Vehicle Subframe Beads for Controlled Crash Buckling

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Solution Overview

Problem

Existing subframes in vehicles face challenges in controlling crash behavior after the stiffening element buckles, leading to rapid drop in force and energy dissipation, which compromises their ability to absorb deformation energy effectively during a crash.

Innovation Solution

The introduction of beads along the longitudinal members at predetermined buckling points optimizes the area moment of inertia, allowing for controlled force distribution and deformation, enabling even energy absorption and improved crash behavior while maintaining lightweight construction and simplicity in manufacturing.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Loss of energy

If the stiffening element is designed to buckle at predetermined points to absorb crash energy, then energy dissipation is improved, but the force level drops rapidly after buckling begins, compromising crash behavior control

Engineering Contradiction:

Improvecrash energy dissipationVSAvoidcrash behavior control

Core Design Contradiction:

Loss of energyVSReliability

Solution Approach 1:

The patent applies local quality by introducing beads only at specific predetermined buckling points along the stiffening element, rather than uniformly throughout. These localized beads create targeted areas of controlled deformation that maintain force levels during buckling, resolving the contradiction between energy dissipation and crash behavior control.

Inventive Principle:

Principle #3Local quality

2Weight of moving object

If the side member is designed with thin walls for lightweight construction, then weight is reduced, but the area moment of inertia and deformation control are compromised

Engineering Contradiction:

Improvesubframe weightVSAvoidarea moment of inertia

Core Design Contradiction:

Weight of moving objectVSStrength

Solution Approach 1:

The beads are introduced at specific locations where buckling is intended to occur, locally increasing the area moment of inertia only where needed for deformation control. This allows the rest of the thin-walled structure to remain lightweight while achieving sufficient strength and deformation control at critical points.

Inventive Principle:

Principle #3Local quality

Solution Approach 2:

The beads are pre-formed during manufacturing at predetermined buckling points, preparing the structure in advance for controlled deformation during crash events. This preliminary action ensures that the thin-walled structure will buckle in a controlled manner when subjected to impact forces.

Inventive Principle:

Principle #10Preliminary action

3Manufacturing precision

If beads are introduced at predetermined buckling points to optimize area moment of inertia, then deformation control is improved, but manufacturing complexity increases

Engineering Contradiction:

Improvedeformation control precisionVSAvoidcomponent structure

Core Design Contradiction:

Manufacturing precisionVSDevice complexity

Solution Approach 1:

The bead formation process is merged with the existing stamping or forming operations during subframe manufacturing. By integrating bead creation into the primary manufacturing process rather than adding separate operations, the patent achieves precise deformation control without significantly increasing manufacturing complexity.

Inventive Principle:

Principle #5Merging (Combining)

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

The solution ensures consistent force absorption and controlled deformation behavior, enhancing the subframe's ability to convert impact energy into deformation energy, thereby improving passenger compartment protection and safety during crashes.

Implementation Method 1

Beads introduced into the longitudinal member, which run approximately in the longitudinal direction of the longitudinal member, offer the possibility of optimizing the area moment of inertia or the moment of resistance of the longitudinal member in accordance with the requirements.

Methodology Applied

Scientific EffectArea moment of inertia: Moment of Inertia

Implementation Method 2

In the event of a crash, the stiffening element buckles downwards at these predetermined buckling points in order to prevent the subframe from blocking

Methodology Applied

Scientific EffectDeformation energy: Deformation

Implementation Method 3

as soon as the stiffening element begins to buckle, the level of force and thus the possible energy dissipation drop rapidly

Methodology Applied

Scientific EffectEnergy dissipation: Damping

Data Source

PatentEP2773549B1Subframe with beads

Publication Date: 2017.02.01 MAGNA INTERNATIONAL INC

AI summary

The invention relates to a subframe (1) designed as a cross member for a vehicle, having two side members (2) and a stiffening structure (3) between the two side members (2), wherein the side members (2) are designed substantially as hollow profile pieces and have at least one predetermined buckling point (18, 19) in the form of a curvature in the longitudinal extension direction of the side members (2). In order to improve this subframe (1) so that it ensures good mechanical properties such as strength, rigidity, acoustics and reinforcement of the body while driving, and absorbs sufficient deformation energy in the event of a crash, and nevertheless can be produced easily and cost-effectively with a low component weight, the side members (2) have at least one bead (16, 17) extending in the longitudinal direction of the side members (2) in the area of the designed buckling point (18, 19).