Dash Crossmember Layout for Frontal Collision Energy Absorption

Solution Overview

Problem

Existing vehicle body structures face challenges in securing sufficient space for a power compartment while maintaining vehicle body rigidity and minimizing dash panel deformation during frontal collisions without increasing mass.

Innovation Solution

A vehicle body structure with a dash crossmember that has varying compressive strengths along its length, featuring a flexible central portion to absorb collision energy and a rigid side portion to maintain rigidity, combined with a backbone structure to distribute collision forces effectively.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Strength

If the dash crossmember is provided on the cabin outer side of the dash panel to improve vehicle body rigidity, then vehicle body rigidity is improved, but the space for the power compartment is reduced and the dash panel may deform during frontal collision

Engineering Contradiction:

Improvevehicle body rigidityVSAvoidpower compartment space

Core Design Contradiction:

StrengthVSVolume of stationary object

Solution Approach 1:

The dash crossmember is designed with non-uniform thickness, having a first thickness in the central portion and a second thickness in the side portions, where the first thickness is greater than the second thickness. This local quality variation allows the central portion to be more rigid for power unit contact during frontal collision, while the side portions are thinner to provide space for the power compartment and reduce overall mass.

Inventive Principle:

Principle #3Local quality

2Strength

If the dash crossmember is provided on the cabin outer side of the dash panel to improve vehicle body rigidity, then vehicle body rigidity is improved, but the dash panel may deform during frontal collision when the power unit moves rearward

Engineering Contradiction:

Improvevehicle body rigidityVSAvoiddash panel deformation

Core Design Contradiction:

StrengthVSObject-affected harmful factors

Solution Approach 1:

The dash crossmember features a first thickness in the central portion and a second thickness in the side portions, where the first thickness is greater than the second thickness. This local quality variation allows the central portion to be more rigid for power unit contact during frontal collision, while the side portions are thinner to provide space for the power compartment and reduce overall mass.

Inventive Principle:

Principle #3Local quality

3Object-affected harmful factors

If the power unit is laid out forward to avoid contact with the dash crossmember during frontal collision, then dash panel deformation is suppressed, but design freedom is reduced

Engineering Contradiction:

Improvedash panel deformationVSAvoiddesign freedom

Core Design Contradiction:

Object-affected harmful factorsVSAdaptability or versatility

Solution Approach 1:

The dash crossmember is designed with non-uniform thickness, having a first thickness in the central portion and a second thickness in the side portions, where the first thickness is greater than the second thickness. This local quality variation allows the central portion to be more rigid for power unit contact during frontal collision, while the side portions are thinner to provide space for the power compartment and reduce overall mass.

Inventive Principle:

Principle #3Local quality

4Object-affected harmful factors

If the dash panel is reinforced to suppress deformation during frontal collision, then dash panel deformation is reduced, but mass increases

Engineering Contradiction:

Improvedash panel deformationVSAvoidvehicle mass

Core Design Contradiction:

Object-affected harmful factorsVSWeight of moving object

Solution Approach 1:

The dash crossmember is designed with non-uniform thickness, having a first thickness in the central portion and a second thickness in the side portions, where the first thickness is greater than the second thickness. This local quality variation allows the central portion to be more rigid for power unit contact during frontal collision, while the side portions are thinner to provide space for the power compartment and reduce overall mass.

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

Simultaneously enhances vehicle body rigidity, minimizes dash panel deformation, and maintains design freedom by absorbing collision energy, thus ensuring passenger safety without excessive mass addition.

Implementation Method 1

the compressive strength of the first portion is lower than the compressive strength of the second portion... suppress deformation of the dash panel at the time when the power unit that moves rearward during a frontal collision comes into contact with the dash crossmember

Methodology Applied

Scientific EffectDeformation: Deformation

Data Source

PatentEP4046895B1Vehicle body structure

Publication Date: 2026.01.07 MAZDA MOTOR CORP

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AI summary

A vehicle body structure includes: a dash panel extending in a vehicle width direction and defining a cabin and a power compartment in front of the cabin; a power unit arranged in the power compartment; a floor panel extending rearward in the cabin from the dash panel; and a dash crossmember projected forward from the dash panel and extending in the vehicle width direction. The dash crossmember has: a first portion at least partially overlapping the power unit in a front view at the time when a vehicle is seen from front; and a second portion extending outward in the vehicle width direction from the first portion, and compressive strength of the first portion is lower than compressive strength of the second portion.