动荷载反分析的模态选择方法

提出了动态载荷识别中新的确定模态的准则与实施方法.提出了模态选取概念,在此基础上提出了反分析中模态选取的准则,并给出了相应的公式.大量算例表明,采用该文准则和公式可以防止因模态选取不当而产生的伪解,避免计算中的数值病态,明显提高了动态载荷识别的成功率和精度.

THE MOTHOD OF MODEL SELECT IN DYNAMIC LOAD IDENTIFICATION

For the computation of structural dynamics with modality analysis method,both the positive analysis and the back analysis all exist the problem of reasonably determining the order of modality.The authors think that the modality determination in back analysis is different from that in positive analysis.For the modality determination in back analysis,the self-characteristics of back analysis must be considered.In back analysis,the unreasonable modality is not only cannot to help the load identification,but also will interfere in identification;and furthermore it will interrupt the identification process.Therefore,a new criterion for determining modality in dynamic load identification and implementation method is proposed.This paper presents a conception of modality selection,which is more reasonable compared with the recent adopted conception of modality-truncation;and on this base,a criterion of modality selection in back analysis has been proposed;and the corresponding formulas are also given.Lots of computational examples show that the criterion and formulas proposed in this paper can prevent producing pseudo-solution due to the unreasonably selecting modality,and can avoid numerical ill-condition so as to obviously increase the reliability and accuracy of dynamic load identification.