Senile Coconut Palm Hierarchical Structure as Foundation for Biomimetic Applications

Abstract

Superior to hardwood and softwood trees, coconut palms are able to withstand extreme weather conditions without failure. Previous studies have shown that the internal structure of coconut palm stems significantly differs from hardwood, softwood and even other palm stems, in terms of fibre orientation and density distribution, likely influencing the mechanical characteristics of the tree. This paper aims at quantifying the cocowood hierarchical structure at an integral level (stem structure). To achieved this, quantitative analysis of more than 40 senile coconut palms from Fiji and Samoa has been carried out. This paper defines and analyses the typical cocowood morphology (form-structure) in terms of such factors as characteristic radius, fibrovascular bundles orientation and density distribution. For the first time, the characteristic triple helix configuration traced out by the fibrovascular bundles within the cocowood structure is modelled for the whole coconut stem. Specific equations are proposed to determine these factors at any given position in the tree. Knowledge advanced from this study will provide a scientific basis for future cocowood biomechanics research, including finite element modelling and analysis for biomimetic engineering applications.

Innovative Bio-composite Sandwich Wall Panels made of Coconut Bidirectional External Veneers and Balsa Lightweight Core as Alternative for Eco-friendly and Structural Building Applications in High-risk Seismic Regions

“…Within this context, the core shear strength of prototype panel 2 is in average 1.5 times greater than prototype panel 1, which in theory is correct as the lighter core section of the sandwich prototype panel 1 is about 1.2 times greater in volume than prototype panel 2, and consequently, it makes the latter prototype less vulnerable to shear stresses. Moreover, it confirms one important finding in [8][9][10][15][16][17][18] that states the mechanical properties in biomaterials are all quasi-linearly proportional to density. On the other hand, it is unfortunately not possible to establish any comparison between the resulting bending performances acquired in this study and conventional wall building elements (e.g.…”

“…April 16, with a moment magnitude of 7.8 and a maximum VIII severe Mercalli intensity. Adapted from [6] Unfortunately, part of the Ecuadorian area affected by the earthquake is currently being rebuilt using the same traditional building methods and materials.…”

Cocowood Fibrovascular Tissue System—Another Wonder of Plant Evolution

“…The structural modeled system has consequently one degree of freedom. In the FE model, the characteristic form, complex structure of the coconut stem-tissue and the cocowood properties were all derived from previous findings by the author (Gonzalez et al, 2014 , 2015 ; Gonzalez, 2015 ). Table 2 gives characteristic green properties [i.e., basic density ( d b ), modulus of elasticity (MOE), compressive modulus of rupture (MOR), shear modulus ( G ), and shear strength (τ max )] at key locations of the cocowood FE model, in the longitudinal (L), radial (R), and tangential (T) directions.…”

“…To fulfil the purposes in this study, a total of 11 finite element analyses (FEA) were carried out over the 3D cocowood FE model exposed to the wind speed of 23 m/s (i.e., Gale tornado, according to the Fujita tornado scale; Cullen, 2002 ); the wind speed that was determined in Gonzalez ( 2015 ) as the critical wind speed (i.e., the wind at which the material tissue starts reaching stress at failure) under the equivalent bending moment of 64.4 kN.m.…”

Experimental Investigation on Rotary Peeling Parameters of High Density Coconut Wood

“…Diameter and density patterns are known to vary from the bottom to the top of the palm, as described by Gonzalez et al (2014) and Bailleres et al (2010). The density variation ranges from around 100 kg/m 3 in the centre of the trunk to more than 1000 kg/m 3 on the periphery.…”