 

The major objective of this research is to model the response of heterogeneous systems subjected to electromagnetic excitation that result in the mechanical dynamic behavior of metallic objects embedded in different soil systems. In this investigation, we characterized how several factors affect the coupled response of the heterogeneous system. One of the factors affecting the response of the system are the coupled effects of electromagnetic and mechanical properties and their interrelated effects on soli behavior and the detection of metallic objects. Other factors affecting the response are the geometric features in the system, such as the buried object depth and the standoff height of the excitation coils.

            The proposed modeling approach utilizes a finite element (FE) framework that is able to couple the electromagnetic and mechanical response. The coupling is accounted for by using the Lorentz force that is obtained from the Maxwell equations and utilized into the mechanical equation of motion as tractable body forces. The model also captures the pressure-dependent deformation nature of the soil using a Drucker-Prager yield model to obtain a detailed understanding of soil interactions with different metallic objects. The model is implemented as a three-dimensional dynamic model using backward differentiation formulas (BDF) for the time integration scheme. The model is also able to run as a quasi-static frequency domain model that uses a harmonic form of the Maxwell equation. The electromagnetic response accounts for relative permittivity, electric potential, surface charge density, and volume charge density.  The EM domain utilizes three-dimensional Nédélec elements as a vector function defined along the element edges and at the center of each edge. The tangential continuity of either electric or magnetic field is imposed automatically on the element's interfaces while the normal components are still can be discontinuous. This framework is validated with experiments and verified with different mathematical models and approaches. We were able to show how linear and nonlinear (frequency-dependent and independent) changes in the magnetic susceptibility of the host soil affects the response of the system in the presence and absence of a buried target. We were also able to predict how standoff height and buried object depths could affect the strength and magnitude of the coupled electromagnetic and mechanical response. By understanding the standoff height effects on the response, we are able to define upper and lower limits for practical standoff heights for sensors. The proposed methodologies and integrated approaches provide a validated computational approach that can be used for the detection of buried heterogeneous objects and materials systems within different soil systems.

 


Modeling the Behavior of Heterogeneous Systems Subjected to the Coupled Effects of Electromagnetic and Mechanical Fields

Division / Sponsors: 
Aerospace, Bioengineering, Applied Mechanics, Design Engineering Division, Advanced Energy Systems, Manufacturing Engineering Division, Noise Control and Acoustics, Nondestructive Evaluation, Diagnosis, and Prognosis (NDPD), Nuclear Engineering Division, Process Industries Division, Fluids Engineering, Heat Transfer, Materials, Microelectromechanical Systems, Safety Engineering and Risk Analysis, Computers & Information in Engineering


Paper Proceedings: https://asmedigitalcollection.asme.org/IMECE/IMECE2020/volume/84478

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