ISO 18431-3:2014 機械的振動と衝撃—信号処理—パート3：時間周波数解析の方法 | ページ 2

Foreword

ISO (the International Organization for Standardization) is a worldwide federation of national standards bodies (ISO member bodies). The work of preparing International Standards is normally carried out through ISO technical committees. Each member body interested in a subject for which a technical committee has been established has the right to be represented on that committee. International organizations, governmental and non-governmental, in liaison with ISO, also take part in the work. ISO collaborates closely with the International Electrotechnical Commission (IEC) on all matters of electrotechnical standardization.

The procedures used to develop this document and those intended for its further maintenance are described in the ISO/IEC Directives, Part 1. In particular the different approval criteria needed for the different types of ISO documents should be noted. This document was drafted in accordance with the editorial rules of the ISO/IEC Directives, Part 2 (see www.iso.org/directives ).

Attention is drawn to the possibility that some of the elements of this document may be the subject of patent rights. ISO shall not be held responsible for identifying any or all such patent rights. Details of any patent rights identified during the development of the document will be in the Introduction and/or on the ISO list of patent declarations received (see www.iso.org/patents ).

Any trade name used in this document is information given for the convenience of users and does not constitute an endorsement.

For an explanation on the meaning of ISO specific terms and expressions related to conformity assessment, as well as information about ISO's adherence to the WTO principles in the Technical Barriers to Trade (TBT) see the following URL: Foreword - Supplementary information

The committee responsible for this document is ISO/TC 108, Mechanical vibration, shock and condition monitoring.

ISO 18431 consists of the following parts, under the general title Mechanical vibration and shock — Signal processing:

• Part 1: General introduction
• Part 2: Time domain windows for Fourier Transform analysis
• Part 3: Methods of time-frequency analysis
• Part 4: Shock-response spectrum analysis

Introduction

Time-frequency analysis is used to quantitatively display a vibration or shock in terms of time and frequency. This is useful for analysing vibrations in a machine at varying speeds, e.g. in an automobile at varying engine rotational frequencies. Time-frequency analysis is also used to quantitatively display impulsive responses from machinery, e.g. the response of an impact. The duration of the impact as well as the frequency response is displayed. The frequency response can be displayed in terms of frequency, RPM, or octaves. The four methods included in this part of ISO 18431 are the short-time Fourier transform, the Wigner-Ville transform, the Choi-Williams transform, and the wavelet transform. When any of these methods is used with the correctly specified parameters, time and frequency components of shocks and vibrations are displayed quantitatively. Quantitative display enables quantitative specification of the machinery.

1 Scope

This part of ISO 18431 specifies methods for the digital calculation of a time-frequency analysis of a given sampled measurement of a physical or engineering quantity, such as acceleration, force, or displacement, over an interval of time. Several mathematical formulations of time-frequency transformations are given with requirements for recording of parameters and recommendations.

The data can be obtained experimentally from measurements of a mechanical structure or obtained from numerical simulation of a mechanical structure. This category of data is very broad because there is a wide variety of mechanical structures, e.g. microscopic instruments, musical instruments, automobiles, manufacturing machines, buildings, and civil structures. The data can determine the response of machines or of humans to mechanical vibration and shock.

2 Normative references

The following documents, in whole or in part, are normatively referenced in this document and are indispensable for its application. For dated references, only the edition cited applies. For undated references, the latest edition of the referenced document (including any amendments) applies.

3 Terms and definitions

For the purposes of this document, the terms and definitions given in ISO 2041, ISO 18431-1, and the following apply.

Bibliography