Trapezoidal Bladder Jig for Composite Stringer Demolding

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Solution Overview

Problem

Existing manufacturing methods for composite material structures using hat stringers face challenges in efficiently demolding and maintaining gas barrier integrity during autoclaving, leading to gas leakage and difficulty in removing the bladder from the stringer.

Innovation Solution

A composite material structure manufacturing jig with a tubular body having a trapezoidal transverse section, coated with an inner gas barrier layer and formed from elastic materials, is used to mold prepreg onto frame components, ensuring easy insertion and removal while maintaining gas barrier capability.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a conventional bladder is used in hat stringer manufacturing, then the bladder can be inserted into the channel, but gas leakage occurs during autoclaving and demolding becomes difficult

Engineering Contradiction:

Improvegas barrier capabilityVSAvoidease of demolding

Core Design Contradiction:

ReliabilityVSEase of operation

Solution Approach 1:

The bladder is divided into multiple segments along its longitudinal direction, with each segment having a substantially rectangular cross-section. These segments can move relative to each other, allowing the bladder to expand and contract. This segmentation enables the bladder to maintain gas tightness during autoclaving while facilitating easy demolding through segmental movement that reduces friction and adhesion to the stringer.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The bladder incorporates movable joints between segments that allow dynamic expansion and contraction. During autoclaving, the bladder expands to fill the channel and maintain pressure. During demolding, the bladder can contract and segments can move relative to each other, reducing the adhesion force and enabling easy removal from the stringer channel.

Inventive Principle:

Principle #15Dynamics

2Ease of operation

If the bladder is made entirely elastic for flexibility, then insertion is easy, but gas barrier integrity is compromised during autoclaving

Engineering Contradiction:

Improveease of insertionVSAvoidgas barrier integrity

Core Design Contradiction:

Ease of operationVSReliability

Solution Approach 1:

The bladder is constructed as a composite structure combining elastic material segments with rigid or semi-rigid connecting elements. The elastic segments provide flexibility for easy insertion and removal, while the connecting elements maintain structural integrity and gas barrier properties during autoclaving. This composite construction allows the bladder to exhibit both flexible behavior during handling and rigid gas-tight behavior during processing.

Inventive Principle:

Principle #40Composite materials

3Ease of manufacture

If the bladder cross-section is circular for ease of manufacturing, then production is simpler, but followability to the skin and structural fit is reduced

Engineering Contradiction:

Improvemanufacturing simplicityVSAvoidfollowability to skin

Core Design Contradiction:

Ease of manufactureVSShape

Solution Approach 1:

The bladder is divided into rectangular segments that can be manufactured using simple molding processes. Each segment has a rectangular cross-section that matches the channel geometry. The segmentation allows these simple rectangular components to be assembled into a configuration that provides excellent followability to the skin and structural fit, while maintaining manufacturing simplicity at the component level.

Inventive Principle:

Principle #1Segmentation

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 enables efficient demolding and reduces gas leakage during autoclaving, enhancing the manufacturing process by improving the gas barrier capability and ease of bladder removal from the stringer.

Implementation Method 1

a tubular body (11) formed of an elastic material containing a reinforcement fiber

Methodology Applied

Scientific EffectReinforcement:

Implementation Method 2

An inner surface of the body is coated with a gas barrier layer

Methodology Applied

Scientific EffectGas barrier:

Data Source

PatentUS12485628B2Composite material structure manufacturing jig, method of manufacturing the same, and method of manufacturing composite material structure

Publication Date: 2025.12.02 KAWASAKI JUKOGYO KK

AI summary

A composite material structure manufacturing jig is used when manufacturing a composite material structure by adhering prepreg to a framework structure including a frame component that includes a channel extending along a longitudinal direction of the frame component. The composite material structure manufacturing jig is inserted in the channel of the frame component and used therein. The jig includes a tubular body formed of an elastic material containing a reinforcement fiber, the body including a trapezoidal transverse section that is a cross section orthogonal to a longitudinal direction of the body, the trapezoidal transverse section including an upper base and a lower base longer than the upper base. An inner surface of the body is coated with an inner peripheral film serving as a gas barrier layer.