Hole Edge Reinforcement in Thermoplastic Fibre Composites
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Solution Overview
Problem
Thermoplastically bound fibre composite materials with low degrees of compaction face challenges in achieving sufficient tear-out strength at hole edges, as increasing material strength reduces the bearing stress area and vice versa, making it difficult to reinforce hole edges without additional material or compromising material properties.
Innovation Solution
A method involving a spike with a constant cross-sectional area and a tapering end to penetrate a hole, followed by scraping fibres with a scraper part to compact the edge region, increasing the fibre quantity and compaction in the edge region without adding material, thereby enhancing tear-out strength.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If the strength of the hole edge material is increased by compacting the porous material, then the material strength increases, but the material thickness of the hole edge region is reduced
Solution Approach 1:
The invention changes the degree of compaction parameter in the hole edge region by applying localized pressure through the pressing device. This increases material strength through compaction while the system manages the resulting thickness reduction through the specific geometry and pressure distribution of the pressing elements
Solution Approach 2:
The invention applies different degrees of compaction to different regions of the workpiece. The hole edge region receives increased compaction for strength, while other regions maintain their original porosity and thickness characteristics, creating localized quality enhancement without global material reduction
2Area of stationary object
If the bearing stress area is increased by enlarging material thickness, then the bearing stress area increases, but the material strength decreases due to increasing material thickness
Solution Approach 1:
The invention changes the compaction parameter locally in the hole edge region rather than uniformly throughout the material. This allows the bearing stress area to be maintained or increased while simultaneously improving material strength through targeted compaction, resolving the inverse relationship between area and strength
3Strength
If fibres are displaced out of the perforated region to increase hole edge strength, then local compaction occurs, but the bearing stress area is reduced
Solution Approach 1:
The invention applies localized compaction pressure through specifically designed pressing elements that concentrate force in the immediate hole edge region. This creates a gradient of material density where the highest compaction occurs at the hole edge for maximum strength, while adjacent regions maintain greater thickness and bearing area
Solution Approach 2:
The invention addresses the two-dimensional trade-off between strength and area by introducing a third dimension through controlled compaction depth and pressure distribution. The pressing device applies force over a controlled volume, creating a three-dimensional density gradient that optimizes both strength and bearing area simultaneously
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
This method effectively increases the tear-out strength of hole edges in porous thermoplastically bound fibre materials by compacting displaced fibres into the edge region, maintaining a substantial bearing stress area and minimizing material wastage, thus improving dimensional stability without additional reinforcement.
Implementation Method 1
providing the workpiece with a softened thermoplastic binder at least in the hole region
Data Source
AI summary
The invention relates to a method for reinforcing a predetermined edge region of a hole in a hole region of a workpiece, the edge region comprising an edge of the hole, the hole region comprising thermoplastically bound fibers, preferably a thermoplastically bund fiber tangle, comprising the steps: providing the workpiece with a softened thermoplastic binder at least in the hole region, penetrating the hole region of the workpiece in a penetration direction with displacement of fibers with a spike, after penetration: scraping fibers from the spike contrary to the penetration direction by a scraper part mobile relative to the spike, and compacting the predetermined edge region surrounding the spike with a pressing surface of the scraper part relative to workpiece regions of the hole region located radially outside the edge region.