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Delivery: <= 3 days. True-PDF full-copy in English will be manually translated and delivered via email. GB/T 29716.4-2018: Mechanical vibration and shock -- Signal processing -- Part 4: Shock-response spectrum analysis Status: Valid
Basic dataStandard ID: GB/T 29716.4-2018 (GB/T29716.4-2018)Description (Translated English): Mechanical vibration and shock -- Signal processing -- Part 4: Shock-response spectrum analysis Sector / Industry: National Standard (Recommended) Classification of Chinese Standard: J04 Classification of International Standard: 17.160 Word Count Estimation: 18,174 Date of Issue: 2018-03-15 Date of Implementation: 2018-10-01 Issuing agency(ies): State Administration for Market Regulation, China National Standardization Administration GB/T 29716.4-2018: Mechanical vibration and shock -- Signal processing -- Part 4: Shock-response spectrum analysis---This is a DRAFT version for illustration, not a final translation. Full copy of true-PDF in English version (including equations, symbols, images, flow-chart, tables, and figures etc.) will be manually/carefully translated upon your order. Mechanical vibration and shock--Signal processing--Part 4. Shock-response spectrum analysis ICS 17.160 J04 National Standards of People's Republic of China Mechanical vibration and shock signal processing Part 4. Analysis of shock response spectrum Part 4. Shock-responsespectrumanalysis (ISO 18431-4..2007, IDT) Published on.2018-03-15 2018-10-01 implementation General Administration of Quality Supervision, Inspection and Quarantine of the People's Republic of China China National Standardization Administration issued ContentForeword III Introduction IV 1 Scope 1 2 Normative references 1 3 Terms and Definitions 1 4 symbols and abbreviations 1 5 Basic Principles of Shock Response Spectrum 2 6 Calculation of shock response spectrum 5 7 Effect of sampling frequency 9 Reference 12ForewordGB/T 29716 "Mechanical Vibration and Shock Signal Processing" consists of the following parts. --- Part 1. Introduction; --- Part 2. Time domain window of Fourier transform; --- Part 3. Time-frequency analysis method; --- Part 4. Impact response spectrum analysis; --- Part 5. Time base analysis method. This part is the fourth part of GB/T 29716. This part is drafted in accordance with the rules given in GB/T 1.1-2009. This section uses the translation method equivalent to ISO 18431-4.2007 "Mechanical vibration and shock signal processing - Part 4. Impact response Spectrum Analysis". The documents of our country that have a consistent correspondence with the international documents referenced in this part are as follows. ---GB/T 2298-2010 Mechanical vibration, shock and condition monitoring vocabulary (ISO 2041.2009, IDT). This part is proposed and managed by the National Technical Committee for Standardization of Mechanical Vibration, Shock and Condition Monitoring (SAC/TC53). This section drafted by. Northwest Institute of Mechanical and Electrical Engineering, Hangzhou Yiheng Technology Co., Ltd., China Testing Technology Research Institute, Ministry of Transport Highway Science Research Institute, Xiaogan Songlin International Measuring Instrument Co., Ltd., Hubei Electric Power Company Electric Power Research Institute, China Shipbuilding Heavy Industry Co., Ltd. graduate School. The main drafters of this section. Li Chaowei, Jiao Minggang, Gu Guofu, Wang Baoyuan, Hong Lina, Zhao Yugang.IntroductionIn recent years, almost all data analysis has been through the widespread use of digital signal acquisition systems and computer data processing equipment for digital The data is implemented by mathematical operations. Therefore, data analysis basically refers to digital signal processing. The experimental mechanics include all steps from test design to data evaluation and understanding, and the analysis of vibration shock test data should be among them. portion. GB/T 29716 assumes that the data has been fully restored and has taken into account the sensitivity impact of the instrument. The data