The aim of this paper is to relate structural inherent characteristic with exterior excitation , to wield experimental mode analysis technique and structure intension theory in order to separate structural leading mode under practical work state on base of spectrum analysis of exterior excitation and identification each rank mode parameter of structure . sequentially , the issue of space complex stress state in effect of static and dynamic coupling transforms into the issue of simple stress state ( under mode form ) in reciprocal effect of each rank mode in order to analyze structural dynamical intensity 將結構本身的固有特性和外部激勵聯系在一起,運用實驗模態分析技術和結構強度理論,在對外部激勵進行譜分析和識別出結構各階模態參數的基礎上,分離出實際工作狀態下結構的主導模態,從而將一靜動耦合力作用下的空間復雜應力狀態問題轉化為各階模態相互作用下的簡單應力狀態(模態形態下)問題進行結構動強度分析。