Patent Publication Number: US-2023150251-A1

Title: Composite structures with embedded electrical grids

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
     This application is a continuation of prior U.S. application Ser. No. 17/177,757, filed Feb. 17, 2021, which claims priority to U.S. Provisional Patent Application Ser. No. 62/979,516, filed Feb. 21, 2020, the disclosures of which are hereby expressly incorporated by reference herein in their entireties. 
    
    
     FIELD OF THE DISCLOSURE 
     The present disclosure relates generally to composite structures and methods of making the same. More particularly, the present disclosure relates to composite structures for use in cargo vehicles and other applications having embedded electrical grids and methods of making the same. 
     BACKGROUND OF THE DISCLOSURE 
     Cargo vehicles are used in the transportation industry for transporting many different types of cargo. Certain cargo vehicles may be refrigerated and insulated to transport temperature-sensitive cargo. Cargo vehicles may be constructed using composite materials, which may lead to an absence of or reduction in metallic and wood materials and associated advantages, including simplified construction, thermal efficiency, reduced water intrusion and corrosion, and improved fuel efficiency through weight reduction, for example. However, such cargo materials must be sufficiently strong and durable to withstand the demands of normal use, both exteriorly (e.g., weather, road conditions, other vehicles) and interiorly (e.g., cargo, forklifts). 
     SUMMARY OF THE DISCLOSURE 
     A composite structure of a cargo body and a method of making the same are disclosed. The composite structure includes at least one electrical grid embedded within fiber-reinforced polymer (FRP) layers. The embedded electrical grid includes a plurality of conductive fibers and a plurality of insulating fibers integrated into a polymer matrix of the FRP layers. The embedded electrical grid may be used for power distribution, structural strengthening and stiffness, and/or puncture detection. 
     According to an exemplary embodiment of the present disclosure, a laminated composite structure of a cargo body is provided, the composite structure including: a core layer; an outer fiber-reinforced polymer layer coupled to the core layer; an inner fiber-reinforced polymer layer coupled to the core layer; and at least one electrical grid embedded within one or more of the outer and inner fiber-reinforced polymer layers. The at least one electrical grid includes: a plurality of horizontal conductive fibers; a plurality of vertical conductive fibers; a plurality of horizontal insulating fibers that extend between adjacent horizontal conductive fibers; and a plurality of vertical insulating fibers that extend between adjacent vertical conductive fibers. 
     According to another exemplary embodiment of the present disclosure, a laminated composite structure of a cargo body is provided, the composite structure including: a core layer; an outer fiber-reinforced polymer layer coupled to the core layer; an inner fiber-reinforced polymer layer coupled to the core layer; a first surface; a first electrically conductive element embedded within the composite structure and extending along the first surface; a second surface substantially perpendicular to the first surface; a second electrically conductive element extending along the second surface; a corner electrical connector in electrical communication between the first and second electrically conductive elements. 
     According to yet another exemplary embodiment of the present disclosure, a cargo body is provided including: a composite panel including at least one electrical grid embedded in a fiber-reinforced polymer; a power source; a control system; an electrical component in communication with the power source; a sensor in communication with the control system. The electrical grid is configured to perform at least one of the following functions: distributing power from the power source to the electrical component; communicating a signal from the sensor to the control system; and detecting a puncture in the composite panel. 
     Additional features and advantages of the present invention will become apparent to those skilled in the art upon consideration of the following detailed description of the illustrative embodiments exemplifying the best mode of carrying out the invention as presently perceived. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The foregoing aspects and many of the intended advantages of this invention will become more readily appreciated as the same becomes better understood by reference to the following detailed description when taken in conjunction with the accompanying drawings. 
