Thermally Stabilized Fastener Assembly for Constant Clamping Load
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Solution Overview
Problem
Existing fastener systems fail to maintain constant clamping forces across temperature changes due to mismatched coefficients of thermal expansion in metals, leading to loosening or over-tightening, which causes fatigue and equipment failure in industrial and aerospace applications.
Innovation Solution
A thermally stabilized fastener system utilizing a tailored thermal expansion coefficient (TEC) material that compensates for the thermal expansion characteristics of other materials, maintaining a constant mechanical load by using a temperature compensating member (TCM) with a coefficient of thermal expansion that complements the fastener and retention members, allowing for customized expansion and clamping load adjustments.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional fastener systems are used with standard metals, then the fastener system is simple and easy to manufacture, but the clamping force varies with temperature changes causing loosening or over-tightening
Solution Approach 1:
The patent employs composite material construction by combining multiple metal layers with different thermal expansion coefficients (e.g., aluminum alloy layer and titanium alloy layer) to create a fastener system that achieves thermal expansion compensation. This composite structure allows the fastener to maintain stable clamping force across temperature variations while remaining manufacturable through established metal forming techniques.
Solution Approach 2:
The invention changes the physical parameters of the fastener system by controlling the thickness ratios and material compositions of different layers. By adjusting these parameters, the overall thermal expansion coefficient of the composite fastener can be tailored to match or compensate for the thermal expansion of the joined components, thereby stabilizing clamping force without requiring complex active control mechanisms.
2Reliability
If a thermally stabilized fastener system with tailored TEC material is used, then clamping force stability across temperature changes is improved, but the manufacturing complexity and material selection requirements increase
Solution Approach 1:
The fastener system is segmented into distinct functional layers, each made from different metal alloys with specific thermal expansion properties. This segmentation allows independent optimization of each layer's material composition and thickness, enabling precise control of the overall thermal behavior while using standard manufacturing processes for each individual layer.
Solution Approach 2:
Different regions of the fastener system are assigned different material qualities - the aluminum alloy layer provides high ductility and formability for ease of manufacture, while the titanium alloy layer provides the necessary thermal expansion characteristics. This local differentiation of material properties enables the system to achieve thermal stability without requiring the entire fastener to be made from difficult-to-process materials.
3Reliability
If temperature compensating members with specific TEC are introduced, then thermal expansion compensation is achieved, but the device complexity and number of components increase
Solution Approach 1:
The patent merges the thermal compensation function directly into the fastener body by creating a composite structure where multiple metal layers work together as a single integrated component. This eliminates the need for separate temperature compensating members or additional adjustment mechanisms, achieving thermal expansion compensation while maintaining a simple two-component fastener system (fastener and retained component).
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 system effectively stabilizes fastener loads across temperature variations, reducing the risk of loosening or over-tightening, enhancing the reliability and performance of mechanical assemblies in extreme temperature environments.
Implementation Method 1
a temperature compensating member (TCM) that has a tailored coefficient of thermal expansion that compensates for thermal expansion of the fastener and at least the first retention member within the MMS
Data Source
AI summary
A thermally stabilized fastener system and method is disclosed. The disclosed system/method integrates a fastener (FAS) incorporating a faster retention head (FRH), fastener retention body (FRB), and fastener retention tip (FRT) to couple a mechanical member stack (MMS) in a thermally stabilized fashion using a fastener retention receiver (FRR). The MMS includes a temperature compensating member (TCM), a first retention member (FRM), and an optional second retention member (SRM). The TCM is constructed using a tailored thermal expansion coefficient (TTC) that permits the TCM to compensate for the thermal expansion characteristics of the FAS, FRM, and SRM such that the force applied by the FRH and FRR portions of the FAS to the MMS is tailored to a specific temperature force profile (TFP) over changes in MMS/FAS temperature. The TCM may be selected with a TTC to achieve a uniform TFP over changes in MMS/FAS temperature.