00:00Hello, I'm Brittany Mark. I'm a postgraduate industrial design student at Victoria University
00:16of Wellington in New Zealand. I'd like to start off by saying thank you to Victoria and also my
00:23supervisor Tim Miller and the maid stream at the university. So the research that I'm presenting
00:31is a part of my master's thesis which has been the last year and a half and it finishes in August so
00:38this is the majority of the research I've done. Primarily I'm speaking about the translation
00:45of auxilia structure theory into tangible outputs made possible through geometric CAD modelling
00:53and then multi-material manufacturing. So firstly there's the translation process which is the
01:00theory of auxilia structures into the realisation of the manufacturing. The main way we are
01:06multi-material printing is with the Strauss's J750 printer. The parametric design modelling is
01:14primarily through Rhino and Grasshopper and then we use the materials that have been fabricated
01:20through to perform a range of mechanical testing to implement kinetic auxetics which is the 4D
01:31structures. On the right you can see unit cells of a metachiral structure which have gone through the
01:38mechanical testing. And then finally once the materials are structurally sound they've been applied
01:47to specific geometries for customised scenarios. So the process that we go through is structure theory.
01:58The structures were chosen based on a range of criteria but primarily the ones that were chosen to be
02:04manufactured were biaxial and three-dimensional. Then the mechanical design principles are translated
02:12through computational Rhino and Grasshopper and then they are put through an optimisation software to
02:20enable additive manufacturing and then they are multi-material printed on the J750 and then mechanically
02:28tested and then applied. So you can see an example of the re-entrant double arrow which was the first
02:36testing that we went through the entire process. So there's the theory and then the grasshopper script,
02:42the Rhino model and then you can see an FDM print that was done with PLA and then the three structures on
02:49the right on the right with the hands they are done multi-material printing. So the hinge is made of an
02:57Agilis rubber-like material and then the struts are a rigid Vero Tango Plus which is a rigid plastic and then
03:08that's a render of what a structure looks like three by three. So in terms of the multi-material printing we
03:18develop the structures through CAD and then at the end they are put through the GrabCAD which is the software that the
03:25Stratus is used to print the structures and then you can see the J750 that's the main printer there.
03:36The structures come out with a huge amount of support material on them. We try to reduce this through
03:41material and design optimization but essentially the support material can come in two forms water
03:50removable or soluble through a chemical bath and so some of the structures are put through in a chemical
03:57bath but obviously that then interferes with some of the elasticity properties and so we're careful
04:04with what goes through the chemical bath and what is manually removed. All the structures on the right
04:10are manual removal and then they all are exhibiting the auxetic effect through the hinge design and the
04:18stripes design as well. So the key part of the research is taking the auxetic structure theory and
04:28making it tangible and many of the obstacles come through the design considerations. So the way that
04:37is printed as in is it relaxed or engaged in the way it is put on the print bed. So we've
04:45we've experimented with a range of relaxed to engaged states. The shortness so you can see on the
04:53left this image is the range of materials that we have on the printer and the material agilis so that's the
04:59rubber structure so it goes from 20 to 80 um and we can vary that in 10 by 10 degrees of increment and um
05:09that increases or decreases the rub rubber like of this um the rubber of the material and so that's the
05:17structure the re-entrant hexagonal structure um exhibiting auxetic through short hardness 20 40 60.
05:26Uh then there's the hinge radius which is how large the hinge is the scale of the hinge in regard to the
05:33scale of the structure and then the strut width and profile so some profiles have been printed circular
05:41and others have been printed square and then the thickness of the strut um up to a maximum where it's
05:47most structurally robust but it still is exhibiting an auxetic effect and then the structures are put
05:55through a range of mechanical testing so the three images at the start are the planar hinges for a range
06:02of trial uh re-entrant and rotating rigid units and then they are they are tested for their position their
06:13maximum height um the degrees of artic how far it articulates and then um after that the material
06:26damage is recognized so this is the metatrial compression twist um and you can see there's a
06:34varying range of damage uh the most damage we see is at the boundary of the agilis and the rigid tango
06:42material um but also there is a certain amount of damage seen at the vertex uh so we can design for
06:51that and increase the strut width and also the hinge radius to compensate for the weakness at the vertex
07:03but also ensuring that we haven't created an elasticity that is so high that the model is acting rather as a
07:12elastic lattice and not as an auxetic open cell foam um so this is the metatrial compression twist we chose this
07:23primarily because it is biaxel and it is three-dimensional uh so it can be
07:32multi-material printed and we can demonstrate a biaxel movement um with a single unit so a range of um
07:42design parameters uh have been experimented with and then selected so the square the profile the
07:50shore hardness and the scale etc and so you can see on the right the rhino and grasshopper cad development
07:56so primarily the structures are developed in rhino so that we can apply all of the mechanical restrictions
08:04to the unit cells and then we use the grasshopper to generate the lattices um so that they can increase
08:11the density and the scale of the um open cell foams and then once the structures are working we then have
08:21kinetic auxetics and so they are moving four dimensionally through the stimuli that we apply to it uh
08:29so to decide the application uh in new zealand we have acc which is a entire um database of all sports
08:39injuries that the country experiences and so we've compressed all of that data and um identified that knee
08:49injuries in football and netball are our biggest um areas for the biggest opportunity areas for um applying
08:59auxetic structures which can be um four-dimensional when they are impacted um in a sports scenario
09:09so the knee is um the scenario can actually be customized specifically to the anatomy of the
09:17individual so if we decide that it's a knee injury perhaps it's an acl injury we have the ability to
09:24scan a person's knee and then you can see on the um right the um render of the knee so that's someone's
09:33knee and then we can take that model into the design software um put the structure that is best suited for
09:41that scenario so for a knee injury acls are primarily as a result of rotational impact if we apply a metachiral
09:50twist um structure that absorbs the rotational impact and so it decreases the um risk of acl
09:59um so this the knee is in the design software we develop a range of curvature to fit the knee
10:09or whichever part in an anatomical part of the body um we are targeting and then the structure is then
10:17morphed to the surface through the grasshopper scripts and we can start to experiment with how
10:24dense the units are as well as how dispersed they are um whether they are on synclastic curvature which
10:32is obviously important for um the body we want the structure to be moving all three in all three
10:38directions um across the surface and then we can apply this script to a range of scenarios um once the
10:49structure is morphed so obviously this is a work in progress and with the uh covert it has been slowed
10:55down slightly um in our ability to be on campus doing the manufacturing and stuff but um in the next
11:01couple of months the structures will be finalized and morphed to the surface and obviously um
11:07parameters such as the um density and whatnot will be um potentially more controlled um but that's
11:15potentially that is how we implement um the multi-material prints into applications um so yeah
11:24that is pretty much as far as we've gotten so far um so thank you for listening and thank you again to
11:33victoria university and tim miller my supervisor as well
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