Rod-reinforced cushion beam

Abstract

A rod-reinforced cushion beam includes a rigid frame having a spaced plurality of main rod members and a longitudinally paced plurality of connecting elements; and a plastic body encapsulating and substantially solidly filling the frame. A preferred embodiment has least 90 percent by weight of the plastic body in a main polymeric component of linear low density polyethylene, and an additive component that does not contain filler material. Also disclosed is a method for forming a rod-reinforced cushion beam.

What is claimed is:  
     
         1 . A composite beam comprising: 
 (a) a frame comprising: 
 (i) a plurality of longitudinal main rod members, at least three of the main rod members being spaced laterally in different corresponding directions relative to a longitudinal axis of the frame;  
 (ii) a longitudinally spaced plurality of transverse rod segments, each transverse rod segment being rigidly connected between a spaced pair of the main rod members, respective pluralities of the transverse rod segments connecting each of the main rod members to at least two others of the main rod members; and  
 (iii) an attachment structure defining a spaced plurality of attachment elements connected to plural spaced apart locations of the frame; and  
   (b) a resilient plastic body member encapsulating the frame, the plastic body having a nominal cross-sectional area of at least 50 square inches.    
     
     
         2 . The composite beam of  claim 1 , wherein the plastic body forms a cushion surface, the beam having an overall thickness between the cushion surface and an opposite surface of the beam, the cushion surface being spaced from the frame by not less than 10 percent of the overall thickness.  
     
     
         3 . The composite beam of  claim 1 , wherein at least some of the transverse rod segments are diagonal rod segments.  
     
     
         4 . The composite beam of  claim 3 , wherein the diagonal rod segments include respective pluralities of first and second diagonal rod segments, opposite end portions of each first diagonal rod segment being rigidly connected between a spaced first pair of the main rod members, opposite ends of each second diagonal rod segment being rigidly connected between a spaced second pair of the main rod members, the rod members of the first and second pairs of main rod members being laterally spaced in at least three lateral directions about the longitudinal axis.  
     
     
         5 . The composite beam of  claim 4 , wherein the plurality of main rod members includes respective third and fourth pairs of the main rod members, the rod members of the third pair being rigidly connected to respective ends of the first diagonal rod segments opposite the rod members of the first pair, the rod members of the fourth pair being rigidly connected to respective ends of the second diagonal rod segments opposite the rod members of the second pair.  
     
     
         6 . The composite beam of  claim 3 , comprising a first secondary rod member forming at least some of the first diagonal rod segments.  
     
     
         7 . The composite beam of  claim 6 , further comprising a second secondary rod member forming at least some of the second diagonal rod segments.  
     
     
         8 . The composite beam of  claim 3 , wherein the main rod members and the transverse rod segments form a cage truss.  
     
     
         9 . The composite beam of  claim 1 , wherein the main rod members and the transverse rod segments are each spaced at least 0.5 inch within an outside contour of the plastic body.  
     
     
         10 . The composite beam of  claim 1 , wherein the main rod members are selected from the group consisting of formed steel reinforcing bars, formed nickel alloy reinforcing bars, fiberglass reinforcing bars, and carbon fiber reinforcing bars.  
     
     
         11 . The composite beam of  claim 10 , wherein at least some of the transverse rod segments are selected from the group consisting of formed steel reinforcing bars, formed nickel alloy reinforcing bars, fiberglass reinforcing bars, carbon fiber reinforcing bars, plastic dowels, and wooden dowels.  
     
     
         12 . The composite beam of  claim 1 , wherein the main rod members have a nominal diameter of between approximately 2 percent and approximately 6 percent of a nominal outside circumference of the plastic body, and at least some of the transverse rod segments have a nominal diameter of between 50 percent and approximately 85 percent of the diameter of the main rod members.  
     
