Tough, Durable Forte Carbon Fiber Spars & Tubes
The toughness and durability of Forte carbon fiber spars and structural tubes (structures) are created with a proven manufacturing technique, use of specially formulated (toughened) resin, and strategic engineering of the laminate cross-section.
Forte structures are built with continuous fibers on four axes, meaning that any one fiber, regardless of its orientation, may be followed continuously from its origin, through its length, to its designated end. Using a 3-axis braider in conjunction with automated hoop winders, the fibers are braided and positioned simultaneously onto a machined aluminum mandrel (i.e., an internal mold), resulting in an engineered, net-form, 4-axis composite.
Our structures are made with Forte's proprietary high-temperature epoxy resin system. At Forte, we compound our own epoxy matrix with tiny, rubber, energy absorbing molecules or Carbon Nano-Tubes for additional strength. These resin enhancements, along with other matrix engineering developments, increase the completed part's interlaminate adhesion and fracture toughness energy.
Forte structures can be built straight or tapered, to specified length. Additionally, the laminate (i.e., the structure wall) can be tapered within the length of the part. We can also dictate fiber orientation, yarn balance, and laminate thickness, so that material properties (i.e., stiffness, weight and strength) can be tailored to the part's structural requirements.
The 4-Axis Continuous Fiber Braiding Advantage
Extreme durability and toughness, offered by braided composite structures, has been utilized in the aerospace and defense industries for years, because each and every interlocking fiber is considered a damage stopper.
Alternatively, carbon fiber structures built with hand-laid layers of pre-formed materials have a tendency toward wholesale delamination, which propagates from the damaged spot and results in catastrophic failure. This is the main feature which distinguishes carbon fiber structures made using hand-laid pre-formed materials and those using 4-axis continuous fiber braided technology.
In the event of localized damage, a braided composite spar or tube retains its structural integrity and the damaged spot can most likely be repaired.
Structural Torsion Tubing
Forte also manufactures small diameter structural torsion tubing up to 40' in length. Our computer-controlled, fully-automated helical winder ensures that your torsion tubing needs are met cost-effectively, helping you to save money.
Fiber Options
Fiber choices are made with Forte engineering staff guidance. Fiber choices include carbon, glass or boron warp yarns, continuous carbon or glass weft yarns, and S2 or E glass bias yarns. Other input yarns can be sourced as well. For example, we have processed, at customer request, silicon carbide fiber, Vectran, Kevlar, PBO, Twaron and Technora.
Optional Carbon Nano-Tube Additives
Carbon Nano-Tube additives are also available. Generally, we have found that compounding Carbon Nano-Tubes into our epoxy matrix increases the compressive strength of an intermediate modulus carbon composite to that of a high modulus composite.
So why use nano-technology? Besides the space age sex appeal and bragging rights, the increase in compressive strength comes at a bargain price compared to incorporating a high modulus fiber, such as IM7. While the Nano-Tube composite will cost more than our standard composite, it will be easily 50% less expensive than the high modulus equivalent.
Forte's Automated Manufacturing Process
All our structural tubing is manufactured with our automated, computer-controlled, closed-loop drive system. This digital feedback process confirms continuous, real-time accuracy and allows all Forte structures to be manufactured according to design plan, a plan that is repeatable and consistent.
Throughout the braiding process, the braiding lines' actuating motors receive precise design signals and are equipped with digital encoders, so that the driving computer can confirm and balance all further command signals. As the structural fibers are wound, braided and plied, a continuously active resin curtain coater and stripping system ensures that every fiber has received the correct dosage of our proprietary resin system.
After the braiding is complete, the composite structure is consolidated and cured. The wet, braided part is tape-wrapped, using two automated counter helix, high tension tapes. The part is then staged on a 40' rolling cart and rolled into our tunnel oven.
Temperature ramp rates and dwell times are programmed to activate the tape wraps when the resin is at a rheological low (i.e., when the resin is still flowing); this allows the composite to be concentrically compacted. Once the composite is consolidated, the oven ramps to a final curing temperature of 300°F to achieve ultimate material properties associated with high performance composites.
Automation Creates Significant Savings
Our cost efficient, automated manufacturing process requires significantly less time and labor to build a spar or tube compared to hand-built spar or tube processes. Savings we achieve are passed on, to keep Forte products affordable and to help our customers save money.