Abstract: A composite material includes stacked reinforced fiber substrates and has a thickness-varying part whose thickness in a stacking direction changes from a large thickness to a small thickness. The reinforced fiber substrate that has the drop-off portion and is positioned between a base substrate and a cover substrate in the stacking direction is set as a cut substrate. Stress analysis is performed on the base substrate, the cut substrate, and the cover substrate to calculate an evaluation value concerning stress on the cut substrate. A reinforced fiber substrate in the thickness-varying part is set at the cut substrate, based on the calculated evaluation value.

Abstract: A method is of designing a composite material that includes stacked reinforced fiber substrates and has a thickness-varying part whose thickness in a stacking direction changes from a large thickness to a small thickness. The method includes setting, as a cut substrate, the reinforced fiber substrate that has the drop-off portion and is positioned between a base substrate and a cover substrate in the stacking direction; performing stress analysis on the base substrate, the cut substrate, and the cover substrate to calculate an evaluation value concerning stress on the cut substrate; and setting, as the cut substrate, a reinforced fiber substrate in the thickness-varying part, based on the calculated evaluation value.