Device for preforming a hollow composite profile and method for preforming a hollow composite profile, in particular of the composite stiffener type
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Solution Overview
Problem
Existing methods for preforming composite stiffeners result in structural defects due to uneven thickness and stress concentrations at the male and female angles, leading to structural fragility.
Innovation Solution
A device comprising a male punch, a bell, and deformable bladders with stiffened and softened wall portions is used to preform a hollow composite profile, applying semi-finished composite material against the punch without mechanical stress, ensuring consistent thickness and structural integrity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Shape
If side clamps and male punch are used to shape semi-finished composite material, then the material can be shaped into desired profile, but strong tensions appear at male angles resulting in insufficient material thickness
Solution Approach 1:
The patent replaces the traditional mechanical punching system with a pneumatic inflation system. Instead of using a male punch that mechanically forces the material, the invention uses an inflatable bag that gently expands to shape the composite material, eliminating the strong tensions and material thinning at male angles while achieving the desired profile shape.
Solution Approach 2:
The inflatable bag acts as an intermediary between the shaping force and the composite material. Rather than direct mechanical contact that causes stress concentrations, the pneumatic pressure through the flexible bag surface distributes the shaping force evenly, preventing material thickness reduction at critical angles.
2Shape
If waterproof tarpaulin and vacuum pressure are used to press semi-finished composite material, then the material can be conformally shaped, but insufficient tension appears at female angles resulting in excessive material thickness
Solution Approach 1:
The patent replaces the vacuum pressure system with a direct pneumatic inflation system. By inflating the bag from the inside, the shaping force is applied uniformly in all directions, eliminating the insufficient tension at female angles that occurs with external vacuum pressure, thereby preventing excessive material thickness while maintaining profile conformity.
3Ease of manufacture
If traditional preforming methods are used, then composite stiffeners can be manufactured, but structural defects appear due to uneven thickness and stress concentrations
Solution Approach 1:
The patent replaces traditional mechanical and vacuum preforming systems with pneumatic inflation, eliminating stress concentrations and thickness variations that cause structural defects. This maintains ease of manufacture while significantly improving structural integrity and reliability of the composite stiffeners.
Solution Approach 2:
The invention changes the pressure application method from mechanical contact or external vacuum to internal pneumatic pressure. This parameter change in the shaping process ensures uniform material distribution and eliminates stress concentrations, producing structurally sound stiffeners without compromising manufacturability.
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 produces composite stiffeners with uniform thickness and improved structural integrity, eliminating stress defects and enhancing the reliability of composite structures.
Implementation Method 1
at least one deformable bladder arranged inside the bell and configured to be put under pressure; the device being configured to preform the hollow composite profile by deformation of the at least one bladder under the effect of pressure
Implementation Method 2
the at least one bladder comprising a wall with a softened wall portion and a stiffened wall portion, the stiffened wall portion being preformed so as to have a predefined profile whose shape at rest corresponds at least in part to the male profile of the hollow composite profile
Data Source
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AI summary
The invention relates to a device (100) for preforming a hollow composite profile comprising a male profile and a female profile, comprising: a male punch (110), a bell (120) facing the punch, and a deformable bladder (130) arranged in the bell and capable of being pressurized; and which is configured to receive a strip of semi-finished composite material (200) between the punch and the bladder; the bladder comprising a wall (131) with a softened wall portion, and a stiffened wall portion which is preformed so as to have a predefined profile whose shape at rest corresponds to the male profile of the profile, and which is configured to come into contact with the strip of material; and which is configured to preform the profile by deforming the bladder under pressure, so as to apply and then compact the strip of material against the punch.