The approach to computational micromechanics based on the fast Fourier transform (FFT), initially developed by Moulinec-Suquet [1] and further developed by a vivid community, is widely regarded as one of the most efficient numerical strategy for this purpose. Almost all variants of FFT-based homogenization have in common that they operate on a regular grid and utilize the fast Fourier transform to evaluate Green’s operator within a Lippmann-Schwinger type solution framework. The success of the strategy rests, on the one hand, on the rather efficient FFT implementations available [2], and, on the other hand, on the use of simple data structures. The bottleneck for most industrial applications is evaluating the typically rather expensive constitutive law on the regular grid. Inspired by the work of Kaiser et al. [3], we have introduced flexible coarsening strategies based on octrees [4] which do not use wavelets for discretization, but retain traditional discretization schemes. In our talk we will discuss the integration into an existing FFT-based computational micromechanics code and apply the resulting solver to a number of challenging microme chanical problems. REFERENCES [1] H. Moulinec and P. Suquet, A numerical method for computing the overall response of nonlinear composites with complex microstructure, Computer Methods in Applied Mechanics and Engineering, vol. 157, pp. 69–94, 1998. [2] M. Frigo and S. G. Johnson, The Design and Implementation of FFTW3, in Proceedings of the IEEE, vol. 93, pp. 216–231, 2005. [3] T. Kaiser, T. Raasch, J. J. C. Remmers, and M. G. D. Geers, A wavelet-enhanced adaptive hierarchical FFT-based approach for the effcient solution of microscale boundary value problems, Computer Methods in Applied Mechanics and Engineering, vol. 409, p. 115959, 2023. [4] M. Kabel, M. Schneider, Adaptive material evaluation by stabilized octree and sandwich coarsening in FFT-based computational micromechanics, International Journal for Numerical Methods in Engineering, submitted.