Abstract
In this paper, a novel stochastic finite element method is introduced. The concept is based on a set of strict necessary and sufficient requirements for nonnegative definiteness of Hermitian matrices with a 2x2 block partitioning, expressed in terms of their constituent submatrices. Further mathematical constructions are suggested, permitting the robust and efficient construction and sampling of random mass and stiffness matrices. The method allows uncertainty to be controlled at the subsystem level in dynamic substructuring problems. Different levels of randomness can be applied to off-diagonal partitions of the component matrices without interfering with the remaining blocks, or the key mathematical properties of the global matrix. Sparsity pattern of the ‘nominal’ deterministic matrix is preserved. The method is validated with a spacecraft test case in a vibroacoustic load scenario. Very good results are demonstrated against direct parametric Monte Carlo simulation, while computational time is reduced by nearly 3 orders of magnitude.