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Multi-sensor additional mass elimination method in modal test

A technique for additional mass and modal testing, which is used in measuring devices, vibration testing, and testing of machine/structural components, etc., and can solve problems such as changes in the inherent characteristics of structures, changes in structural characteristics, and reduction in the accuracy of modal test results. Eliminate adverse effects, eliminate the effect of measurement errors

Active Publication Date: 2017-11-17
SOUTHEAST UNIV
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Problems solved by technology

Contact measurement needs to arrange sensors (such as acceleration sensors) on the structure to measure the dynamic response of the structure; non-contact measurement (such as laser vibrometer), there is no additional impact due to contact with the measured object, but the measurement cost is high , the measurement environment is demanding, and the versatility is poor
[0003] Therefore, the contact measurement method is more widely used, but for light and flexible structures, the arrangement of sensors will inevitably cause additional mass, resulting in changes in structural characteristics, resulting in measurement errors
Especially when multiple sensors are arranged on a lightweight flexible structure, the impact of the additional mass is more serious, which changes the inherent characteristics of the structure and reduces the accuracy of the modal test results

Method used

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Examples

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Embodiment

[0048] Embodiment: A multi-sensor additional mass elimination method in a modal test is verified by using a simple three-degree-of-freedom spring-damper-mass system. The parameters of the system are respectively: the quality of the mass block is m 1 = m 2 = m 3 =0.1kg, spring stiffness coefficient k 1 =k 3 =500N / m,k 2 =800N / m, the damping coefficient is c 1 =0.4N·m / s, c 2 =c 3 =0.2N m / s, acceleration sensor mass m a1 = m a2 = m a2 =0.02kg, such as figure 1 shown.

[0049]The specific operation is as follows:

[0050] The additional masses of the 3 acceleration sensors are respectively m i (i=1, 2, ... 3), the layout position nodes are 1, 2, 3 respectively. The frequency response function of excitation at 3 points and measurement at 1 point is denoted as The superscript on the right (1, 2, 3) indicates that the frequency response function includes the influence of the additional mass of the acceleration sensor at points 1, 2, and 3, and the corresponding frequenc...

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Abstract

The invention provides a multi-sensor additional mass elimination method in a modal test. A multi-sensor mass influence elimination formula in the modal test is deducted, the number of sensors arranged in the modal test and the sequence for eliminating the mass of the sensors are determined, and frequency response functions for eliminating the influence of the mass of the sensors are calculated one by one according to the elimination formula based on actual measurement frequency response functions. According to the method, firstly, the sensor mass influence elimination formula is deducted based on the Sherman-Morrison formula, the required frequency response functions are actually measured according to the formula and substituted into the formula in sequence for elimination one by one, and finally elimination of the mass of multiple sensors is realized. According to the method, measuring errors caused by additional mass of the sensors in the contact type measuring method in the modal test are eliminated, the unfavorable influence of the mass of multiple sensors on the frequency response functions is eliminated through the processing of actual measurement frequency response function signals, and the practical engineering significance is achieved.

Description

technical field [0001] The invention relates to a modal test, in particular to a method for eliminating additional mass of multiple sensors in the modal test. Background technique [0002] There are mainly two measurement methods for modal tests: contact and non-contact. Contact measurement needs to arrange sensors (such as acceleration sensors) on the structure to measure the dynamic response of the structure; non-contact measurement (such as laser vibrometer), there is no additional impact due to contact with the measured object, but the measurement cost is high , the measurement environment is demanding and the versatility is poor. [0003] Therefore, the contact measurement method is more widely used, but for light and flexible structures, the arrangement of sensors will inevitably cause additional mass, resulting in changes in structural characteristics, resulting in measurement errors. Especially when multiple sensors are arranged on a lightweight flexible structure,...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): G01M7/02
CPCG01M7/02
Inventor 费庆国朱锐杭晓晨姜东
Owner SOUTHEAST UNIV
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