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Vibration-based condition monitoring : industrial, aerospace and automotive applications
\"Without doubt the best modern and up-to-date text on the topic, wirtten by one of the world leading experts in the field. Should be on the desk of any practitioner or researcher involved in the field of Machine Condition Monitoring\" Simon Braun, Israel Institute of Technology Explaining complex ideas in an easy to understand way, Vibration-based Condition Monitoring provides a comprehensive survey of the application of vibration analysis to the condition monitoring of machines. Reflecting the natural progression of these systems by presenting the fundamental material and then moving onto detection, diagnosis and prognosis, Randall presents classic and state-of-the-art research results that cover vibration signals from rotating and reciprocating machines; basic signal processing techniques; fault detection; diagnostic techniques, and prognostics. Developed out of notes for a course in machine condition monitoring given by Robert Bond Randall over ten years at the University of New South Wales, Vibration-based Condition Monitoring: Industrial, Aerospace and Automotive Applications is essential reading for graduate and postgraduate students/ researchers in machine condition monitoring and diagnostics as well as condition monitoring practitioners and machine manufacturers who want to include a machine monitoring service with their product. Includes a number of exercises for each chapter, many based on Matlab, to illustrate basic points as well as to facilitate the use of the book as a textbook for courses in the topic. Accompanied by a website www.wiley.com/go/randall housing exercises along with data sets and implementation code in Matlab for some of the methods as well as other pedagogical aids. Authored by an internationally recognised authority in the area of condition monitoring.
eBook
Ground Vibration Testing of a Flexible Wing: A Benchmark and Case Study
Beam-like flexible structures are of interest in many fields of engineering, particularly aeronautics, where wings are frequently modelled and represented as such. Experimental modal analysis is commonly used to characterise the wing’s dynamical response. However, unlike other flexible structure applications, no benchmark problems involving high-aspect-ratio flexible wings have appeared in the open literature. To address this, this paper reports on ground vibration testing results for a flexible wing and its sub-assembly and parts. The experimental data can be used as a benchmark and are available to the aeronautical and structural dynamics community. Furthermore, non-linearities in the structure, where present, were detected. Tests were performed on the whole wing as well as parts and sub-assembly, providing four specimens. These were excited with random vibration at three different amplitudes from a shaker table. The modal properties of a very flexible high-aspect-ratio wing model, its sub-assembly and parts, were extracted, non-linear behaviour was detected and the experimental data are shared in an open repository.
Journal Article
Combined Estimation of Structural Displacement, Rotation and Strain Modes on a Scaled Glider
Incorporating sensors such as microelectromechanical system (MEMS)-based inertial measurement units (IMUs) and strain gauges into aircraft structures has the potential to complement ground vibration testing results and improve the tracking of structural modes and wing shape in flight, as well as structural health monitoring. This study evaluates the feasibility and accuracy of employing MEMS accelerometers and gyroscopes together with strain gauges to estimate the structural modes of an aircraft. For this purpose, a ground vibration test was carried out on a 1:3 scaled Diana 2 glider model from which the displacement, rotation, and strain modes were estimated. The estimated modal parameters were compared with traditional piezoelectric accelerometer results and Finite Element Method model predictions. The results showed that the modal frequencies, damping ratios, and mode shapes estimated using MEMS IMUs and strain gauges closely matched the reference accelerometer estimates. Furthermore, the combination of displacement, rotation, and strain mode shapes allowed for greater insight into the structural dynamics. The exploratory use of gyroscopes for aircraft GVT allowed the structural torsion to be captured directly, thereby potentially simplifying future GVT setups by eliminating the need for placing accelerometers in pairs across the structure.
Journal Article
Case histories in vibration analysis and metal fatigue for the practicing engineer
This highly accessible book provides analytical methods and guidelines for solving vibration problems in industrial plants and demonstrates their practical use through case histories from the author's personal experience in the mechanical engineering industry. It takes a simple, analytical approach to the subject, placing emphasis on practical applicability over theory, and covers both fixed and rotating equipment, as well as pressure vessels. It is an ideal guide for readers with diverse experience, ranging from undergraduate students to mechanics and professional engineers.
eBook
Dynamic and cyclic response of a full-scale 2-storey cold-formed steel structure with and without infill materials
Cold-Formed Steel (CFS) has become more and more popular in recent years as an alternative construction material. Short construction time and very high strength to weight ratio under lateral forces made cold-formed steel an attractive option in earthquake prone countries such as Japan, New Zealand and the US. These structures are formed of CFS frames with either boards and sheatings attached to the frames or infill materials sprayed to the frames on-site. This paper presents the results of dynamic and cyclic experiments conducted on two different 3-D and 2-storey models. The first model was CFS frame system without infill material and the second one was with infill material. In order to identify the actual dynamic characteristics of models such as modal frequencies and damping ratios, large-scale tests are conducted instead of 2-D panel tests. Ambient vibration tests were carried out to determine modal frequencies of the models at different damage states and forced vibration tests were carried out to determine modal damping ratios at high vibration levels. In addition to ambient and forced vibration tests, cyclic tests were performed to obtain the hysteretic behavior of the model. It was observed that with the application of infill material, lateral load resisting capacity increased by 3.5 times, ductility of the model increased from 2.58 to 3.96 and damping ratio increased from 6.7 to 9.0%. In addition to identification of dynamic characteristics, the main motivation of this study is to investigate the possible use of ambient vibration surveys in the determination of damage level. Results showed that ambient vibration surveys can be used as a damage detection tool after an earthquake or any other hazard.
