In explicit transient analyses, the maximum stable time increment is controlled by the highest discrete eigenfrequency of the spatial discretization. For models that employ thin solid or solid-shell elements, this stability limit is typically dominated by thickness-stretch modes [1], which require very small time steps and, thus, high computational cost. Selective mass scaling (SMS) addresses this issue by selectively reducing the highest frequencies, thereby decreasing the number of time steps required for explicit time integration. However, common SMS concepts result in non-diagonal mass matrices. For large discretized systems, iterative solvers are therefore typically employed in each time step [2]. Consequently, the practical benefit of SMS depends on the interplay between the reduced number of time steps, the numerical cost of overhead associated with SMS per time step, and the desired accuracy threshold. This contribution presents first results of extending our recent SMS approach [3] to solid-shell formulations and geometrically non-linear analyses. The proposed method is compared with SMS concepts from the literature, focusing on accuracy in spectral problems and on overall efficiency in representative transient analyses. REFERENCES [1] G. Cocchetti, M. Pagani, U. Perego Selective mass scaling and critical time-step estimate for explicit dynamics analyses with solid-shell elements, Computers & Structures, Vol. 127, pp. 39–52, 2013. [2] L. Olovsson, K. Simonsson Iterative solution technique in selective mass scaling, Communications in Numerical Methods in Engineering, Vol. 22, pp. 77-82, 2006. [3] M. Hoffmann, A. Tkachuk, M. Bischoff, B. Oesterle Finite element technology-based selective mass scaling for explicit dynamic analyses of thin-walled structures using solid elements, COMPDYN 2023, 9th ECCOMAS Thematic Conference, M. Papadrakakis, M. Fragiadakis (eds.), Athens, Greece , pp. 1974–1982, 2023.