mentioned in the article are vibration or rush The time domain sampling point sequence of the hit acceleration signal, the test method for obtaining these data is not within the scope of this standard (all parts). This section is a numerical calculation of the impulse response spectrum and is not limited to typical shock signals. However, this method is for analysis The impact signal defined in GB/T 2298 (ISO 2041) is meaningless. This shock is an emergency and its time ratio is The basic period of the system is short and there is no frequency characteristic in the frequency range of interest. It can only be described as a time domain integral and pulse corresponding to a constant frequency. Although the “maximum response spectrum” is more relevant, the term “shock response spectrum” is still in use. Historically, shock response spectra were originally used to describe a transient phenomenon that was then called "shock." Response analysis is often a method of describing vibration or shock that is used when other methods of frequency analysis are not adequately applied. E.g, Response analysis is used when comparing different types of vibrations. Analysis of different kinds of signals based on spectrum analysis based on Fourier transform Whenever a periodic signal, a random signal, or a transient signal, a different spectrum is produced. A typical application of the impulse response spectrum is to describe a dynamic mechanical environment. The analyzed vibration (or shock) signal is usually an acceleration signal. Number, recorded as a digital quantity and converted into an impulse response spectrum by analysis. This spectrum can be used for environmental testing of a device. How to give according to The impact response spectrum parameter design test can refer to the corresponding national standards such as GB 2423.57 (IEC 60068-2-81, detailed information can be found Test literature). When a vibration and/or impact environment measurement is completed, certain measures must be taken, such as ensuring proper movement at the measurement point. These measures are beyond the scope of this part of this standard. There are many manuals and materials available in this field [1][2]. Mechanical vibration and shock signal processing Part 4. Analysis of shock response spectrum1 ScopeThis part of GB/T 29716 describes a digital processing method for shock response spectroscopy (SRS), which passes a digital The filtered acceleration input signal is given. For different types of shock response spectra, the corresponding filter coefficients and suggested sampling are given. frequency. Note. According to the definition of the impulse response spectrum given in ISO 2041, an impulse response spectrum can be defined as the shape of the acceleration, velocity or displacement transfer function. formula. This section only discusses the case of acceleration inputs.2 Normative referencesThe following documents are indispensable for the application of this document. For dated references, only dated versions apply to this article. Pieces. For undated references, the latest edition (including all amendments) applies to this document. ISO 2041 Mechanical vibration, shock and condition monitoring vocabulary (Mechanicalvibration, shockandconditionmonito- ring-Vocabulary)3 Terms and definitionsThe following terms and definitions as defined by ISO 2041 apply to this document. 3.1 Maximum impact response spectrum maximaxshock-responsespectrum Take the SRS obtained from the maximum absolute value of the response. 3.2 Negative shock response spectrum negativeshock-responsespectrum The SRS obtained by taking the negative response maximum value. 3.3 Positive shock response spectrum positiveshock-responsespectrum Take the SRS obtained by the positive response maximum value. 