         FIG.  1    is a perspective view of a cargo vehicle having a cargo body with a nose, a floor, a roof, and right and left sidewalls; 
         FIG.  2    is a cross-sectional view of the left sidewall of  FIG.  1   , including an embedded electrical grid; 
         FIG.  3    is an exploded perspective view of the electrical grid of  FIG.  2   ; and 
         FIG.  4    is a schematic perspective view of the left sidewall of  FIG.  1   ; 
         FIG.  5    is a detailed view of a first circled area in  FIG.  4   ; 
         FIG.  6    is a detailed view of a second area circled in  FIG.  4   ; 
         FIG.  7    is an exploded perspective view of another embodiment of the electrical grid; and 
         FIG.  8    is a perspective view of a corner electrical connector for use with the electrical grid of  FIG.  2   . 
     
    
    
     Corresponding reference characters indicate corresponding parts throughout the several views. Although the drawings represent embodiments of various features and components according to the present disclosure, the drawings are not necessarily to scale and certain features may be exaggerated in order to better illustrate and explain the present disclosure. The exemplification set out herein illustrates an embodiment of the invention, and such an exemplification is not to be construed as limiting the scope of the invention in any manner. 
     DETAILED DESCRIPTION OF THE DRAWINGS 
     For the purposes of promoting an understanding of the principals of the invention, reference will now be made to the embodiments illustrated in the drawings, which are described below. The embodiments disclosed below are not intended to be exhaustive or limit the invention to the precise form disclosed in the following detailed description. Rather, the embodiments are chosen and described so that others skilled in the art may utilize their teachings. It will be understood that no limitation of the scope of the invention is thereby intended. The invention includes any alterations and further modifications in the illustrative devices and described methods and further applications of the principles of the invention which would normally occur to one skilled in the art to which the invention relates. 
     1. Cargo Vehicle 
     Referring initially to  FIG.  1   , a cargo vehicle  100  is shown for supporting and transporting cargo. The illustrative vehicle  100  is a tractor-trailer that extends along a longitudinal axis L from a front end  102  to a rear end  104 . The vehicle  100  includes a tractor  110  and a cargo body  120 , specifically a refrigerated van trailer. 
     The tractor  110  of the vehicle  100  includes an engine  112 , a plurality of wheels  114  powered by the engine  112 , and a fifth wheel assembly  116 . 
     The cargo body  120  of the vehicle  100  includes a power source  117  (i.e., a battery) charged by the engine  112  of the tractor  110  or another suitable charging device, a control system  118  in communication with the power source  117 , a floor  122  for supporting cargo, a roof  124 , right and left sidewalls  126 R,  126 L, a front wall or nose  128 , and a rear door assembly  130  having a rear frame  132  and a door (not shown) to access the cargo body  120 . The power source  117  and the control system  118  are shown as being incorporated into the front wall  128  of the cargo body  120  in  FIG.  1   , although this arrangement may vary. The cargo body  120  includes a king pin assembly (not shown) that couples to the fifth wheel assembly  116  of the tractor  110 . The cargo body  120  also includes an electrical connector  134 , such as a 7-way plug, that communicates with the tractor  110  when coupled together to charge the power source  117  and/or power electrical components of the cargo body  120 . 
     The cargo body  120  further includes a plurality of electrical components, illustratively upper marker lights  140 A,  140 B,  140 C, a lower marker light  142 , a mid-ship turn light  144 , and interior dome lights  146 A,  146 B. Although not shown in  FIG.  1   , it will be understood that the cargo body  120  may have other electrical components, such as brake lights, reverse lights, license plate lights, batteries, a refrigeration unit, and/or temperature sensors, for example. These electrical components may be powered by the power source  117  of the cargo body  120 , as described further in Section 4 below. 
     The cargo body  120  further includes a plurality of electrical sensors, illustratively a thermocouple  150 , a moisture sensor  152 , a GPS sensor  154 , a load sensor  156  in the floor  122 , and an accelerometer  158 . These electrical sensors may communicate electrical signals to the control system  118  of the cargo body  120 , as described further in Section 4 below. 
