Segmented Bumper Energy Absorbers for Stiffness Trade-offs

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Solution Overview

Problem

Vehicle bumpers face a design challenge in balancing stiffness for low-speed damageability and pedestrian protection, as existing regulations create competing design principles that require different stiffness levels for these scenarios.

Innovation Solution

A bumper assembly with multiple energy-absorbing devices, including a first elastically deformable device and a second device with higher crush resistance, which absorb energy in stages to adapt to varying impact conditions, providing adjustable stiffness for both low-speed damageability and pedestrian protection.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Strength

If the bumper stiffness is increased to prevent damage at low speed, then low-speed damageability is improved, but pedestrian protection is worsened due to excessive stiffness at high speed impact

Engineering Contradiction:

Improvebumper stiffnessVSAvoidpedestrian injury

Core Design Contradiction:

StrengthVSObject-affected harmful factors

Solution Approach 1:

The bumper system is segmented into multiple energy-absorbing devices with different crush resistance levels. The first energy-absorbing device has lower crush resistance for pedestrian protection, while the second energy-absorbing device has higher crush resistance for low-speed damageability, allowing the system to provide different stiffness characteristics for different impact scenarios.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The system changes the effective stiffness parameter based on impact conditions by utilizing multiple energy-absorbing devices with different crush resistance characteristics. This allows the bumper to exhibit lower stiffness during pedestrian impacts and higher stiffness during low-speed vehicle collisions, resolving the contradiction between the two opposing requirements.

Inventive Principle:

Principle #35Parameter changes

2Object-affected harmful factors

If the bumper stiffness is decreased to improve pedestrian protection, then pedestrian protection is improved, but low-speed damageability is worsened due to insufficient stiffness

Engineering Contradiction:

Improvepedestrian injuryVSAvoidbumper stiffness

Core Design Contradiction:

Object-affected harmful factorsVSStrength

Solution Approach 1:

The bumper system is divided into multiple energy-absorbing devices with differentiated functions. The first device provides lower crush resistance for pedestrian safety, while the second device provides higher crush resistance to maintain bumper strength during low-speed collisions, allowing the system to satisfy both opposing requirements simultaneously.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The system dynamically adjusts its effective stiffness based on the impact scenario. During pedestrian impacts, the lower crush resistance of the first energy-absorbing device dominates to protect pedestrians. During low-speed vehicle collisions, the higher crush resistance of the second energy-absorbing device engages to prevent bumper damage, creating a dynamic stiffness adaptation mechanism.

Inventive Principle:

Principle #15Dynamics

3Ease of manufacture

If a single stiffness value is used for the bumper, then manufacturing is simplified, but the bumper cannot adapt to different impact conditions

Engineering Contradiction:

Improvebumper manufacturing simplicityVSAvoidimpact condition adaptation

Core Design Contradiction:

Ease of manufactureVSAdaptability or versatility

Solution Approach 1:

Instead of manufacturing a single complex adjustable stiffness bumper, the system is segmented into multiple energy-absorbing devices with fixed but different crush resistance values. This segmentation approach maintains manufacturing simplicity for each individual component while achieving adaptability at the system level through the combination of multiple devices with different characteristics.

Inventive Principle:

Principle #1Segmentation

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 bumper assembly effectively absorbs energy across multiple stages, allowing for tunable stiffness to meet different impact conditions, enhancing both low-speed damageability and pedestrian protection while maintaining a high-quality aesthetic appearance.

Implementation Method 1

a first energy absorbing device extending from the bumper, the first energy absorbing device having a second axis perpendicular to the first axis, the first energy absorbing device being elastically deformable along the second axis

Methodology Applied

Scientific EffectElastic deformation: Elasticity

Implementation Method 2

a second energy absorbing device within the first energy absorbing device and being shorter than the first energy absorbing device

Methodology Applied

Scientific EffectEnergy absorption through crushing: Plasticity

Data Source

PatentUS10723297B2Vehicle energy absorbing device

Publication Date: 2020.07.28 FORD GLOBAL TECH LLC

AI summary

A bumper assembly includes a bumper elongated along a first axis. The bumper assembly includes a first energy absorbing device extending from the bumper, the first energy absorbing device having a second axis perpendicular to the first axis, the first energy absorbing device being elastically deformable along the second axis. The bumper assembly includes a second energy absorbing device within the first energy absorbing device and being shorter than the first energy absorbing device.