3.4 Initial shock response spectrum primaryshock-responsespectrum Take the SRS obtained from the maximum response time during the shock excitation time. 3.5 Residual shock response spectrum residualshock-responsespectrum Take the SRS obtained from the maximum response after the end of the impact excitation.4 symbols and abbreviationsThe following symbols and abbreviations apply to this document. a(s) Laplace transform of acceleration (m/s2)·s c Damping constant N/(m/s) in SDOF system d(s) displacement Laplace transform m·s Fn SDOF system natural frequency Hz Fs sampling frequency, sampling rate Hz G(s) s domain transfer function H(z) z domain transfer function k SDOF system elastic coefficient N/m m SDOF system mass kg, N/(m/s2) QQ value, resonance gain s Laplace variable, complex frequency rad/s SDOF single degree of freedom system SRS shock response spectrum T sampling interval s Laplace transform (m/s)·s of v(s) (vibration) velocity Zz transform variable α digital filter denominator Beta digital filter molecule Ωn natural angular frequency rad/s 阻尼 damping factor, critical damping fraction5 Basic Principles of Shock Response Spectrum5.1 Overview In this section, the impulse response spectrum refers to a single degree of freedom vibration system, ie SDOF or mass-damping-spring system, for a given addition The response of the speed input. The given acceleration is applied to the entire system, and the maximum response of each subsystem is transverse to the natural frequency. The coordinates are composed, as shown in Figure 1. Description. a---input motion; b---Responsive movement. Note. The response of a single degree of freedom (SDOF) mechanical system determines the impulse response spectrum, where m, c and k differ from each other. Figure 1 Response of a single degree of freedom mechanical system (SDOF) Each single degree of freedom system in Figure 1 is defined by a unique set of parameters. mass m, damping coefficient c, and elastic coefficient k. Each parameter is traditional The definition is given in Chapter 4. Applying a given acceleration stimulus a1 on the basis, if the measured acceleration response is a2, then the transmission of an SDOF system The function G(s) is as shown in equation (1). G(s)= A2(s) A1(s)= Cs k Ms2 cs k (1) Where s is the Laplace variable (complex frequency) in rad/s. The single degree of freedom system can be described by the following parameters. (undamped) natural frequency fn, in Hz, given in equation (2). The resonance gain Q (Q factor) is given in equation (3). Fn= 2π (2) Q= Km (3) Then the transfer function can be written in the form of equation (4). G(s)= A2(s) A1(s)= Ωns Q ω S2 Ωns Q ω (4) Here ωn=2πfn is the natural angular frequency in rad/s. The amplitude-frequency curve of the transfer function is shown in Fig. 2, taking the natural frequency as 1 Hz and Q=10 as an example. Note the gain Q at the resonance point (Note. In the transfer function defined by equation (4), the maximum value is approximately Q, and the corresponding frequency is approximately fn. The larger the Q value, the higher the degree of approximation). Description. X --- frequency, in Hz; Y --- transfer function. Figure 2 SDOF system transfer function expressed by frequency as an independent variable The damping gain ζ can be replaced by the damping ratio ,, which means “critical damping ratio”, which is defined as shown in equation (5). ζ= 2Q= 2 km (5) Note. The critical damping coefficient is cc = 2 km. To calculate the impulse response spectrum, apply the analyzed acceleration signal to the SDOF-based system, and each system uses its natural frequency. Rate and Q value description. After the response of each SDOF system is calculated, its maximum response as a function of its natural frequency constitutes the entire system. Shock response spectrum. In a basic type of impulse response spectrum, the maximum value of the absolute value of the response is taken to calculate the impulse response spectrum. In the calculation of the impulse response spectrum, the natural frequency is selected logarithmically, and the Q of all SDOF systems is selected to the same value. inherent The number of frequencies depends on the Q value (or damping). If Q=10, the damping ratio is 5%, and the recommended minimum frequency per octave is 6, phase The minimum frequency should be 20 per decade. A small damping value