Polymer Foam Core Crash Absorber with Stiff Shell
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Current crash absorbers in automobile construction face challenges such as requiring a minimum size for force absorption, non-ideal absorption behavior, and sudden failure under impact due to their material properties, which limits their compactness and effectiveness in pedestrian protection.
Innovation Solution
A module comprising a polymer foam core with a density of at most 0.2 g/cm3 and a polymer material shell or insert with a tensile modulus of at least 700 MPa, designed to achieve an ideal force/displacement curve with uniform deformation and increased energy absorption in a compact form.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If crash absorbers are made of elastic foam material to absorb energy through deformation, then energy absorption capability is improved, but the module requires a prescribed minimum size and cannot achieve compact design
Solution Approach 1:
The patent employs a composite structure consisting of a polymer foam core (with density 0.05-0.2 g/cm³ and compressive modulus ≤200 MPa) enclosed by a shell made of polymer material (with density ≤2.0 g/cm³ and tensile modulus ≥700 MPa). This composite configuration allows the foam core to provide energy absorption through deformation while the shell maintains structural integrity and enables immediate force response, achieving both energy absorption and compact design in a single integrated module
2Use of energy by moving object
If crash absorbers are made of foam material to allow deformation for energy absorption, then energy absorption is improved, but the force/displacement curve is not ideal and does not rise immediately to maximum value
Solution Approach 1:
The composite structure combines a soft polymer foam core (providing gradual deformation and energy absorption) with a stiffer shell made of polymer material (providing immediate structural response). The shell's higher tensile modulus (≥700 MPa) enables an immediate rise in force to maximum value upon loading, while the foam core's compression characteristics maintain the force at this maximum level throughout the deformation process, producing the desired rectangular force/displacement curve with ideal absorption behavior
3Volume of moving object
If crash absorbers are made of metal or plastic rib structures to reduce size, then compactness is improved, but sudden failure occurs instead of uniform deformation
Solution Approach 1:
The patent utilizes a porous polymer foam core material with controlled density (0.05-0.2 g/cm³) and compressive modulus (≤200 MPa). This porous structure enables progressive, uniform deformation through cell collapse mechanisms that distribute stress evenly throughout the material volume, preventing sudden localized failure. The foam's cellular architecture allows controlled energy absorption through gradual compression while maintaining structural integrity throughout the deformation process
4Reliability
If foam density is increased to improve force response, then force/displacement behavior is improved, but the module size and weight increase
Solution Approach 1:
The patent optimizes the foam core density to a specific range (0.05-0.2 g/cm³) and compressive modulus (≤200 MPa) to achieve the desired force/displacement characteristics. By precisely controlling these material parameters, the foam provides sufficient deformation resistance to maintain force at maximum level while keeping the module compact. The shell's high tensile modulus (≥700 MPa) compensates for the low foam density, ensuring immediate force response without requiring increased foam density or module size
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 module achieves efficient energy absorption with a shorter deformation distance, preventing sudden collapse and allowing for more compact designs while maintaining effective force distribution, thus enhancing pedestrian protection and reducing repair costs.
Implementation Method 1
Module for absorbing energy from an impact to which the module has been subjected, via deformation
Implementation Method 2
a tensile modulus of elasticity of at least 700 MPa
Data Source
AI summary
The invention relates to a module for absorbing energy from an impact to which the module (3) has been subjected, via deformation, comprising a core (5) made of a polymer foam with a density of at most 0.2 g/cm3 and with a compressive modulus of elasticity of at most 200 MPa measured to DIN EN 826, wherein the core (5) has an at least to some extent enclosing shell (7) made of a polymer material, and/or comprises an insert (15) made of a polymer material, where the density of the polymer material of the shell (7) and/or of the insert (15) is at most 2.0 g/cm3 and its tensile modulus of elasticity is at least 700 MPa, measured to DIN EN ISO 527.