ME5517 Revision Session

Why do we study nature, its designs and solutions, and derive principles that we can apply to modern materials?

• (A) Look to nature for new ideas

• (B) Efficient use of natural resources in a more sustainable manner

• (C) The materials that nature has at its disposal are weak, but they are combined in a very ingenious way to produce tough components and robust designs.

• (D) All the natural materials have better functionalities than engineering materials

Which of the following is/are natural materials?

• (A) Sea shells

• (B) Biological materials

• (C) Wood

• (D) Water

Biological (or natural) materials can be classified as:

• (A) Soft and hard biological materials

• (B) Biopolymers and biominerals 

• (C) Protein, sugar and mineral

• (D) Biopolymers, biominerals, bioelastomers and biocellular materials

In the Mayers Heptahedron, which of the following is/are relevant to mechanical properties of biological systems:

• (A) Self-assembly

• (B) Hydration

• (C) Ambient environment synthesis

• (D) Hierarchy

Which of the following structural design elements can improve toughness:

• (A) Helical structures

• (B) Layered structures

• (C) Gradient structures

• (D) Tubular structures

How much enhancement of fracture toughness for hydrated nacre compared to the monolithic aragonite?

• (A) The same

• (B) Four times

• (C) Eight times

• (D) Three thousand times

What is the thickness of the “brick” platelets in abalone nacreous shells:

• (A) ~ 20 – 50 nm

• (B) ~ 400 nm

• (C) ~ 20 – 50 µm

• (D) ~ 400 µm

Which of the following is the second most abundant natural polymer?

• (A) Collagen

• (B) Cellulose

• (C) Chitin

• (D) Chitosan

In terms of the Classical Gibson-Ashby, what is the relationship between elastic modulus and relative density for open-cell structures?

• (A) Linear

• (B) Square

• (C) 3/2

• (D) Cubic

What are the characteristic regions in typical mechanical behavior of cellular structures?

• (A) An elastic region

• (B) A collapse plateau

• (C) A plastic necking region

• (D) A densification region