Body Bound Shear Connection With Broken Tabs
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Solution Overview
Problem
Conventional methods for securing workpieces together, such as using mechanical fasteners or press-fits, often require a large number of fasteners or precise dimension control, which can be cumbersome and prone to errors, especially in heavy-duty applications where high loads and stresses are involved.
Innovation Solution
A joint design featuring a workpiece with a cavity and a shear member where one workpiece has a lower hardness and shear strength, incorporating shear tabs with a base and end portion, where the end portion is broken away to secure the workpieces together, reducing the need for multiple fasteners and avoiding the precision issues of press-fits.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If mechanical fasteners are used to secure workpieces together, then joint strength can be achieved, but a relatively great number of fasteners and/or relatively heavy fasteners are required
Solution Approach 1:
The invention extracts the fastening function from separate mechanical fasteners and integrates it into the workpiece structure itself through shear tabs that are broken away during assembly. The shear tabs are formed as integral parts of the workpieces, eliminating the need for separate fastener components.
Solution Approach 2:
The invention merges the structural component with the fastening mechanism by integrating shear tabs directly into the workpieces. The shear tabs serve dual purposes: maintaining alignment during assembly and creating the fastening connection when broken away, combining structural and fastening functions in one element.
2Device complexity
If a press-fit is used to reduce the number of fasteners, then fewer fasteners are required, but critical dimensions must be carefully toleranced to ensure proper fit
Solution Approach 1:
The invention changes the material parameter (hardness) distribution between workpieces, with one workpiece having lower hardness to enable the shear tab breaking away during assembly. This parameter change allows for less stringent dimensional tolerancing while still achieving proper fit and function.
Solution Approach 2:
The shear tabs are pre-formed as integral parts of the workpieces with predetermined break points. During assembly, the shear tabs automatically break away at these predetermined locations, eliminating the need for precise dimensional control that would be required for a press-fit application.
3Ease of operation
If the formation or member is too small for press-fit, then assembly is easier, but a sufficiently strong press-fit cannot be created
Solution Approach 1:
The shear tabs are designed with curved outer surfaces that conform to the cavity geometry, creating optimal contact area and stress distribution. This curved geometry allows the shear tabs to be small enough for easy assembly while still providing sufficient surface area for strong bonding when the tabs break away and engage the cavity walls.
4Strength
If the formation or member is too large for press-fit, then press-fit strength increases, but it cannot be properly pressed into the cavity
Solution Approach 1:
The connection mechanism is segmented into shear tabs that are broken away during assembly, creating smaller engagement elements that can be properly inserted into the cavity while still providing substantial bonding surface area. This segmentation allows the effective engagement area to be large for strength while the individual elements remain small for ease of 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
This design reduces the number of mechanical fasteners required, decreases assembly time and cost, and enhances structural integrity by transferring shear loads to bearing loads between the shear member and tabs, while allowing for variations in tolerancing without compromising joint strength.
Implementation Method 1
At least a portion of the shear member is inserted into the cavity so as to break away the end portion of the shear tab
Data Source
AI summary
A joint is formed between first and second workpieces. The first workpiece defines a cavity, while the second workpiece includes a shear member. The shear member is at least partially inserted into the cavity to secure the first workpiece to the second workpiece. One of the workpieces has a lower hardness and/or shear strength than the other workpiece and includes at least one shear tab with a base portion and an end portion. In inserting the shear member into the cavity, the end portion of the shear tab is broken away from the base portion, leaving the base portion to extend between the cavity and the shear member, thereby securing the first workpiece to the second workpiece.