     While the concepts of this disclosure are described in relation to a refrigerated van trailer, it will be understood that they are equally applicable to other cargo bodies generally, and more specifically to other trailers (e.g., dry van trailers, flatbed trailers, commercial trailers, small personal trailers), straight or box truck bodies, and the like. Accordingly, those skilled in the art will appreciate that the present invention may be implemented in a number of different applications and embodiments and is not specifically limited in its application to the particular embodiments depicted herein. 
     2. Composite Sidewalls and Other Composite Structures 
     Cargo body  120  may be constructed, at least in part, of composite materials. For example, the floor  122 , roof  124 , right and left sidewalls  126 R,  126 L, and/or front wall  128  of the composite cargo body  120  may be constructed of composite materials. As such, the floor  122 , roof  124 , right and left sidewalls  126 R,  126 L, and/or front wall  128  of the composite cargo body  120  may be referred to herein as composite structures. Each composite structure may be a single, unitary component, which may be formed from a plurality of layers permanently coupled together. Exemplary composite materials for use in the composite cargo body  120  include fiber-reinforced polymers or plastics (FRPs), for example glass-fiber-reinforced polymers or plastics (GFRPs) and carbon-fiber-reinforced polymers or plastics (CRPs). 
     A laminated composite left sidewall  126 L is shown in cross-section in  FIG.  2   . Those skilled in the art will appreciate that the following teachings related to the left sidewall  126 L may also be applied to the floor  122 , roof  124 , right sidewall  126 R, and/or front wall  128  of the composite cargo body  120 . 
     The illustrative sidewall  126 L of  FIG.  2    includes a core layer  200 , an outer skin layer  210  that faces outwardly from the cargo body  120  ( FIG.  1   ) toward the surrounding environment, and an inner skin layer  220  that faces inwardly toward the cargo in cargo body  120  ( FIG.  1   ). Each of these laminated layers  200 ,  210 ,  220  is described further below. 
     Referring still to  FIG.  2   , the core layer  200  of the composite sidewall  126 L may include one or more structural supports or preforms. Exemplary preforms for use in core layer  200  include PRISMA® preforms provided by Compsys, Inc. of Melbourne, Fla. Each preform may include an inner foam core  202 , an intermediate layer  204 , and an outer FRP layer  206 , each of which is described further below. 
     The inner foam core  202  of each preform may include a self-expanding, self-curing structural foam material. Suitable foams include polyurethane foams, such as a methylene-diphenyl-methane diisocyanate (MDI) based rigid polyurethane foam, for example. 
     The outer FRP layer  206  (which may be referred to herein as the “first” FRP layer  206 ) of each preform may include a polymer matrix reinforced with fibers configured to enhance the structural properties of the surrounding polymer matrix. Suitable reinforcing fibers include glass fibers, carbon fibers, aramid fibers (e.g., Kevlar® fibers available from DuPont Protection Technologies of Richmond, Virginia), linear polyethylene or polypropylene fibers (e.g., Spectra® fibers available from Honeywell International Inc. of Morris Plains, N.J.), or polyester fibers. The reinforcing fibers may be present in fabric form, which may be mat, woven, or knit, for example. Exemplary fabrics include chopped fiber fabrics, such as chopped strand mats (CSM), and continuous fiber fabrics, such as 0°/90° fiberglass fabrics, +45°/−45° fiberglass fabrics, +60°/−60° fiberglass fabrics, 0° warp unidirectional fiberglass fabrics, and other stitched fiber fabrics, for example. Exemplary fabrics are commercially available from Vectorply Corporation of Phenix City, Ala. and include the E-LM  1810  fiberglass fabric with 0° unidirectional fibers, the E-LTM 3610 fiberglass fabric with 0°/90° fibers, and the E-LTM 2408 fiberglass fabric with 0°/90° fibers, for example. Such fabrics may have an area density of about 800 g/m 2  to about 1,500 g/m 2  or more. 
