- Tau Delta Phi National Fraternity Delta Eta Chapter Welcome to the Tau Delta Phi Home Page. We hope this page can help you become better acquainted with who we are and our goals as a national fraternity. Tau Delta Phi has been at Cooper Union for over 20 years, and continues to be a thriving and integral part of the Cooper Community. To find out more about us click on the links below. Why a ...cooper.edu/organizations/greek/tdp/home.html