Could coconuts prevent earthquake deaths? Structure of fruit's walls may inspire new shake-proof buildings

• Coconuts have three protective layers including inner and outer exocarp
• Endocarp contains vessels that have a design to withstand bending forces
• The vessels' structure could be imitated to create super-strong concrete
• This concrete could be used to build earthquake-proof buildings

Coconuts are renowned for their hard shells, which are vital to ensure their seeds successfully germinate.

But the specialised structure of coconut walls could help engineers design buildings capable of withstanding earthquakes and other natural disasters.

This could mean fewer deaths as a result of crumbling buildings in a quake.

Coconut palms can grow 98 feet (30 metres) high, meaning that when the ripe fruits fall to the ground, their walls have to withstand the impact to stop them from splitting open.

To protect the internal seed, the coconut has a complex structure of three layers: the outer brown, leathery exocarp, a fibrous mesocarp and a tough inner endocarp surrounding the pulp, which contains the developing seedling.

Researchers at the Plant Biomechanics Group of the University of Freiburg are working with civil engineers and material scientists to investigate how this specialised structure could be used to strengthen buildings.

They used compression machines and an impact pendulum to investigate how coconuts disperse energy.

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To protect the internal seed, the coconut has a complex structure of three layers: the outer brown, leathery exocarp, a fibrous mesocarp and a tough inner endocarp surrounding the pulp, which contains the developing seedling. The distinct ladder-like design and angle of the vessels in coconut shells helps to dissipate energy

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The death toll rose to 41 after a 7.4 scale earthquake destroyed roads, bridges and homes on 15 April in southern Kyushu island, Japan

Plant biomechanist Dr Stefanie Schmier explained: 'By analysing the fracture behaviour of the samples and combining this with knowledge about the shell's anatomy gained from microscopy and computed tomography, we aimed to identify mechanically relevant structures for energy absorption' said.

The team found that within the endocarp layer, which consists mainly of highly lignified, or woody, stone cells - the vessels that make up the coconut's vascular system have a distinct, ladder-like design, which is thought to help withstand bending forces.

Each cell is surrounded by several woody rings, joined together by parallel bridges.

'The endocarp seems to dissipate energy via crack deflection' Dr Schmier said.

'This means that any newly developed cracks created by the impact don't run directly through the hard shell'.

It is thought that the angle of the vascular bundles, which are designed to transport water and minerals, helps to 'divert' the trajectory of the cracks.

The longer a crack has to travel within the endocarp, the more likely it is that it will stop before it reaches the other side.

The angle to the vascular bundles could be applied to the arrangement of textile fibres within concrete, the experts believe.

This would create a super-strong building material able to deflect cracks and control the way concrete breaks up to prevent as much damage as possible.

'This combination of lightweight structuring with high energy dissipation capacity is of increasing interest to protect buildings against earthquakes, rock fall and other natural or manmade hazards,' Dr Schmier said.

BUILDINGS WITH STEEL FRAMES COULD SURVIVE TOO 

Engineers are testing whether steel frames are superior to wooden ones when helping builsings withstand major tremors.

Researchers at the University of California in San Diego recently rocked and rattled a six-story steel frame building on a giant shake table to see how the structure would withstand major earthquakes.

The shaking simulated an earthquake of the 6.7 magnitude that occurred in 1994 in Los Angeles, causing significant damage.

During the test, the building shuddered and let out a hollow, grinding sound but remained standing.

The water heaters and at least some of the flat-screen TVs seemed to remain in place, though researchers still need to review drone footage to see exactly how the building fared inside and out.

The test is part of a $1.5 million series of experiments aimed at determining whether the lightweight steel structure is a better option than wood frame structures for tall, residential buildings in earthquake-prone areas like California.

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The angle to the vascular bundles could be applied to the arrangement of textile fibres within concrete, the experts believe. This would create a super-strong building material able to deflect cracks and control the way concrete breaks up to prevent as much damage as possible.

http://www.dailymail.co.uk/sciencetech/article-3675480/Could-coconuts-prevent-earthquake-deaths-Structure-fruit-s-walls-inspire-new-shake-proof-buildings.html