     
         13 . The composite beam of  claim 12 , wherein the plastic body sealingly surrounds the cage frame, having a thickness over each of the main rod members and the transverse rod segments being not less than approximately 4 percent of the nominal outside circumference of the plastic body.  
     
     
         14 . The composite beam of  claim 12 , wherein the outside circumference of the plastic body is approximately 48 inches, the diameter of the main rod members is approximately 1¼ inch, and the diameter of the diagonal rod segments is approximately 1 inch.  
     
     
         15 . The composite beam of  claim 14 , wherein the plastic body is rectangular in cross-section.  
     
     
         16 . The composite beam of  claim 14 , wherein the plastic body is square in cross section.  
     
     
         17 . The composite beam of  claim 1 , wherein the plastic body substantially fills the space occupied by the frame.  
     
     
         18 . The composite beam of  claim 1 , wherein the plastic body consists of a main polymeric component and an additive component, the main polymeric component consisting of low-density polyethylene of which at least 60 percent is linear low density polyethylene, the additive component including an effective amount of an ultraviolet inhibitor.  
     
     
         19 . An installed fender assembly comprising a plurality of composite beams according to  claim 1 .  
     
     
         20 . A composite beam comprising: 
 (a) a cage truss of longitudinal main rod members and transverse rod elements;    (b) an attachment structure defining a spaced plurality of attachment elements connected to plural spaced apart locations of the cage truss; and    (c) a resilient plastic body encapsulating the frame, substantially filling the frame, and having a nominal cross-sectional area of at least 50 square inches.    
     
     
         21 . The composite beam of  claim 20 , wherein the main rod members are approximately 1¼ inch diameter steel bars, the diagonal rod segments and the lateral rod segments are approximately 1 inch diameter formed steel reinforcing rod, and the plastic body is approximately square in cross-section, measuring approximately 12 inches on a side.  
     
     
         22 . A method for forming a composite beam, comprising: 
 (a) providing a plurality of elongate main rod members;    (b) providing a plurality of transverse rod segments;    (c) rigidly securing opposite end portions of each of the transverse rod segments between a laterally spaced pair of the main rod members such that each of the main rod members has pluralities of the transverse rod segments projecting therefrom in at least two directions having components perpendicular to the respective main rod members to form a cage frame; and    (d) encapsulating the cage frame in a plastic body.    
     
     
         23 . The method of  claim 22 , wherein the securing is further such that at least some of the transverse rod segments are oriented diagonally such that the main rod members and the transverse rod segments are loaded primarily in tension and compression in response to bending and shear loading of the resulting cage truss.  
     
     
         24 . The method of  claim 22 , wherein at least some of the securing is by welding.  
     
     
         25 . The method of  claim 22 , wherein at least some of the securing is by forming joints of reinforced epoxy resin.  
     
     
         26 . A method for forming a composite beam, comprising: 
 (a) rigidly securing a parallel spaced first plurality of main rod members to opposite ends of a first longitudinal array of diagonal rod segments to form a first truss;    (b) rigidly securing a parallel spaced plurality of main rod members to opposite ends of a second longitudinal array of diagonal rod segments to form a second truss    (c) locating the first and second trusses in laterally spaced relation;    (d) rigidly securing a longitudinal array of lateral rod segments between the first and second trusses to form a cage frame;    (e) rigidly securing a plurality of fastener attachments to the cage frame; and    (f) encapsulating the bonded cage frame in a plastic body.    
     
     
         27 . The method of  claim 26 , wherein the encapsulating comprises: 
 (a) providing an injection mold having an elongate cylindrical cavity;    (b) loading the mold with the welded cage frame;    (c) centering the welded cage frame within the mold;    (d) injecting a polymeric composition into the mold thereby covering the cage frame; and    (e) cooling the mold to form the structural plastic member.    
     
     
         28 . The method of  claim 27 , wherein the injecting comprises formulating the polymeric composition to consist of low density polyethylene, at least 60 percent of the polymeric composition being linear low-density polyethylene.