Structural Elements Made From Syntactic Foam Sandwich Panels
A structural member comprising at least one syntactic foam sandwich panel; the sandwich panel having a syntactic foam core and at least one skin; and at least one reinforcement element attached to the sandwich panel.
This invention relates to a method of manufacturing structural elements.
BACKGROUND OF THE INVENTIONThe superior structural properties of fibre reinforced polymer composites are well recognised. However, to date there have been difficulties with producing viable structural elements of fibre reinforced polymer composites due to cost constraints.
A popular approach to producing structural elements using fibre reinforced polymers has been through the use of the pultrusion process. However, the dies and machines needed to produce large structural elements with this method are very expensive. Further, many of the structures being produced require “one-off” construction and therefore are not economically produced using the pultrusion process.
It is well known from basic engineering mechanics that in most structural members under load there are areas in the member that are subjected to much higher internal stresses than other areas in the same member. For example in a beam loaded in uniform bending the material near the top and bottom of the beam are subjected to significantly higher bending stresses than material near the centre of the beam. Hence locating large amounts of expensive fibre composite material near the centre of such a beam is generally uneconomical. However, there is limited flexibility in the pultrusion process to incorporate other materials or to vary the orientation of the fibres.
In order to incorporate other materials and to optimize the fibre orientation in large structural elements many of them are made using alternative production methods such as hand-lay up or resin infusion methods. However, these methods require large moulds which are generally specific to a particular type of structural member. Hence, if another structural element needs to be produced, another mould is required reducing cost effectiveness. Furthermore, the labour involved in these alternative manufacturing methods is quite significant leading to expensive products.
OBJECT OF THE INVENTIONIt is an object of the invention to overcome and/or alleviate one or more of the above disadvantages or provide the consumer with a useful or commercial choice.
SUMMARY OF THE INVENTIONIn one form, the invention resides in a structural member comprising:
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- a least one syntactic foam sandwich panel; the sandwich panel having a syntactic foam core and at least one skin; and
- at least one reinforcement element attached to the sandwich panel.
The syntactic foam core may include microspheres made from polymeric materials such epoxy resin, unsaturated polyester resin, silicone resin, phenolics, polyvinyl alcohol, polyvinyl chloride, polypropylene, and polystyrene or from inorganic materials such as glass, silica-alumina ceramics or Cenospheres (hollow fly ash particles)
The skins of the syntactic foam sandwich panels may be made from fibre reinforced polymers. The fibres may be made from glass, carbon, Kevlar, thermoplastics or combinations thereof. The polymer may be made of polyester, vinylester, epoxy, polyurethane, thermoplastics or combination thereof. Preferably the polymer used in the skins is the same as that used in the syntactic foam. More preferably the syntactic foam sandwich panel is produced in single manufacturing process, in this way a strong primary bond can be created between the skins and the syntactic foam core.
The reinforcement elements may be made from steel, concrete, timber, fibre reinforced polymers or any other material. An adhesive is typically used to adhere the syntactic foam sandwich panels to the reinforcement elements.
If the reinforcement elements are made from fibre reinforced polymers, then the fibres may be made from glass, carbon, Kevlar, thermoplastic or combinations thereof and the polymer may be made of polyester, vinylester, epoxy, polyurethane, thermoplastic resins or combinations thereof.
One or more tie elements may span across the adhesive in order to avoid delamination of the adhesive and provide the assembly with robustness. The tie elements may be made from steel, concrete, timber, fibre reinforced polymers or any other material. The tie elements might also act as a reinforcement element.
The structural elements may include bulkheads, diaphragms, strong points and/or internal ties.
In one form, though not the only or broadest form, the invention resides in a method of producing an improved structural element, said method including the steps of:
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- obtaining at least one syntactic foam sandwich panel;
- obtaining at least one reinforcement element; and
- joining the at least one syntactic foam sandwich panel and reinforcement element to form the improved structural element.
The structural elements produced using this method may be used in conjunction with each other to produce improved structures.
Embodiments of the invention will be described with reference to the accompanying drawings in which:
In order to produce the structural member 20, two grooves are cut in the syntactic foam core 11 of the syntactic panel 10. Adhesive is then placed on the two steel reinforcement strips 21 and the two steel reinforcement strips 21 are located within the grooves to contact the syntactic foam core. The two steel reinforcement strips 21 increase the strength and stiffness.
