Composite Reinforcement with Perforated Zones for Bolted Joints

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Solution Overview

Problem

Hybrid composite materials with reinforcement layers, such as metal sheets, face challenges in maintaining strength while reducing laminate density and preventing delamination, especially in areas subjected to varying stress conditions and bolted connections.

Innovation Solution

A composite material design featuring fiber composite layers with reinforcement layers that have perforations only in areas away from high-stress regions, allowing for a homogeneous, non-perforated area around bolts and strategically placed perforations in less stressed areas, optimized by laser or mechanical processes, to manage stress and prevent delamination.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Strength

If reinforcement layers are integrated into fiber composite laminates to improve embedment strength and shear strength, then the coupling efficiency to adjacent structures is improved, but the laminate density and overall mass increase

Engineering Contradiction:
Improveembedment strengthVSAvoidlaminate mass
Core Design Contradiction:
StrengthVSWeight of stationary object

Solution Approach 1:

The patent applies local quality by providing reinforcement layers only in specific reinforcement areas where embedment strength and shear strength are needed, rather than throughout the entire laminate. The reinforcement layers are strategically positioned in coupling areas to improve local properties without uniformly increasing the overall laminate mass.

Inventive Principle:
Principle #3Local quality

Solution Approach 2:

The patent segments the reinforcement strategy by dividing the laminate into different zones: reinforcement areas with embedded metal sheets for improved strength, and non-reinforcement areas with standard fiber composite layers for weight efficiency. This segmentation allows optimization of strength-to-weight ratio in different regions.

Inventive Principle:
Principle #1Segmentation

2Strength

If solid metal plates are glued on both sides of the fiber composite laminate to improve joint properties, then the coupling efficiency is improved, but the laminate mass increases significantly

Engineering Contradiction:
Improvejoint strengthVSAvoidlaminate mass
Core Design Contradiction:
StrengthVSWeight of stationary object

Solution Approach 1:

The patent extracts the essential reinforcement function from solid metal plates by using thin metal sheets embedded between fiber composite layers. This extraction removes the excess mass of solid plates while retaining the key benefit of improved embedment strength and shear strength in joint areas.

Inventive Principle:
Principle #2Taking out (Extraction)

Solution Approach 2:

The patent changes the parameters of the reinforcement approach by transitioning from thick solid metal plates to thin metal sheets, and from external gluing to internal embedding. These parameter changes reduce the mass contribution of reinforcement elements while maintaining their strengthening effect.

Inventive Principle:
Principle #35Parameter changes

3Weight of stationary object

If thin metal sheets are embedded between individual fiber composite layers to improve reinforcement efficiency, then the weight is reduced, but the bond strength and risk of delamination become critical issues

Engineering Contradiction:
Improvelaminate massVSAvoidbond strength
Core Design Contradiction:
Weight of stationary objectVSReliability

Solution Approach 1:

The patent applies the nested doll principle by embedding thin metal sheets within the layered structure of fiber composite laminates. The metal sheets are nested between specific fiber composite layers, creating a hierarchical structure where reinforcement elements are integrated within the composite system rather than applied externally.

Inventive Principle:
Principle #7Nested doll (Nesting)

Solution Approach 2:

The patent uses composite materials by creating a hybrid laminate structure that combines fiber composite layers with embedded metal sheets. This composite approach leverages the advantages of both materials: the lightweight and high tensile strength of fiber composites, and the high compressive strength and stiffness of metal sheets, while addressing bond strength through proper interface design.

Inventive Principle:
Principle #40Composite materials

4Strength

If reinforcement layers are made homogeneous without perforations to maintain strength, then the structural integrity is improved, but the manufacturing complexity and weight increase

Engineering Contradiction:
Improvestructural integrityVSAvoidmanufacturing complexity
Core Design Contradiction:
StrengthVSDevice complexity

Solution Approach 1:

The patent applies local quality by creating reinforcement layers with non-uniform properties: homogeneous (solid) in areas requiring high strength such as around bolt holes, and perforated in areas where weight reduction is prioritized. This spatial variation in structure allows optimization of both strength and manufacturing efficiency.

Inventive Principle:
Principle #3Local quality

Solution Approach 2:

The patent segments the reinforcement layer into different zones with different properties: solid regions for strength-critical areas and perforated regions for weight-critical areas. This segmentation enables differentiated functionality within a single reinforcement layer, balancing structural integrity and manufacturing complexity.

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

This design enhances the strength and lightweight properties of composite materials by reducing laminate weight and minimizing the risk of delamination, while maintaining structural integrity and ease of manufacturing, particularly in bolted connections.

Implementation Method 1

optimized by laser or mechanical processes

Methodology Applied
Scientific EffectLaser ablation: Laser Ablation

Implementation Method 2

optimized by laser or mechanical processes

Methodology Applied
Scientific EffectMechanical machining:

Data Source

PatentEP2363282B1Composite substance comprising multiple fibre compound layers and a reinforcement area
Publication Date: 2019.08.28 DEUTSCHES ZENTRUM FÜR LUFT UND RAUMFAHRT E V
  • EP2363282B1 patent drawingFigure 1~3
  • EP2363282B1 patent drawingFigure 4~5
  • EP2363282B1 patent drawingFigure 6~7

AI summary

The composite material has multiple fiber composite layers (31) and a reinforcement with a reinforcement layer made of a material that reinforces the fiber composite layers. One or multiple boreholes are guided in the area by the composite material, in which the fiber composite layers are provided with one or multiple reinforcement layers. One of the reinforcement layers is formed around the boreholes in homogeneous and perforation-free manner.