BMI727 From United States of America, joined Feb 2009, 15086 posts, RR: 26 Reply 3, posted (10 months 1 week 10 hours ago) and read 3169 times:
Quoting SAAFNAV (Reply 2): He concurs with what I said above, but he also said that a fir-tree is probably the most effective design to ensure proper 'grip' of the blade wrt. thermal expansion coefficients.
That's what I would have figured. The turbines will experience more heat and therefore more expansion which probably affects the design.
Why do Aerospace Engineering students have to turn things in on time?
dhawald3 From India, joined Jun 2011, 17 posts, RR: 0 Reply 5, posted (10 months 5 days 15 hours ago) and read 2733 times:
After much searching on Google in addition to the above explanation I found this.
Fir tree root gives it a large bearing area to take up the heavy stresses, and this bearing area is nearer to the axis of the blade.
Resulting in resistance to cracking at the root as compared to the root in which the bearing area is at a more distance from the axis of the blade.