DEVELOPMENTS

JANUARY 2011

As stated in previous posts, we envisage this core to be made out of whatever material is suited to the end use.  It is therefore apparent that there can be different ways of manufacture depending on that use.  For example, a metal sheet would be cut out into the required pattern, and then after creasing and scoring, would be folded into the required core configuration.  Similarly, paper or cardboard would be diecut and folded.  Another method would be to chop-spray a material over a prepared form. Another method which occurred to us more recently, is that of vacuum forming, and as the photos indicate, we set about making a rig that would enable us to prove the concept.  The picture at left shows a single formed panel, approximately 12" in diameter and 1" core depth. and pictures 2 and 3 show how the panels edge-lap together to form required shapes.

Utilizing the properties of various materials including Kevlar or Aramid fiber, or even recyclables, it would be possible to create cores with a variety of different characteristics such as added strength and heat resistance.  

OCTOBER 2013

Due to the unfortunate circumstance of inventor Bob Burdon being diagnosed with an Inguinal Hernia, we realized that perhaps Hexaflex could be used to create a hernia mesh.  

The use of mesh has become essential in the repair of all hernias. To move forward into a new era of hernia mesh prosthetics, a panel of nine experts in hernia repair and experimental mesh evaluation agreed that new technologies and novel approaches must be investigated and designed. We propose a new concept in the design & manufacturing of a prosthetic latticework for inguinal, ventral or incisional hernia repair.

The 'smooth' side, having a small pore size, is placed adjacent to the bowel and resists tissue attachment.

The unique geometry of the lattice allows it to stretch in more than one direction and then return to its original shape. Existing hernia meshes are made of relatively stiff and inelastic material.  We strongly believes that these characteristics may be a contributing factor for hernia recurrence and patient discomfort.

The proposed lattice easily assumes the conformity of the abdominal wall musculature anatomy and thus improves the long term comfort and well-being of the patient.

The 'rough' side, with a more open pore size, is next to the tissues that surround the bowel where tissue incorporation is an advantage. Lattice cell size of 4mm (5/32nds) and thickness of 2mm (5/64ths).  Lattice width of 150mm (6”).

Manufacture.

The method of manufacture of this surgical lattice uses 3D printing technology. 

The basic materials are:

• ePTFE. (expanded polytetrafluoroethylene ) The use of modified ePTFE surface in hernia repair enables early tissue attachment, reduces adhesions, and could reduce the incidence of recurrences. This would be the first layer that is printed (smooth side down)
• Polypropylene. This material has been used for the past 20 years because of its stability, strength, inertness and handling qualities. Polypropylene is overprinted on the PTFE layer and provides the basic structure of the lattice.
• Collagen. A final layer of collagen is printed to encourage speedy host tissue incorporation into the latticework.

Potential attributes of lattice.

• May result in the permanent repair of the abdominal wall, to reinforce and replace tissue for long-term stabilization of the abdominal wall.
• Ingrowth characteristics that mimic normal tissue healing. May stimulate adequate fibroblastic activity for optimum incorporation into the tissues. May prevent adhesions. The ePTFE  protects the edge of the lattice minimizing tissue attachment to the material.
• Strong.  May provide sufficient biomechanical strength to meet physiological requirements in order to permanently protect the fascial defect.
• Pliable. It has elasticity in more than one dimension, allowing it to stretch in more than one direction and then return to its original shape. Easily assumes the conformity of the abdominal wall musculature anatomy
• Handling characteristics should be amenable to laparoscopic instruments.
• The lattice may have an adequate adhesive quality that requires minimal or no additional fixation, even for large defects.
• Non-allergenic.
• Inert.
• Non-biodegradable.
• Non-carcinogenic.
• Cuts easily without fraying.

It is worth noting that due to the relatively recent upsurge in 3D printing technology, what we envisage for the mesh has only just become possible.  The ability to create on demand, one-of-a-kind meshes for each patient is new and gives the medical profession opportunities they never had before.  It will be interesting to see where this fledgling technology goes.

In addition to mesh creation, we also envisage a 3D printed system of tubular structures for blood vessels, veins, and even muscles and valves. We are at the beginning of a new age in terms of what 3D printing can bring to the (operating) table!  

So we are at an interesting phase. We are talking to mesh manufacturers and medical companies that use hernia mesh, gauging their interest and believing strongly that this hitherto unrealized possibility, could well provide the stimulus to take the whole Hexaflex concept to the next level.

September 2014

We were asked by a potential client to come up with a working method to produce a metallic honeycomb, and to those ends have added more details to a manufacturing concept we first outlined in our patent.  

