User:Nicholas.Hoffman/sandbox

This is the current state of the Bouligand Structure article to be edited here in the sandbox before it is returned to the read article:

A Bouligand structure is a layered and rotated microstructure resembling plywood, which is frequently found in naturally designed materials. It consists of multiple lamellae, or layers, each one composed of aligned fibers. Adjacent lamellae are progressively rotated with respect to their neighbors. This structure enhances the mechanical properties of materials, especially its fracture resistance, and enables strength and in plane isotropy. It is found in various natural structures including the cosmoid scale of the coelacanth, and the dactyl club of the mantis shrimp and many other stomatopods.

Due to its desirable mechanical properties, there are ongoing attempts to replicate Bouligand arrangements in the creation of failure resistant bioinspired materials. For example, it has been shown that layered composites (such as CFRP) utilizing this structure have enhanced impact properties. However, replicating the structure on small length scales is challenging, and the development and advancement of manufacturing techniques continually improves the ability to replicate this desirable structure.

''To improve the page, looking to add analysis of the bouligand structure and specifically focus on its mechanical properties. Some of the sources that could be used to this end are listed below. Most of the references listed there are open source and will be good sources to add figures comparing the performance of bouligand vs non-bouligand of the same material, and show failure mechanisms. Will look at the mechanical properties of the structure as found in nature, as well as compare property improvements in synthetic materials made using the bouligand structure. Specific properties covered are toughness, impact resistance, tensile, and compression strengths. All these would most likely go in as subsections under something like "Properties". Eg, Main section: Mechanical Properties, Subsections: Tensile analysis, Toughening mechanisms, Impact Resistance.''

Mechanical Properties
data table of tensile, yield, modulus, etc? - it may be too difficult to compare one lab's report on collagen / chitin (done one way) to another lab's report on mineralized collagen vs another lab's report on mineralized collagen in bouligand structure.

Toughening Mechanisms
The Bouligand structure found in many natural materials is credited with imparting a very high toughness and fracture resistance to the overall material it is a part of. The mechanisms by which this toughening occurs are many, and no one mechanism has yet to be identified as the main source of the structure's toughness. Both computational work and physical experiments have been done to determine these pathways by which the structure resists fracture so that synthetic tough Bouligand structures can be taken advantage of.

"crack bridging, deflection, arrest, and twisting. deflection and arrest slow propagation, crack twist allow multiple cracks to grow from various nucleation sites without coalescing. High crack surface to volume ratio maximizes energy dissipation. crack bridging at impact locations minimizes crack tip stress concentration - arrests further crack opening"

Citation 4: attribution-NonCommercial 3.0 Unported (CC BY-NC 3.0)     - ie. can use figures fromthis

Fracture Modes


[fracture images ] (Citation 6: CC BY 4.0)   - ie. can use figures from this

Adaptability
[rotation mechanisms ]

Single vs. Double Bouligand Structure
[single vs double image might have to make it yourself]

The most common Bouligand structure found in nature is the twisted plywood structure where there is a constant angle of misalignment between layers. A rare variation of this structure is the so-called "double twisted" Bouligand structure. This structure uses stacks of two as units to be twisted with respect to each other at some constant misalignment angle. The two fibril layers in each of these units in this case lay such that their fibril orientation is perpendicular to each other. It is also found in nature that this double twisted structure is accompanied by extra "interlbundle fibrils" that run up through the planes of the twisted Bouligand structure.

The mechanical differences between the single and double twisted bouligand structure has been observed.

[summarize finds since not open source and figures are not available]

It has also been observed that a structure can form mostly similar to the single twisted bouligand structure, but with a non-constant angle of misalignment (link to nature section?). It is still unclear how this structural difference affects mechanical properties.

Impact Resistance
[figures ]