Published: Jan 1993
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Methods are presented to estimate the errors in estimating peak and slope values in tensile tests when there are limitations due to the electrical bandwidth of the measuring system and the finite data rate of the digital data acquisition system. Various “events” are defined that can occur along the measured stress-strain characteristic. By convolving with the impulse response of a typical low-pass filter, the effects on these waveform shapes is measured, and graphs are shown which relate the error in estimating the peak value or slope as a function of the bandwidth for a known “event” duration. It is shown that for most simple events a bandwidth of 3/(event-duration) is adequate for peak and slope measurements. For data rates it is shown that a rate of about 30 times minimum bandwidth is necessary for errors less than 1% in peak estimates. A simple method of estimating the actual system bandwidth is demonstrated.
data rate, bandwidth, impulse response, tensile testing
Manager, Corporate Product Planning, Instron Corporation, Canton, MA