Rotor Blade Spars Using Unidirectional Fibre Strips
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Solution Overview
Problem
The manufacturing of rotor blades in fibre composite design is cost-intensive and prone to errors due to the extensive manual work involved in the wet or prepreg construction method, necessitating a more efficient and cost-effective approach.
Innovation Solution
The use of unidirectional flat fibre strips to form spars running in the longitudinal direction of the rotor blade, which absorb bending and centrifugal forces, and are optimally loaded to minimize material usage while allowing for simpler handling and reduced production costs, along with the integration of a nose weight and fibre cap for resin infusion and erosion protection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If wet or prepreg construction method is used, then rotor blades can be manufactured with fibre composite design, but the manufacturing process requires large amount of manual work and is cost-intensive
Solution Approach 1:
The blade structure is divided into distinct functional components: spars made from unidirectional flat fibre strips for longitudinal strength, rib structures for cross-sectional support, and blade skin for aerodynamic surface. This segmentation allows each component to be optimized and manufactured separately using appropriate methods, reducing overall manufacturing complexity and cost while maintaining structural integrity
Solution Approach 2:
The invention transitions from traditional wet or prepreg methods to a hybrid approach combining resin injection technology for the blade skin with separate spar and rib construction. This parameter change in manufacturing methodology reduces manual work requirements and lowers costs while improving production efficiency
2Strength
If traditional fibre strands are used for spars, then structural strength can be achieved, but many individual small-cross-section fibre strands require complex positioning during laying process
Solution Approach 1:
The invention transitions from using multiple thin fibre strands in three-dimensional space to using flat fibre strips that can be positioned and laid more easily. The flat strips maintain the necessary longitudinal strength while reducing the complexity of positioning operations, as they can be handled as broader, more stable elements rather than numerous thin strands
Solution Approach 2:
Instead of using many individual fibre strands that are difficult to position, the invention uses flat fibre strips that replicate the load-bearing function of multiple strands but with simplified geometry. The flat strips can be manufactured and positioned as single elements, copying the structural function of bundled strands while eliminating the positioning complexity
3Ease of manufacture
If rectangular spars are used, then manufacturing is simplified, but they cannot easily be integrated in the profile body of a rotor blade due to aerodynamic profile requirements
Solution Approach 1:
The spar structure uses flat fibre strips with varying widths at different locations along the blade span. This local variation in strip width allows the spars to maintain a relatively simple manufacturing process while adapting to the changing cross-sectional requirements of the aerodynamic profile, enabling seamless integration into the blade body
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
This configuration optimizes material usage with minimal weight, enhances the structural integrity of the rotor blade, and simplifies the manufacturing process by reducing the number of fibre strands required, thereby lowering production costs and improving quality.
Implementation Method 1
the spars also absorb the bending and centrifugal forces acting on the rotor blade during operation
Implementation Method 2
the spars also absorb the bending and centrifugal forces acting on the rotor blade during operation
Implementation Method 3
The fibre layers of one step of the spar can then have substantially the same width, with the result the laying of the individual fibre layers is not unnecessarily complicated
Implementation Method 4
a nose weight or a nose lead is usually integrated in the profile nose in the profile of the rotor blade
Implementation Method 5
In its posterior half, in the finished state of the rotor blade the filling core is merely covered with a blade skin
Data Source
Figure 1~2
Figure 3~5
Figure 6~8
AI summary
A profile body in fibre composite design, in particular a rotor blade of a rotary-wing aircraft, comprising a filling core (10), comprising a blade skin (12) enveloping the filling core (10), comprising a nose shell (14) as erosion protection at a leading edge (16) of the rotor blade, comprising a nose weight (18) at the leading edge (16) of the rotor blade, and comprising spars (20) running in the longitudinal direction of the blade, is further developed in that the spars (20) are constructed of unidirectional flat fibre strips. A method for manufacturing a profile body is also specified.