Abstract
Pultrusion manufacturing of fiber reinforced polymers has been shown to yield some of the highest mechanical properties for unidirectional composites, having a high degree of fiber alignment with consistent performance. Pultrusions offer a low-cost manufacturing approach for producing unidirectional composites with a constant cross-section and are used in many applications, including spar caps of wind turbine blades. However, as an intermediate processing step for wind blades, the additional cost of manufacturing pultrusions must be accompanied by sufficient increases in mechanical performance and system benefits. Wind turbine blades are manufactured using vacuum-assisted resin transfer molding with infused unidirectional fiberglass or carbon pultrusions for the spar cap. Infused fiberglass composites are among the most cost-effective structural materials available and replacing this material in the cost-driven wind industry has proven challenging, where infused fiberglass spar caps are still the predominant material system in use. To evaluate alternative material systems in a pultruded composite form, it is necessary to understand the costs for this additional manufacturing step which are shown to add 33%–55% on top of the material costs. A pultrusion cost model has been developed and used to quantify cost sensitivities to various processing parameters. The mechanical performance for pultruded composites is improved versus resin-infusion manufacturing with a 17% increase in design strength at a constant fiber volume fraction, but also enables higher achievable fiber volume fractions. The cost-specific mechanical performance is compared as a function of processing parameters for pultruded composites to identify the opportunities for alternative material and manufacturing approaches for wind turbine spar caps. Four materials are compared in a representative wind turbine blade model to assess the performance of pultruded carbon fiber systems and pultruded fiberglass relative to infused fiberglass, where the pultruded systems produce lower weight blades with various cost distinctions.
| Original language | English |
|---|---|
| Article number | 110960 |
| Journal | Composites Part B: Engineering |
| Volume | 265 |
| DOIs | |
| State | Published - Oct 2023 |
Funding
The pultrusion process as depicted in Fig. 2 offers opportunity to provide greater alignment of the reinforcing fiber in the direction of the dominantly longitudinal loading of the spar caps compared to VARTM infusion. There are some notable distinctions for pultrusions for spar cap manufacturing, including utilization of a rotary take up system as opposed to the traveling cut-off saw, the surfacing veil being replaced with peel-ply application, and the removal of continuous filament mat. The pultrusion process is relatively automated requiring small amounts of labor with respect to its higher continuous throughput [5]. Unidirectional fiber rovings, or tows, are input to the pultrusion process and are among the lowest cost forms for carbon fiber and fiberglass. Production quality is highly consistent and the capital requirements for pultrusion equipment are somewhat modest with respect to the material throughput as compared to other high performance composite production approaches, such as with prepreg fabrics or filament winding. The Department of Energy (DOE) is supporting work at Oak Ridge National Laboratory and other organizations in the Institute of Advanced Composite Manufacturing Innovation to demonstrate approaches for manufacturing low-cost carbon fiber (LCCF) by utilizing alternative precursors and manufacturing techniques such as pultrusion [6]. As alternative forms of lower cost carbon fibers with various cost-performance relationships are becoming available, it becomes critical to have tools to evaluate and optimize the many processing options available to identify those materials with the greatest opportunity to reduce the levelized cost of energy. There is need for an enhanced pultrusion cost model to accurately compare material and manufacturing choices through incorporating the cost of this intermediate manufacturing step for wind blades.This research has been funded by the Wind Energy Technologies Office within the U.S. Department of Energy as part of the Big Adaptive Rotor project. Sandia National Laboratories is a multimission laboratory managed and operated by National Technology & Engineering Solutions of Sandia LLC, a wholly owned subsidiary of Honeywell International Inc. for the U.S. Department of Energy's National Nuclear Security Administration under contract DE-NA0003525. Oak Ridge National Laboratory is operated by UT-Battelle, LLC. under Contract No. DEAC05-00OR22725 with the U.S. Department of Energy. This research has been funded by the Wind Energy Technologies Office within the U.S. Department of Energy as part of the Big Adaptive Rotor project. Sandia National Laboratories is a multimission laboratory managed and operated by National Technology & Engineering Solutions of Sandia LLC, a wholly owned subsidiary of Honeywell International Inc. for the U.S. Department of Energy's National Nuclear Security Administration under contract DE-NA0003525. Oak Ridge National Laboratory is operated by UT-Battelle, LLC. under Contract No. DEAC05-00OR22725 with the U.S. Department of Energy.
