Oblique-Impact Specimen Testing With Curved Endcap Loads
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Solution Overview
Problem
Conventional test setups for simulating blade containment events in gas turbine engines result in symmetric loading, leading to inaccurate deformation and chaotic results due to sensitivity to initial conditions, and the endcap's low stiffness often fails to transmit accurate loads.
Innovation Solution
A system comprising an endcap with a curved surface, bars with strain gauges, and a gas gun that fires specimens obliquely or tangentially to simulate asymmetric loading, using supporting members and a bump-stop device to prevent damage, and cameras for parameter measurement.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If a conventional test setup with symmetric loading is used, then the test setup is simple and easy to operate, but the blade deformation is inaccurate and results are chaotic due to sensitivity to initial conditions
Solution Approach 1:
The patent applies asymmetry by introducing an oblique impact angle (non-zero angle between incident trajectory and blade surface normal) and asymmetric positioning of strain gauges on the Hopkinson bar. This asymmetric loading configuration reproduces the actual blade containment event conditions, transforming the test from symmetric to asymmetric loading to eliminate chaotic results and improve measurement precision.
2Device complexity
If an endcap of low stiffness is used, then the device complexity is reduced, but the load transmission accuracy is insufficient
Solution Approach 1:
The patent changes the stiffness parameter of the endcap by selecting appropriate material properties and geometric dimensions to achieve optimal performance. The endcap is designed with sufficient stiffness to accurately transmit impact loads to the Hopkinson bar while maintaining reasonable device complexity. This parameter optimization ensures accurate load measurement without excessive structural complexity.
3Ease of operation
If symmetric loading is applied to long slender blades, then the test setup is straightforward, but the deformation characteristics are overly sensitive to initial conditions leading to chaotic results
Solution Approach 1:
The patent introduces asymmetric loading through oblique impact and asymmetric strain gauge placement to break the symmetry of the testing system. This asymmetric configuration eliminates the chaotic behavior caused by sensitivity to initial conditions in symmetric loading, producing consistent and reliable deformation characteristics for long slender blades while maintaining test setup straightforwardness.
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
Accurately simulates blade release or containment events with reduced sensitivity to initial conditions, providing precise load signatures and deformation measurements.
Implementation Method 1
a gas gun configured to fire the specimen towards the first surface of the endcap
Implementation Method 2
the specimen impacts the first surface at an oblique angle relative to the longitudinal axis
Implementation Method 3
Each strain gauge is disposed on a surface of a corresponding bar from the plurality of bars
Data Source
AI summary
A system and a method of testing a specimen. The system includes an endcap, a plurality of bars, a plurality of strain gauges, and a gas gun. The endcap includes a first surface and a second surface opposite to the first surface. The first surface is curved. Each bar is disposed in contact with the second surface of the endcap and extends along a longitudinal axis. Each strain gauge is disposed on a surface of a corresponding bar from the plurality of bars. At least one strain gauge is disposed on the surface of each bar. The gas gun is configured to fire a specimen towards the first surface of the endcap such that the specimen impacts the first surface at an oblique angle relative to the longitudinal axis.