Chapter 36 Real-Time Theoretical and Experimental Dynamic Mode Shapes for Structural Analysis Using Augmented Reality Maimuna Hossain, John-Wesley Hanson, and Fernando Moreu Abstract Researchers conduct dynamic experiments to quantify changes in frequencies and mode shapes of interest for the safety and performance of structures. Even with sensor data and advanced computing techniques, valuable information of the experiment is always best observed with physical presence during the experiment. However, as of today, there exists no method for engineers to observe the dynamics experiments in the physical field and conduct dynamic analysis real-time. This paper describes a software application that conducts dynamic analysis in order to resolve this issue. The research consists of theoretical and experimental modal analyses of a cantilever beam using Augmented Reality (AR). The physical experiment involves a continuous aluminum beam attached to a shake table. First, a theoretical modal analysis is performed using Euler-Bernoulli equations in order to determine the modal parameters of this beam. A software application is built for the AR headset which contains a scaled hologram of the beam and depicts the first three theoretical mode shapes. This hologram is anchored to shake table to superimpose the physical beam. Using sinusoidal vibrations, the shake table can then excite the experimental mode shapes. The hologram and the actual beam are overlaid to compare real time structural data with theoretical mode shapes. By incorporating AR visualization of mode shapes, this prototype enables a new interface for structural analysis. Use of AR in the field of structural dynamics can expand human cognition by introducing a new interface for humans to interact with. Keywords Augmented reality · Structural dynamics · Mode shapes · Euler-Bernoulli · Human-machine interface 36.1 Introduction The goal of this project is to introduce a way to visualize dynamic properties of a structure using Augmented Reality (AR). Here, AR refers to the process of taking one’s surroundings and enhancing it by overlaying digital content. A Generation 1 Microsoft HoloLens serves as the main tool for visualization. The project investigates the dynamic property called mode shape. Mode shapes refer to a pattern of vibration created by a structure associated with its natural frequency. The use of AR as a form of engineering analysis and simulation has progressively increased in the past decade [1]. Previous works in the field include real-time finite element structural analysis in AR [2]. Although their paper demonstrates Finite Element Analysis using loads, it does not indicate mode shapes or natural frequencies of the model. Closest to mode shapes is demonstrated in an iOS application that visualized 3D frame deflection [3]. This application also enables mobile structural dynamics through the phone. When it comes to wearable technology, the AR headset allows developers to incorporate hand gestures, head motions, as well as a tangible user interface to determine location, data points and environment [4]. This paper describes a new first step towards visualizing mode shapes of a structure in real-time. The approach is innovative because of its contribution to the fields of AR and Structural Dynamics. The visualization of mode shapes has been M. Hossain ( ) Department of Mechanical Engineering, University of New Mexico, Albuquerque, NM, USA e-mail: hossainm@unm.edu J.-W. Hanson Department of Business Information Technology, Central New Mexico Community College, Albuquerque, NM, USA F.Moreu Department of Civil, Construction, and Environmental Engineering, University of New Mexico, Albuquerque, NM, USA e-mail: fmoreu@unm.edu © The Society for Experimental Mechanics, Inc. 2021 B. Dilworth (ed.), Topics in Modal Analysis & Testing, Volume 8, Conference Proceedings of the Society for Experimental Mechanics Series, https://doi.org/10.1007/978-3-030-47717-2_36 351
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