Thesis or Fecis

It all comes down to this…

Posts Tagged ‘porosity

23 – Thesis Title

leave a comment »

It has recently been brought to my attention that the title of my blog is too long. “The Effect of Material Organization on the Structural Properties of Porous Architectures? What does that even mean? Who do you want to read this thing? What are you putting it up for?”

This person was on vicodin.

Right after this conversation she congratulated me for another brilliant post on Stuff White People Like, saying “San Francisco! That’s so funny. You are so white! You’re in grad school and you like The Wire and Eternal Sunshine… and you do crosswords every day. I’m sure that you write that blog, c’mon admit it!”

Drugs aside, it got me thinking why I’m doing this blog: for myself. I don’t care who reads it, I’m not jumping up and down clamoring for people to pore over the inanity of my work from the past seven years, I already abuse twitter heavily enough for that. I’ve got less than 30 days til I defend, I stopped writing in my gurnal over a year ago (So what if I’m not as smart as you!), there needs to be a document of last days…this is it.

But if you do stumble upon this and want to know wtf “The Effect of Material Organization on the Structural Properties of Porous Architectures” means, let’s break it down:

Porosity is a measure of the amount of void space in any unit volume. If you have an empty box and you put something in it, the porosity, which used to be 100% has now been reduced by the volume of material in that box. Bone is around 80 – 90 % porous. It’s on the 90% side if you have osteoporosis where if you fall you shatter like glass, like my mother. It’s on the 80% side if you are a fine shining example of a fit and healthy human like that pitcher guy whose wife took all those steroids for him. The architectures that I work with are ranged in porosity between 50% and 90%. When you change porosity, you change the strength of an architecture: less material, less strength. The exciting part is that if you use the same architecture, you can compare the effects of material arrangement alone:

Von Mises Distribution - Rhombitruncated Cuboctahedron
The porous architecture, Rhombitruncated Cuboctahedron, at five porosities, left to right, 50% through 90%

By “Material Organization” I mean the arrangement of material in any configuration. You have 100 lego bricks and you arrange them into some configuration and then crush them. It’s got a certain strength, say x. Then, you arrange those 100 legos into a completely different arrangement and again, crush it. It has a strength, say y. Unless you know what you’re doing or are extremely lucky, xy. And the difference is the “material organization” not the porosity, since you used the same amount of bricks thus you have the same amount of porosity. Material properties are the characteristics of the construction material: playdoh, steel, clay, plastic. The specific heat, tensile strength, ultimate strength (crushing strength as a friend would understand it), and stiffness. These properties all have to do with the material itself. When you arrange that material into a shape, say a porous architecture, and crush it, you get the structural properties of that architecture.

Structural Properties work the same as Material Properties (stiffness, modulus, ultimate strength, etc. etc.) but they are solely due to the arrangement of the material the architecture is built with. You build a tower out of steel and that steel has its own material properties. The structure that you build then has its own structural properties.

So let’s recap “The Effect of Material Organization on the Structural Properties of Porous Architectures”
I study polyhedra which are “porous architectures”.
There are several polyhedra in the set that I study, each one has a different “material organization”.
Each polyhedra is built with the same material but has a different architecture which means they all have different “structural properties”.
I am looking to create rules which govern how a material organization can result in a tailored structural property.
The application of this is tailored patient implants for spinal repair.

So after all this I’ve decided to change the title to “Thesis or Fecis”

…it all comes down to this.

Written by Matthew Wettergreen

March 24, 2008 at 10:19 am