Netlike Sheet Corner Bending for Composite Surface Smoothness
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Solution Overview
Problem
The challenge in manufacturing composite materials for aircraft is achieving a smooth surface texture, as reinforcing fiber substrates with woven fabrics result in irregularities due to the use of high-rigidity sheet materials that are difficult to bend at corners, leading to variations in reinforcing fiber content and surface irregularities.
Innovation Solution
A method involving a netlike sheet with warp and weft yarns disposed in a lattice pattern, forming acute angles with the corners of the reinforcing fiber substrate, allowing easy bending and conformability, even with high-rigidity materials, by placing the sheet such that its peripheral edges are parallel or orthogonal to the corners, and using a vacuum-assisted resin transfer molding process.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a sheet material with high rigidity is used to cover the reinforcing fiber substrate, then surface irregularities are eliminated, but bending at corners becomes difficult and variation in fiber content occurs
Solution Approach 1:
The sheet material is segmented into a netlike structure with discrete warp and weft yarns forming a lattice pattern, replacing a continuous solid sheet. This segmentation allows the material to bend more easily at corners while maintaining rigidity in the planar state, resolving the contradiction between surface smoothness and bending ease.
Solution Approach 2:
The sheet material's structure is changed from a solid continuous form to a netlike lattice structure with controlled yarn spacing and intersection points. This parameter change reduces the material's resistance to bending while preserving its ability to eliminate surface irregularities, allowing easy corner bending without compromising surface smoothness.
2Shape
If a sheet material is forcibly bent at corners, then coverage is achieved, but contact strength varies locally and fiber content uniformity is compromised
Solution Approach 1:
The netlike sheet's segmented structure with discrete yarns and mesh openings allows progressive deformation at corners without creating localized stress concentrations. The segmentation distributes the bending load across multiple yarn intersections, preventing areas of strong and weak contact, thereby maintaining uniform fiber content while achieving corner conformability.
Solution Approach 2:
The sheet material functions as a composite structure combining flexibility (from the netlike open structure) and rigidity (from the yarn intersections). This composite nature enables the material to conform to corner shapes while maintaining sufficient structural integrity to prevent variation in fiber content distribution.
3Ease of manufacture
If the netlike sheet is placed with acute angles at corners, then bending becomes easy, but the placement geometry becomes more complex
Solution Approach 1:
The netlike sheet is deliberately placed with an asymmetric orientation where the lattice pattern forms acute angles with the corner edges rather than being aligned symmetrically. This asymmetric placement exploits the geometric properties of the lattice structure to facilitate bending at corners, and the complexity is managed through standardized placement protocols.
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 method enables uniform fiber content and surface smoothness by facilitating easy bending of the sheet at corners, preventing irregularities and ensuring consistent resin impregnation, thereby improving the quality and work efficiency of composite material production.
Implementation Method 1
a pressure in an interior of the bag film is reduced to a predetermined degree of vacuum, whereby a resin composition is injected into the bag film to be impregnated in the reinforcing fiber substrates
Implementation Method 2
a plurality of reinforcing fiber substrates are laminated and disposed on a forming die, the reinforcing fiber substrates are covered with a pass medium that is a netlike sheet for resin diffusion
Data Source
AI summary
A method for manufacturing a composite material includes placing a netlike sheet material, through which a resin composition permeates, on reinforcing fiber substrates disposed on a forming die. The method includes covering the reinforcing fiber substrates disposed on the forming die and the bag surface-smoothing sheet with a bag film to form a sealed forming space between the bag film and the forming die. The method includes infusing a resin composition into the forming space to impregnate the reinforcing fiber substrates. The method includes curing the resin composition impregnated in the reinforcing fiber substrates. Warp yarns and weft yarns are disposed in a lattice pattern and, after placing the bag surface-smoothing sheet on the reinforcing fiber substrates so that the warp yarns and the weft yarns form acute angles with respect to corners of the reinforcing fiber substrates, the bag surface-smoothing sheet projecting from the reinforcing fiber substrates is bent.