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ASTM E467-2008 轴向疲劳试验系统中恒振幅动态力验证的标准实施规范

ASTM E467-2008 轴向疲劳试验系统中恒振幅动态力验证的标准实施规范

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【英文标准名称】: Standard Practice for Verification of Constant Amplitude Dynamic Forces in an Axial Fatigue Testing System
【原文标准名称】: 轴向疲劳试验系统中恒振幅动态力验证的标准实施规范
【标准号】: ASTM E467-2008
【标准状态】: 现行
【国别】: 美国
【发布日期】: 2008
【实施或试行日期】:
【发布单位】: 美国材料与试验协会(US-ASTM)
【起草单位】: E08.03
【标准类型】: (Practice)
【标准水平】: ()
【中文主题词】:
【英文主题词】: Axial loading tests; Constant-load-amplitude fatigue crack growth rates; Displacement; Dynamic verification data; Dynamometer testing; Fatigue; Static tests--metals/alloys; Verification
【摘要】: It is well understood how to measure the forces applied to a specimen under static conditions. Practices E 4 details the required process for verifying the static force measurement capabilities of testing machines. During dynamic operation however, additional errors may manifest themselves in a testing machine. Further verification is necessary to confirm the dynamic force measurement capabilities of testing machines. Note 18212;The static machine verification accomplished by Practices E 4 simply establishes the reference. Indicated forces measured from the force cell are compared with the dynamometer conditioned forces statically for confirmation and then dynamically for dynamic verification of the fatigue testing system''s force output. Note 28212;The dynamic accuracy of the force cell''s output will not always meet the accuracy requirement of this standard without correction. Dynamic correction to the force cell output can be applied provided that verification is performed after the correction has been applied. Note 38212;Overall test accuracy is a combination of measurement accuracy and control accuracy. This practice provides methods to evaluate either or both. As control accuracy is dependent on many more variables than measurement accuracy it is imperative that the test operator utilize appropriate measurement tools to confirm that the testing machinex2019;s control behavior is consistent between verification activities and actual testing activities. Dynamic errors are primarily span dependent, not level dependent. That is, the error for a particular force endlevel during dynamic operation is dependent on the immediately preceding force endlevel. Larger spans imply larger absolute errors for the same force endlevel. Due to the many test machine factors that influence dynamic force accuracy, verification is recommended for every new combination of potential error producing factors. Primary factors are specimen design, machine configuration, test frequency, and loading span. Clearly, performing a full verification for each configuration is often impractical. To address this problem, dynamic verification is taken in two parts. First, one or more full verifications are performed at least annually. The main body of this practice describes that procedure. This provides the most accurate estimate of dynamic errors, as it will account for electronic as well as acceleration-induced sources of error. The second part, described in Annex A1, is a simplified verification procedure. It provides a simplified method of estimating acceleration-induced errors only. This procedure is to be used for common configuration changes (that is, specimen/grip/crosshead height changes). Dynamic verification of the fatigue system is recommended over the entire range of force and frequency over which the planned fatigue test series is to be performed. Endlevels are limited to the machine''s verified static force as defined by the current static force verification when tested in accordance with Practices E 4. Note 48212;There is uncertainty as to whether or not the vibration in a frame will be different when operating in compression as opposed to tension. As a consequence, this practice recommends performing verifications at maximum tension and maximum compression endlevels. The total span does not need to be between those two levels, but can be performed as two tests. Note 58212;Primary electronic characteristics affecting dynamic measurement accuracy are noise and bandwidth. ............
【中国标准分类号】: H22
【国际标准分类号】: 77_040_10
【页数】: 11P.;A4
【正文语种】: 英语

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