ignored. In this study, the dynamic responses of a flexible planar scissor-like truss deployment mechanism with imperfect joint considering clearance and input fluctuation are investigated using computational methodology. First, the mathematic model of clearance joint is established. The revolute clearance joint is considered as force constraint and the joint components of an imperfect joint with clearance are modeled as contact bodies. The normal contact force model of clearance joint is established using a continuous contact force model considering energy loss. The friction effect is considered using a modified Coulomb friction model. Further, the dynamics equations of the mechanism considering clearance joint is established. Then, the dynamics performances of the flexible planar scissor-like truss deployment mechanism with imperfect joint considering clearance and input fluctuation are presented and discussed. First, the effects of clearances on dynamic performance of the truss deployment mechanism are analyzed. The dynamics responses of the mechanism are obviously vibration and presents higher peaks of its values. It indicates that clearance has significant effects on motion acceleration, which represents high peaks caused by contact and impact forces in clearance joint. When considering clearance, the motion acceleration of the mechanism is obvious vibration with higher peaks of value, which will lead to the dynamic performance as well as motion stability of the deployment mechanism system decrease. Therefore, clearance has severe effects on the performances of the deployment mechanism. Then, different case studies for the scissor-like truss deployment mechanism with clearance are investigated considering driving input fluctuation. The effects of the frequency and amplitude of input fluctuation are studied respectively. The simulation results show that the dynamic characteristics of the mechanism with clearance joint are changed more obviously when considering driving input fluctuation. Therefore, the investigation of this work indicates that when considering clearance joint and input fluctuation in dynamics analysis of the truss deployment mechanism, the dynamics responses of the truss deployment mechanism are more worse, which indicates that driving input fluctuation leads to more obvious degradation of the dynamic performance of the truss deployment mechanism with imperfect joint.


Dynamics Analysis of Truss Deployment Mechanism With Imperfect Joint Considering Input Fluctuation

Division / Sponsors: 
Aerospace, Bioengineering, Applied Mechanics, Design Engineering Division, Advanced Energy Systems, Manufacturing Engineering Division, Noise Control and Acoustics, Nondestructive Evaluation, Diagnosis, and Prognosis (NDPD), Nuclear Engineering Division, Process Industries Division, Fluids Engineering, Heat Transfer, Materials, Microelectromechanical Systems, Safety Engineering and Risk Analysis, Computers & Information in Engineering


Paper Proceedings: https://asmedigitalcollection.asme.org/IMECE/IMECE2020/volume/84478

IMECE2020 - Virtual Conference

Supporting the need among researchers worldwide for additional online and multimedia content, ASME now offers the ASME Conference Video Collection. This platform will collect and provide long-term access to conference presentation videos, encompassing all technology areas within ASME's technical conference and events program. About 30,000-40,000 engineers across all mechanical engineering and related disciplines participate in ASME conferences each year. This includes authors of approximately 6,000 to 8,000 technical papers published by ASME, the majority of whom also submit video presentations for our virtual conferences. The video collection will be available as an add-on to existing product packages or as a separate subscription.