Design optimization is a critical aspect in the development of mechanical systems, particularly flexible multibody systems, to enhance performance metrics such as weight reduction, efficiency, and cost-effectiveness. Gradient-based optimization methods are often employed for this purpose due to their computational efficiency, especially for large design spaces. These methods rely heavily on accurate sensitivity analysis, which involves computing the derivatives of system responses with respect to design parameters. While significant research exists on sensitivity analysis for the full dynamic trajectory of multibody systems, details the computation of the initial position and velocity sensitivities is a crucial step and is scarcely documented, being treated as an implementation detail. This paper highlights the importance of computing these initial sensitivities and presents a specific proposal for their systematic computation within the context of flexible multibody dynamics. • Systematic method presented for computing initial sensitivities in rigid and flexible systems. • Flexible components are rigidized if initially undeformed in a Perturbed Initial Model (PIM). • Initial sensitivities severely impacts the evolution of sensitivities and potentially optimization results. • Formulation provided to handle flexible components treated as rigid in PIMs.
Orden et al. (Mon,) studied this question.