Fiber Reinforced Laminate Wrinkle Prevention via Stiffness Grading
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Solution Overview
Problem
Fibre reinforced laminates often develop wrinkles during manufacturing due to thermal expansion mismatches and uneven surfaces, leading to reduced stiffness and strength, which can exceed safety margins and require repair or rejection.
Innovation Solution
A method involving the use of laterally extended layers with greater stiffness in one direction than another, which are integrated into the laminate to prevent wrinkles by alternating with fibre layers and infused with resin to maintain flexibility and strength, particularly suitable for wind turbine blades.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If the laminate thickness is increased to achieve desired structural strength, then the strength is improved, but the thermal expansion differences cause more severe wrinkles to occur
Solution Approach 1:
The laminate is segmented into multiple fibre layers separated by wrinkle-preventing layers. This segmentation allows the structure to achieve desired strength through multiple layers while the intermediate wrinkle-preventing layers prevent thermal expansion-induced wrinkling in each section.
Solution Approach 2:
Wrinkle-preventing layers are introduced as intermediary elements between adjacent fibre layers. These intermediate layers have different thermal expansion characteristics and mechanical properties that mediate the thermal expansion differences, preventing wrinkles while allowing the overall laminate to achieve required strength.
2Manufacturing precision
If wrinkle-preventing material is added between fibre layers to prevent wrinkles, then the wrinkle prevention is improved, but the device complexity increases
Solution Approach 1:
Wrinkle-preventing material is applied locally only at interfaces where wrinkles are most likely to occur, rather than throughout the entire laminate. This localized approach provides wrinkle prevention where needed while minimizing the added complexity and material usage.
Solution Approach 2:
The wrinkle-preventing layers use composite materials with specific combinations of fibres and matrix materials that provide the necessary wrinkle prevention properties. This allows achieving wrinkle prevention through material composition rather than structural complexity alone.
3Ease of manufacture
If the laminate is designed with uniform fibre orientation in all layers, then the manufacturing process is simplified, but wrinkles occur more easily due to thermal expansion
Solution Approach 1:
The laminate employs asymmetric fibre orientation patterns where adjacent fibre layers have different fibre directions (e.g., +θ and -θ angles). This asymmetric arrangement creates complementary thermal expansion behaviors that counteract wrinkles while maintaining manufacturing feasibility through standard layup procedures.
Solution Approach 2:
The fibre orientation angles are specifically adjusted to create thermal expansion compensation. By changing the orientation parameters of fibres in adjacent layers, the laminate achieves wrinkle prevention through controlled thermal expansion differences without complicating the manufacturing process.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The method effectively prevents wrinkles in fibre reinforced laminates by maintaining flexibility in one direction while ensuring stiffness in critical directions, enhancing the laminate's structural integrity and reducing the risk of delamination, making it suitable for complex shapes like wind turbine blades.
Implementation Method 1
The thermal expansion of a laminate during curing may exceed the thermal expansion of the mould, in which case the laminate may come under compressive pressure before the matrix material, typically a thermoplastic or thermosetting material, is cured sufficiently to maintain the fibres in the desired orientation.
Implementation Method 2
infusing resin into the stacked sheet and plies so that resin flows through the perforations in the metal foil sheet and intersperses between the plurality of fibre plies to form the laminated composite body
Implementation Method 3
the laminate may come under compressive pressure before the matrix material, typically a thermoplastic or thermosetting material, is cured sufficiently to maintain the fibres in the desired orientation
Data Source
AI summary
A method for manufacturing of a fiber reinforced laminate is provided that includes building up a part of the laminate to a determined thickness using at least one layer of fiber material placing a laterally extended layer on top of the partially completed laminate, the layer having in a first lateral direction a greater stiffness than in a second lateral direction and having in the first lateral direction a greater stiffness than the other layers constituting the laminate, building up a new part of the laminate to a determined thickness, and in case the thickness of the laminate built up pursuant is not as large as a desired thickness of the completed laminate, repeating steps placing a laterally extended layer and the building up a new part until the thickness of the laminate built up is equal to the desired thickness of the completed laminate.