Tuesday, August 31, 2010

Spicole_ a design DRAFT

Now, here we are with this second post that involves a study for a structural system that should have resembled the structural behaviour of the spicules ("spicole" in Italian), structural elements found in most sponges.

"They provide structural support and deter predators. Large spicules, visible to the naked eye are referred to as megascleres, while smaller, microscopic ones are termed microscleres." wikipedia

This study remained only a draft and stopped before involving digital modelling and testing tools, but I think that some suggestions from this work were nice and I decided to share it anyway. It was prepared during preliminary studies for my thesis project under the supervision of prof.eng.Alessio Erioli

I was fascinating by the spicule's behaviour after reading about on "Growth and Form" by D'Arcy Wentworth Thompson (I strongly recommend reading this book, you can find it easily, i.e. on Amazon).
What is interesting is that spicules are not a primary building material but only the results of cells’ secretion wich becomes, after depositing, structural and envelope a space even when cells who formed it are dead or have been disgregated.

I firstly built a conceptual model for a bi-dimensional joint using the form of a base spicule. It divides the space in three sectors with an angle of 120 degrees.
I observed that modifying the dimention of the “fibres” connecting different spicules even if the main body could be considered as fixed element the network can develop through different space directions.

Then I tried with different base configurations. Cellular disposition influences the way spicules form. The planar disposition of three cells creates a texture with spicules linked in 120 angles one another. In space the disposition of three cells creates tethraedrical spicules. The angle of 109° (called “Maraldi Angle” as D’Arcy Thompson underline) is the same we can found in the bottom of honeycomb cells and is like the top part of a rhombic dodecaedron. The way cells pack in space influences the formation of the spicules. It may happen that, instead of a tetrahedrical packing, cells assemble themselves in a cubic packing. In this case the angle between every “branch” of a spicule will be of 90 degrees.
Different configurations define not only different angles but also a different spatial accumulation and disposition. So while in the first case we had only three branches we can also have four, five and also six branches (in the cubic disposition).

As some calcareous taxa were found either loose in, attached to, trapped within or engulfing parts of the meshwork of spicules’ deposits ( Crithionina, Gaudryina, Karreriella, Placopsilina, cf. Tritaxis, Trochammina, Islandiella, Lobatula and Ramulina) I suggested that void spaces that spicules create might be covered with forms or surfaces.
I also defined an ipotetical behaviour from an initial condition that could have been later developed in a digital script.
So, from an initial number of points in space (00), that might have been positionated with a predefined manner, a L-sistem branching could have started (in the picture is 2-dimensional but it should be in space). After a certain number of generation, if the end of two branches were closer enough they could have linked and stopped the proliferation (or not?). There might have been the influence of one or more attractors in the proliferation direction and lenght.
Also the formation of different tipes of spicule forms could have been either random or influenced.
When all the branches had formed an almost close network, surfaces could have spread over the structure, and their disposition and form, even their opacity could have been defined through attractors.

Then to physical modelling. To reproduce the functioning I went to the ironmongery and I bought a lot of thin pipes of different diameters and a lot of wire. I tried firstly to evaluate the behaviour of the plastic tubes (torsion, compression, traction) and the possibility to create the conceptual base form I had defined previous. Then the links between different base forms.

Starting from singular joints, then linking, then develop more and more articulated structured. Let them growing from the simplest to the most complicated.

This was made to gather information and additional cues to develop the system. Finally I tried to catch some glimpses of what a structure of that kind could resembled.

I know it is an uncompleted work, as I have alredy said, but some ideas and possible developments appeared interesting to me. Here is a collection of photo from the modelling process.

Let me know what do you think about it!

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