Synopsis

The article is concerned with the determination of the stiffness matrix from the experimentally determined modal properties of a structure. Systems with proportional damping possess unique normal modes and natural frequencies. The normal modes can be determined by several synchronized harmonic exciters. The appropriate mathematical explanation for the experimental determination is presented in the vector-matrix form. A method which enables t'o calculate the stiffness matrix of a structure from the experimentally determined modal properties is given. The basic idea of the procedure is the orthogonalization of the measured inaccurate set of modal vectors. The orthogonalization keeps the first vector, which is supposed to be the exact modal vector, unchanged. An example for a five degrees of freedom is added. A fair consistancy of both, the exact and the computed stiffness matrix is obvious.