Mandrel With Sliding Lateral Members For Composite Curing
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Solution Overview
Problem
Mandrels with a high coefficient of thermal expansion cause gaps between composite parts and their lateral projections during heat curing, leading to premature disengagement, porosity, and laminate quality issues, and can crush lateral projections during cool-down due to their design.
Innovation Solution
A mandrel design featuring a central steel member with movable lateral members and rigid strut members having a coefficient of expansion similar to the composite part, allowing the lateral members to slide and preventing disengagement and crushing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If a steel mandrel is used to form composite parts with lateral projections, then the mandrel provides structural support during curing, but the high coefficient of thermal expansion of steel causes gaps to form between the lateral member and the composite part during heat curing
Solution Approach 1:
The patent changes the material parameter (coefficient of thermal expansion) of the lateral member to match that of the composite part. The lateral member is made from a material having a coefficient of thermal expansion substantially similar to the composite part, preventing gap formation during thermal cycling while maintaining structural support capability.
2Stress or pressure
If the lateral member is made from steel with high coefficient of thermal expansion, then the mandrel provides sufficient supporting pressure during cool-down, but the lateral member crushes the lateral projections of the composite part
Solution Approach 1:
The patent changes the material parameter (coefficient of thermal expansion) of the lateral member to match that of the composite part. This ensures that both materials expand and contract at similar rates during thermal cycling, maintaining appropriate supporting pressure during cool-down without exceeding the composite part's structural limits and causing crushing.
3Object-affected harmful factors
If the lateral member is designed as a floating lateral member free to slide along the mandrel, then the lateral member avoids crushing the lateral projections during cool-down, but the final disposition of the lateral member cannot be accurately controlled
Solution Approach 1:
The patent changes the material parameter (coefficient of thermal expansion) of the lateral member to match that of the composite part. This eliminates the relative movement and disengagement issues that plague floating lateral members, allowing the lateral member to maintain accurate positioning throughout the curing and cool-down process while still accommodating thermal effects.
4Manufacturing precision
If the lateral member is rigidly attached to the mandrel, then the lateral member maintains fixed position, but the lateral member cannot accommodate thermal expansion differences and causes gap formation or disengagement
Solution Approach 1:
The patent changes the material parameter (coefficient of thermal expansion) of the lateral member to match that of the composite part. This allows the lateral member to be rigidly attached to the mandrel while accommodating thermal effects, maintaining both position control and reliability throughout the curing process.
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 maintains supporting pressure during curing and cool-down, ensuring accurate placement and reducing defects in composite parts with lateral projections.
Implementation Method 1
rigid strut members (16) having a coefficient of expansion substantially similar to the composite part
Implementation Method 2
The mandrel, including the lateral member on the mandrel used to support the lateral projection, expands at a greater rate than the composite part
Data Source
Figure 1~2
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Figure 5~6
AI summary
A mandrel 10 suitable for forming a hollow part from a heat curable material includes an (a) an elongate central member 12 having a coefficient of expansion which is different than the coefficient of expansion of the cured heat curable material, (b) at least one lateral member 14, disposed at a first location 28 and projecting away from the outer surface 24 of the central member 12, the lateral member 14, being slidably attached to the central member 12, and (c) a rigid elongate strut member 16 having a coefficient of expansion substantially similar to the coefficient of expansion of the cured heat curable material. The first end 34 of the strut member 16 is affixed to the lateral member 14, and the second end 36 of the strut member 16 is affixed spaced apart from the lateral member 14.