Uv-ir combination curing system and method of use for wind blade manufacture and repair

Abstract

A UV-IR combination curing system and method for manufacture and repair of composite parts, such as for use in wind blade manufacture and repair. The system and method utilize UV and IR dual radiation sources to cure glass fiber reinforced laminates containing a photo initiator. The UV and IR dual radiation sources can be configured as discrete stand-alone UV and IR lamps used in a side by side configuration, a plurality of UV lamps with thermal IR radiation, a combined UV / IR lamp, or other forms of light sources providing both UV and IR radiation. To achieve high glass transition and complete curing of thick laminates, the IR radiation source is initially turned on to heat the laminate to close to 40° C-100° C. before the UV radiation source is turned on. The IR radiation source can be turned off after UV radiation source is activated.

Description

BACKGROUND[0001]Embodiments presented herein relate generally to curing techniques for composite materials, and more particularly, to curing techniques for use in manufacturing and repairing damage to structural composite products, such as wind turbine rotor blade laminates.[0002]Wind turbines have received increased attention as environmentally safe and relatively inexpensive alternative energy sources. With this growing interest, considerable efforts have been made to develop manufacturing and repair techniques for wind turbines that are reliable and efficient.[0003]Generally, a wind turbine includes a rotor having multiple blades. The rotor is mounted to a housing or nacelle, which is positioned on top of a truss or tubular tower. Utility grade wind turbines (i.e., wind turbines designed to provide electrical power to a utility grid) can have large rotors (e.g., 30 or more meters in length) and generally have an average wind turbine rotor blade size of 24 meters to 47 meters in l...

AI Technical Summary

Benefits of technology

"The patent describes a system and method for manufacturing or repairing a composite structure by heating and curing layers of the structure using two different radiation sources. The first layer contains a reinforced resin and a photoinitiator, while subsequent layers are added on top. The first layer is preheated throughout its thickness using a first radiation source, and then the entire structure is simultaneously cured through its thickness using a second radiation source. This process forms strong bonds between the layers and results in a composite structure with improved strength and durability."

Problems solved by technology

Wind turbine rotor blade designs have become increasingly complex to maximize aerodynamic properties and to withstand a variety of environments and conditions.

A wind turbine cannot generate electricity without the wind turbine rotor blades.

In many instances, if certain material failures occur in the wind turbine rotor blade, the wind turbine may be taken off-line and the wind turbine rotor blade must be replaced or repaired.

The costs and time associated with transportation of replacement blades and the installation of the replacement blades is very high.

Current methods used to repair wind turbine rotor blades are time and labor intensive and require special repair methods and facilities, as such, fabrication and repair of wind turbine rotor blades is difficult and expensive.

The adhesion between layers is generally good but other disadvantages sometimes make this approach impractical.

For instance, in manufacturing or repairing the root section of a wind turbine blades, sagging and dimensional distortion and fiber wrinkling during compaction may occur during the curing cycle.

Also, excessive reaction exotherm from thick parts may cause problems.

Unfortunately, this fabrication technique creates relatively weak secondary adhesive bonds between the composite layers.

These secondary adhesive bonds result in undesirably low interlaminar strength.

The up-tower time required for a long thermal curing process contributes significant man-hour cost for wind blade repair processes.

UV curing may provide faster laminate curing as an efficient in-field repair process, however, UV curing processes alone have been limited to thin laminate curing only.

It is widely known that UV curing processes alone cannot achieve high glass transition, and full curing of thick composite laminates.

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