Elastic Mandrel with Internal Open Spaces for Uniform Thermal Expansion
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Solution Overview
Problem
Existing mandrels used for curing composite structures often cause distortion and uneven pressure during the curing process, leading to suboptimal shape retention and structural integrity in composite materials.
Innovation Solution
A removable mandrel with internal open spaces designed for uniform thermal expansion, comprising an elastic body with an elastomeric material, allowing the mandrel to expand inwardly while exerting even pressure on the composite layup, reducing distortion and ensuring uniform support during curing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If solid rubber or composite mandrels are used for curing, then the mandrel can provide structural support during curing, but the mandrel may produce a cavity having a distorted cross-sectional shape and/or may exert uneven pressure on the composite laminate when subjected to heat and pressure
Solution Approach 1:
The mandrel is designed with an internal open space configuration that allows controlled thermal expansion. The open space geometry (such as daisy-shaped cross-section) enables the mandrel material to expand uniformly in all directions when heated, preventing distortion while maintaining structural support during autoclave curing
Solution Approach 2:
The invention changes the thermal expansion parameters of the mandrel by introducing internal open spaces. This modification allows the mandrel to expand uniformly when subjected to autoclave heat and pressure, converting the harmful effect of thermal expansion into a beneficial uniform pressure distribution that prevents cavity distortion
2Shape
If solid rubber or composite mandrels are used for curing, then the mandrel can maintain cavity shape, but the mandrel may exert uneven pressure on the composite laminate during curing at elevated temperatures
Solution Approach 1:
The internal open space structure acts as a thermal expansion buffer that allows the mandrel to expand uniformly when heated. This uniform expansion ensures even pressure distribution across the composite laminate surface, preventing localized stress concentrations while maintaining cavity shape retention
3Manufacturing precision
If a removable mandrel is designed to allow thermal expansion, then the mandrel can exert uniform pressure on the layup, but the mandrel requires complex internal open space geometry to achieve substantially uniform thermal expansion
Solution Approach 1:
The mandrel employs a specific asymmetric open space geometry (such as daisy-shaped cross-section) that is strategically designed to compensate for non-uniform thermal expansion patterns. The asymmetric configuration ensures that expansion occurs uniformly in all radial directions, achieving even pressure distribution while maintaining a manufacturable geometry
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 mandrel effectively minimizes distortion and ensures uniform pressure application, resulting in a more reliable and durable composite structure with reduced risk of shape collapse during the curing process.
Implementation Method 1
The mandrel includes one or more internal open spaces therein designed to allow the mandrel to thermally expand inwardly, while the exterior of the mandrel expands substantially uniformly to exert an even pressure over the layup
Data Source
AI summary
A mandrel used to cure a composite part layup has an elastic body and at least one internal open space therein. The internal open space is configured to allow substantially uniform thermal expansion of the body during curing.