Evaluation Method Of Uncertainty In Impact Acceleration Measurement

The impact acceleration sensor and test system are the core components of the current access to a variety of high impact transient signal and various ballistic parameters,whose accuracy plays a decisive role in the success of the whole testing process and the reliability of the test results.So it is necessary to evaluate the uncertainty of the impact acceleration sensor and testing system.According to the result of uncertainty evaluation,we can determine whether the impact acceleration is accurate.The following research was carried out in this paper:1.The several commonly used measurement uncertainty evaluation methods,such as GUM method,Monte Carlo method and Bayesian evaluation method were studied on,and shown the general process of measurement uncertainty evaluation.2.Using Hopkinson bar calibration system to calibrate the peak sensitivity of the impact acceleration sensor.The calibration results were evaluated by GUM,Bias and Monte Carlo method,and the advantages and disadvantages of the three methods were analyzed in detail.The results shown that the three methods are not universally applicable for different test systems,and unable to estimate the uncertainty of the whole continuous process in the dynamic test.In order to solve these problems,a new dynamic uncertainty evaluation method based on frequency domain is proposed,which can be used to estimate the uncertainty of different test systems in a certain range.3.The specific process of evaluating the uncertainty of dynamic measurement in frequency domain is: according to the actual test system,establish an ideal test system,calculated the dynamic measurement error of two test systems;The amplitude frequency response and phase frequency response of the two measurement systems are calculated respectively,then the power spectrum function of the dynamic error is calculated according to the Paz Val theorem;According to the power spectrum,the actual dynamic measurement uncertainty is calculated.Finally,the dynamic measurement uncertainty evaluation method is applied to the actual case of the dynamic calibration system and the test system of the impact acceleration.4.Modeling of dynamic calibration system and test system,calculate the system characteristics.The uncertainty of measurement is obtained by comparing the response curve of the input signal with the actual measured response curve.Finally compare the estimation results and the results in frequency domain,and the feasibility of the proposed method is validated.