SMP Mandrel for Composite Part Fabrication
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Current methods for fabricating composite parts are hindered by the difficulty and cost of removing rigid cure tools or mandrels, which often require destruction or are expensive and time-consuming, and existing solutions for reusable mandrels lack strength and rigidity.
Innovation Solution
The use of shape memory polymer (SMP) apparatuses that can change modulus from rigid to malleable states through temperature changes, allowing for the compression of composite materials against a mold during curing and easy removal by inducing a pressure differential, enabling the reuse of the SMP apparatus.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If a rigid cure tool or mandrel is used to fabricate composite parts, then the composite material can be properly supported and cured, but the mandrel becomes difficult and costly to remove, often requiring destruction or segmentation
Solution Approach 1:
The mandrel material's mechanical properties are changed by altering its temperature. At low temperatures, the SMP mandrel is rigid to support composite layup. At high temperatures (above glass transition temperature), the mandrel becomes soft and rubbery, enabling easy removal from the cured composite part without destruction or segmentation.
Solution Approach 2:
The mandrel is made from shape memory polymer (SMP) material, which is a composite material that combines rigid structural properties at low temperature with flexible removable properties at high temperature. This allows the same material to provide both structural support during manufacturing and ease of removal after curing.
2Ease of operation
If a segmented mandrel is used to facilitate removal, then the mandrel can be disassembled and removed after curing, but the installation and removal process becomes time-consuming and expensive
Solution Approach 1:
Instead of segmenting the mandrel structure, the invention changes the material's physical state through temperature. The SMP mandrel transitions from rigid to soft by heating above its glass transition temperature, allowing single-piece removal without time-consuming segmentation or complex installation procedures.
3Ease of operation
If an inflatable mandrel is used to enable removal by deflation, then the mandrel can be removed after curing, but the mandrel lacks strength and rigidity during composite lay-up
Solution Approach 1:
The SMP mandrel provides rigidity at low temperatures for proper composite support during layup, then transitions to a soft, flexible state at high temperatures for easy removal. This eliminates the need for inflatable structures while maintaining both structural integrity during manufacturing and ease of removal after curing.
4Ease of repair
If foam tooling with silicon coating is used, then the silicon bag can be removed and reused, but the foam tooling itself is not reusable and must be machined out of new foam each cycle
Solution Approach 1:
The entire mandrel is made from SMP material that can be reused indefinitely. After curing, the SMP mandrel is heated above its glass transition temperature to become soft and rubbery, allowing easy removal from the composite part. The mandrel can then be cooled and reused for the next production cycle, eliminating the need to machine new foam tooling each time.
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 facilitates efficient fabrication and removal of composite parts with integrated stiffeners, reducing production costs and time, while allowing the SMP apparatus to be reused multiple times, maintaining structural integrity during the process.
Implementation Method 1
triggering a change in modulus of the SMP apparatus from a rigid state to a malleable state
Implementation Method 2
systems and methods for using a reusable apparatus made of shape memory polymer (SMP)
Implementation Method 3
inducing a pressure differential that drives the SMP apparatus, in its malleable state, toward the composite material before and/or during cure to compress the composite material against a rigid mold
Data Source
Figure 1~2
Figure 3~4
Figure 5~6a
AI summary
A method and apparatus for fabricating a composite part, such as a fuselage or internal stiffener, with a shape memory polymer (SMP) apparatus usable as a rigid lay-up tool. The SMP apparatus may be heated until malleable, shaped, and then cooled in a desired rigid tool configuration. For example, cavities may be formed into the SMP apparatus for nesting components therein to co-bond or co-cure with the composite part. The composite material and/or nested components may be heated and compressed against the SMP apparatus. The SMP apparatus may be configured to remain rigid during the composite cure cycle. Once the composite material is cured, the SMP apparatus may be triggered to a malleable state and urged away from the cured composite material.