Abstract:
The invention provides a method for constructing a composite structure by creating a 3-D actual or non-virtual model of the structure or feature, scanning the model into a computer program, importing the model into a Finite Element Analysis (FEA) program, meshing the model, performing a FEA on the model in the FEA program to determine the materials and the dimensions for the materials making up the composite and building the composite structure.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application is a continuation application of Ser. No. 12/150,043 filed Apr. 24, 2008 now abandoned by Nasser Saebi for Method of Constructing a Composite Structure which claims priority of Ser. No. 60/926,199 filed Apr. 24, 2007 by Nasser Saebi for Method of Constructing a Composite Structure. 
     The following references are incorporated by reference: U.S. Pat. No. 6,308,490 issued Oct. 30, 2001 and U.S. Pat. No. 6,912,488 issued Jun. 28, 2005 to Nasser Saebi for Method of Constructing Curved Structures as Part of a Habitable Building and U.S. Pat. No. 6,721,684 issued Apr. 13, 2004 and U.S. Pat. No. 6,985,832 issued Jan. 10, 2006 to Nasser Saebi for Method of Manufacturing and Analyzing a Composite Building. 
    
    
     BRIEF DESCRIPTION OF THE INVENTION 
     The invention provides a method for constructing a composite structure by creating a 3-D actual or non-virtual model of the structure, scanning the model into a computer program, meshing the model as disclosed in U.S. Pat. No. 6,721,684, importing the model into a Finite Element Analysis (FEA) program, performing a FEA on the model in the FEA program to determine the materials and the dimensions for the materials making up the composite, and building the composite structure. 
     In this invention, a solid polyurethane model has been made. For example, the scale of the model is 1:24. The model is scanned to create a similar CAD model in a computer and enlarged to the actual dimensions. The CAD model is exported to a Finite Element Analysis (FEA) program. In the FEA program, the model is surface meshed. Then, the model is again surface meshed to create the coating and is solid meshed tp create the core of solid mesh or discrete volumes. 
     In the FEA, program various loadings can be run on the computer model to predict the results or effects of the loads in a similar composite structure. The mechanical properties of the materials of the building and their dimensions are fed into the FEA program before the analysis. 
     The materials that can be used to build the display are a FRC (Fiber Reinforced Coating), such as Glass Fiber Reinforced Concrete (GFRC) which coats plastic foam, such as Expanded PolyStyrene (EPS). The Fiber Reinforced Coating (FRC) coats the surfaces of the foam core and can be other materials than GFRC. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIGS. 1-13  are perspective views of the invention. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       FIG. 1  shows a 3-D actual model  100  of a display or feature that is to be constructed in a museum. The display or feature has several pieces, one of which is back portion  110  which is to be a granite mountain with a passage  111  for people to walk through. For example, the granite mountain will be 19.5 feet high with a maximum width 38 feet at the base. 
     The model portion  110  is shown supported on a table or other support surface  400 . 
     The model  100  can be created out of modeling clay, plastic foam or other material. Round markers  10  are added by adhesive to the model. Not all of the markers  10  are shown. 
       FIG. 2  shows the scanning of part of the model. The back portion  110  of the model of the display is scanned by using a hand held scanner  200 , such as HANDYSCAN 3D™ (now known as REVscan™) held by hand  300 . More information on the scanner is available from the Creaform 3D Company. 
     Other portions of the model  100  of the display have been removed for the scanning process. 
       FIG. 3  shows another portion of the model being scanned, front portion  120  of the model  100 . Portion  120  is a sandstone range and will be 16 feet high, 35 feet long and 6 feet wide at the base. 
     The size or dimensions of the markers  10  is constant and known. Therefore, the dimensions of the display  100  can be computed by the scanning software/program, and a model is built in the computer. 
     During the scanning, the back portion  110  of the model and other portions of the model are picked-up and the bottom surface and inner surfaces of the portions are scanned. All of the surfaces to be scanned are provided with markers  10 . 
     The information from the scanning is fed into the software/program in the computer, such as XVScan™ for the HANDYSCAN 3D (REVscan) scanner. The data is used to create a solid 3-D model  400  in the computer. 
     The 3-D computer model  400  is then exported to a Finite Element Analysis (FEA) program such as ALGOR FINITE ELEMENT™. The FEA program is used to mesh the computer model  400 . 
     Using the teachings of our U.S. Pat. No. 6,721,684, the model is subjected to a FEA using the following steps: 
     The model is surface meshed. 
     The model is solid meshed to create solid mesh or bricks in the FEA program. 
     A coating mesh is added to the model on its inner and outer surfaces. 
     Then, the solid mesh and the coating mesh on the inner and outer surface of the model are assigned the values of strength, thickness, etc. related to the mechanical properties of the materials that are to be used in building the display. The core or solid mesh is plastic foam, such as EPS, and the coatings or surface mesh are Fiber Reinforced Coatings, FRC, such as GFRC. 
