Braided Preform Consolidation Using Pulsed Pressure to Prevent Shear Lock

Solution Overview

Problem

Braided composite parts face challenges during consolidation due to shear lock and friction locking issues at fiber intersections, leading to uneven or out-of-tolerance results, necessitating reworking or discarding of the composite parts.

Innovation Solution

A method and apparatus for pulsed-pressure consolidation of braided preforms, where the consolidation pressure is iteratively increased and decreased to relax locked fiber intersections, allowing for continued consolidation without shear locking.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Force

If continuous consolidation pressure is applied to braided preforms, then consolidation force is maintained, but shear lock and friction locking occur at fiber intersections

Engineering Contradiction:

Improveconsolidation forceVSAvoidbraid uniformity

Core Design Contradiction:

ForceVSManufacturing precision

Solution Approach 1:

The patent applies periodic pulsing of consolidation pressure during the braiding process. The pressure alternates between applied and released states, creating a rhythmic cycle that prevents fiber intersections from locking while maintaining overall consolidation. This periodic action allows the braid to continue forming uniformly without the harmful effects of continuous pressure.

Inventive Principle:

Principle #19Periodic action

Solution Approach 2:

The consolidation pressure is transformed from a static continuous force into a dynamic pulsing force. The system adjusts the pressure state between applied and released conditions during the braiding operation, creating a dynamic environment that accommodates fiber movement at intersections while maintaining consolidation integrity.

Inventive Principle:

Principle #15Dynamics

2Productivity

If consolidation pressure is increased to improve consolidation, then consolidation effectiveness increases, but shear locking and friction locking are triggered

Engineering Contradiction:

Improveconsolidation effectivenessVSAvoidbraid tolerance

Core Design Contradiction:

ProductivityVSReliability

Solution Approach 1:

The patent implements periodic pulsing of consolidation pressure during the braiding process. The pressure alternates between applied and released states, creating a rhythmic cycle that prevents fiber intersections from locking while maintaining overall consolidation. This periodic action allows the braid to continue forming uniformly without the harmful effects of continuous pressure.

Inventive Principle:

Principle #19Periodic action

Solution Approach 2:

The consolidation pressure is transformed from a static continuous force into a dynamic pulsing force. The system adjusts the pressure state between applied and released conditions during the braiding operation, creating a dynamic environment that accommodates fiber movement at intersections while maintaining consolidation integrity.

Inventive Principle:

Principle #15Dynamics

3Object-affected harmful factors

If shear lock occurs at fiber intersections, then friction locking is prevented, but braid uniformity deteriorates

Engineering Contradiction:

Improvefriction locking preventionVSAvoidbraid uniformity

Core Design Contradiction:

Object-affected harmful factorsVSManufacturing precision

Solution Approach 1:

The patent implements periodic pulsing of consolidation pressure during the braiding process. The pressure alternates between applied and released states, creating a rhythmic cycle that prevents fiber intersections from locking while maintaining overall consolidation. This periodic action allows the braid to continue forming uniformly without the harmful effects of continuous pressure.

Inventive Principle:

Principle #19Periodic action

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 approach enables the prevention of shear locking and friction locking, ensuring that braided composite parts are fabricated within tolerance, reducing rework and discarding, and enhancing manufacturing efficiency and cost-effectiveness.

Implementation Method 1

consolidation pressure is iteratively increased and decreased to relax locked fiber intersections

Methodology Applied

Scientific EffectPulsed pressure: Pressure Increase

Implementation Method 2

areas within a weave that have encountered a friction lock or a shear lock relax, releasing the lock and enabling consolidation to continue

Methodology Applied

Scientific EffectStress relaxation: Stress Relaxation

Data Source

PatentEP3756846B1Pulsed-pressure consolidation of braided preforms for composite parts

Publication Date: 2023.09.06 THE BOEING CO

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AI summary

Systems and methods are provided for consolidating a preform (160) of braided fiber. One embodiment is a method that includes acquiring (202) a braided preform comprising fibers of unidirectional material that have been woven into a shape having a closed cross-section (162), disposing (204) the braided preform within a mandrel (150), disposing (206) an inflatable bladder (170) within the closed cross-section of the braided preform, and iteratively applying (208) pressure to the braided preform via the bladder to consolidate the braided preform against the mandrel.