Free boundary simulation system for modal test

Abstract

A free boundary simulation system for a modal test comprises N limiting mechanisms placed on the ground and an air bag, at least two limiting mechanisms are arranged around the air bag, and the air bag is connected with an air supply system; wherein the limiting mechanism and the air bag are arranged at the product bearing structure, a tested product is placed on the limiting mechanism when not working, and during working, the air bag is inflated to lift and float the product, and the product is kept stable at a certain height; the switching tool is fixed to the upper portion of the air bag, when the air bag does not work, a tested product is placed on the limiting mechanism through the switching tool, and the appearance of the contact face of the switching tool and the tested product is matched; when the system does not work, a tested product is placed on the limiting mechanism through the switching tool; when the system works, a product can be lifted and floated by inflating the airbag and is kept stable at a certain height, and free boundary simulation of the tested product is realized, so that a modal test can be carried out.

Description

technical field [0001] The invention belongs to the field of modal tests, and in particular relates to building a free boundary simulation system, which can meet the boundary requirements of modal tests. Background technique [0002] Usually, in order to obtain the dynamic characteristic parameters such as the frequency, mode shape, damping and mode shape slope of the product, it is necessary to conduct a modal test on the product. The normal working environment of the tested product should be reproduced as much as possible. The normal working environment of a considerable part of the products is under completely free boundary conditions, such as an aircraft in flight. For this reason, it is necessary to simulate this free boundary condition on the ground, so as to facilitate Carrying out modal tests. Usually, the rigid body motion frequency of the boundary support system is lower than 1 / 5 to 1 / 6 of the elastic fundamental frequency of the product, which meets the support r...

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Problems solved by technology

[0003] Modal tests for large-scale products (such as launch vehicles) are often carried out in vibrating towers, and the boundary simulation system is mainly based on spring-steel cable flexible suspension. The supporting suspension equipment of the product often has a large dead weight, which will bring a large additional mass to the product and affect the results of the modal test. At the same time, the temporary suspension system often has high requirements on the test site and brings certain safety hazards

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