Alternating Fiber Thickness Substrate to Counteract Resin Shrinkage Warping

Solution Overview

Problem

Composite materials used in vehicle bodies experience warping due to resin shrinkage, particularly because non-crimp fabric substrates with fibers aligned in a single direction have higher resistance to resin shrinkage in the fiber direction but not in directions intersecting the fibers, leading to uneven shrinkage and potential warping.

Innovation Solution

A reinforced substrate with alternating regions of reinforcing fibers aligned in a single direction and thinner regions with a higher volumetric content of resin, arranged in a specific pattern to minimize warping, where the first region includes large tows and the second region includes regular tows, and a third region with an increased resin content is formed to counteract shrinkage forces.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Strength

If a non-crimp fabric substrate with fibers aligned in a single direction is used, then the strength of the reinforced substrate in the fiber direction is improved, but warping occurs due to uneven resin shrinkage resistance

Engineering Contradiction:

Improvestrength in fiber directionVSAvoidwarping of composite material

Core Design Contradiction:

StrengthVSShape

Solution Approach 1:

The patent applies local quality by creating regions with different fiber thicknesses within the same substrate. Specifically, it defines a first region with a first fiber bundle thickness and a second region with a second fiber bundle thickness different from the first. This local variation in fiber distribution allows different regions to have different resistance characteristics to resin shrinkage, thereby compensating for the overall warping tendency while maintaining high strength in the fiber direction where needed.

Inventive Principle:

Principle #3Local quality

2Ease of manufacture

If resin is impregnated into the reinforced substrate, then the composite material is formed, but resin shrinkage causes warping due to anisotropic fiber arrangement

Engineering Contradiction:

Improvecomposite material formationVSAvoidwarping due to shrinkage

Core Design Contradiction:

Ease of manufactureVSShape

Solution Approach 1:

The patent applies local quality by creating regions with different fiber thicknesses within the same substrate. Specifically, it defines a first region with a first fiber bundle thickness and a second region with a second fiber bundle thickness different from the first. This local variation in fiber distribution allows different regions to have different resistance characteristics to resin shrinkage, thereby compensating for the overall warping tendency while maintaining high strength in the fiber direction where needed.

Inventive Principle:

Principle #3Local quality

Solution Approach 2:

The patent applies asymmetry by intentionally creating an asymmetric fiber bundle thickness distribution pattern. The first and second regions are arranged in a specific asymmetric pattern where the thickness variation is not uniform throughout the substrate. This asymmetric arrangement is designed to counterbalance the shrinkage forces that occur during resin curing, preventing warping while allowing the composite material to form properly.

Inventive Principle:

Principle #4Asymmetry

3Productivity

If fibers are aligned in a single direction to increase strength, then manufacturing efficiency is improved, but resistance to resin shrinkage becomes uneven in different directions

Engineering Contradiction:

Improvemanufacturing efficiencyVSAvoiduniformity of shrinkage resistance

Core Design Contradiction:

ProductivityVSStability of the object's composition

Solution Approach 1:

The patent applies local quality by creating regions with different fiber thicknesses within the same substrate. Specifically, it defines a first region with a first fiber bundle thickness and a second region with a second fiber bundle thickness different from the first. This local variation in fiber distribution allows different regions to have different resistance characteristics to resin shrinkage, thereby compensating for the overall warping tendency while maintaining high strength in the fiber direction where needed.

Inventive Principle:

Principle #3Local quality

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 configuration reduces warping by creating a reaction force that counteracts the shrinkage-induced warping force, maintaining structural integrity and reducing deformation in composite materials.

Implementation Method 1

A resin with which a reinforced substrate is impregnated shrinks when cured

Methodology Applied

Scientific EffectShrinkage: Thermal Contraction

Data Source

PatentUS11203178B2Reinforced substrate for composite material, composite material, and method for manufacturing reinforced substrate for composite material

Publication Date: 2021.12.21 NISSAN MOTOR CO LTD

AI summary

A reinforced substrate is used for molding a composite material. The reinforced substrate includes a first region and a second region. The first region includes reinforcing fibers extending in a fiber direction that is aligned in a single direction. The second region includes the reinforcing fibers aligned in the same direction as the fiber direction and being thinner than the first region. The first region and the second region are lined up in alternating fashion in a plane along a direction intersecting the fiber direction.