Fatigue Test Bench Support Optimization
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Solution Overview
Problem
Current low-cycle and polycyclic fatigue test benches for turbomachine parts, such as blade roots on rotor disks, are inadequate as they do not account for the characteristics of the support member, contact quality, and dynamic behavior, leading to inaccurate lifespan predictions due to insufficient representation of industrial conditions.
Innovation Solution
A method to optimize the test bench by determining and modifying variable parameters like arm dimensions and angles to achieve objectives like parallelism, homogeneous contact pressure, and maximum sliding amplitude between the support surfaces, using software like DesignXplorer for parameter optimization.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a conventional test bench design is used, then the basic fatigue testing function is provided, but the representativeness of the test with respect to industrial application is insufficient
Solution Approach 1:
The patent applies parameter changes by systematically varying geometric parameters of the support member (arm lengths, angles, thicknesses) to optimize test representativeness. The optimization process modifies parameters such as the length of arms connecting the support member to the frame, the angles of these arms, and the thickness of the support member components to achieve desired contact characteristics and stress distribution.
Solution Approach 2:
The patent implements dynamics by transitioning from a static test bench design to one that accounts for dynamic behavior during polycyclic fatigue testing. The support member is designed with specific geometric parameters that optimize its dynamic response, allowing it to accurately reproduce the dynamic conditions experienced by actual blade-disc attachments during operation.
2Manufacturing precision
If the support member geometry is not optimized, then the manufacturing is simpler, but the contact quality between support surfaces is insufficient
Solution Approach 1:
The patent uses parameter changes to optimize the geometric dimensions of the support member, including arm lengths, angles, and thicknesses. These parameter modifications are designed to achieve homogeneous contact pressure and perfect plane-to-plane contact between the support surfaces, directly improving manufacturing precision of the contact interface.
3Reliability
If conventional test bench parameters are used, then the setup is simpler, but the ability to dissociate normal and shear stresses is insufficient
Solution Approach 1:
The patent applies parameter changes by optimizing specific geometric parameters of the support member to enable dissociation of normal and shear stresses. The angles and dimensions of the arms are carefully selected to create a configuration where normal and shear stress components can be independently analyzed, improving the reliability of fatigue life predictions.
4Measurement precision
If the test bench is not optimized for dynamic behavior, then the construction is simpler, but the accuracy of lifespan predictions is insufficient
Solution Approach 1:
The patent implements dynamics by designing the support member with geometric parameters optimized for dynamic polycyclic fatigue testing. The arm lengths, angles, and thicknesses are configured to accurately reproduce the dynamic behavior and stress cycles experienced by actual blade-disc attachments, thereby improving measurement precision of lifespan predictions.
Data Source
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AI summary
A method for optimising a cycle and optionally high-cycle fatigue test bench (200), said test bench being intended to reproduce a support for turbomachine parts, characterised in that it comprises the steps consisting of determining variable geometric parameters of the support member (126) and/or of the workpiece (110) of the bench, in addition to ranges of variation of these parameters, determining at least one aim to be achieved, a variation in the values of at least a part of the abovementioned parameters having an influence on this aim, modifying one or a plurality of the values of the abovementioned parameters, in the respective ranges of same, and determining those that make it possible to achieve the aim, and producing or modifying a support member and/or a workpiece on the basis of the optimised parameters.