An Experimental Validation of Phase-Based Motion Magnification for Structures with Developing Cracks and Time-Varying Configurations

In this study, Computer Vision and Phase-Based Motion Magnification (PBMM) are validated for continuous Structural Health Monitoring (SHM) purposes. The aim is to identify the exact instant of occurrence for damage or abrupt structural changes from video-extracted, very low amplitude (barely visible) vibrations. The study presents three experimental datasets: a box beam with multiple saw cuts of different lengths and angles, a beam with a full rectangular cross section and a mass added at the tip, and the spar of a prototype High-Aspect-Ratio wing. Both mode-shape- and frequency-based approaches are considered, showing the potential to identify the severity and position of the damage as well A high-definition, high-speed camera and a low-cost commercial alternative have been successfully utilised for these video acquisitions. Finally, the technique is also preliminarily tested for outdoor applications with smartphone cameras.

Computation of dimensional variations on the structural analysis of multi-cell aircraft box beams with python scripting

Purpose Python codes are developed for the versatile structural analysis on a 3 spar multi-cell box beam by means of idealization approach. Design/methodology/approach Shear flow distribution, stiffener loads, location of shear center and location of geometric center are computed via numpy module. Data visualization is performed by using Matplotlib module. Findings Python scripts are developed for the structural analysis of multi-cell box beams in lieu of long hand solutions. In-house developed python codes are made available to be used with finite element analysis for verification purposes. Originality/value The use of python scripts for the structural analysis provides prompt visualization, especially once dimensional variations are concerned in the frame of aircraft structural design. The developed python scripts would serve as a practical tool that is widely applicable to various multi-cell wing boxes for stiffness purposes. This would be further extended to the structural integrity problems to cover the effect of gaps and/or cut-outs in shear flow distribution in box-beams.

Seasonal use of bridges as day-roosts by bats in the Trans-Pecos of Texas

Bats commonly use highway infrastructure as day- or night-roosts. Nonetheless, little is known regarding how regularly bats use these structures or whether they do so only on a seasonal basis. We surveyed 13 parallel box beam bridges along 15 km of State Highway 17 in Jeff Davis County, Texas monthly for 12 months to examine seasonality of day-roost use. Bats using bridges, ranked based on abundance, were: Tadarida brasiliensis, Myotis velifer, M. californicus/ciliolabrum, M. yumanensis, Antrozous pallidus, and M. thysanodes. Myotis velifer, M. californicus/ciliolabrum, and M. yumanensis exhibited significant differences among bridges and significant seasonality in roost use. Tadarida brasiliensis exhibited significant differences among bridges but no significant seasonality of bridge use. Seasonality of use of bridges as day-roosts likely reflects seasonal patterns of distribution of species in the Trans-Pecos. Moreover, these results suggest that surveys of bats roosting in highway infrastructure should be planned carefully and consider the seasonal nature of roost use

Theoretical and Experimental Analysis of Thin-Walled Curved Rectangular Box Beam under In-Plane Bending

Thin-walled curved box beam structures especially rectangular members are widely used in mechanical and architectural structures and other engineering fields because of their high strength-to-weight ratios. In this paper, we present experimental and theoretical analysis methods for the static analysis of thin-walled curved rectangular-box beams under in-plane bending based on 11 feature deformation modes. As to the numerical investigations, we explored the convergence and accuracy analysis by normal finite element analysis, higher-order assumed strain plane element, deep collocation method element, and inverse finite element method, respectively. The out-of-plane and in-plane characteristic deformation vector modes derived by the theoretical formula are superimposed by transforming the axial, tangential, and the normal deformation values into scalar tensile and compression amounts. A one-dimensional deformation experimental test theory is first proposed, formulating the specific contributions of various deformation modes. In this way, the magnitude and trend of the influence of each low-order deformation mode on the distortion and warping in the actual deformation are determined, and the significance of distortion and warping in the actual curved beams subjected to the in-plane loads is verified. This study strengthens the deformation theory of rectangular box-type thin-walled curved beams under in-plane bending, thus providing a reference for analyzing the mechanical properties of curved-beam structures.