Why the wings of Boeing 787 Dreamliner are curved?
The wings of Boeing 787 Dreamliner are curved due to the presence of carbon fiber material on its wings. The carbon fiber material can be stretched more hence providing flexibility to its wings. The carbon fiber material has high aspect ratio of 11 which ultimately magnifies this bending effect.
The amount of bending depends on the following three factors:
The curvature of the wing due to the bending at wing root causes a tip displacement. This tip displacement is proportional to the distance at that tip from the root.
The curvature of the wing grows with inverse of the square of the spar height. Hence a lower relative thickness of the wing causes more bending.
The material present in the wing is carbon fiber. Carbon fibre has a higher Young’s modulus than aluminum, but is elastic until rupture, so can be stretched more which results in more bending at yield stress.