Vehicle Frame Member Rigidity Layout for Stable Collision Load Absorption

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Solution Overview

Problem

Existing frame members in vehicles fail to efficiently absorb collision loads when the impact absorbing member deforms unexpectedly, leading to a deterioration in collision-load absorption capacity.

Innovation Solution

A frame member with a closed-cross section design featuring varying bending rigidities in its components, where the first and third portions have higher rigidity than the second portion, allowing for uniform compression and efficient load absorption.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Loss of energy

If the impact absorbing member is allowed to deform freely, then it can absorb collision load through buckling deformation, but it may deform unexpectedly and fail to transmit collision load efficiently to the frame member

Engineering Contradiction:

Improvecollision load absorptionVSAvoidcollision load transmission reliability

Core Design Contradiction:

Loss of energyVSReliability

Solution Approach 1:

The lateral walls are designed with non-uniform thickness, where the first and third portions have greater thickness (higher bending rigidity) than the second portion. This local quality variation provides differential support: the higher rigidity portions prevent unexpected deformation and ensure reliable load transmission, while the lower rigidity second portion allows controlled buckling for energy absorption.

Inventive Principle:

Principle #3Local quality

2Strength

If the frame member has high bending rigidity throughout, then it can provide strong support, but it may hinder proper compression of the frame member along its extension direction during collision

Engineering Contradiction:

Improvesupport rigidityVSAvoidcompression along extension direction

Core Design Contradiction:

StrengthVSEase of operation

Solution Approach 1:

The lateral walls feature localized thickness variations with the second portion having reduced thickness (lower bending rigidity). This creates a compliant region that facilitates proper compression of the frame member along its extension direction during collision, while the thicker first and third portions maintain adequate support rigidity.

Inventive Principle:

Principle #3Local quality

Solution Approach 2:

The lateral walls are segmented into three distinct portions with different thicknesses along the extension direction. This segmentation allows each portion to perform its specific function: the first and third portions provide support, while the second portion enables compression, resolving the contradiction between overall strength and compressibility.

Inventive Principle:

Principle #1Segmentation

Data Source

PatentUS20250346297A1Frame member for vehicle and vehicle-body front structure

Publication Date: 2025.11.13 MAZDA MOTOR CORP

AI summary

A frame member comprises a first vertical wall, a second vertical wall, a first lateral wall, a second lateral wall, a first inner wall arranged between the first and second vertical walls in a vehicle width direction and extending in a vertical direction, interconnecting the first and second lateral walls, and a second inner wall arranged between the second vertical wall and the first inner wall in the vehicle width direction and extending in the vertical direction, interconnecting the first and the second lateral walls. Each of the first and second lateral walls comprises a first portion interconnecting the first vertical wall and the first inner wall, a second portion interconnecting the first and second inner walls, and a third portion interconnecting the second vertical wall and the second inner wall. Each bending rigidity of the first portion and the third portion is larger than that of the second portion.