ensures a finer resolution. Figure 3 shows an example of a (maximum) impulse response spectrum for a half-sine pulse with a pulse width of 11 ms and an amplitude of 10 gn. Description. X --- frequency, in Hz; Y --- maximum acceleration SRS, the unit is g value. Fig. 3 Shock response spectrum of half sinusoidal pulse (pulse width 11ms, amplitude 10gn, Q=10) 5.2 Shock response spectrum changes 5.2.1 Overview In the basic impulse response spectrum, the maximum acceleration response of the SDOF system is calculated. When considering relative speed or relative displacement In time, it is a variation of the impulse response spectrum. In addition to this, you can also introduce different maximum values to calculate, such as the maximum value (forward maximum Value) or minimum value (negative maximum). If a positive maximum is used, it is called a positive impulse response spectrum; if a negative maximum is used, it is called a negative Shock response spectrum; if the maximum absolute value is used, it is called the maximum impulse response spectrum. In some cases, it is also necessary to distinguish between the following. the maximum is the duration of the excitation (especially the excitation has a pulse Characteristics), or after the end of the incentive. The former is called the initial impulse response spectrum, and the latter is called the residual impulse response spectrum. To avoid confusion, the type of spectrum being calculated should be indicated, such as the "relative displacement maximum response spectrum". 5.2.2 Relative Velocity Response Spectrum When the response of the SDOF system is calculated using the relative speed between the system quality and the basis, the transfer function becomes equation (6) or The form given by equation (7). G(s)= V2(s)-v1(s) A1(s) = -ms Ms2 cs k (6) G(s)= V2(s)-v1(s) A1(s) = S2 Ωns Q ω (7) 5.2.3 Relative displacement response spectrum When the response of the SDOF system is calculated using the relative displacement between the system quality and the basis, the transfer function becomes equation (8) or The form given by equation (9). G(s)= D2(s)-d1(s) A1(s) = Ms2 cs k (8) G(s)= D2(s)-d1(s) A1(s) = S2 Ωns Q ω (9) 5.2.4 pseudo speed response spectrum The relative displacement response is multiplied by the natural angular frequency ωn to obtain a pseudo velocity response. In this case, the transfer function can be written as equation (10) or The form shown in formula (11). G(s)= D2(s)-d1(s) A1(s) ·ωn= -mωn Ms2 cs k (10) G(s)= D2(s)-d1(s) A1(s) ·ωn= -ωn S2 Ωns Q ω (11) 5.2.5 Relative displacement response spectrum expressed by equivalent static acceleration The equivalent static acceleration response is obtained by multiplying the relative displacement response by the square of the natural angular frequency ω2n. At this point the transfer function can be written as The form shown in formula (12) or formula (13). G(s)= D2(s)-d1(s) A1(s) ·ω2n= -mωn2 Ms2 cs k (12) G(s)= D2(s)-d1(s) A1(s) ·ω2n= -ω2n S2 Ωns Q ω (13)6 Calculation of shock response spectrum6.1 Overview Calculating the impulse response spectrum is equivalent to inputting an acceleration signal into a series of digital filters similar to those in Chapter 5. The defined transfer function. The acceleration time domain signal should be correctly recorded, which means that not only mechanical properties (such as acceleration sensors) are taken into account. Installation, etc.), but also to adopt adequate anti-aliasing measures. This section describes how to handle digital signals. If the digital signal is sampled at a frequency The rate is fsHz, and the interval between adjacent sampling points is T seconds. T= Fs (14) There are several ways to design a filter based on a given analog transfer function. Slope-invariant method (RrampInvariantMethod) [6] [7]. Calculation of filter coefficients corresponding to different response types defined in 5.2.2~5.2.5 The method will be given in 6.2~6.6. The digital filter corresponding to the response of different SDOF systems is second-order, and its general z-transform expression is as shown in equation (15). H(z)=β0 11·z-1 β2·z-2 1 α1·z-1 α2·z-2 (15) The filter expression for calculating the response time series yn according to the input acceleration time series xn is as shown in (16). Syn.