Lightweight Motor Vehicle Structural Part Using Continuous Fiber Mats
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Solution Overview
Problem
Existing structural composite parts for motor vehicles fail to meet requirements of being lightweight, economical, and having satisfactory mechanical characteristics, particularly in bending and creep at high temperatures, due to issues with fiber orientation, porosity, and the need for multiple manufacturing stages.
Innovation Solution
A structural composite part is produced in a single pressing step using mats with continuous webs of stacked, unidirectional fibers, preferably natural fibers like flax, and a thermosetting resin, combined with a lightweight spacer, to achieve high density and optimal fiber volume ratio, allowing for excellent mechanical properties and environmental sustainability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Weight of moving object
If homogeneous panels based on wood or particleboard or compressed flax, hemp, kenaf mats are used, then the structural part can be manufactured, but the mass is too high
Solution Approach 1:
The patent uses a sandwich structure composed of three distinct materials: natural fiber mats (flax, hemp, or kenaf) for the skins providing mechanical strength, cardboard for the spacer providing structural support and spacing, and resin binding the components together. This composite approach allows each material to contribute its optimal properties, achieving lightweight construction while maintaining structural integrity and meeting manufacturing requirements
2Ease of manufacture
If structural sandwich-type parts are made with short flax fiber mats and cardboard spacer in a single pressing step, then the manufacturing process is simplified, but the mechanical characteristics are insufficient due to poor fiber orientation and low density
Solution Approach 1:
The patent changes the physical state and arrangement parameters of the fiber mats by using long continuous fibers instead of short chopped fibers, and by arranging them in a unidirectional pattern parallel to the pressing direction. This parameter change allows the fibers to maintain their length and orientation through the single pressing process, providing excellent mechanical properties without requiring multiple manufacturing stages
3Manufacturing precision
If mats are highly compressed to achieve high optimal density, then the mechanical performance improves, but the pressure crushes the cardboard spacer
Solution Approach 1:
The patent applies preliminary action by pre-assembling the sandwich structure with the cardboard spacer positioned between the fiber mats before the final compression step. The spacer's rigid honeycomb structure provides preliminary support that distributes the compression force evenly, preventing localized crushing while allowing the mats to achieve their optimal density under controlled pressure
4Strength
If two-stage manufacturing process is used to produce structural components with high density mats, then the mechanical properties improve, but the cost increases due to additional tooling and cycle time
Solution Approach 1:
The patent merges the mat preparation and assembly operations into a single integrated pressing step. The long continuous fiber mats are cut to size and stacked with the cardboard spacer in one operation, then compressed simultaneously in a single mold. This consolidation eliminates the need for separate tooling and intermediate handling steps, reducing manufacturing complexity and cost while maintaining high mechanical properties through proper fiber orientation and density
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 results in a lightweight, economical structural composite part with superior mechanical characteristics, including high Young's modulus and low porosity, while incorporating natural fibers for environmental benefits, and simplifying the manufacturing process by eliminating the need for multiple stages.
Implementation Method 1
a resin binding the fibers
Implementation Method 2
the mats exhibit significant porosity (low density)... if the mats are compressed highly to achieve a high optimal density
Data Source
Figure 1~3
AI summary
The structural part (10) comprises first (12A) and second (12B) mats, each mat comprising fibres and a resin that binds the fibres, and - a separator (14) inserted between the first (12A) and second (12B) mats, the first (12A) and second (12B) mats being attached to opposite faces of the separator (14). At least one of the first (12A) and second (12B) mats comprises at least one continuous web of fibres (16), said web (16) comprising a plurality of parallel fibres bonded together by a thermosetting resin, at least one portion of the fibres of each web (16) having a length of greater than 20 cm, in particular greater than 50 cm. A method of manufacturing the structural part is also presented.