Flexible Compactor for Contoured Composite Mandrels

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Solution Overview

Problem

Elongate composite members, such as stringers in the aircraft industry, often develop wrinkles when compacted against contoured mandrel surfaces, leading to undesirable performance and structural issues due to uneven material distribution and compression.

Innovation Solution

A method involving a flexible compactor that adheres to the composite member, aligns it with the mandrel surface, and forms it by drape or lash forming, starting at the apex of the contour, allowing controlled wrinkling into kerfs to distribute excess material uniformly, reducing localized compressive forces and maintaining a constant relationship with the mandrel.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Shape

If conventional compaction methods are used to compact uncured composite members against contoured mandrel surfaces, then the composite member conforms to the mandrel contour, but wrinkles develop in the composite material particularly near the center of curvature

Engineering Contradiction:

Improvecontour conformityVSAvoidwrinkle control

Core Design Contradiction:

ShapeVSManufacturing precision

Solution Approach 1:

The method applies preliminary action by first bringing the uncured composite member into contact with the mandrel at the apex of the contour before progressively forming outward. This sequential approach from apex to sides allows controlled material flow and prevents excessive compression that causes wrinkles, while still achieving full contour conformity.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The contoured mandrel surface is conceptually segmented into different zones: the apex region and the side regions. The forming process treats these zones differently by initiating contact at the apex and progressively forming the sides, allowing each zone to be formed under optimized conditions that prevent wrinkle development.

Inventive Principle:

Principle #1Segmentation

2Adaptability or versatility

If flexible compactors are used to conform to contoured tool surfaces, then the compactor can adapt to complex mandrel geometries, but material compression still causes excess material to accumulate and bunch into wrinkles

Engineering Contradiction:

Improvecontour adaptationVSAvoidmaterial wrinkling

Core Design Contradiction:

Adaptability or versatilityVSObject-generated harmful factors

Solution Approach 1:

The flexible compactor is pre-positioned to contact the composite member at the apex of the mandrel contour before compression begins. This preliminary positioning ensures that material flow is controlled from the apex outward, preventing accumulation and wrinkle formation while the compactor adapts to the full contour geometry.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The compaction process applies different local qualities to different regions of the composite member. The apex region receives initial contact and controlled forming, while the side regions are formed progressively afterward. This localized control of the compaction sequence prevents uniform compression that would cause wrinkles.

Inventive Principle:

Principle #3Local quality

Data Source

PatentEP2986440B1Compacting uncured composite members on contoured mandrel surfaces

Publication Date: 2020.01.15 THE BOEING CO

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AI summary

An uncured composite member (30) is formed over a mandrel (66) having a contour using a flexible compactor (44). Forming is performed outwardly from the apex of the contour.