Thermally Densified Foam Core for Curved Sandwich Stability
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Solution Overview
Problem
Existing contoured structural elements used as core layers in curved sandwich composite elements, such as those for wind turbines and marine applications, suffer from low mechanical stability, brittle fracture behavior, and require complex scrim application methods, which are time-consuming and increase weight.
Innovation Solution
A contoured structural element made of thermoplastic foam is subdivided into body elements with a thermally densified connecting layer, eliminating the need for additional scrim material and ensuring high mechanical stability without weight increase, achieved through a simple production method that thermally densifies the surface to seal pores and reinforce the connection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If additional scrim material is used to reinforce the connecting layer, then mechanical stability and crack resistance are improved, but weight increases and the structure becomes more complex
Solution Approach 1:
The patent changes the physical and chemical parameters of the connecting layer material itself by using thermally densified foam with controlled cell structure and cross-linked polymer chains. This transforms the material properties to achieve high strength and crack resistance without adding external reinforcement layers, thereby avoiding weight increase and structural complexity
Solution Approach 2:
The patent creates a composite structure within the connecting layer by combining thermally densified foam material with specific additives and cross-linking agents. This internal composite structure provides enhanced mechanical stability and crack resistance while maintaining the single-layer design, eliminating the need for additional scrim materials
2Strength
If scrim material is applied to body elements, then adhesion to cover layers is improved, but the production process becomes more complex and time-consuming
Solution Approach 1:
The patent merges the adhesion function into the connecting layer itself by incorporating adhesive promoters and optimizing the thermal densification process. This integration eliminates the separate scrim material application step, simplifying the production process while maintaining or improving adhesion to cover layers
Solution Approach 2:
The connecting layer is designed to provide its own adhesion properties through its thermally densified structure and material composition. The layer self-generates the necessary bonding characteristics without requiring external scrim materials, thereby reducing production complexity and cycle time
3Weight of moving object
If the connecting layer is made of thin pore walls to reduce weight, then lightweight construction is achieved, but brittle fracture behavior occurs
Solution Approach 1:
The patent changes the parameters of the pore structure by thermally densifying the connecting layer, which modifies cell wall thickness, pore size distribution, and material density. This creates an optimized pore structure that maintains lightweight characteristics while providing sufficient fracture resistance through controlled cellular architecture and cross-linking
Solution Approach 2:
The patent applies different pore structure qualities to different regions: the connecting layer has a thermally densified structure with thicker effective walls and reduced pore size for strength, while other parts of the structural element maintain lighter pore structures. This local differentiation achieves both lightweight construction and fracture resistance where needed
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 provides a lightweight, mechanically stable core layer with improved adhesion to cover layers, reducing resin absorption and preventing crack formation, while allowing for complex curvature without additional reinforcement materials.
Implementation Method 1
at least one surface layer of the connecting layer and the adjoining surface layer of the body elements at least partly have a thermally densified layer
Data Source
AI summary
The invention relates to a contoured structural element (100) for use as a core layer in a curved sandwich composite element, the contoured structural element (100) being formed from a thermoplastic foam, in particular PET, the contoured structural element (100) being subdivided, except for a connecting layer (12), into a plurality of body elements (10), and the body elements (10) and the connecting layer (12) being aligned parallel to a base area (26) of the contoured structural element (100) which is in a planar state. According to the invention, at least one surface layer (16) of the connecting layer (12) and the adjoining surface layer (18) of the body elements (10) at least partly have a thermally densified layer (14); the body elements (10), the connecting layer (12) and the thermally densified layer (14) being made of the same material.