从自由试验提取约束结构模态

已有的“从自由试验提取约束结构模态”的动柔度法，仅适用于刚性支承情况．在工程中，弹性支承状态是常见的，为此，建立了这一情况下的提取方法．该方法具有普遍性，因为当支承刚度很大时，可得到刚性支承下的结果；当支承刚度很小时，便可获得工程中用橡皮绳悬吊结构后所测得的自由-自由试验模态．总之，当支承刚度为任何值时，用此方法都能提取到相应约束结构的满意试验模态参数．表明该算法是非常稳定的，对于工程应用至关重要．

EXTRACTION OF CONSTRAINED STRUCTURAL MODES FROM FREE TEST

The previous dvnamic flexibility (DF) method and improved DF method for extracting constrained struc-tural modes from a free test are only suitable to structures with rigid supports. However elastic supports are widely used in engineering structures. For this reason, a general method for extracting modes of constrained struc- tures with elastic supports from a free test is developed in the present article. It is called a general method because: (i) When the stiffness of the supports is very large, the method gives modes of a constrained structure with rigid supports; (ii) When the stiffness of the supports is quite small, free-free modes are obtained, in which the structure is suspended by using rubber ropes etc; (iii) When the stiffness of the supports is arbitrary, the method can give satisfactory results. They show that the algorithm propsed in this paper has a wide applications in engineer-ing.