     The intermediate layer  204  of each preform may serve as a transition layer for coupling the inner foam core  202  to the outer FRP layer  206 . The intermediate layer  204  may be sufficiently porous to at least partially receive foam from the adjacent foam core  202  and the polymer matrix from the adjacent FRP layer  206 . The intermediate layer  204  may also be mechanically coupled (e.g., stitched) to the adjacent FRP layer  206  to simplify manufacturing, to ensure proper placement, and to prevent shifting and/or bunching. The intermediate layer  204  may be a nonwoven fabric with continuous or chopped fibers. 
     The individual preforms of the core layer  200  may be designed to accommodate the needs of the particular application. For example, in areas of the final structure requiring more strength and/or insulation, a low-density foam core  202  may be replaced with a high-density foam core  202  or a hard, plastic block. The individual preforms of the core layer  200  may also be sized, shaped, and arranged in a manner that accommodates the needs of the particular application. For example, in areas of the final structure requiring less strength, the preforms may be relatively large in size, with the foam cores  202  spanning relatively large distances before reaching the surrounding layers  204 ,  206 . By contrast, in areas of the final structure requiring more strength, the preforms may be relatively small in size, with the foam cores  202  spanning relatively small distances before reaching the surrounding layers  204 ,  206 . Stated differently, the preforms may be shaped as relatively wide panels in areas of the final structure requiring less strength and as relatively narrow support beams in areas of the final structure requiring more strength. 
     Referring still to  FIG.  2   , the outer skin layer  210  of the composite sidewall  126 L may include a FRP layer  212  and an outer gel coat  214 . The FRP layer  212  (which may be referred to herein as the “second” FRP layer  212 ) may be similar to the above-described first FRP layer  206 , including a polymer matrix reinforced with suitable reinforcing fibers. According to an exemplary embodiment of the present disclosure, a plurality of different reinforcing fiber layers may be stacked together and used in combination to form the FRP layer  212 . For example, a chopped fiber fabric (e.g., CSM) may be positioned adjacent to a continuous fiber fabric. In this stacked arrangement, the chopped fibers may help support and maintain the adjacent continuous fibers in place, especially around corners or other transitions. Also, the chopped fibers may serve as a web to resist column-type loads in compression, while the adjacent continuous fibers may resist flange-type loads in compression. Adjacent reinforcing fiber layers may be stitched or otherwise coupled together to simplify manufacturing, to ensure proper placement, and to prevent shifting and/or bunching. The outer gel coat  214  may be a polymer-rich or polymer-only layer that provides a smooth outer finish in a desired color. 
     Referring still to  FIG.  2   , the inner skin layer  220  of the composite sidewall  126 L may include a FRP layer  222  and an optional inner gel coat  224 . The FRP layer  222  (which may be referred to herein as the “third” FRP layer  222 ) may be similar to the above-described first and second FRP layers  206 ,  212 , including a polymer matrix reinforced with suitable reinforcing fibers. The inner gel coat  224  may be a polymer-rich or polymer-only layer similar to the above-described outer gel coat  214  that provides a smooth inner finish in a desired color. 
     The illustrative composite sidewall  126 L further includes one or more conductive electrical layers  400 ,  410  embedded within the sidewall  126 L. The electrical layers  400 ,  410  may be referred to herein as the “fourth” and/or “fifth” FRP layers  400 ,  410 . The electrical layers  400 ,  410  are described further in Section 4 below. 
     3. Composite Molding Method 
     The composite structures of the present disclosure, including the composite sidewall  126 L of  FIG.  2   , may be formed by a layered molding process. An exemplary molding process involves (1) applying a gel-coat resin onto a mold surface to form the outer gel coat  214 , (2) layering the reinforcing fibers of the outer FRP layer  212 , the preforms of the core layer  200 , the reinforcing fibers of the inner FRP layer  222 , and any other desired layers (e.g., electrical layers  400 ,  410  of Section 4 below) onto the outer gel coat  214 , (3) wetting out the layers  212 ,  200 ,  222 , and any other applied layers with at least one laminating resin to impregnate and/or coat the fibers, (4) optionally applying another gel-coat resin onto the layers  212 ,  200 ,  222  to form the inner gel coat  224 , and (5) curing the materials upon the mold surface (either sequentially and/or simultaneously) to form a single, integral, laminated composite sidewall  126 L. 