     Then, the model is subjected to FEA using various loading schemes. 
       FIGS. 4-7  show the back portion  410  of the meshed model in the FEA program from several angles. The computer generated meshed back portion  410  of the display has a passage  411  and a base  412 . The meshing divided the model  410  into discrete volumes or “bricks”  500  delineated by the mesh lines  501 . 
       FIG. 5  shows the back portion  410  from a bottom view. 
       FIG. 6  shows the back portion  410  with the model flipped over, that is bottom surface upward. 
       FIG. 7  shows the meshed model  410  of the back portion with the circles or bubbles  502  on the base  412  indicating the fixed nodes in the FEA. A node is a meeting of two or more mesh lines  501 . 
       FIG. 8  shows spot loads indicated by arrows  600  which indicating the loading of eight workers at 300 pounds per worker on the display portion. 
       FIG. 9  shows the results of a FEA on the shell or coating only in stress and displacement. The loading was the dead load and eight men at 300 pounds per man. 
       FIG. 10  shows the front portion  420  of the meshed model  400  in the FEA program. 
       FIGS. 11 and 12  show the results of a FEA on the shell and core combined in displacement in the x and z directions, respectively. The loading as indicated by arrows  600  is 1,000 pounds at each peak and 300 pounds horizontally on each top side of the peaks (representing ladder loads). 
       FIG. 13  shows the results of a FEA on the shell and core combined in displacement in the x direction of another portion of the display, the small sandstone mountain  430 . The loading as indicated by arrows  600  is four men at 300 pounds each at each peak and 300 pounds horizontally on each top side of the peaks (representing ladder loads). 
     Once the FEA proves that the design will handle the required loading, the structure can be permitted by the building certification authorities. That is, the materials and the dimensions of the materials for the composite to meet the required building standards for the geographic area of the display have been selected from the results of the FEA. 
     Then, the construction can begin. The foam can be cut into slabs, such as pieces 4 feet×8 feet×31 inches. 
     These slabs can then be cut using a robotic cutter to form the inner and outer surfaces in the plastic foam. Such a robotic cutter can be FROGMILL™4 th  Axis CNC Foam Router made by STREAMLINE AUTOMATION. 
     The cut slabs are bonded together using a suitable bonding agent. The resulting structure is coated on all exposed surfaces with a strengthening coating such as, a FRC, such as GFRC. 
     The structure can then be painted or otherwise ornamented. 
     Various changes and modifications to the embodiments herein chosen for purposes of illustration will readily occur to those skilled in the art. 
     The FRC can be a Glass Fiber Reinforced Concrete (GFRC). a Fiber Reinforced Polymer (FRP) or a Glass Fiber Reinforced Gypsum (GFRG). The fibers can be plastic, glass, carbon, single-wall carbon nanotubes (SWNTs or Buckytubes), Aramid or other fibers. The Polymer can be Epoxies, Polyesters, Vinlyesters or other materials. 
     The coating also can be without fibers if the design loading is low enough. For the strongest structure, fibers should be added to the coating. The number of coats of the coating and the composition of those coats can be varied. 
     Bonding agents that bond foam to foam, foam to concrete and concrete to concrete can be structural or non-structural as certified by International Code Council (ICC). 
     One structural bonding agent is Glass Fiber Reinforced Concrete (GFRC). A thickness of 0.25-0.50 inches is suitable. 
     A formula for GFRC is: 
     1 bag of cement (Portland Cement Type III)—94 pounds, 
     No. 30 silica sand—100 pounds, 
     water and ice—25 pounds, 
     polymer (Forton™ VF-774)—12 pounds, 
     retarder (Daratard™ 17)—2-5 ounces, 
     plasticizer (Daracem™ 19)—2-6 ounces, 
     0.5 inch glass fibers (Cem-FIL™ or Nippon AR™)—1.5 pounds and 
     1.5 inch glass fibers—1.5 pounds. 
     Another structural bonding agent can be Glass Fiber Reinforced Gypsum (GFRG) which can be purchased from the US Gypsum Company under the brand name Hydrocal® FGR—115 gypsum cement. Glass fibers can be added to the mix to form the GFRG. The GFRG coating can have a flexural strength of 3,200-4,000 psi. 
     A non-structural bonding agent can be expansive plastic foams, such as Expansive PolyUrethane (EPU), etc. These can be used where the joint strength need not be structural, such as a joint that is later covered with FRC to create structural strength. 
     The type of plastic foam can be different from Expanded PolyStyrene (EPS). The EPS can have a density of 1.5 pounds per cu. ft. (nominal) which is actually 1.35 pounds per cu. ft. (actual). EPS was used because a Finite Element Analysis was done using EPS and GFRC. Suitable plastic foam could be PU, EPS, etc. 
     The specific materials used to build the structure may be varied, such as the type of plastic foam, the bonding agents, the coatings, etc.