Abstract
Cantilever beams can often be used as representative models for more complex systems and can accurately display the expected behavior of these systems under different loads. The health of a cantilever beam after being subjected to harmonic excitation at its second resonance frequency is determined using a nondestructive health monitoring technique. Nonlinear Modal Tracking assumes a second order differential equation that factors in mass, stiffness, and damping of the beam with a cubic nonlinearity parameter. Research so far has confirmed that a drastic shift in this nonlinear term is a result of crack initiation and an indicator of the beam’s transition from healthy to unhealthy. Application of this Nonlinear Modal Tracking can be beneficial in monitoring the health of structures in order to predict catastrophic failure. The purpose of this study was to investigate several new techniques and conditions to verify the robustness of the model.
This experimental study included three newly considered beam geometries and then induced cracks using stress concentrations. Additionally, multiple frequency excitation was considered, and noise was added to the excitation frequency. This method of study is vital to future implementation of Nonlinear Modal Tracking in more complex systems. The technique successfully predicted the onset of beam failure during 5 of 6 beam experiments.
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Abbreviations
- Ω:
-
Excitation Frequency
- ∝:
-
Nonlinear parameter
- A:
-
Vertical displacement
- c:
-
Damping
- D ξ :
-
Bending stiffness
- F:
-
Input force
- L:
-
Length of total beam
- m:
-
Mass
- NDE:
-
Nondestructive evaluation technique
- NMT:
-
Nonlinear modal tracking
- s:
-
Horizontal displacement
- t:
-
Time
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Doughty, T.A., Blaser, A.K., Johnston, J.R. (2017). Monitoring the Health of a Cantilever Beam Using Nonlinear Modal Tracking. In: Niezrecki, C. (eds) Structural Health Monitoring & Damage Detection, Volume 7. Conference Proceedings of the Society for Experimental Mechanics Series. Springer, Cham. https://doi.org/10.1007/978-3-319-54109-9_7
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DOI: https://doi.org/10.1007/978-3-319-54109-9_7
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