document: Functionally Graded Materials (FGMs), described in detail by Suresh and Mortensen [1], are a type of heterogeneous composite materials exhibiting gradual variation in volume fraction of their constituents from one surface of the material to the other, resulting in properties which vary continuously across the material. The idea of a Functionally Graded Material is not a new one, there are in fact many natural materials which exhibit this property. Study of bone, shell, balsawood and bamboo shows that they are all graded with their greatest strength on the outside, in areas where the greatest protection is required. However it was not until the 1980s in Japan [2] that the idea of a Functionally Graded Material was actively researched in order to gain advances in heat resistant materials for use in aerospace and nuclear fission reactors.
doc_bio_tags: B I I B O O O O O O O O O O O O B I I O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O B I I O O O O O O O O O O O O O O O O O O B B B O B O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O B I I O O O O O O O O O B I I O O O B O B I I
extractive_keyphrases: aerospace balsawood bamboo bone fgms functionally graded material functionally graded materials heat resistant materials heterogeneous composite materials nuclear fission reactors shell
abstractive_keyphrases: study of bone, shell, balsawood and bamboo