Fatigue Testing Component Mass Alteration
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Solution Overview
Problem
High-cycle fatigue testing of components in complex vibration modes is challenging due to the high energy required to excite them at higher frequencies, as existing drive systems cannot supply the necessary energy, making it difficult to test components effectively without physically altering them.
Innovation Solution
Attaching masses to the component to alter its stress distribution and vibrational characteristics, allowing for high-cycle fatigue testing at a low fundamental frequency, which is easier to excite, and using a finite element model to determine the optimal mass distribution for specific eigenvectors to induce failure at desired positions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the component is excited at its resonant frequency or flutter mode to achieve complex vibration modes, then the component can be tested for fatigue failure, but the energy required to drive the component increases significantly at higher frequencies
Solution Approach 1:
The patent changes the excitation frequency parameter from high frequency (complex modes) to low frequency (fundamental mode), while compensating for the parameter change by adding masses to the component. This allows the component to be excited at lower frequencies with reduced energy, while still achieving the desired vibration characteristics through mass modification.
Solution Approach 2:
The patent introduces masses as intermediary elements attached to the component. These masses act as mediators that modify the component's vibrational characteristics, allowing the fundamental mode excitation to produce stress distributions similar to complex modes. The masses serve as an intermediary means to achieve the desired testing objectives without requiring high-frequency excitation.
2Reliability
If the component is physically altered to change its vibrational characteristics, then complex vibration modes can be achieved, but the component cannot be tested in its original state
Solution Approach 1:
The patent segments the vibration modification function from the component structure itself by adding separate mass elements. This allows the component to be tested in its original state while the added masses provide the necessary vibrational modification. The segmentation enables the testing system to be configured independently of the component being tested.
Solution Approach 2:
The patent makes the testing system dynamic and adaptable by allowing the masses to be positioned at different locations and with different magnitudes. This dynamic configuration capability enables the same testing apparatus to characterize different vibration modes and stress distributions in the component without permanent modification to the component itself.
3Measurement precision
If high-frequency excitation is used to achieve complex vibration modes, then accurate fatigue testing can be performed, but the testing time increases due to the difficulty of excitation
Solution Approach 1:
The patent changes the excitation frequency parameter from high frequency to low frequency, which significantly reduces the time required to excite the component and achieve steady-state vibration. The mass addition compensates for this parameter change, ensuring that the low-frequency excitation still produces the desired stress distribution for accurate fatigue testing.
Solution Approach 2:
The patent utilizes mechanical vibration at the component's fundamental frequency, which is much easier to excite and requires less time to reach steady-state conditions compared to high-frequency complex modes. The added masses create the necessary vibration characteristics through their inertial effects, enabling rapid and efficient fatigue testing.
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 method reduces testing time and cost, increases reliability, and allows for the identification and potential acceptance of defects, preventing the scrapping of expensive components by simulating complex vibration modes at lower frequencies.
Implementation Method 1
The invention relates to a method of component testing. The invention is particularly, but not exclusively, concerned with a method for failure-testing components in complex vibration modes.
Implementation Method 2
This generally relates to situations where more than 10^4 cycles are required before failure, the stress is low and the deformation experienced is primarily elastic.
Data Source
AI summary
The present invention provides processes by which fatigue testing can be carried out by altering the vibrational characteristics of a component, but without physically altering the component itself. In particular the invention provides a method of performing high-cycle fatigue testing on a component, the method including the steps of: attaching one or more masses to the component to alter the stress distribution of the component under vibration; and carrying out high-cycle fatigue testing by exciting the component at a low fundamental frequency of the component. The component can then be tested at a low frequency, which is easier to excite, but fail in a position of the component characteristic of a more complex modeshape.