Composite Laminate Wrinkle Prevention via Mandrel Relief

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Solution Overview

Problem

Composite laminates for aircraft structures often wrinkle during formation into complex shapes, with existing solutions either increasing weight or being prohibitively labor-intensive, and manual methods compromise mechanical properties.

Innovation Solution

A method involving a lamination mandrel with preselected non-planar surface features to form a laminate with raised areas, which is then shaped into a three-dimensional object, ensuring a wrinkle-free surface without weight increase or labor costs.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If manual lamination is used to form complex shapes, then wrinkle formation is reduced, but labor costs become prohibitively high

Engineering Contradiction:

Improvewrinkle-free surfaceVSAvoidlabor cost

Core Design Contradiction:

ReliabilityVSEase of manufacture

Solution Approach 1:

The invention applies preliminary action by pre-forming raised surface features on the mandrel before laminate application. These pre-formed features create corresponding raised areas in the cured laminate that prevent wrinkle formation during subsequent forming operations. This preliminary preparation eliminates the need for manual wrinkle suppression techniques while maintaining automated manufacturing efficiency.

Inventive Principle:

Principle #10Preliminary action

2Reliability

If fiber cutting is performed to suppress wrinkles, then wrinkle formation is reduced, but mechanical properties decrease requiring weight increase

Engineering Contradiction:

Improvewrinkle-free surfaceVSAvoidpart weight

Core Design Contradiction:

ReliabilityVSWeight of moving object

Solution Approach 1:

The invention applies local quality by creating localized raised areas only in specific regions of the laminate where wrinkle formation is anticipated during forming. These localized features are formed by corresponding raised surface features on the mandrel, and they provide wrinkle suppression without requiring fiber cutting or additional weight throughout the entire structure.

Inventive Principle:

Principle #3Local quality

3Reliability

If joggle design is altered to shallower ramp angle to overcome wrinkling, then wrinkle formation is reduced, but structure weight increases

Engineering Contradiction:

Improvewrinkle-free surfaceVSAvoidstructure weight

Core Design Contradiction:

ReliabilityVSWeight of moving object

Solution Approach 1:

The invention applies dimensionality change by introducing a new dimension (surface height/depth) to the mandrel design. Instead of modifying the joggle geometry in the traditional planar dimensions, the solution adds vertical relief features to the mandrel surface that translate into raised areas in the laminate, providing wrinkle prevention through a different dimensional approach.

Inventive Principle:

Principle #17Another dimension (Dimensionality change)

Data Source

PatentUS9440401B1Method for producing composite laminated parts with non-ruled surfaces

Publication Date: 2016.09.13 THE BOEING CO

AI summary

Methods and apparatuses are disclosed for forming a three-dimensional object on a lamination mandrel having preselected areas comprising raised surface features, and forming a laminate with raised or lowered areas in preselected locations on the laminate such that the part comprises a wrinkle-free surface. The object is preferably a non-ruled part comprising a substantially wrinkle-free surface, and, according to preferred variations, the object is selected from the group including, for example, a joggled blade stringer, a joggled hat stringer, a curved spar, a joggled skin, etc.