Composite Fastener Joint With Chamfered Holes for Tensile Strength
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Solution Overview
Problem
In composite material assemblies, stress concentration at the edges of holes and uneven contact between fasteners and composite materials lead to a decrease in strength when tensile forces are applied.
Innovation Solution
The formation of chamfered portions on the edges of holes in composite materials, along with matching chamfered portions on the fastener holes, helps to distribute stress and reduce concentration, thereby enhancing the structural integrity under tensile forces.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If members are joined by a fastener (metal bolt) through a through-hole in composite materials, then joining is achieved, but stress concentration occurs at the edge of the hole and uneven contact between fastener and hole reduces strength
Solution Approach 1:
The patent applies local quality by forming chamfered portions at specific locations (both ends of the through-hole) in the composite material members. These chamfered portions create localized stress distribution improvements without altering the entire structure, allowing uniform contact between the fastener and hole while maintaining the overall joining function.
Solution Approach 2:
The chamfered portions are formed in advance during the composite material manufacturing process, before the fastening operation. This preliminary action ensures that when the fastener is inserted, the stress distribution is already optimized, preventing stress concentration and uneven contact from the outset.
2Ease of manufacture
If a through-hole is formed in composite material members for fastener insertion, then joining is enabled, but stress concentration and uneven contact occur reducing overall assembly strength
Solution Approach 1:
The chamfered portions are created at specific locations (both ends of the through-hole) to locally improve stress distribution and contact uniformity. This localized modification enables effective joining while preventing the strength reduction that would otherwise occur due to stress concentration at the hole edges.
Data Source
AI summary
Provided is a composite material assembly (100) includes: a first composite material member (1) in which a first hole (51) is formed, a second composite material member (2) in which a second hole (52) is formed, and a fastener (3) that is to be inserted through the first hole (51) and second hole (52) to thereby connect the first composite material member (1) to the second composite material member (2). A first chamfered section (51C) is formed on at least one of both ends of the first hole (51), and a second chamfered section (52C) is formed on at least one of both ends of the second hole (52).