The multi-body dynamics model comprises an additional dummy and drive combined constraint construction method

Abstract

The invention provides a method for constructing a combined constraint containing an additional dummy and a drive in a multi-body dynamics model. According to the method, a point-line higher pair constraint of a matt element and a convergence skeleton midplane curve is added; driving of the dumb element is realized by means of online constraint of the A8 roller on the dumb element; meanwhile, according to the geometric dimension of the mechanism, a normal direction angle of a tangent point of an A8 roller and a convergence framework midplane curve is analyzed and expressed by using an A8 ringstroke; the A8 roller is driven according to the angle value; the dummy element is always positioned at the tangent point of the A8 roller and the skeleton midplane curve; meanwhile, bidirectional limiting force in the direction of a roller shaft is added between the A8 roller and the dummy element to prevent the A8 ring from rotating at a large angle; according to the method, over-constraint generated by linear higher pair constraint can be effectively eliminated, simulation application shows that the method can give consideration to fidelity of motion, loading and force transmission characteristics under the condition that simulation stability is guaranteed, and result deviation caused by automatic over-constraint elimination is effectively avoided.

Description

technical field [0001] The invention belongs to the technical field of aero-engines, and in particular relates to a multi-body dynamics model including an additional dummy element and a driving combined constraint construction method, which is applied to the modeling and simulation of an axisymmetric vector nozzle mechanism. Background technique [0002] Axisymmetric thrust vector control technology (Thrust Vector Control, TVC) has small thrust loss, can realize vector propulsion in all directions, and is easy to modify. It is an essential key technology for the fourth-generation and above domestic fighters that require super maneuverability . This nozzle device has many moving parts (more than 800), complex structure, and most of the constraints between the parts are realized by contact, while the local links are numerically over-constrained due to the formation of a closed constraint ring, that is, the number of differential equations The number of algebraic equations is ...

AI Technical Summary

Problems solved by technology

In the process of dynamic modeling and simulation, some simulation platforms (such as: MSC.ADAMS) have the function of automatically eliminating over-constraints, but this function is not perfect. When the mechanism is too complex, its over-constraint The elimination of overconstraints will often change the motion, load and force transmission characteristics of the mechanism, thus making the simulation results lose credibility. Therefore, reasonable manual removal of overconstraints is particularly important in the dynamic modeling and simulation of complex mechanisms

Some existing calculation methods include 1. The contact algorithm is used to model the A8 roller and the convergent frame. The disadvantage is that the calculation amount is very large; 2. The conventional line-line-height pair constraints are used for the A8 roller and the convergent frame. Causes the over-constraint of the whole mechanism, resulting in the inconsistency between the load and force transmission characteristics and the actual situation

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