Why do new engines have a case with a triangular tiling pattern?
This type of structure is called isogrid structure. Solid walls are usually very heavy and therefore engineers use more weight-efficient structures such as sandwich structures or stiffened structures with stringers and frames. A downside is the huge manufacturing cost compared to other options.
As you can see from NASA Report CR-124075 &quot;Isogrid Design Handbook&quot;, which was written 50 years ago, it is not a new type of structure.