Aluminum Door Beam Neutral Axis Weld Placement

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Solution Overview

Problem

Aluminum alloy extrusion door beams with closed-section structures have welded portions that exhibit lower mechanical properties, particularly a low fracture limit, leading to reduced strength and energy absorption due to microstructural differences between welded and normal portions.

Innovation Solution

The door beam design features welded portions located in the vicinity of the neutral axis, minimizing bending loads during deformation and enhancing energy absorption by distributing loads more evenly across the structure.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Shape

If a hollow die (porthole die, bridge die, or spider die) is used to manufacture the aluminum alloy extrusion with a closed-section structure, then the closed-section structure can be formed, but welded portions are necessarily created which have low mechanical properties and low fracture limit

Engineering Contradiction:

Improveclosed-section structureVSAvoidfracture limit of welded portion

Core Design Contradiction:

ShapeVSStrength

Solution Approach 1:

The patent applies local quality by strategically positioning welded portions only in the webs rather than throughout the entire extrusion, and specifically locating them near the neutral axis where stress is minimized. This localized approach maintains the closed-section structure while concentrating welding only where structurally acceptable, thereby preserving overall strength despite the inherent weakness of welded areas.

Inventive Principle:

Principle #3Local quality

2Ease of manufacture

If welded portions exist in the aluminum alloy extrusion, then the closed-section structure can be manufactured, but the mechanical properties and energy absorption of the door beam are reduced

Engineering Contradiction:

Improvemanufacturability of closed-section structureVSAvoidenergy absorption capacity

Core Design Contradiction:

Ease of manufactureVSUse of energy by moving object

Solution Approach 1:

The patent applies preliminary action by pre-positioning welded portions near the neutral axis during the extrusion manufacturing process. This advance placement ensures that when collision occurs and energy absorption is required, the welded portions are already in optimal locations where they will experience minimal stress, thereby preserving the door beam's energy absorption capacity despite the presence of welds.

Inventive Principle:

Principle #10Preliminary action

3Productivity

If welded portions are present in the door beam, then the closed-section extrusion can be produced, but deformation starts from the welded portions during collisions reducing overall strength

Engineering Contradiction:

Improveproduction efficiency of door beamVSAvoidstructural integrity during collision

Core Design Contradiction:

ProductivityVSReliability

Solution Approach 1:

The patent converts the harmful effect of welded portions (which are inherently weaker and prone to deformation) into a beneficial arrangement by positioning them near the neutral axis. This strategic placement transforms the weakness into an acceptable feature, as the welded portions experience minimal stress during collision, preventing them from becoming initiation points for deformation and maintaining structural integrity.

Inventive Principle:

Principle #22Blessing in disguise (Convert harm into benefit)

Data Source

PatentUS10814368B2Door beam

Publication Date: 2020.10.27 KOBE STEEL LTD

AI summary

A door beam including an aluminum alloy extrusion extended in a longitudinal direction and having a pair of webs and a pair of flanges to be positioned on an inside and an outside in a vehicle width direction. The pair of webs connect the pair of flanges at joint portions of each of the pair of webs such that the pair of webs and the pair of flanges form a closed cross section in a direction perpendicular to the longitudinal direction, and each of the pair of webs has a welded portion in a vicinity of a neutral axis passing through a centroid of the closed cross section and parallel to the pair of flanges.