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在动态载荷反分析和识别过程中,离散响应测试信号的采样时间△t对荷载识别的计算量精度和稳定性都有重要影响,因此在进行荷载反分析测试时,必须合理确定采用时间△t.以往的工作一般是借鉴正分析时确定采样时间△t的方法,或者是从数值计算要求的角度提出确定△t的方法,没有从反分析的角度来确定△t,导致识别的不正确.为此从研究反分析问题的特点,即从分析其特有的不适定性出发,提出了新的△t的确定原则,并根据这一原则推导了相应的△t的计算方式.应用新的原则和公式,在实际计算中取得识别精度高、稳定性好、减少计算量的效果,为合理、正确地识别动荷载提出了依据和保证.“,”The sampling interval time(△t) of vibrating responses signal is very huge influence for the calculating accuracy and stable of dynamic loads identification , when dynamic loads are back analyzed and identified . So that △t is must determined when the signal will be tested for back analysis of dynamic loads.The methods, which △t is determined at present, is by means of the sampling law or the method that △t is determined in the numerical analysis. △t is not determined according to the character of back analysis.Therefore the method to determinate △t for dynamic loads identification has not been realized enough, but also is chaos. It is studied by the character of back analysis in this paper. Begin with to study the ill-posed problems which is resulted by △t in dynamic loads identification techniques, a reasonable criterion of determining △t has been proposed; and the corresponding formulas are also given. It is a basis and assurance for dynamic loads identification.