Perforated Heating Element Shear Stress in Composite Panels
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Solution Overview
Problem
Composite sandwich panels used in aircraft heated floor systems face structural failures due to high shear stress when a heating element is internally integrated, as the shear stress exceeds the material's withstand capacity, leading to potential damage from even low loads.
Innovation Solution
Incorporating a perforated heating element within the composite sandwich panel, secured between structural plies with a resin, which distributes shear stress through the resin and perforations, enhancing structural strength without adding weight or complexity, using materials like carbon fiber, fiberglass, and honeycomb cores for support and insulation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If a heating element is internally integrated into the composite sandwich panel, then thermal control and insulation are improved, but the panel becomes susceptible to structural failures due to high shear stress exceeding the material's withstand capacity
Solution Approach 1:
The heating element is made perforated with multiple holes, allowing the resin to penetrate through and create strong bonding points. This porous structure enables the resin to distribute shear stress effectively across the heating element and surrounding composite layers, preventing structural failure while maintaining thermal control functionality
Solution Approach 2:
The patent uses a composite sandwich panel structure with multiple layers including face sheets, core layers, and structural plies. The heating element is bonded between structural plies using resin, creating a multi-material composite system that distributes and manages shear stress across different material layers, enhancing overall structural strength while maintaining thermal performance
2Loss of energy
If a heating element is placed internally in the sandwich panel, then thermal insulation is improved, but the shear stress on the panel becomes greater than the heater element material can withstand, causing structural failures
Solution Approach 1:
The perforated heating element allows resin penetration through the holes, creating anchoring points that distribute shear stress. This porous design enables the heating element to withstand high shear forces without structural failure, improving reliability while maintaining internal placement for thermal insulation
Solution Approach 2:
The resin acts as an intermediary material that bonds the perforated heating element to the structural plies. It transfers and distributes shear stress from the heating element to the surrounding composite structure, preventing stress concentration and structural failure while enabling internal integration for thermal insulation
3Strength
If the heating element is secured between structural plies with resin, then structural strength is enhanced, but the manufacturing process becomes more complex
Solution Approach 1:
The heating element is perforated in advance before assembly, creating pre-defined stress distribution pathways. This preliminary action allows the resin to easily penetrate and bond during assembly, enhancing structural strength without requiring complex manufacturing processes or additional manufacturing steps
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 allows for the creation of heated floor panels that can withstand shear stress and provide structural support, ensuring the heating element's integrity and the panel's durability without increasing weight or manufacturing steps, while maintaining thermal control and insulation.
Implementation Method 1
the shear stress on the composite sandwich panel can be greater than the heater element material can withstand
Implementation Method 2
a perforated heating element bonded to the first structural ply
Implementation Method 3
using materials like carbon fiber, fiberglass, and honeycomb cores for support and insulation
Implementation Method 4
honeycomb cores for support and insulation
Data Source
Figure 1
Figure 2
AI summary
A composite sandwich panel includes a perforated heater element (18) in the middle of two structural plies (16,20), attached by a resin infiltrating perforations on the surface of the heater element. The heater element in the sandwich panel can withstand greater shear stress than non-perforated elements. The composite sandwich panel includes support layers such as honeycomb or foam.