Prof. Tsai @stevewtsai has been advocating double-double laminates in recent years. Very recently, he gave the Lagace Lecture on it and a couple of years ago he also gave a lecture in the Global Composites Experts Webinar Series. However, not many people have a good understanding of double-double laminates. Recently, Prof. @FDanzi, in his introduction, mentioned that he is doing research related to double-double laminates. It believe it is a good chance for us to have a deep discussion about it for better understanding. Below is his opinions about DD laminates. Feel free to add your opinions.