     The laminating resin of step (3) may be a typical thermosetting resin, such as a vinyl ester, epoxy resin, or unsaturated polyester resin, although thermoplastic resins are also contemplated. The gel-coat resin of steps (1) and (4) may be a typical polyester gel-coat resin or a co-cure resin containing one or more elastomer components, such as urethane, co-cured with one or more laminating resin components, such as a vinyl ester, epoxy resin, or unsaturated polyester components. Exemplary co-cure resins are disclosed in U.S. Pat. No. 9,371,468 and U.S. Publication No. 2016/0263873, the disclosures of which are hereby incorporated by reference in their entireties. 
     Additional information regarding the construction of composite structures is disclosed in the following patents, each of which is incorporated by reference in its entirety herein: U.S. Pat. Nos. 5,429,066, 5,664,518, 5,800,749, 5,830,308, 5,897,818, 5,908,591, 6,004,492, 6,013,213, 6,206,669, 6,496,190, 6,497,190, 6,543,469, 6,723,273, 6,755,998, 6,869,561, 6,911,252, 8,474,871, 10,239,265. 
     4. Embedded Electrical Grid 
     Referring still to  FIG.  2   , the left composite sidewall  126 L includes the first electrical layer  400  and the second electrical layer  410 . The first (i.e., outer) electrical layer  400  is embedded within the outer skin layer  210  of the composite sidewall  126 L between the core layer  200  and the adjacent outer gel coat  214 , and the second (i.e., inner) electrical layer  410  is embedded within the inner skin layer  220  of the composite sidewall  126 L between the core layer  200  and the adjacent inner gel coat  224 . Although the composite sidewall  126 L is shown with both outer and inner electrical layers  400 ,  410 , it is within the scope of the present disclosure for the composite sidewall  126 L to have only a single, outer or inner electrical layer. 
     The inner electrical layer  410  of the left composite sidewall  126 L is shown schematically in  FIGS.  3 - 6   . Those skilled in the art will appreciate that the following teachings related to the inner electrical layer  410  of the left sidewall  126 L may also be applied to the outer electrical layer  400  of the left sidewall  126 L and/or electrical layers of the floor  122 , roof  124 , right sidewall  126 R, and/or front wall  128 . 
     The left composite sidewall  126 L includes horizontal conductive fibers  420  and vertical conductive fibers  430  arranged perpendicular to each other in a grid pattern to form an electrical grid. The horizontal conductive fibers  420  are electrically insulated from the vertical conductive fibers  430 . In the illustrated embodiment of  FIGS.  3 - 6   , one or both electrical layers  400 ,  410  form independent electrical grids on either side of the core layer  200 , with one or both electrical layers  400 ,  410  having horizontal conductive fibers  420  as well as vertical conductive fibers  430 . In the illustrated embodiment of  FIG.  7   , the electrical layers  400 ,  410  cooperate to form the electrical grid on either side of the core layer  200 , with one electrical layer  400  having horizontal conductive fibers  420  and the opposing electrical layer  410  having vertical conductive fibers  430 , or vice versa. 
     As shown in  FIG.  3   , the electrical layer  410  forms an independent electrical grid (irrespective of the opposing electrical layer  400 ). The electrical layer  410  illustratively includes a plurality of horizontal and vertical conductive fibers  420 ,  430 , such as carbon fibers, and a plurality of horizontal, vertical, and intermediate insulating fibers  440 ,  442 ,  444 , such as E-glass fibers, arranged in the grid pattern. The horizontal insulating fibers  440  extend between adjacent horizontal conductive fibers  420 , the vertical insulating fibers  442  extend between adjacent vertical conductive fibers  430 , and the intermediate insulating fibers  444  are sandwiched between the horizontal conductive fibers  420  on one side and the vertical conductive fibers  430  on the other side. The intermediate insulating fibers  444  may be present in the form of a mat (e.g., CSM), for example. 