Journal Article
Touch Piezoelectric Sensor for Vibration Intensity Testing
The article presents research on a wide frequency range piezo sensor applied to surfaces by touch. It details the design of the piezo sensor, its operating principles, and usage characteristics. Calculations of the main vibration forms and modes, modeling, and experimental verifications are provided. The objective of the research was to create a lightweight, ergonomic device that enables quick detection and testing of ultrasonic vibrations on objects (ultrasonic concentrators, their replaceable tips, concentrator mounting structures, device casings, etc.) with a brief touch—up to 1 s. After optimizing the design parameters and conducting tests, it was determined that the piezo sensor identifies vibrations in the range of 20–96 kHz, which is a commonly used range in ultrasonic vibration systems (UVS). A distinctive feature of the sensor is that in this frequency range, it does not generate amplitude peaks, and its structural elements do not enter into the resonances of lower modes (1–5). The piezo sensor is not intended to determine precise vibration amplitudes and forms. It is designed to quickly find the points of minimum and maximum vibrations in vibrating objects, where precise measurements will later be conducted. The conducted research will assist in the design and manufacturing of such devices.
Journal Article
Evaluation of the Mechanical Stability of Optical Payloads for Remote Sensing Satellites Based on Analysis and Testing Results
This paper presents the results of numerical modeling and vibration testing of a nanosatellite’s optical payload, aimed at assessing its mechanical stability under the mechanical impacts of launch. The purpose of the study is to compare finite element modeling (FEM) data with experimental testing to refine the computational model and improve the reliability of mechanical stability predictions. The methodology included an FEM analysis with an average damping coefficient, an adapter blank test, a resonance study with a low-level sinusoidal run, random vibration tests, and a sinusoidal pulse test. The FEM results showed an average yield margin of safety MoS = 2.5 with a minimum MoS = 1.8 in the primary mirror mount area. The adapter blank test confirmed the absence of natural resonances in the operating range. The resonance study revealed modes in the 300–1340 Hz range, with the most pronounced peaks in the secondary mirror bracket (520–600 Hz) and the electronics unit (1030–1100 Hz). A comparison of the root mean square (RMS) acceleration values between calculations and tests revealed discrepancies due to the heterogeneous nature of the damping. The values of ζ determined by the half-power method varied from 0.9% to 4.8%, which confirms the dependence of the damping properties on the frequency and localization of the modes. The obtained results confirmed the structural integrity of the payload, allowed for the localization of structural elements, and substantiated the need to consider actual damping coefficients in FEM models. The presented data can be used to optimize the design and improve mechanical stability during payload integration into the satellite platform.
Journal Article
Optimal Sensor Placement for Enhanced Efficiency in Structural Health Monitoring of Medium-Rise Buildings
Output-only modal analysis using ambient vibration testing is ubiquitous for the monitoring of structural systems, especially for civil engineering structures such as buildings and bridges. Nonetheless, the instrumented nodes for large-scale structural systems need to cover a significant portion of the spatial volume of the test structure to obtain accurate global modal information. This requires considerable time and resources, which can be challenging in large-scale projects, such as the seismic vulnerability assessment over a large number of facilities. In many instances, a simple center-line (stairwell case) topology is generally used due to time, logistical, and economic constraints. The latter, though a fast technique, cannot provide complete modal information, especially for torsional modes. In this research, corner-line instrumented nodes layouts using only a reference and a roving sensor are proposed, which overcome this issue and can provide maximum modal information similar to that from 3D topologies for medium-rise buildings. Parametric studies are performed to identify the most appropriate locations for sensor placement at each floor of a medium-rise building. The results indicate that corner locations at each floor are optimal. The proposed procedure is validated through field experiments on two medium-rise buildings.
Journal Article
Corrugated board packaging with innovative design for enhanced durability during transport
Laboratory tests were conducted on innovatively designed corrugated board packaging under random vertical vibrations. The innovative designs had reinforced critical corner zones and lid–base interfaces through geometry modifications that increased double-wall regions. A total of 25 packaging variants, differentiated in structure, layer configuration (three-layer and five-layer boards), and surface finish (with and without coatings) were evaluated. The experimental study included box compression tests (BCT) and random vibration tests according to international standards (ISO 12048:1994 and ISO 13355:2016), simulating storage and transportation conditions. All packages were assessed before and after random vibration tests to determine the influence of dynamic loads on structural load-bearing capacity. Unlike previous studies limited to static testing, this work evaluated combined vibration and compression effects under standardized dynamic loading conditions for packaging with relatively low probability of being dropped. Furthermore, it was shown that the innovative design of corrugated board transport packaging presents higher static load capacity after random vibration testing in terms of column compression strength, indicating that no reduction in box strength was observed during simplified transport simulation under pure one-direction dynamic loading. The findings contribute to the optimization of high-durability packaging solutions tailored for the growing demands of complex logistics chains.
Journal Article