Center Pillar Inner Metal-CFRP Composite Impact Resistance

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Solution Overview

Problem

Current center pillars with CFRP inner members face challenges in securing impact resistance while reducing weight and costs, as CFRP is lightweight but low in elongation, and filling reinforcing members increases weight and costs.

Innovation Solution

A center pillar design featuring a metal inner member with a CFRP member joined to its surface, where the CFRP member has a fiber direction within ±5 degrees of the longitudinal direction and a thermoplastic resin matrix, strategically placed between the opening and side sill mounting portion, enhancing impact resistance and weight reduction.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Weight of moving object

If a CFRP inner member is used in the center pillar, then weight is reduced, but impact resistance is insufficient due to low elongation of CFRP

Engineering Contradiction:

Improveweight of center pillarVSAvoidimpact resistance

Core Design Contradiction:

Weight of moving objectVSStrength

Solution Approach 1:

The patent applies composite materials by combining metal inner member (with high elongation) and CFRP member (with high strength) to create a center pillar structure that achieves both weight reduction and sufficient impact resistance. The metal inner member provides ductility and energy absorption during impact, while the CFRP member provides high strength and stiffness, creating a synergistic composite structure that overcomes the limitations of using CFRP alone.

Inventive Principle:

Principle #40Composite materials

2Strength

If a CFRP inner member is used throughout the entire center pillar, then impact resistance is improved, but cost increases significantly

Engineering Contradiction:

Improveimpact resistanceVSAvoidmanufacturing cost

Core Design Contradiction:

StrengthVSEase of manufacture

Solution Approach 1:

The patent applies local quality by strategically positioning the CFRP member only in specific high-stress regions (between the opening and side sill mounting portion) rather than using it throughout the entire center pillar. This localized application focuses the expensive CFRP material where it is most needed for impact resistance while using cheaper metal material in other regions, thereby reducing overall manufacturing cost while maintaining sufficient impact resistance.

Inventive Principle:

Principle #3Local quality

3Strength

If a reinforcing member is filled between outer member and inner member, then impact resistance is improved, but vehicle weight increases

Engineering Contradiction:

Improveimpact resistanceVSAvoidvehicle weight

Core Design Contradiction:

StrengthVSWeight of moving object

Solution Approach 1:

The patent applies composite materials by integrating the CFRP member as a surface-layer component bonded to the metal inner member, rather than filling a bulky reinforcing member between the outer and inner members. This composite structure provides reinforcement with minimal additional weight because the CFRP member is applied as a thin high-strength layer rather than a thick filling material, achieving impact resistance improvement without significant vehicle weight increase.

Inventive Principle:

Principle #40Composite materials

Data Source

PatentUS11897544B2Center pillar inner and center pillar

Publication Date: 2024.02.13 NIPPON STEEL CORPORATION

AI summary

Both weight reduction and impact resistance of a center pillar are satisfied while increase in cost is suppressed. A center pillar inner 20 is configured to include: an inner member 21 having an opening 21a to be a place where a retractor of a seat belt is mounted and a side sill mounting portion 21b to be a place where a side sill 30 is mounted; and a CFRP member 22 joined to a surface of the inner member 21, wherein the CFRP member 22 is provided at least between the opening 21a and the side sill mounting portion 21b.