     The illustrative electrical grid of electrical layer  410  may be a non-woven, non-crimped, carbon/glass hybrid fabric. To form this fabric, the horizontal conductive fibers  420  and the horizontal insulating fibers  440  may be stitched into one side of the mat of intermediate insulating fibers  444 , and the vertical conductive fibers  430  and the vertical insulating fibers  442  may be stitched into the other side of the mat of intermediate insulating fibers  444 . Suitable fabrics for use as the electrical grid of electrical layer  410  are available from SAERTEX USA of Huntersville, N.C. 
     Referring next to  FIG.  4   , the electrical grid of electrical layer  410  is arranged across the composite sidewall  126 L with the horizontal conductive fibers  420  extending horizontally across the composite sidewall  126 L and the vertical conductive fibers  430  extending vertically across the composite sidewall  126 L and perpendicular to the horizontal conductive fibers  420 . The horizontal conductive fibers  420  include a plurality of (e.g., five) spaced-apart subsets  422 A-E with the horizontal insulating fibers  440  positioned therebetween, and the vertical conductive fibers  430  include a plurality of (e.g., fourteen) spaced-apart subsets  432 A-N with the vertical insulating fibers  442  positioned therebetween. In certain embodiments, the horizontal subsets  422 A-E and the vertical subsets  432 A-N are spaced apart from one another by about 1-10 inches, more specifically about 1-6 inches, more specifically about 1-3 inches. It is understood that the number of horizontal subsets  422 A-E and vertical subsets  432 A-N and the spacing therebetween may vary. Each subset  422 A-E,  432 A-N may include one or more filaments, which may be arranged in parallel as shown in  FIG.  4    (i.e., a tow) or intertwined (e.g., twisted). 
     The conductive fibers  420 ,  430  may be gathered near the front end  102  of the composite sidewall  126 L for communication with the power source  117 , control system  118 , and/or electrical connector  134  in the front wall  128  ( FIG.  1   ). As shown in  FIG.  4   , for example, the vertical conductive fibers  430  are directed across the top and/or bottom of the composite sidewall  126 L and toward the front end  102  while maintaining insulation therebetween. As shown in  FIG.  5   , the horizontal conductive fibers  420  are also wrapped and gathered near the front end  102  while maintaining insulation therebetween. Although not shown in  FIG.  4   , the conductive fibers  420 ,  430  may wrap across the rear end  104  of the composite sidewall  126 L in a similar manner. The conductive fibers  420 ,  430  may be wrapped in tape or another suitable protective layer, especially at bent or gathered locations. 
     The electrical grid formed by one or both electrical layers  400 ,  410  may be embedded within the composite sidewall  126 L during the molding process of Section 3 above. During the layering step (2), the electrical grid of one or both electrical layers  400 ,  410  may be placed in its desired location. During the wetting step (3), the electrical grid of one or both electrical layers  400 ,  410  may be impregnated and/or coated with resin along with the other FRP layers  212 ,  222  ( FIG.  2   ). Then, during the curing step (5), the electrical grid of one or both electrical layers  400 ,  410  may become an integral part of the laminated composite sidewall  126 L with the conductive carbon fibers  420 ,  430 , and the insulating fibers  440 ,  442 ,  444 , embedded within the surrounding polymer matrix. Allowing the polymer matrix to integrate evenly into the electrical grid of one or both electrical layers  400 ,  410  throughout the composite sidewall  126 L may reduce the risk of surface disruptions and/or delamination. 
     Referring still to  FIG.  4   , the electrical grid formed by one or both electrical layers  400 ,  410  may serve one or more functions in the composite sidewall  126 L, including (1) power storage and/or distribution, (2) telematics and connectivity, (3) structural strengthening and stiffness, and/or (4) puncture detection. Each of these functions is described further below. 
