Am I approaching this incorrectly? Each side is the same length, is under the same load, and is the same weight. I started the triangles with 0.1" round radius and I worked up to 0.25" (in picture), adjusting their dimensions to keep the volumes the same as I went. There is still higher stress in the piece lightened with triangles and if I increase the radius of the round much more then they might as well be circles.
https://drive.google.com/file/d/0B4u...it?usp=sharing