Rotating Die Tool for Wrinkle-Free Composite Stiffener Forming
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Solution Overview
Problem
In the aerospace industry, stiffeners attached to composite skins often experience wrinkling when deformed to conform to non-planar surfaces, leading to localized stress points and reduced strength, necessitating larger stiffeners and preventing complete compression of L-sections to form T-sections.
Innovation Solution
A die tool system with rotatable, telescopic inner and outer dies having radiused convex and concave portions that vary in radius of curvature, allowing for the formation of C-section and T-section fibre reinforced composite elements with adaptable radiused shoulders, enabling the production of stiffeners that can conform to ramped skin surfaces without wrinkling.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If stiffeners are deformed to conform to ramped skin surfaces, then the stiffeners can be attached to non-planar composite skins, but wrinkling occurs in the T-section stiffener reducing overall strength
Solution Approach 1:
The stiffener is divided into multiple sections with different radius of curvature values along its length. Each section can have a different radius of curvature to match the specific geometry of the ramped skin surface it needs to conform to, allowing the stiffener to adapt to complex geometries without wrinkling while maintaining structural integrity
Solution Approach 2:
The die tool incorporates rotatable features that allow the radius of curvature to be dynamically adjusted during the forming process. By rotating the die, different sections of the stiffener can be formed with different radius of curvature values, enabling the stiffener to conform to ramped surfaces without compromising strength
2Shape
If the radius of curvature is reduced to match ramped surfaces, then the stiffener can conform better to the skin, but the length of the die must be increased
Solution Approach 1:
The die incorporates a rotatable feature that allows the radius of curvature to be dynamically changed during the forming process. By rotating the die, different sections can be formed with different radius of curvature values without requiring multiple dies of increasing length, thus maintaining a compact tool design while achieving complex geometries
Solution Approach 2:
The invention changes the radius of curvature parameter along the length of the stiffener by rotating the die to different positions. This allows the formation of sections with varying curvature radii using a single die of fixed length, avoiding the need to increase die length while achieving the required shape conformity
Data Source
AI summary
A die tool for forming a C-section component having radiused shoulders, the includes a cylindrical inner die and an outer die having a cylindrical central portion connected to opposing end flanges by respective radiused concave portions. A portion of the inner die is arranged to be disposed between the end flanges of the outer die and spaced apart therefrom to define a cavity corresponding to the desired cross-section of the C-section component to be formed. The radiused convex and concave portions have a radius of curvature that varies about the circumference of the respective inner and outer dies. The inner and outer dies are rotatable such that the radius of curvature of the radiused convex and concave portions where the inner and outer dies are adjacent to one another varies as the inner and outer dies are rotated.