Vibration Fatigue by Spectral Methods relates the structural dynamics theory to the high-cycle vibration fatigue. The book begins with structural dynamics theory and relates the uniaxial and multiaxial vibration fatigue to the underlying structural dynamics and signal processing theory. Organized in two parts, part I gives the theoretical background and part II the selected experimental research. The time- and frequency- domain aspects of signal processing in general, related to structural dynamics and counting methods are covered in detail. It also covers all the underlying theory in structural dynamics, signal processing, uniaxial & multiaxial fatigue; including non-Gaussianity and non-stationarity. Finally, it provides the latest research on multiaxial vibration fatigue and the non-stationarity and non-Gaussianity effects. This book is for engineers, graduate students, researchers and industry professionals working in the field of structural durability under random loading and vibrations and also those dealing with fatigue of materials and constructions.
COBISS.SI-ID: 34544899
The use of high-speed camera systems in vibration measurements is typically limited to identifying motion, transversal to the optical axis, due to an inherent limitation of 2D imaging systems. Depth information, lost in the imaging process, can be recovered by using the well-established 3D DIC technique, but is still limited to a single face of the object, observed by the stereo pair. In this research a full-field 3D operating-deflection-shape measurement technique, based on frequency-domain triangulation of image-data, is presented. A mathematical model of frequency-domain perspective transformation of small harmonic motion is introduced. This model is used to relate multiview image data to spatial amplitude spectra of the observed displacement. Using the developed method, spatial small harmonic motion of arbitrary-shaped specimen can be identified in the frequency domain using only a single, moving high-speed camera, extending the field-of-view of the established image-based vibration measurement methods.
COBISS.SI-ID: 16751899
The dynamic properties of modern products are analysed using an experimental approach through the measurement of frequency-response functions (FRFs). For an individual measurement, the coherence offers an online check during the system acquisition. More general tools for determining the consistency of the complete measurement set are based on a comparison of the FRFs or the modal shapes with a numerical model. They are useful tools, but they rely on a comparison with a numerical model that might not reflect the behaviour of the actual system. This paper aims to develop a comprehensive experimental method to check the consistency of individual measurements based on comparisons with the complete experimental response model. The numerical model is introduced only to enable the experimental model to be expanded using the System Equivalent Model Mixing method. The entire formulation is developed in the frequency domain, so that the transition to the modal domain, which might remove the physically relevant information from the system, is not required. In the frequency domain, it is possible to assess the consistency of the FRF across the entire frequency range of interest and not only in the region of the natural frequencies. This is of great importance in the area of frequency-based substructuring, where even small inaccuracies in the substructure's FRFs (e.g., the position of the anti-resonance) can lead to erroneous coupling results due to the inversion process. The...
COBISS.SI-ID: 46607363
SciPy is an open-source scientific computing library for the Python programming language. Since its initial release in 2001, SciPy has become a de facto standard for leveraging scientific algorithms in Python, with over 600 unique code contributors, thousands of dependent packages, over 100,000 dependent repositories and millions of downloads per year. In this work, we provide an overview of the capabilities and development practices of SciPy 1.0 and highlight some recent technical developments.
COBISS.SI-ID: 17044763
Dynamic substructuring methods serve as a powerful tool in the analysis of modern complex systems. The coupling of substructures has been successful with analytically obtained results. However, substructuring with experimentally obtained data remains challenging. One of the main problems associated with experimental substructuring is the coupling of the rotational degrees of freedom (RDoFs). A promising method where RDoFs are included implicitly is the virtual point transformation. Even though the transformation has been successfully used in the substructuring process, it is still highly susceptible to inaccuracies in the sensor sensitivity and positioning. In this paper an expansion to the virtual point transformation is proposed, which enables the projection of a directly measured rotation response on the interface deformation modes. A novel formulation of the weighting matrix is introduced to consistently include the measured rotations in the transformation. The proposed expansion is demonstrated on a numerical model of a simple beam-like structure and compared with the standard transformation. The effects of inaccuracies in the sensor sensitivity and placement on the overall quality of both transformation are analysed with a global sensitivity analysis. Finally, an experimental validation of the proposed expansion is carried out on a steel beam.
COBISS.SI-ID: 17033755