Abstract
Joints in deployable structures can degrade the stiffness and the stability of spacecraft. In this study, the nonlinear stiffness of spherical joints is investigated. The traditional contact model of spherical joints based on non-conforming contact assumption is presented. A new contact model for spherical joints based on the Winkler model and geometric constraints is established to calculate the stiffness of spherical joints with small clearances. The finite element model (FEM) of spherical joints is built to evaluate the accuracy of the theoretical model. The effects of the clearance and the contact force of spherical joints on the deformation of joints are investigated. When compared with FEM results, the error of the new spherical model is smaller than that of the traditional contact model when the clearance of spherical joint is not excessively large. The new contact model for spherical joint is more accurate than the traditional contact model when the clearance of spherical joint is large.
Highlights
Given the need of sending large payloads and high volume of launchers in space missions, deployable structures as supporting ones have been widely used in spacecraft (Puig et al, 2010; Gruber et al, 2007)
The dynamic performance of deployable structures is important for space structure design
Sarkar modeled the space trusses with nonlinear force caused by joint that is expressed by harmonic function (Sarkar et al, 2004). (Li et al, 2011) investigated the transient dynamic response of plane mechanics and analyzed the effect of clearance on the dynamic performance of structures by utilizing gap element to model clearance joint in ANSYS software
Summary
Given the need of sending large payloads and high volume of launchers in space missions, deployable structures as supporting ones have been widely used in spacecraft (Puig et al, 2010; Gruber et al, 2007). The contact model of a joint is mainly based on elastic theory and finite element theory. Tian et al (2009) calculated the contact force of spherical joint in spatial flexible multibody systems by using the continuous contact model proposed by Lankarani and Nikravesh. Liu et al (2006) built an approximate contact model of spherical joints with clearance that is based on distributed elastic forces.
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