Fiber-Reinforced Plastic Body Support with Variable Wall Thickness

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Solution Overview

Problem

Current body structure supports for motor vehicles, particularly those made of fiber-reinforced plastic, fail to effectively absorb collision energy through deformation and instead experience brittle failure, which is inefficient in energy dissipation and control of deceleration/acceleration forces on occupants.

Innovation Solution

A body structure support with hollow sections of varying diameters and wall thicknesses, designed to fail at different force levels, utilizing continuous fiber-reinforced plastic manufacturing processes like braiding, pultrusion, or winding, allowing for controlled energy absorption and deceleration management during collisions.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Weight of moving object

If body structure support is made of fiber-reinforced plastic with uniform wall thickness, then lightweight construction is achieved, but collision energy absorption is insufficient due to brittle failure at single force level

Engineering Contradiction:
Improveweight of body structure supportVSAvoidcollision energy absorption
Core Design Contradiction:
Weight of moving objectVSLoss of energy

Solution Approach 1:

The body structure support is divided into multiple wall sections with different wall thicknesses along its longitudinal axis. Each wall section is designed to fail at a different force level, creating multiple failure stages that progressively absorb collision energy. This segmentation allows the structure to maintain lightweight construction while improving energy absorption through controlled multi-level failure.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

Different wall sections of the body structure support are assigned different local properties, specifically varying wall thicknesses. The first wall section has a first wall thickness while the second wall section has a second wall thickness that differs from the first. This local quality variation enables each section to fail at different force levels, transforming the uniform brittle failure into a progressive energy absorption mechanism.

Inventive Principle:
Principle #3Local quality

2Device complexity

If body structure support is designed to fail at single force level, then structural simplicity is maintained, but deceleration force control on occupants is insufficient

Engineering Contradiction:
Improvestructural complexity of body structure supportVSAvoiddeceleration force control
Core Design Contradiction:
Device complexityVSEase of operation

Solution Approach 1:

The body structure support transitions from a static, uniform structure to a dynamic, variable-thickness structure. The varying wall thicknesses create a progressive failure sequence that dynamically adapts to collision forces. As collision force increases, different wall sections fail in sequence, providing dynamic deceleration control that better protects occupants while maintaining relatively simple manufacturing processes.

Inventive Principle:
Principle #15Dynamics

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

Enables controlled failure and energy absorption, managing deceleration/acceleration forces on vehicle occupants while maintaining a lightweight structure, preventing excessive deceleration and ensuring adequate collision energy absorption.

Implementation Method 1

During crushing, a fiber breakage mechanism combined with friction comes into effect to reduce the kinetic energy of the collision

Methodology Applied
Scientific EffectFiber breakage: Fracture Mechanics

Implementation Method 2

During crushing, a fiber breakage mechanism combined with friction comes into effect to reduce the kinetic energy of the collision

Methodology Applied
Scientific EffectFriction: Friction

Implementation Method 3

The failure sections have different sized diameters. The larger the diameter of a failure section, the smaller the wall thickness of the respective section of the body structure member

Methodology Applied
Scientific EffectStress distribution:

Data Source

PatentEP3003830B1Body structural support for a motor vehicle
Publication Date: 2019.02.27 BAYERISCHE MOTOREN WERKE AG
  • EP3003830B1 patent drawingFigure 1

AI summary

A body structural support for a motor vehicle according to the present invention is made of a fibre-reinforced plastic. The body structural support has a hollow profiled element, which has failure segments. The failure segments are designed in such a way that the failure segments fail, in particular in a brittle manner, in order to dissipate collision energy in the event of a load caused by a collision of the motor vehicle with a collision opponent, such as another vehicle or a rigid obstacle. The failure segments have diameters of different magnitude. The greater the diameter of a failure segment, the smaller a wall thickness of the particular segment of the body structural support.