     First, the electrical grid of one or both electrical layers  400 ,  410  may store and/or distribute power throughout the composite sidewall  126 L without the need for a traditional, exposed wiring harness. The power source  117  may allow the cargo body  120  to store energy and operate the electrical grid of one or both electrical layers  400 ,  410  independently, whether or not the cargo body  120  is coupled to the tractor  110 . Also, because they are insulated from one another, the horizontal subsets  422 A-E and the vertical subsets  432 A-N may be powered independently. In the illustrated embodiment of  FIG.  4   , for example, the horizontal subsets  422 A-E are powered in an alternating positive/negative manner (e.g., subset  422 A is positive, subset  422 B is negative, subset  422 C is positive, subset  422 D is negative, and subset  422 E is positive). Each electrical component of the cargo body  120  (e.g., the upper marker lights  140 A,  140 B,  140 C, the lower marker light  142 , the mid-ship turn light  144 , and the interior dome lights  146 A,  146 B ( FIG.  1   )) may be connected to at least one positive and at least one negative conductive fiber  420 ,  430  to complete the electrical circuit and power the electrical component. In some embodiments, each electrical component may be coupled to more than one positive and/or negative conductive fiber  420 ,  430  within the same electrical grid for redundancy. In other embodiments, each electrical component may be coupled to multiple electrical grids for redundancy. In one example, the electrical component may be coupled to multiple electrical grids of electrical layers  400 ,  410  within the same sidewall  126 L ( FIG.  2   ). In another example, the electrical component may be coupled to multiple electrical grids within different composite panels, such as the electrical grid of electrical layer  410  of the sidewall  126 L and a similar electrical grid of the opposing sidewall  126 R ( FIG.  1   ). In this way, the electrical component may continue to operate despite damage to any single fiber  420 ,  430  or electrical layer  400 ,  410 . 
     Second, the electrical grid of one or both electrical layers  400 ,  410  may communicate electrical signals from one or more sensors to the control system  118  to facilitate telematics and connectivity. For example, the electrical grid of electrical layer  410  may communicate signals indicative of temperature from the thermocouple  150 , signals indicative of moisture level from the moisture sensor  152 , signals indicative of location from the GPS sensor  154 , signals indicative of weight on the floor  122  from the load sensor  156 , and/or signals indicative of a collision from the accelerometer  158 . The control system  118  may be programmed to process these signals and communicate relevant information to the driver, the owner, or other parties. 
     Third, the electrical grid of one or both electrical layers  400 ,  410 , in particular the conductive carbon fibers  420 ,  430 , of the electrical grid  410 , may provide stiffness and strength to the composite sidewall  126 L. The insulating fibers  440 ,  442 ,  444 , of the electrical grid of one or both electrical layers  400 ,  410  may also help distribute structural loads throughout the electrical grid and to surrounding FRP layers  212 ,  222  ( FIG.  2   ) of the composite sidewall  126 L. 
     Fourth, the electrical grid of one or both electrical layers  400 ,  410  may enable puncture detection. If any of the conductive fibers  420 ,  430  are damaged or cut in a way that breaks the electrical circuit, the control system  118  may alert the driver, the owner, or other parties of the puncture. According to an exemplary embodiment of the present disclosure, the control system  118  may also be programmed to identify the x-coordinate of the puncture by identifying which vertical subset  432 A-N was cut and/or the y-coordinate of the puncture by identifying which horizontal subset  422 A-E was cut. In  FIG.  4   , for example, the control system  118  may identify the x-/y-coordinates of a fork-lift puncture  450  by identifying breaks in vertical subset  432 C and horizontal subset  422 D. Upon receiving the puncture alert, the responsible parties may inspect the composite sidewall  126 L, take steps to prevent additional damage, and make any necessary repairs. 
