Incised Prepreg for 3D Shape Conformity and Mechanical Strength

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Solution Overview

Problem

Current intermediate base materials for fiber reinforced plastics face challenges in achieving high mechanical properties and good surface quality, particularly in conforming to three-dimensional shapes and preventing incision openings, while also dealing with issues of positional deviation and wrinkle formation during production.

Innovation Solution

An incised prepreg with unidirectionally oriented reinforcing fibers and a resin, featuring a specific pattern of incisions that ensure a mean value of 10 or greater incisions per small circular region and a coefficient of variation within 20%, along with a cross-ply laminate configuration where prepregs intersect at right angles, is used to enhance mechanical properties and moldability.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Strength

If continuous reinforcing fibers are used in prepregs, then high mechanical properties are achieved, but deformation capability is insufficient causing wrinkles and bracing of reinforcing fibers

Engineering Contradiction:

Improvemechanical propertiesVSAvoiddeformation capability

Core Design Contradiction:

StrengthVSEase of manufacture

Solution Approach 1:

The continuous reinforcing fibers in the prepreg are incised into segmented sections along the fiber length, creating a structure that combines continuous fiber reinforcement with localized segmentation. This allows the fibers to maintain overall continuity for strength while being divided into manageable sections that can deform more easily during molding, preventing wrinkles and bracing issues.

Inventive Principle:

Principle #1Segmentation

2Shape

If incisions are provided in prepreg to improve flow and reduce mechanical property variation, then shape conformity is improved, but incision openings may occur affecting surface quality

Engineering Contradiction:

Improvethree-dimensional shape conformityVSAvoidsurface quality

Core Design Contradiction:

ShapeVSManufacturing precision

Solution Approach 1:

The incisions are provided with controlled depth and spacing, creating local variations in fiber structure without completely severing the fibers. The incision depth is optimized to allow sufficient fiber segmentation for improved flow and shape conformity, while maintaining enough fiber continuity to prevent opening at incision locations, thus preserving surface quality.

Inventive Principle:

Principle #3Local quality

Solution Approach 2:

The incision parameters including depth, spacing, and angle are precisely controlled to achieve optimal balance between shape conformity and surface quality. By adjusting these parameters, the prepreg can flow into three-dimensional shapes effectively while preventing incision openings that would compromise surface appearance.

Inventive Principle:

Principle #35Parameter changes

3Ease of manufacture

If punching die with blade is used to produce incised prepreg, then incisions are provided, but positional deviation occurs in fine incisions

Engineering Contradiction:

Improveincision productionVSAvoidincision position accuracy

Core Design Contradiction:

Ease of manufactureVSManufacturing precision

Solution Approach 1:

The mechanical punching die system is replaced with a rotary blade roll system that provides continuous incision action. This substitution eliminates the intermittent punching action that causes positional deviation, replacing it with a continuous rotary mechanism that maintains consistent incision positioning throughout the prepreg width and length.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The rotary blade roll operates with periodic blade contact points arranged around the roll circumference, creating regular, evenly-spaced incisions as the roll rotates. This periodic action ensures consistent incision positioning and spacing, eliminating the random positional deviations associated with intermittent punching operations.

Inventive Principle:

Principle #19Periodic action

4Productivity

If incised prepreg is produced by pressing against rotary blade roll, then continuous incisions are achieved, but wrinkle formation and positional deviation occur during production

Engineering Contradiction:

Improvecontinuous production capabilityVSAvoidproduction stability

Core Design Contradiction:

ProductivityVSManufacturing precision

Solution Approach 1:

The prepreg is pre-tensioned and pre-positioned before contacting the rotary blade roll, ensuring proper alignment and tension control. This preliminary action prevents wrinkle formation during the incision process and maintains consistent positional accuracy throughout continuous production, enhancing overall production stability.

Inventive Principle:

Principle #10Preliminary action

Data Source

PatentUS11926074B2Incised prepreg, cross-ply laminate, and production method for incised prepreg

Publication Date: 2024.03.12 TORAY INDUSTRIES INC

AI summary

An intermediate base material is provided that is excellent in the conformity to three-dimensional shapes and that, when formed into a fiber reinforced plastic, develops good surface quality and high mechanical properties.According to one aspect, an incised prepreg is provided that has, in at least a partial region in a prepreg that contains unidirectionally oriented reinforcing fibers and a resin, a plurality of incisions that divide reinforcing fibers, wherein, in the case where a population is made up of the numbers of incisions contained in ten small circular regions of 10 mm in diameter randomly selected in the aforementioned region, a mean value for the population is 10 or greater and a coefficient of variation therefor is within 20%.