FRP Stiffener Door Panel Resolving Weight and Thermal Trade-offs
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Solution Overview
Problem
Traditional insulated door panels using steel components are heavy, conductive, and prone to corrosion, leading to increased weight, hardware wear, and reduced thermal efficiency, while also impacting freight and shipment costs.
Innovation Solution
A door panel design featuring thermally non-conductive fiber-reinforced polymer stiffeners and a foamed-in-place insulation material that eliminates the need for steel, providing structural integrity, reduced mass, and improved thermal efficiency, with thermoplastic polycarbonate end caps for secure positioning and corrosion resistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If steel components are used for structural reinforcement, then structural integrity and strength are improved, but weight increases and thermal efficiency deteriorates
Solution Approach 1:
The patent replaces traditional steel reinforcement with fiber-reinforced polymer (FRP) composite materials. The FRP stiffeners provide the necessary structural strength and rigidity while being significantly lighter than steel, directly resolving the contradiction between strength and weight. The composite material maintains structural integrity without the penalty of steel's high density.
Solution Approach 2:
The invention extracts and eliminates steel components from the door panel construction entirely. By removing steel end caps, steel stiffeners, and steel reinforcement, the design achieves weight reduction while maintaining structural performance through alternative non-metallic materials that do not conduct thermal energy as readily.
2Strength
If steel components are used for structural reinforcement, then structural integrity is improved, but thermal efficiency deteriorates due to thermal conduction
Solution Approach 1:
The FRP composite stiffeners and end caps replace conductive steel components with thermally insulating materials. Fiber-reinforced polymers have low thermal conductivity, creating thermal breaks that reduce heat transfer through the door panel while maintaining the necessary structural reinforcement, thus improving thermal efficiency without sacrificing strength.
Solution Approach 2:
By completely removing steel components from the door assembly, the invention eliminates the thermal conduction pathways that steel creates. The non-metallic FRP materials do not conduct thermal energy as readily, thereby reducing thermal transfer and improving the door's energy efficiency while maintaining structural integrity.
3Strength
If steel components are used, then structural strength is improved, but corrosion resistance deteriorates
Solution Approach 1:
The fiber-reinforced polymer materials used for stiffeners and end caps are inherently corrosion-resistant, eliminating the rust and degradation issues associated with steel. These composite materials maintain their structural strength over time without being susceptible to oxidative corrosion, thereby improving reliability while preserving the necessary structural performance.
4Strength
If heavy gage steel components are used to meet performance requirements, then structural strength is improved, but manufacturing cost and shipping cost increase
Solution Approach 1:
The FRP composite components can be manufactured using automated fiber placement or molding processes that are more cost-effective than working with heavy gage steel. The lighter weight of the composites reduces shipping costs for both raw materials and finished products, while the automated manufacturing processes reduce labor costs and improve manufacturing efficiency compared to steel fabrication and assembly.
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 lighter, thermally efficient, and corrosion-resistant door panel with reduced thermal transfer and dimensional stability, eliminating the need for steel components and weld marks, thereby lowering production and shipping costs.
Implementation Method 1
A hardenable insulation material is disposed between adjacent exterior panels, stiffeners, and frame members in the shell interior portion. The hardenable insulation provides both thermal insulation and an adhesive to bond the exterior panels, frame members, and stiffeners.
Implementation Method 2
The stiffeners comprise a thermally non-conductive fiber reinforced polymer. An insulated panel which employs stiffeners which are also corrosion resistant and provide dimensional stability to the panel under thermal loading.
Implementation Method 3
The insulation material may chemically bond with the surface of the stiffeners in the shell interior portion.
Data Source
AI summary
An insulated door panel comprises a shell having spaced first and second exterior panels and frame members adjacent edges of the panels, a plurality of stiffeners in a shell interior portion extending along a length or width of the panels, and a hardenable insulation material creating a bond between the exterior panels, stiffeners, and frame members in the shell interior portion. The stiffeners comprise a thermally non-conductive fiber reinforced polymer. The hardenable insulation fills substantially all of the space between the adjacent exterior panels, stiffeners, and frame members. The door panel also comprises end cap members composed of thermoplastic polycarbonate material, and has openings therein to receive the ends of the stiffeners.