Vehicle Outer Panel Ridgeline Design for Dent Resistance

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Solution Overview

Problem

Existing outer panels in vehicle bodies face challenges in maintaining dent resistance while achieving a beautiful appearance, particularly when thinned to reduce weight, as higher material strength exacerbates line displacement issues.

Innovation Solution

The outer panel is designed with a sheet thickness of less than 0.6 mm and an attainable yield stress of 360 MPa or more, featuring consistent surface properties in adjacent and separation regions, controlled ridgeline curvature, and managed stress differentials to suppress line displacement.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Weight of moving object

If the outer panel is thinned to reduce vehicle body weight, then weight reduction is achieved, but dent resistance is reduced

Engineering Contradiction:

Improvevehicle body weightVSAvoiddent resistance

Core Design Contradiction:

Weight of moving objectVSStrength

Solution Approach 1:

The patent changes the material parameter (yield stress) to 360 MPa or more while controlling sheet thickness to less than 0.6 mm, achieving weight reduction while maintaining dent resistance through optimized material properties

Inventive Principle:

Principle #35Parameter changes

2Strength

If a high-strength material is used to maintain dent resistance when the outer panel is thinned, then dent resistance is maintained, but line displacement becomes more significant

Engineering Contradiction:

Improvedent resistanceVSAvoidline displacement

Core Design Contradiction:

StrengthVSManufacturing precision

Solution Approach 1:

The patent optimizes multiple parameters simultaneously: sheet thickness (less than 0.6 mm), yield stress (360 MPa or more), and ridgeline radius of curvature (20 mm or less), achieving both dent resistance and suppressed line displacement through coordinated parameter control

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent creates different surface quality requirements for different regions: the adjacent region near the ridgeline allows for controlled surface properties while the separation region maintains consistent evaluation, addressing line displacement locally without compromising overall dent resistance

Inventive Principle:

Principle #3Local quality

3Ease of manufacture

If conventional press forming is used to form character lines, then the process is simple, but line displacement occurs on the outer surface

Engineering Contradiction:

Improvepress forming process simplicityVSAvoidline displacement

Core Design Contradiction:

Ease of manufactureVSManufacturing precision

Solution Approach 1:

The patent changes the material and geometric parameters (sheet thickness less than 0.6 mm, yield stress 360 MPa or more, ridgeline radius of curvature 20 mm or less) to enable conventional press forming to produce character lines without line displacement

Inventive Principle:

Principle #35Parameter changes

Data Source

PatentUS20250313069A1Outer panel

Publication Date: 2025.10.09 NIPPON STEEL CORPORATION

AI summary

An outer panel includes a ridgeline and a surface portion adjacent to both sides of the ridgeline on an outer surface. The outer panel has a sheet thickness of less than 0.6 mm and an attainable yield stress of 360 MPa or more. The surface portion includes an adjacent region adjacent to the ridgeline and a separation region adjacent to the adjacent region on an opposite side of the ridgeline. Evaluations of surface properties of the adjacent region and the separation region are consistent with each other.