The beam shown in
The beam 40 is manufactured by applying adhesive to the two fibre reinforced polymer U-shape sections 41 and placing the two fibre reinforced polymer U-shape sections 41 over respective ends of the sandwich panel. Due to the shape of the fibre reinforced polymer U-shape sections 41, the contact area between the reinforcement modules and the syntactic foam panel 10 is significantly increased compared to the fibre reinforced polymer reinforcement strips 31 in
To produce the hollow beam 80, the four syntactic foam panels 10 are adhered to the two pultruded fibre reinforced polymer square sections 81. The two pultruded fibre reinforced polymer square sections 81. The square reinforcement elements have large planar surfaces which bond strongly to the two fibre reinforced polymer skins 12. The structural member of
The hollow beam 100 is manufactured by using adhering the four pultruded fibre reinforced polymer square sections 102 and the syntactic foam panels 10 are together using an epoxy adhesive. The fibre reinforced polymer U-shape sections 101 are then adhered to the syntactic foam panels 10 using the phenolic resin. The space between the reinforcement modules 92 can be provided with bulkheads as shown in
The solid beam 130 is formed by adhering the two syntactic foam sandwich panels 10 together using an epoxy adhesive. The top of the double syntactic foam sandwich panel is provided with an aggregate interface 132. The aggregate interface 133 is made of aggregate having an average size of 10 mm and is adhered to a top fibre reinforced polymer skin 12 of the syntactic foam sandwich panel 10 with epoxy adhesive. The layer of standard concrete 131 is then laid directly onto the aggregate interface. The concrete layer is approximately 150 mm thick. During the casting of the standard concrete, the syntactic foam panels act as formwork and support the wet concrete. Once the concrete has cured the syntactic foam sandwich panels act as external fibre composite reinforcement for the concrete. This aggregate interface 133 provides an excellent bonding surface for the layer of polymer concrete 132 to prevent delamination of the layer of standard concrete 132 from the top of the syntactic foam sandwich panel 10.
The properties of these structural elements such as stiffness, strength and mass can be tailored to specific applications by selection of the materials and dimensions of the syntactic foam sandwich panels and reinforcement elements.
It should be appreciated that various other changes and modifications may be made to the embodiments described without departing from the spirit or scope of the invention.
Claims
1. A structural member comprising:
- at least one syntactic foam sandwich panel; the sandwich panel having a syntactic foam core and at least one skin; and
- at least one reinforcement element attached to the sandwich panel.
2. The structural member of claim 1 wherein the reinforcement element is made from a section of steel, concrete, timber, fibre reinforced polymers.
3. The structural member of claim 1 wherein an adhesive is used to adhere the at least one syntactic foam sandwich panel to the at least one reinforcement element.
4. The structural member of claim 1 wherein tie elements that span across the glue joints in order to avoid delamination of the adhesive and provide the assembly with robustness. The tie elements may be made from steel, concrete, timber, fibre reinforced polymers or any other material. The tie elements might also act as a reinforcement element.
5. The structural member of claim 1 wherein the at least one reinforcement element is made from fibre reinforced polymers, the fibre being selected from glass, carbon, Kevlar, thermoplastic fibres or combinations therefore and the polymer selected from polyester, vinylester, epoxy, phenolic, polyurethane, thermoplastic resins or combinations thereof.
6. The structural member of claim 1 wherein the syntactic sandwich panel includes microspheres, the microspheres being selected from polymeric materials including epoxy resin, unsaturated polyester resin, silicone resin, phenolics, polyvinyl alcohol, polyvinyl chloride, polypropylene, and polystyrene
7. The structural member of claim 1 wherein the syntactic sandwich panel includes microspheres, the microspheres being selected from inorganic materials such as glass, silica-alumina ceramics or Cenospheres (hollow fly ash particles).
8. The structural member of claim 1 wherein the syntactic sandwich panel include skins, the skins being made from fibre reinforced polymers, the fibres being selected from glass, carbon, Kevlar, thermoplastics or combinations thereof and the polymer being selected from polyester, vinylester, epoxy, phenolic, polyurethane, thermoplastics or combination thereof.
9. The structural member of claim 1 wherein the skins includes a polymer and the syntactic foam uses a polymer, the polymers being the same.
10. The structural member of claim 1 wherein the syntactic foam sandwich panel is produced in single manufacturing process.
11. The structural elements may include bulkheads, diaphragms, strong points and/or internal ties.
12. A method of producing an improved structural element, said method including the steps of:
- obtaining at least one syntactic foam sandwich panel;
- obtaining at least one reinforcement element; and
- joining the at least one syntactic foam sandwich panel and reinforcement element to form the improved structural element.
Type: Application
Filed: Jul 26, 2006
Publication Date: Aug 21, 2008
Applicant: LOC COMPOSITES PTY LTD (Holland Park, Queensland)
Inventor: Darren James Browne ( Queensland)
Application Number: 11/996,622
International Classification: E04C 2/26 (20060101); E04C 2/10 (20060101); E04C 2/24 (20060101); E04C 2/38 (20060101);