Variable Radii Flanges for Crush Tube Retention
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Solution Overview
Problem
Stresses at the opening of extruded aluminum support assembly members can lead to defects such as cracks, compromising the structural integrity of the support assembly when crush tubes are retained at these locations.
Innovation Solution
A flanging operation is performed on the opening of the support assembly member to create flanges that securely retain the crush tube at a desired location, using a specific curvature and radius configuration to distribute stress and prevent fractures, with the radius R3 calculated as (R1-R2)/Z, where Z is empirically determined to be 0.8, ensuring effective retention and prevention of cracks.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If a crush tube is retained at the opening of the support assembly member, then the structural support and load-bearing capability are improved, but stresses concentrate at the opening causing cracks and compromising structural integrity
Solution Approach 1:
The patent applies different radius values at different locations around the opening. Specifically, the first radius R1 is different from the second radius R2, creating non-uniform curvature distribution. This local variation in geometric quality allows stress to be redistributed away from critical concentration points while maintaining the crush tube retention function at the opening location.
Solution Approach 2:
The patent utilizes curved flange surfaces with specific radius configurations (R1, R2, R3) instead of sharp corners or uniform curvature. The rounded geometry with calculated radius relationships creates smooth stress transitions and eliminates stress concentration at the opening, preventing crack formation while retaining the crush tube.
2Reliability
If the opening is flanged to retain the crush tube, then the retention capability is improved, but the curvature and radius configuration must be precisely controlled to prevent fractures
Solution Approach 1:
The patent specifies precise parameter relationships for the flange geometry, including the formula R3=(R1-R2)/Z where Z=0.8. By defining specific numerical relationships between the radii parameters, the invention transforms a complex geometric design into controllable manufacturing parameters, ensuring both reliable crush tube retention and fracture prevention through mathematically defined curvature characteristics.
Data Source
AI summary
A support assembly for an assembly comprised of an extruded member that defines a cavity, the member including an opening having a plurality of sides, and a crush tube inserted into the cavity of the member and mechanically retained in the member at or near a desired location by flanging the sides of the opening into an open end of the crush tube.