This is the 2nd in a series of informal articles about one engineer’s usage of LS-DYNA to solve a variety of non-crash simulation problems. The first was on LS-DYNA: Observations on Implicit Analysis, the third was LS-DYNA: Observations on Explicit Meshing, and the fourth was
My academic background is in micro-mechanics and I have a good understanding of how many angels can dance on the head of a pin. A lot of my academic work was on fracture mechanics from a theoretical aspect and whenever I got into the laboratory, it was often a crazy chase in trying to correlate real-world fracture behavior to numerical models. I find the same behavior in composites. Ask ten composite experts and one can get 20 opinions. We have a myriad of theories that I don’t even want to start mentioning. My favorite reference to the uncertainties of composite analysis is that of the World Wide Failure Exercise (WWFE) where brave scientists were given raw composite data and had to make failure predictions without having access to the experimental data. Given that they couldn’t curve fit or pick their preferred layups or whatever, the reality was that theory could match experiment within 20%. This really isn’t as bad as it sounds since experimental data has a typical range of 10%.