Bio-inspiration - Turtle Shell used as Body Armour

Protective armours were found in nature a long time ago and they consist of several number of designs. However, these designs are rarely structurally rigid: nature often prefers multi-layer material systems providing maximum impact protection at a weight that has the possibility of exhibiting high fracture toughness and impact resistance. The materials for armours are usually from ceramics and polymer matrix composites whereby composite armour is made of a hard strike ceramic face made of tiles as well as fiber reinforced composite backing plate. The purpose of the front ceramic layer is to prevent the high pressure forces on the backing composite plate by projectile deformation whereas composite backing plate is utilized in absorbing its kinetic energy.

Armours can be mimicked from the turtle shells whereby the shells are covered by thin keratinous wavy multi-layers and termed scutes. These keratins are useful in such a way that the proteins from keratins are able to protect the epithelial cells from damage. Hence, these features serve as a defense mechanism whenever they are attacked by predators. Similarly, when these feature is applied in body armours as well as shields, it will be able to protect the soldiers from incoming attacks during combat. Here are 2 examples: Traditional and modern day body armour:

Figure 1. Traditional body armour worn by Roman soldiers. The shield is design according to the shape of turtle shell

Figure 2. Modern military body armour from Korea Military Force (KMF)

In the present day, the analysis of body armour evolution in turtles results in several design principles:

1.      Maximize size of body armour

2.      Create smooth surfaces

3.      Create multilayer body armour

4.      Introduce shock absorbing layers

5.      Minimize weight

6.      Maximize articulation

The Romans have imitated the function of the turtle shell with military maneuver in which soldiers marched in a rectangular formation apart from body armour:

1.      Head holding shields at the front

2.      Side holding shields at the side

3.      Soldiers in the middle holding shields over their heads

Figure 3. Soldiers in rectangular formation with their shield to cover from external impact

References

1. B. Achrai, B. Bar-On, and H.D. Wagner, “Biological armors under impact-effect of keratin coating,     and synthetic bio-inspired analogues,” Bioinsp. Biomim, vol. 10, 2015.

2. T Arciszewski, and J. Cornell, “Bio-inspiration: Learning Creative Design Principal ,”