In certain applications, lightweight and extremely stiff space frame structures are very useful. From electronics enclosures and unmanned vehicles to automation robotics and metrology tools, a structure that is both light and rigid can provide significant benefits. Traditional truss and frame construction methods utilize aluminum or steel members. Although metal is robust and often the most cost effective up front, in applications where weight and stiffness are the driving design criteria, the return on investment for developing an optimized lower weight solution often outweighs the initial cost of the greater engineering time and higher performance components. Dragonplate has developed two different systems for building carbon fiber structures using a catalog of base materials.
The first carbon fiber frame system uses square and rectangular carbon fiber tubes and flat carbon fiber gusset plates to bond the members together. This type of space frame is extremely strong, several times stiffer than a comparable aluminum truss, and easily integrates with other non-composite components in the final assembly. One of the primary advantages of using this tube/gusset construction method is that often a legacy system, for example a robotic arm, end effector, or cantilevered support, can very quickly be replaced with a similar, but substantially lower weight, carbon fiber frame. The resulting higher speeds and reduced cycle times significantly reduce cost and increase output. This first system lends itself well to custom enclosures, covers, and shelf support structures, for example for electronics and scientific measurement equipment. The high stiffness and low weight of the carbon fiber components also have the ability to raise the natural frequency of an enclosure, often reducing vibrations.
A good example of this is in vibration and shock isolation cabinets, where the ability to not only lower the weight of the structure, but also eliminate the large response due to low frequency excitations, allows carbon fiber to outperform even much heavier metal systems. Lastly, due to the low thermal expansion of carbon fiber, in applications where the materials selection is limited to only a few very expensive options, such an Invar, carbon fiber can often be not only the lighter and easier to work with option, but also a less expensive one.
The second method for building a carbon fiber truss structure involves connecting pultruded tubes utilizing an assortment of patent-pending carbon-filled injection molded joints. Although not quite as strong as the braided tube frames of method one, this system of pultruded tubes and connectors offers the user extremely high stiffness to weight ratio, easy assembly, and a lower cost solution. These frames lend themselves to projects where the driving design criteria is stiffness (i.e. minimum deflection), and where maximum loading is less critical. Using the clamshell connectors and nylon screws, the entire assembly can be dry-fit together before anything is bonded permanently.
Dragonplate offers a complete line of component building blocks for each of these two structural frame systems. Whether the application requires low weight and deflection, such as in automation robotics and shock isolation cabinets, or long fatigue life, such as in vibration table supports, carbon fiber trusses and frames may be a good fit. Interestingly, many people have found that they can not only reduce weight by moving to carbon fiber, but cost as well by using a hybrid metal/carbon frame, where only a portion of the structure is replaced by carbon fiber tubes.
To start the design process, the CAD models [http://dragonplate.com/sections/Download-CAD-Models.asp] for all of the carbon fiber frame components are available on the Dragonplate website. In addition, technical support is available for helping to make decisions on which truss system would be most appropriate for your application, as well as general sizing, interfacing with other components, and even composite finite element analysis.
For more information and ordering, go to DragonPlate.com [http://dragonplate.com/Carbon-Fiber-Truss] or give us a call.
Allred - DragonPlate Carbon Fiber Composites [DragonPlate.com]
321 Route 5 West
Elbridge, New York 13060