Pre-formed Spar Cap Assembly with Sloped Ramp Sections
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Solution Overview
Problem
The manufacturing of wind turbine rotor blades faces challenges with positional tolerance and thickness variations of pre-formed spar caps, leading to the formation of problematic regions that can result in longitudinal wrinkles and structural weaknesses during the manufacturing process.
Innovation Solution
A spar cap assembly with a pre-formed spar cap section and sloped ramp sections, encapsulated by wrapping layers, which allows for increased positional tolerance and gradual transitions with blade panels, reducing the risk of longitudinal wrinkles by aligning with complementary panel shapes and maintaining equal thicknesses.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If pre-formed spar caps with constant thickness are used, then manufacturing process is simplified, but positional tolerance deviations cause longitudinal wrinkles and structural weaknesses
Solution Approach 1:
The spar cap is designed with variable thickness along its length, with thicker sections at ramp locations and thinner sections at mid-span locations. This local variation in geometry allows the spar cap to accommodate positional tolerance deviations without creating sharp thickness transitions, thereby preventing longitudinal wrinkles while maintaining structural integrity.
Solution Approach 2:
The spar cap geometry is made adaptive through its variable thickness profile, which dynamically responds to positional variations in the ramp sections. The gradual thickness transition allows the structure to absorb manufacturing tolerances and maintain reliability despite variations in assembly positioning.
2Adaptability or versatility
If hand lay-up of composite structures is used to form spar caps, then manufacturing flexibility is maintained, but production time increases significantly with increased thickness and number of layers
Solution Approach 1:
The spar cap is pre-formed as a complete three-dimensional component with the required variable thickness profile and ramp sections integrated beforehand. This preliminary formation eliminates the need for time-consuming hand lay-up of multiple layers during final assembly, significantly reducing production time while maintaining manufacturing flexibility through modular design.
Solution Approach 2:
Multiple functional elements (spar cap body, ramp sections, and encapsulating layers) are merged into a single pre-formed integrated component. This consolidation reduces the number of separate manufacturing steps and assembly operations required, thereby increasing productivity without sacrificing design adaptability.
3Strength
If sharp thickness transitions are present at ramp locations, then structural efficiency is improved, but longitudinal wrinkles form due to improper resin flow and fiber alignment
Solution Approach 1:
The spar cap incorporates rounded transitions and curved surfaces at ramp locations instead of sharp angular transitions. This curvature allows for gradual thickness changes that facilitate proper resin flow and fiber alignment during manufacturing, eliminating the conditions that lead to longitudinal wrinkles while preserving structural efficiency.
Solution Approach 2:
The thickness parameter of the spar cap is varied continuously along its length, with gradual transitions at ramp locations rather than abrupt changes. This parameter modification ensures smooth resin impregnation and fiber distribution, preventing wrinkle formation while maintaining the structural efficiency needed for load-bearing performance.
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 solution enhances the structural strength of wind turbine rotor blades by reducing the formation of longitudinal wrinkles and improving manufacturing precision, resulting in a more reliable and cost-effective blade production process.
Implementation Method 1
The one or more wrapping layers within which the spar cap section, the first ramp section and the second ramp section are encapsulated by resin injection molding
Data Source
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AI summary
A spar cap assembly (30) for a wind turbine rotor blade (10), the spar cap assembly (30) comprising: - a spar cap section (50) comprising a composite material, the spar cap section (50) having a longitudinally extending slab shape defined by first and second mutually opposed and longitudinally extending faces (51,52) and by first and second longitudinally extending lateral sides (61,62), the separation between the first and second faces (51,52) defining thickness of the spar cap section (50), the spar cap section (50) having a vertical axis (97) extending between the first and the second faces (51, 52) and a transverse axis (96) extending between the first and the second lateral sides (61,62), wherein a longitudinal axis (99), the vertical axis (97) and the transverse axis (96) are mutually perpendicular; - a first ramp section (70) extending longitudinally and positioned adjoining the first lateral side (61) of the spar cap section (50), the first ramp section (70) having mutually opposed spar cap side (71) and sloped side (72), wherein the spar cap side (71) of the first ramp section (70) adjoins the first lateral side (61) of the spar cap section (50) and has a thickness (ti ) substantially equal to the thickness (tsi ) of the first lateral side (61) of the spar cap section (50), and wherein the sloped side (72) of the first ramp section (70) slopes outward with respect to the spar cap section (50), and wherein the first ramp section (70) further comprises a mid-section (M) having a thickness (tM ) equal to or greater than the thickness (ti ) of the spar cap side (71) of the first ramp section (70), the thicknesses (ti ,tM ) of the spar cap side (71) and the mid-section (M) of the first ramp section (70) measured parallel to the vertical axis (97) of the spar cap section (50); - a second ramp section (80) extending longitudinally and positioned adjoining the second lateral side (62) of the spar cap section (50), the second ramp section (80) having spar cap side (81) and sloped side (82), wherein the spar cap side (81) of the second ramp section (80) adjoins the second lateral side (62) of the spar cap section (50) and has a thickness (t2 ) substantially equal to the thickness (ts2 ) of the second lateral side (62) of the spar cap section (50), and wherein the sloped side (82) of the second ramp section (80) slopes outward with respect to the spar cap section (50), the thickness (t2 ) of the spar cap side (81) of the second ramp section (80) measured parallel to the vertical axis (97) of the spar cap section (50); and - one or more wrapping layers (90) encapsulating the spar cap section (50), the first ramp section (70) and the second ramp section (80), wherein the one or more wrapping layers (90), the spar cap section (50), the first ramp section (70) and the second ramp section (80) are resin injection molded.