     Referring next to  FIG.  7   , the electrical layers  400 ,  410  cooperate to form the electrical grid on either side of the core layer  200  ( FIG.  2   ). Non-woven, non-crimped, carbon/glass hybrid fabrics similar to the fabric shown in  FIG.  3    may also be used in this embodiment. However, a first fabric  460  containing the horizontal conductive fibers  420  and the horizontal insulating fibers  440  stitched to a first backing sheet  462  may serve as the first electrical layer  400 , and a second fabric  464  containing the vertical conductive fibers  430  and the vertical insulating fibers  442  stitched to a second backing sheet  466  may serve as the second electrical layer  410 , or vice versa. The intermediate insulating fibers  444  ( FIG.  3   ) may be replaced by the core layer  200  ( FIG.  2   ) in this embodiment. The first and second fabrics  460 ,  464  may be identical to one another except for their orientation in the composite sidewall  126 L. 
     5. Corner Electrical Connectors 
     Referring next to  FIG.  8   , a plurality of exemplary corner electrical connectors  500 M,  500 N are shown for connecting the above-described electrical grid to another electrical component (illustratively, a wiring harness  510  adhered to and running across the bottom surface of the composite sidewall  126 L) across a corner (illustratively, a bottom corner  127  of the composite sidewall  126 L). The corner electrical connectors  500 M,  500 N may provide safe, reliable, rugged, customizable electrical connections across the bottom corner  127  of the composite sidewall  126 L. Although the corner electrical connectors  500 M,  500 N are illustratively positioned across the bottom corner  127  of the composite sidewall  126 L in  FIG.  8   , similar corner electrical connectors may be positioned across other corners of the cargo body  120  ( FIG.  1   ), including upper corners, front corners, and/or rear corners of the cargo body  120 . 
     The corner electrical connectors  500 M,  500 N may be constructed of metal (e.g., copper) or another suitable conductive material. The illustrative corner electrical connectors  500 M,  500 N of  FIG.  8    are L-shaped components, each having a first plate  502  and a second plate  504  arranged at a 90-degree angle, but this shape may vary. The first plate  502  includes a plurality of selectively moveable first prongs  506 , and the second plate  504  includes a plurality of selectively moveable second prongs  508 . If necessary, these prongs  506 ,  508  may puncture and extend through certain layers of the composite sidewall  126 L to reach embedded electrical components. The corner electrical connectors  500 M,  500 N may be adhered to, embedded within, or otherwise coupled to the composite sidewall  126 L. 
     With respect to the corner electrical connector  500 M of  FIG.  8   , the first plate  502  is positioned adjacent to the subset  432 M of vertical conductive fibers  430 , and the second plate  504  is positioned adjacent to the wiring harness  510 . All of the first prongs  506  have been pressed downward to contact the subset  432 M of vertical conductive fibers  430 . A second row of the second prongs  508  has been pressed downward to contact a corresponding wire  512 M of the wiring harness  510 , while other second prongs  508  remain raised to avoid contacting other wires of the wiring harness  510 . In this arrangement, the corner electrical connector  500 M places the subset  432 M of vertical conductive fibers  430  in electrical communication with the corresponding wire  512 M of the wiring harness  510  across the bottom corner  127  of the composite sidewall  126 L. 
     With respect to the corner electrical connector  500 N of  FIG.  8   , the first plate  502  is positioned adjacent to the subset  432 N of vertical conductive fibers  430 , and the second plate  504  is positioned adjacent to the wiring harness  510 . All of the first prongs  506  have been pressed downward to contact the subset  432 N of vertical conductive fibers  430 . A first row of the second prongs  508  has been pressed downward to contact a corresponding wire  512 N of the wiring harness  510 , while other second prongs  508  remain raised to avoid contacting other wires of the wiring harness  510 . In this arrangement, the corner electrical connector  500 N places the subset  432 N of vertical conductive fibers  430  in electrical communication with the corresponding wire  512 N of the wiring harness  510  across the bottom corner  127  of the composite sidewall  126 L. 
     While this invention has been described as having an exemplary design, the present invention may be further modified within the spirit and scope of this disclosure. This application is therefore intended to cover any variations, uses, or adaptations of the invention using its general principles. Further, this application is intended to cover such departures from the present disclosure as come within known or customary practices in the art to which this invention pertains.