Sheet Fastener Assembly With Controlled Sidewall Buckling
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Solution Overview
Problem
Existing mechanical assembly (MA) features for connecting polymeric sheets, such as truncated cones, require significant force to buckle and form a consistent connection, leading to inconsistent failure locations and shapes, which affects connection strength and consistency.
Innovation Solution
Incorporating a deliberate discontinuity or failure area in the sidewall of the MA feature to control the failure mode during assembly, allowing for a predictable and repeatable projection-depression coupling that reduces the force required for connection and increases strength consistency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If truncated cones with linear sidewalls are used for mechanical assembly, then connection strength can be achieved, but the force required to buckle and form connection is significant and inconsistent failure locations occur
Solution Approach 1:
The sidewall of the truncated cone is segmented by introducing a discontinuity or failure area at a specific location. This segmentation allows the structure to buckle in a controlled manner at the discontinuity point rather than requiring significant force to buckle the entire linear sidewall, thus reducing the force required while maintaining connection strength
Solution Approach 2:
A discontinuity or failure area is preliminarily introduced into the sidewall during manufacturing. This preliminary action creates a predetermined weak point that will fail first during the buckling process, controlling the failure mode and reducing the force needed to initiate buckling while ensuring consistent connection formation
2Ease of manufacture
If truncated cones with consistent cross-sectional thickness are used, then manufacturing is simplified, but inconsistent failure locations and shapes occur during buckling
Solution Approach 1:
The sidewall is designed with non-uniform properties by introducing a local discontinuity or failure area at a specific location. This local quality change creates a predetermined weak point that ensures consistent failure location during buckling, improving manufacturing precision without significantly complicating the overall manufacturing process
3Strength
If significant force is applied to buckle truncated cones, then connection can be formed, but variation in connection strength increases
Solution Approach 1:
A discontinuity is preliminarily introduced to control the buckling initiation point, ensuring that all truncated cones fail in the same location and manner. This preliminary action reduces variation in the buckling process, leading to more consistent connection strength and improved reliability
Solution Approach 2:
The sidewall geometry is modified by introducing a discontinuity that changes the local structural parameters. This parameter change creates a predictable failure mode that reduces variation in connection strength, improving reliability while maintaining adequate connection strength
Data Source
AI summary
A mechanical assembly for securing a first sheet to a second sheet includes a first projection having a first sidewall and a first top wall. The first sidewall extends from the first top wall at a first acute angle. The first sidewall includes a first top end and a first bottom end. A first discontinuity is defined in the first sidewall between the first top end and the first bottom end. A first base wall extends from the first bottom end. The first base wall extends generally parallel to the first top wall.