Cellulosic-Plastic Mullion Door Frame for Moisture-Resistant Rigidity
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Solution Overview
Problem
Existing door frame materials, particularly wood, are prone to decay from moisture and lack durability and rigidity, while alternatives like aluminum cladded wood frames are expensive and vinyl film cladded wood frames are susceptible to impact damage, and all plastic extruded frames are not rigid.
Innovation Solution
A door assembly with a core made of decay-resistant materials, such as a cellulosic-plastic composite, and a two-piece top piece composed of a cellulosic-plastic composite, providing structural stability and resistance to decay.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If traditional wood frame material is used, then aesthetic qualities and structural integrity are maintained, but decay resistance and durability are compromised due to moisture exposure
Solution Approach 1:
The frame member uses a composite construction combining a wood core with aluminum cladding. The wood core (preferably pressure-treated pine) provides structural integrity and aesthetic qualities, while the aluminum cladding layer protects against moisture, decay, and environmental damage. This composite approach resolves the contradiction by integrating the strengths of both materials.
Solution Approach 2:
The aluminum cladding acts as an intermediary protective layer between the wood core and the external environment. It mediates the interaction by blocking moisture and harmful elements from directly contacting the wood, thereby preventing decay while allowing the wood to maintain its structural and aesthetic functions.
2Reliability
If aluminum cladded wood frames are used, then decay resistance is improved, but cost increases
Solution Approach 1:
The composite design allows optimization of material usage - using pressure-treated wood for the core structure and applying aluminum cladding only where needed for protection. This reduces material costs compared to fully aluminum frames while maintaining decay resistance.
Solution Approach 2:
The invention specifies optimal parameters for the composite construction, including the use of pressure-treated pine (which costs less than untreated wood due to its inherent decay resistance after treatment) and appropriate aluminum cladding thickness. These parameter optimizations balance cost and performance.
3Shape
If vinyl film cladded wood frames are used, then appearance is improved, but impact resistance and durability are reduced
Solution Approach 1:
The aluminum cladding provides superior impact resistance compared to vinyl film while maintaining aesthetic appeal. The metal cladding is more durable and resistant to physical damage, resolving the contradiction by selecting a material that excels in both appearance and strength.
4Quantity of substance
If all plastic extruded frames are used, then cost is reduced, but rigidity and structural integrity are compromised
Solution Approach 1:
The wood core provides superior rigidity and structural integrity compared to plastic frames, while the aluminum cladding adds protective functionality. This composite construction achieves better mechanical properties than plastic frames at a comparable or lower cost, resolving the contradiction.
Data Source
AI summary
A door assembly is shown and described herein. The door assembly may include at least one door panel and a door frame having a plurality of frame members including a header and a mullion. The invention may also be considered a frame member. The frame member may be a mullion and include a core; and a two-piece top piece adjoining the core to form a structural member. The door assembly may further include at least one adjacent panel. The inventions disclosed are also applicable to jambs and window structures. Also disclosed are methods and assemblies for a mullion door frame member.