By using 2 sets of dies (A) - top and bottom, shown here in red and pink, and placing them between top and bottom clamp plates (B), when the clamps are drawn together, the dies, which are constrained by a sheet of polyester which we have called "living hinge," (C) come together to crease and fold the metal sheet.  D, E and F show the range of motion where D is the start before any compression, E is half complete and F is a closed version of conceptual Hexaflex honeycomb.

If this proposal works, it will be the first time that Hexaflex honeycomb has been manufactured in any sort of quantity. The project will call for about 50- 75 sheets using a hexagon size of 12" and a core depth of around the same.  We will keep you posted on the project as we move forward.

January 2015

During the course of our research into the possible uses of Hexaflex, we have come to the realization that the core is lacking in compression strength when compared to standard honeycomb. This shortcoming can be solved by the ability of this design to be injected/infused with syntactic foam into its galley ways, completely filling all voids between the face sheets.Compression forces can be tailored to optimize the structure by strategically infusing syntactic foam of varying crush strengths. The high crush strength and low density of syntactic foam makes it an ideal core material for hybrid sandwich composites. This latest modification to the property mix of Hexaflex, indicates a strong likelihood that delamination can be avoided in most incidences, a condition that the aerospace industry will no doubt welcome.

Shear experiments have showed that the bond between a syntactic foam core alone and the composite face sheets could be a weak link in a standard honeycomb sandwich design.  However, by combining the attributes of Hexaflex and syntactic foam together, it is possible to create an ultra lightweight hybrid core, wherein Hexaflex provides the tensile properties and the syntactic foam provides the compression properties.

September 2015

We have known for some time that one of the best ways to manufacture Hexaflex, using a variety of different materials, is to use 3D printing. After some months of file preparation and modification, we submitted our designs to Shapeways, obtaining some 150 3D printed tiles, a mixture of hexagons and squares, and assembled them into a sheet of Hexaflex. 

One of the first things we noticed was the comparative ease by which they could be assembled into such objects as spheres, domes, buckeyballs, nanotubes, torus/donuts, terraced planes, rhombic dodecahedrons and parabolic dish structures, to name but a few.

This unorthodox building kit could be an educational toy incorporating multiple layers of learning. These layers, which promote both critical thinking and discovery, include:

1. Exploring the world of polyhedra.
2. Discovering the intricacies of Nanotechnology.
3. Creating robotic structures.
4. Integral construction possibilities with Lego


January 2016

Incorporating a earlier invention called the Nodlet truss into the hexaflex pattern, we were surprised to discover an entirely new form of curvable lattice, not unlike a mechanical skin...

Using components engineered in 3D printed nylon, inventor Bob Burdon discusses a newly-discovered foldable lattice created using Hexaflex and a earlier invention called the Nodlet.  We are currently embarking on a program of reaching out to major aerospace and automotive companies who are looking for adaptive structures that change shape according to desired performance criteria.

April, 2019

Elon Musk made the decision to use stainless steel instead of carbon fiber/epoxy materials for his Starship.

Stainless steel properties:

·     Very ductile, very tough. No fracture issues

·     At cryogenic temperatures, the strength is boosted by 50 percent.

·     “it’s obviously cheap, it’s obviously fast.”

·     It can safely withstand a temperature of 1600 degrees Fahrenheit.

Elon Musk also proposed a transpirational heat shield:

“You just need, essentially, [a stainless-steel sandwich]. You flow either fuel or water in between the sandwich layer, and then you have [very tiny] perforations on the outside and you essentially bleed water [or fuel] through them … to cool the windward side of the rocket.” – SpaceX CEO Elon Musk.

Open view of a proposed panel section

A cutaway view showing lower nozzles and interior Hexaflex framework

Interior view of Hexaflex without side walls

This could be the another Aerospace application for Hexaflex.
Hexaflex can be fabricated from a continuous sheet of stainless steel that has been die cut with a repeating geometric design, creased and folded concertina style in upon itself to make a double sided core material that is flexible, able to vent, exhibits good bend and shear strength and has a large surface bonding area rendering it suitable in the construction of lightweight sandwich panels.

A transpirational heat shield must be able:

·      to efficiently join inner and outer shell surfaces with stringers

·      to provide a clear interstitial space, allowing fluids to flow through its structure

·      to be formed into compound curvatures

·      to serve double duty as structure.

The ability of a Hexaflex panel to serve double duty as a structural component opens up the possibility of making the entire rocket skin from Hexaflex panels. They can be stacked in multi-layers or plies in order to create alternative storage for gasses liquids or rocket fuel

The future is exciting.  With 3D printing fast becoming a legitimate manufacturing platform, and machines being developed that can print multiple materials concurrently - a concept completely in sync with the Hexaflex system, it remains to be seen where Hexaflex will fit in, and which applications will be among the first to find a viable and sustainable market.

So