Method for producing a sandwich structure comprising two steel face sheets separated by a polymer layer, comprising steps in which: - the sandwich structure is dimensioned according to a target to be achieved by following sub-steps in which: ∘ the target to be achieved is defined by three target values, namely its tensile stiffness T c expressed in kN/mm, its bending stiffness B c expressed in kN/mm and its surface density M c expressed in kg/m 2, ∘ a tolerance in the achievement of the target values is defined, ∘ the sandwich structure is defined by five variables, namely the thickness E a of the steel face sheets expressed in mm, the thickness E p of the polymer layer expressed in mm, the intrinsic Young's modulus Y p of the polymer layer, the intrinsic density d p of the polymer layer and the volume ratio R p of the polymer layer expressed as the volume percentage of the polymer layer having material, ∘ the combinations of E a, E p, Y p, d p and R p allowing the target values to be achieved with the defined tolerance are identified, ∘ an operating range is derived therefrom, for each variable, - the steel and the polymer layer for which each variable is within the range defined in the preceding step are selected, - the corresponding sandwich structure is produced. - the sandwich structure is dimensioned according to a target to be achieved by following sub-steps in which: ∘ the target to be achieved is defined by three target values, namely its tensile stiffness T c expressed in kN/mm, its bending stiffness B c expressed in kN/mm and its surface density M c expressed in kg/m 2, ∘ a tolerance in the achievement of the target values is defined, ∘ the sandwich structure is defined by five variables, namely the thickness E a of the steel face sheets expressed in mm, the thickness E p of the polymer layer expressed in mm, the intrinsic Young's modulus Y p of the polymer layer, the intrinsic density d p of the polymer layer and the volume ratio R p of the polymer layer expressed as the volume percentage of the polymer layer having material, ∘ the combinations of E a, E p, Y p, d p and R p allowing the target values to be achieved with the defined tolerance are identified, ∘ an operating range is derived therefrom, for each variable, ∘ the target to be achieved is defined by three target values, namely its tensile stiffness T c expressed in kN/mm, its bending stiffness B c expressed in kN/mm and its surface density M c expressed in kg/m 2, ∘ a tolerance in the achievement of the target values is defined, ∘ the sandwich structure is defined by five variables, namely the thickness E a of the steel face sheets expressed in mm, the thickness E p of the polymer layer expressed in mm, the intrinsic Young's modulus Y p of the polymer layer, the intrinsic density d p of the polymer layer and the volume ratio R p of the polymer layer expressed as the volume percentage of the polymer layer having material, ∘ the combinations of E a, E p, Y p, d p and R p allowing the target values to be achieved with the defined tolerance are identified, ∘ an operating range is derived therefrom, for each variable, - the steel and the polymer layer for which each variable is within the range defined in the preceding step are selected, - the corresponding sandwich structure is produced.