Patent ID: 8562041

Claim:
A bumper structure comprising: a front flange and a rear flange comprising metal and forming a front surface and a rear surface of the bumper structure, respectively; an upper web and a lower web comprising metal and forming a upper surface and a lower surface of the bumper structure, respectively; and an intermediate web comprising metal, wherein the front flange, the rear flange, the upper web, and the lower web are connected to each other so as to form a box shape comprising a hollow space therein, wherein the intermediate web is connected to the front flange and the rear flange between the upper web and the lower web such that the hollow space is divided into an upper portion and a lower portion, wherein, of the front flange, the rear flange, the upper web, the lower web, and the intermediate web, at least one of the upper web, the lower web, and the intermediate web is made of a second material, and the others are made of a first material, and wherein, the first material and second material satisfy an equation: E 1 /ρ 1 3 <E 2 /ρ 2 3 , wherein the Young's modulus and density of the first material are E 1 and ρ 1 , respectively, and the Young's modulus and density of the second material are E 2 and ρ 2 , respectively.