β0·xn β1·xn-1 β2·xn-2-α1·yn-1-α2·yn-2 (16) It is worth noting that in digital filters corresponding to different responses, the denominator (α coefficient) is always the same, and the variation is the β coefficient. 6.2 Filter coefficients for absolute acceleration response Sampling frequency. fs, Hz Sampling interval. T= Fs , s Natural frequency. fn, Hz Natural angular frequency. ωn=2πfn, rad/s Resonance gain. Q Transfer function. G(s) G(s)= A2(s) A1(s)= Ωns Q ω S2 Ωns Q ω Digital filter. H(z)=β0 11·z-1 β2·z-2 1 α1·z-1 α2·z-2 The coefficients are defined as follows. 00=1-exp(-A)·sin(B)/B 11=2exp(-A)· sin(B)/B-cos(B){ } 22=exp(-2A)-exp(-A)·sin(B)/B 11=-2exp(-A)·cos(B) 22=exp(-2A) here A= Ωn·T 2Q B=ωn·T· 1- 4Q2 6.3 Filter coefficients for relative speed response Sampling frequency. fs, Hz Sampling interval. T= Fs , s Natural frequency. fn, Hz Natural angular frequency. ωn=2πfn, rad/s Resonance gain. Q Transfer function. G(s) G(s)= V2(s)-v1(s) A1(s) = S2 Ωns Q ω Digital filter. H(z)=β0 11·z-1 β2·z-2 1 α1·z-1 α2·z-2 The coefficients are defined as follows. 00= Ω2n·T · -1 exp(-A)·cos(B) Exp(-A)·sin(B) 4Q2-1{ } 11= Ω2n·T · 1-exp(-2A)- 2exp(-A)·sin(B) 4Q2-1{ } 22= Ω2n·T · exp(-2A)-exp(-A)·cos(B) Exp(-A)·sin(B) 4Q2-1{ } 11=-2exp(-A)·cos(B) 22=exp(-2A) here A= Ωn·T 2Q B=ωn·T· 1- 4Q2 6.4 Filter coefficient of relative displacement response Sampling frequency. fs, Hz Sampling interval. T= Fs , s Natural frequency. fn, Hz Natural angular frequency. ωn=2πfn, rad/s Resonance gain. Q Transfer function. G(s) G(s)= D2(s)-d1(s) A1(s) = S2 Ωns Q ω Digital filter. H(z)=β0 11·z-1 β2·z-2 1 α1·z-1 α2·z-2 The coefficients are defined as follows. 00= Ω3n·T · 1-exp (-A)·cos(B) Q -q ·exp(-A)·sin(B)-ωn·T{ } 11= Ω3n·T · 2exp(-A)·cos(B)·ωn·T- 1-exp(-2A) Q 2q ·exp(-A)·sin(B){ } 22= Ω3n·T · -exp(-2A)· ωn·T Exp(-A)·cos(B) Q -q ·exp(-A)·sin(B){ } 11=-2exp(-A)·cos(B) 22=exp(-2A) here A= Ωn·T 2Q B=ωn·T· 1- 4Q2 q= 2Q2- 4Q2 6.5 Filter coefficients for pseudo-speed response Sampling frequency. fs, Hz Sampling interval. T= Fs , s Natural frequency. fn, Hz Natural angular frequency. ωn=2πfn, rad/s Response gain. Q Transfer function. G(s) G(s)= D2(s)-d1(s) A1(s) ·ωn= -ωn S2 Ωns Q ω Digital filter. H(z)=β0 11·z-1 β2·z-2 1 α1·z-1 α2·z-2 The coefficients are defined as follows. 00= Ω2n·T · 1-exp (-A)·cos(B) Q -q ·exp(-A)·sin(B)-ωn·T{ } 11= Ω2n·T · 2exp(-A)·cos(B)·ωn·T- 1-exp(-2A) Q 2q ·exp(-A)·sin(B){ } 22= Ω2n·T · -exp(-2A)· ωn·T Exp(-A)·cos(B) Q -q ·exp(-A)·sin(B){ } 11=-2exp(-A)·cos(B) 22=exp(-2A) here A= Ωn·T 2Q B=ωn·T· 1- 4Q2 q= 2Q2- 4Q2 6.6 Relative displacement response filter coefficients expressed by equivalent static acceleration Sampling frequency. fs, Hz Sampling interval. T= Fs , s Natural frequency. fn, Hz Natural angular frequency. ωn=2πfn, rad/s Response gain. Q Transfer function. G(s) G(s)= D2(s)-d1(s) A1(s) ·ω2n= -ω2n S2 Ωns Q ω Digital filter. H(z)=β0 11·z-1 β2·z-2 1 α1·z-1 α2·z-2 The coefficients are defined as follows. 00= Ωn·T · 1-exp (-A)·cos(B) Q -q ·exp(-A)·sin(B)-ωn·T{ } 11= Ωn·T · 2exp(-A)·cos(B)·ωn·T- 1-exp(-2A) Q 2q ·exp(-A)·sin(B){ } 22= Ωn·T · -exp(-2A)· ωn·T Exp(-A)·cos(B) Q -q ·exp(-A)·sin(B){ } 11=-2exp(-A)·cos(B) 22=exp(-2A) here A= Ωn·T 2Q B=ωn·T· 1- 4Q2 q= 2Q2- 4Q27 Effect of sampling frequencyThe slope invariance method includes a deviation ε related to the sampling frequency, which is a function of the sampling frequency f, and its specific expression is as follows As shown in equation (17). ε(f)=1- sin Πf Fs Πf Fs Êê Úú (17) Figure 4 shows the deviation curve. Description. X --- ......Tips & Frequently Asked Questions:Question 1: How long will the true-PDF of GB/T 29716.4-2018_English be delivered?Answer: Upon your order, we will start to translate GB/T 29716.4-2018_English as soon as possible, and keep you informed of the progress. The lead time is typically 1 ~ 3 working days. 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