JPH04254734A - Evaluating apparatus of stress of piping system - Google Patents

Abstract

PURPOSE:To make it possible to evaluate a stress simply at all necessary places by a method wherein a vibrational characteristic of a vibration analysis model is made to accord with the vibrational characteristic measured by an accelerometer and the stress of each part of a piping system is evaluated by estimation. CONSTITUTION:Accelerometers 1 are fitted at several places to a branch piping 3 connected to a main piping 2, and the piping 3 is supported by a fixed wall through a support 8 and provided with a valve 7, etc. The accelerometers 1 deliver outputs to a personal computer 6 through amplifiers 4 etc. In the computer 6, an analysis model is prepared by modeling the piping 3, and the frequency of this model and the sensitivity for a change in the vibration in a normal mode of the model are determined by analysis respectively. Subsequently, the frequency of an actual piping and that of the analysis model are compared with each other, the frequencies of them are made to accord with each other with the rigidity of the support and the mass of the valve adjusted, and thereby a final analysis model is determined. By using this model, a response analysis is executed and the correspondence of a response acceleration to a generated stress is made clear. Based on this, the stress is estimated from a signal of acceleration measured from the actual piping and evaluation of the stress is conducted.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a piping system stress evaluation device.

0002

2. Description of the Related Art In a piping system as shown in the perspective view of FIG. 3, the branch piping 3 vibrates due to the vibration of the main piping 2, and the vibration may cause damage to the base of the branch piping. Therefore, conventionally, as shown in the figure, strain gauges 21 are pasted at various locations on the branch pipe 3, and the output signals are sent to the amplifier 4.
The strain is input to the personal computer 6 via the A/D converter 5, and the stress in the piping is evaluated based on the strain measurement results. FIG. 4 is a flow diagram showing the software of this stress evaluation device.

0003

However, such conventional piping system stress evaluation devices have the following problems. (1) With conventional equipment, it is necessary to attach strain gauges to all locations where stress is likely to occur, which is time-consuming. (2) Attaching strain gauges requires a skilled technique and cannot be done easily. (3) It is not possible to evaluate stress in areas where strain gauges are not attached. The present invention has been proposed in view of these circumstances, and provides a piping system stress evaluation device that can easily determine stress at all required points in the piping system without requiring time and effort for pasting work. The purpose is to

0004

[Means for Solving the Problems] Therefore, the present invention provides a computer in which a vibration analysis model of a target piping system is created, an accelerometer attached to the target piping system, and measurement data of the accelerometer. and an A/D converter for inputting the data into the computer, and by matching the vibration characteristics of the vibration analysis model with the vibration characteristics measured from the accelerometer, each part of the target piping system is It is characterized by estimating and evaluating the stress of

[0005]

[Operation] According to such a configuration, only a few accelerometers are attached to the piping, and the number of accelerometers is only a few, making it easy to handle. Furthermore, since the generated stress is estimated using an analytical model, the stress at any point can be obtained.

[0006]

[Embodiment] An embodiment of the present invention will be explained with reference to the drawings. Fig. 1 is an overall perspective view of the same, in which a branch pipe 3 connected to a main pipe 2 is the target pipe, and an accelerometer 1 is attached to this pipe. Attach it in place. Generally, the branch pipe 3 is supported by a fixed wall via several supports 8, and valves 7 and the like are installed here and there. The output from the accelerometer 1 is input to a personal computer 6 via an amplifier 4 and an A/D converter 5. FIG. 2 is a diagram showing the software flow of this stress evaluation device. In the computer, the branch pipe 3 is modeled using a branch pipe beam model 13, support rigidity 11, and valve mass 12 as shown in the figure, and an analysis model creation step 10 is performed. I do. Next, the frequency of this model is determined by natural vibration analysis 1.
Find it by 4. The obtained frequency is usually different from the result of the actual piping frequency measurement 16, but this is considered to be because the settings of the support rigidity 11 and the valve mass 12 when modeling were different from the actual ones.

[0007] Therefore, in order to match the vibration frequency of the model to that of the actual machine, the support rigidity 11 and the valve mass 12 are adjusted.
need to be adjusted. Therefore, the influence (sensitivity) on changes in the natural frequency of the model due to changes in the support rigidity 11 and valve mass 12 is determined by sensitivity analysis 15. A comparison17 was made between the frequency of the actual piping and the frequency of the analytical model.
The final analysis model is determined by adjusting the support rigidity 11 and valve mass 12 using sensitivity to match the vibration frequencies of both. Response analysis 1 using the obtained analytical model
9 to clarify the correspondence between response acceleration and generated stress. Based on this, stress can be estimated from the acceleration signal 18 measured by the actual machine, and stress evaluation 20 can be performed.

[0008]

[Effects of the Invention] According to the present invention, the following effects can be obtained. (1) Since accelerometers are only installed in several locations, measurement and evaluation time can be shortened. (2) The installation work is easy and does not require any skill and can be easily performed by anyone. (3) Since stress is estimated from an analytical model, many generated stresses can be estimated and evaluated at any point. (4) Not only local stress but also stress of the entire branch piping,
Responses such as displacement and acceleration can be understood. In short, according to the present invention, a computer in which a vibration analysis model of a target piping system is created, an accelerometer attached to the target piping system, and measurement data of the accelerometer are input into the computer. The system includes an amplifier and an A/D converter for estimating and evaluating the stress in each part of the target piping system by matching the vibration characteristics of the vibration analysis model with the vibration characteristics measured from the accelerometer. As a result, the present invention is extremely useful industrially because it provides a piping system stress evaluation device that can easily determine stress at all required points in the piping system without requiring much time and effort in pasting work.

[Brief explanation of the drawing]

FIG. 1 is an overall perspective view showing an embodiment of the present invention.

FIG. 2 is a software flow diagram of the stress evaluation device in FIG. 1;

FIG. 3 is an explanatory diagram showing a known stress evaluation procedure for a piping system.

FIG. 4 is a software flow diagram of the conventional stress evaluation device in FIG. 3;

[0009]

[Explanation of symbols]

1 Accelerometer 2 Main piping 3 Branch piping 4 Amplifier 5 A/D converter 6 Personal computer 7 Valve 8 Support 9 Fixed wall 10 Analysis model creation 11 Support rigidity 12 Valve mass 13 Branch piping beam model 14 Natural vibration analysis 15 Sensitivity analysis 16 Measurement of actual machine piping frequency 17 Comparison of actual machine frequency and analysis model frequency 18
Actual machine acceleration signal measurement 19 Response analysis 20 Stress evaluation 21 Strain gauge 22 Actual machine strain measurement

Claims (1)

[Claims] Claim 1: A computer in which a vibration analysis model of a target piping system is created, an accelerometer attached to the target piping system, and a computer for inputting measurement data of the accelerometer to the computer. Amplifier and A/
D converter, the vibration characteristics of the vibration analysis model are
A piping system stress evaluation device characterized in that the stress in each part of the target piping system is estimated and evaluated by matching the vibration characteristics measured by the accelerometer.