Flex Flange Ball Stud for Turbocharger Vibration
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Solution Overview
Problem
Turbocharger applications face issues with high embedding in bolted joints due to short grip lengths, leading to loss of preload and joint failure, especially under high temperatures and vibration, as standard ball studs result in stiff fasteners and high stress per fastener.
Innovation Solution
A flex flange ball stud design with adjustable stiffness, allowing subtle flex for thermal expansion and load management, effectively emulating a longer fastener by altering the spring rate through the design of the flexible flange, which reduces embedding and maintains clamp load.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If standard ball studs with short grip lengths are used, then the fastener can accommodate tight spaces and small packaging environments, but the fastener becomes stiff resulting in high material embedding and preload loss
Solution Approach 1:
The ball stud is segmented into distinct functional zones: a rigid threaded shaft portion for load bearing, a flexible flange section for compliance and thermal expansion, and a ball end for positioning. This segmentation allows each portion to optimize its mechanical properties independently, resolving the contradiction between short grip length and preload retention.
Solution Approach 2:
The flexible flange's geometry parameters (thickness, width, curvature radius) are specifically designed to achieve an optimal spring rate. By changing these parameters, the flange provides controlled flexibility that compensates for the short grip length, reducing material embedding while maintaining compact dimensions.
2Volume of moving object
If standard ball studs with short grip lengths are used, then the fastener can fit within compact turbocharger spaces, but high stress per fastener and material embedding occur under thermal and vibrational loads
Solution Approach 1:
The flexible flange acts as a pre-designed cushioning element that absorbs thermal expansion stresses and vibrational loads before they can cause material embedding or joint failure. This beforehand cushioning protects the joint durability in compact turbocharger environments.
Solution Approach 2:
The ball stud employs composite construction with different material properties in different sections: the shaft portion uses high-strength material for load bearing, while the flange uses a more compliant material or geometry for stress absorption. This composite approach enhances joint durability within compact dimensions.
3Reliability
If the grip length is increased to reduce stiffness and material embedding, then preload retention improves, but the fastener can no longer accommodate tight turbocharger spaces
Solution Approach 1:
Instead of increasing length in the axial dimension, the solution introduces flexibility in the radial and circumferential dimensions through the flexible flange. This dimensional transition allows the fastener to achieve compliance without increasing overall length, maintaining compactness while improving preload retention.
Solution Approach 2:
The flexible flange serves as an intermediary element between the rigid threaded shaft and the clamped components. It mediates the mechanical interaction by providing compliance and thermal expansion accommodation, enabling preload retention in short grip length applications.
4Strength
If thicker flanges are used to increase strength, then fastener strength improves, but the flexible flange's ability to accommodate thermal expansion and provide compliance decreases
Solution Approach 1:
The flange design applies local quality by varying thickness and geometry across different regions: thicker sections provide strength where needed, while thinner or more curved sections provide flexibility for thermal expansion. This localized optimization resolves the contradiction between strength and compliance.
Solution Approach 2:
The flexible flange incorporates curved and spherical geometric features that enhance its ability to deform elastically under thermal expansion while maintaining structural strength. The curvature allows stress distribution that simultaneously achieves strength and compliance.
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
The flex flange ball stud enhances vibration resistance and load tolerance, reducing material embedding and preload loss, thereby improving the effectiveness and reliability of bolted joints in turbocharger applications.
Implementation Method 1
The flange allows subtle flex for thermal expansion
Implementation Method 2
Spring rates can be tailored by the design, thickness and size of the flexible flange
Data Source
AI summary
A ball stud (12) with a relatively short grip length, adapted for use with a turbocharger, having a flexible flange (18) extending from a center of the ball stud (12). The flexible flange (18) is between a ball section (14) and a first shaft portion (20) adjacent to the flexible flange (18) and preferably a narrower threaded shaft portion (22) extending further from the ball section (14). The first shaft portion (20) may be tapered to fit in a complementary aperture (32) of a plate (30). The flexible flange (18) preferably includes a narrow circumference (24) adjacent to a center of the ball stud (12) with a circumferential lip (26) adapted to engage a plate (30). The flexible flange (18) allows subtle flex for thermal expansion and essentially changes a spring rate of the ball stud (12) to emulate a longer fastener.