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PROPELLER BLADE VIBRATION AND STRESS ANALYSIS
GENERAL APPLIED SCIENCE LABS INC WESTBURY NY
Presented is a computer program for generating the natural frequencies, mode shapes, and modal stress distributions for the ten lowest modes of vibration of propeller blades. This information, coupled with the fact that the eigenvectors are normalized with respect to the strain energy matrix is sufficient to conduct any response analyses of propeller blades. After accepting the input data which describe the blade geometry, the program generates a polynomial which fits, in the least squares sense, the camber distribution over the planform of the blade. The program then constructs a quadrature mesh which is later used to integrate the strain energy and kinetic energy, matrices over the blade planform. The two-matrix eigenvalue problem is reduced to a one matrix eigenvalue problem by factoring the strain energy matrix in triple- precision. This problem is then solved, and the resulting eigenvalues and eigenvectors are written as output. The relative stresses and displacements are calculated at mesh points over the blade planform, and are written as output.
Approved for public release; distribution is unlimited.