How to make large wind turbine blades?
The manufacturing of large wind turbine blades is a highly precise and technology intensive process, mainly using composite materials such as glass fiber reinforced plastic (GFRP) or carbon fiber reinforced plastic (CFRP), and produced through mold forming technology. The following are the main production steps and key technical points:
1. Design and mold preparation
Pneumatic and structural design: Based on the requirements of wind energy conversion efficiency, load strength, noise control, etc., CAD/CAE software is used for blade 3D modeling and mechanical simulation.
Mold manufacturing: The blades are usually divided into upper and lower half shells, which are made separately. Molds are usually made of steel or composite materials, and their surfaces require high-precision polishing and coating with release agents to ensure smooth blade surfaces (reducing wind resistance).
2. Material preparation
Main materials:
Reinforcement materials: glass fiber cloth (commonly used), carbon fiber cloth (used for ultra long blades to reduce weight).
Base material: Epoxy resin or polyester resin (epoxy resin has better performance and is used for large blades).
Core material: balsa or PVC foam, which is used to fill the inside of the blade to form a "sandwich structure" to improve stiffness and reduce weight.
Structural components: blade root embedded bolt sleeve (connecting hub), front and rear edge shear beams, etc.
3. Layering and vacuum infusion
This is the core process of blade forming, commonly using vacuum assisted resin infusion (VARI) technology:
Laying: Lay fiber cloth, core materials, and structural components layer by layer in the mold. The layer design needs to adjust the fiber direction and thickness according to the stress situation of different parts of the blade.
Sealing and Vacuuming: Cover the layer with a vacuum film and seal it, evacuate to remove air, and allow the resin to uniformly infiltrate the fibers under negative pressure.
Resin infusion: Inject the mixed resin into the mold through a pipeline and infiltrate all fiber layers under vacuum.
Curing: Heat the mold (usually 50 ° C-80 ° C) to cure the resin, forming a high-strength composite shell.
4. Mold closing and bonding
Demolding: Remove the upper and lower half shells from the mold after solidification.
Adhesive: Align the upper and lower shells and use structural adhesive (usually epoxy adhesive) to bond them together. At the same time, bond the web plate internally (to strengthen the structure).
Root treatment: Strengthen the root area of the blade connecting the hub (such as thickening the layer or metal lining).
5. Post processing and testing
Trimming: Cut excess material at the edges and polish the surface.
Coating: Spray protective coating (anti UV, anti ice, anti corrosion) and logo color.
Balance test: Check the center of gravity and weight distribution of the blades to ensure dynamic balance.
Non destructive testing: using ultrasonic or X-ray to inspect internal defects (such as bubbles, delamination).
Static load and fatigue testing (sampling): Simulate extreme wind loads for mechanical testing to ensure the design life (usually 20-30 years).
6. Technological development trends
Intelligent manufacturing: Automated layer laying robot, real-time infusion monitoring system.
Material innovation: Carbon fiber hybrid application, recyclable resin (such as thermoplastic composite materials).
Modular design: Segmented blades facilitate transportation and installation
Retired blade recycling: Developing green recycling technologies such as pyrolysis and mechanical crushing for reuse.
key challenges
Large scale limitations: The blade length has exceeded 100 meters (for offshore wind turbines), facing challenges in transportation, mold size, and structural stiffness.
Quality control: Minor defects may lead to fatigue failure, and strict monitoring of process consistency is required.
Cost control: Material and process costs account for a relatively high proportion of the total cost of the fan, and production efficiency needs to be optimized.
Through the aforementioned precision processes, modern wind turbine blades achieve a balance between high strength, lightweight, and long lifespan, becoming one of the core components of wind energy technology.
