Composite Forming Apparatus Wrinkle Prevention
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Solution Overview
Problem
Existing methods for forming highly contoured composite structures, such as stringers, often result in wrinkling or buckling due to stress creation during the forming process, leading to undesirable fiber distortions and increased production costs and downtime, and rely on labor-intensive hand lay-up techniques.
Innovation Solution
A forming apparatus and method utilizing a constraining assembly with a first die and a second die, where the constraining assembly applies an upward resistive force to prevent wrinkling in the cap portion of the composite charge, using a constraining device that transfers stress away from the cap and retains the structure to prevent upward movement after forming.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Shape
If known forming apparatuses and methods are used to form highly contoured composite structures, then the desired contoured shape is achieved, but stresses are created that cause wrinkling or buckling in the contoured regions
Solution Approach 1:
The forming process is divided into multiple stages: initial forming of the contoured shape, followed by a separate stress relief stage where the formed structure is held in position while allowing stresses to redistribute and relax, preventing wrinkling and buckling
Solution Approach 2:
The apparatus applies constraints during the forming process to prevent wrinkling and buckling before they occur. The constraining elements are positioned in advance to counteract the stresses that would otherwise cause defects in the contoured regions
2Manufacturing precision
If hand lay-up techniques are used to reduce wrinkling or buckling, then wrinkle-free structures can be achieved, but the process becomes labor intensive and time consuming
Solution Approach 1:
The forming apparatus automatically applies and maintains the necessary constraints during forming through its mechanical design, eliminating the need for manual intervention. The system self-regulates the forming process to prevent wrinkles and buckles without requiring labor-intensive hand lay-up techniques
Solution Approach 2:
The manual mechanical process of hand lay-up is replaced by an automated forming apparatus that uses controlled mechanical constraints and force application to achieve wrinkle-free structures, significantly improving productivity while maintaining manufacturing precision
3Manufacturing precision
If hand lay-up techniques are used to prevent wrinkling, then manufacturing precision is improved, but manufacturing costs increase
Solution Approach 1:
The automated forming apparatus performs wrinkle prevention through its built-in mechanical constraints and control systems, eliminating the need for costly manual hand lay-up processes while maintaining high manufacturing precision
Solution Approach 2:
The expensive manual hand lay-up process is replaced by an automated forming system that achieves wrinkle prevention through controlled mechanical means, reducing labor costs and overall manufacturing costs while maintaining precision
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 effectively prevents wrinkling and fiber distortions in highly contoured composite structures, reducing production costs and downtime by automating the process and eliminating the need for hand lay-up techniques, resulting in wrinkle-free composite structures.
Implementation Method 1
The constraining device is designed to apply an upward resistive force against the cap portion, and against a downward compressive force applied by the second die
Implementation Method 2
The constraining device is designed to transfer stress away from the cap portion, and against a downward compressive force applied by the second die
Implementation Method 3
The retaining element is designed to retain the constraining device, when the second die is retracted after the highly contoured composite structure is formed
Data Source
AI summary
There is provided a forming apparatus for constraining a composite charge and forming the composite charge into a highly contoured composite structure. The forming apparatus includes a first die and a second die between which the composite charge is formed. The first die has pairs of first die portions spaced apart to define a die cavity into which the composite charge is formed into a contoured hat section having a cap. The forming apparatus includes a constraining assembly having a constraining device positioned in the die cavity. The constraining device is designed to constrain a cap portion, and to apply an upward resistive force against the cap portion, and against a downward compressive force applied by the second die, to provide wrinkle prevention in the cap as the contoured hat section is formed. The constraining assembly has a retaining element to retain the constraining device.