Perturbation procedures in nonlinear finite element structural analysis

Author(s):  
Richard H. Gallagher
2020 ◽  
Vol 2020 ◽  
pp. 1-13
Author(s):  
Guoqiang You

A structural analysis method is proposed in this paper for cable-beam composite structure with a large number of cable elements; it can improve computational efficiency and accuracy. Firstly, we use a structural division method to divide the whole cable-beam structure into inner cablenet system and edge cablenet-beam system. Because inner cablenet is a pure cablenet structure with given shape and topology, balance matrix analysis method is used to help obtain the best pretension distribution of it with the evenness as objective. For edge cablenet-beam system, with obtaining equilibrium forces of inner cablenet’s pretensions as goal, an iterative pretension losses compensation calculation combined with nonlinear finite element method and balance matrix analysis method is used for edge cablenet to adjust its pretension distribution and make the whole cablenet system keep its preset ideal shape under influence of beams’ deformations. Because edge cablenet-beam system has a lot less cable elements than overall structure, its nonlinear finite element calculations are much easier and faster than those for the whole cable-beam composite structure. In order to verify the above method’s validity, it is used for a spaceborne cablenet deployable antenna example, and the computed results indicate that the method is feasible.


Author(s):  
Jing Zhang ◽  
Hong-wei Guo ◽  
Juan Wu ◽  
Zi-ming Kou ◽  
Anders Eriksson

In view of the problems of low accuracy, small rotational angle, and large impact caused by flexure joints during the deployment process, an integrated flexure revolute (FR) joint for folding mechanisms was designed. The design was based on the method of compliance and stiffness ellipsoids, using a compliant dyad building block as its flexible unit. Using the single-point synthesis method, the parameterized model of the flexible unit was established to achieve a reasonable allocation of flexibility in different directions. Based on the single-parameter error analysis, two error models were established to evaluate the designed flexure joint. The rotational stiffness, the translational stiffness, and the maximum rotational angle of the joints were analyzed by nonlinear finite element analyses. The rotational angle of one joint can reach 25.5° in one direction. The rotational angle of the series FR joint can achieve 50° in one direction. Experiments on single and series flexure joints were carried out to verify the correctness of the design and analysis of the flexure joint.


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