Full engineering tests. In medical devices it's called V&V, verification and validation. You verify the design is suitable and meets the invite requirements,

Full engineering tests. In medical devices it's called V&V, verification and validation. You verify the design is suitable and meets the invite requirements, you validate that your manufacturing process creates that design, exactly. You use software like this, or the custom academic Fortran code of the times before you mention as a design tool, as a way finding tool to help maximize strength or minimize weight of a particular part.