Vibration Analysis Research Articles

Comprehensive Analysis of Major Fault-to-Failure Mechanisms in Harmonic Drives

The present paper proposes a detailed Failure Mode, Effects, and Criticality Analysis (FMECA) on harmonic drives, focusing on their integration within the UR5 cobot. While harmonic drives are crucial for precision and efficiency in robotic manipulators, they are also prone to several failure modes that may affect the overall reliability of a system. This work provides a comprehensive analysis intended as a benchmark for advancements in predictive maintenance and condition-based monitoring. The results not only offer insights into improving the operational lifespan of harmonic drives, but also provide guidance for engineers working with similar systems across various robotic platforms. Robotic systems have advanced significantly; however, maintaining their reliability is essential, especially in industrial applications where even minor faults can lead to costly downtimes. This article examines the impact of harmonic drive degradation on industrial robots, with a focus on collaborative robotic arms. Condition-Based Maintenance (CBM) and Prognostics and Health Management (PHM) approaches are discussed, highlighting how digital twins and data-driven models can enhance fault detection. A case study using the UR5 collaborative robot illustrates the importance of fault diagnosis in harmonic drives. The analysis of fault-to-failure mechanisms, including wear, pitting, and crack propagation, shows how early detection strategies, such as vibration analysis and proactive maintenance approaches, can improve system reliability. The findings offer insights into failure mode identification, criticality analysis, and recommendations for improving fault tolerance in robotic systems.

Analysis of aging effects on the mechanical and vibration properties of quasi-isotropic basalt fiber-reinforced polymer composites

Eco-friendly natural fiber composites, such as basalt fiber composites, are gaining traction in material science but remain vulnerable to environmental degradation. This study investigates the mechanical and vibrational properties of quasi-isotropic basalt fiber composites subjected to aging in two different environments: ambient (30 ºC) and subzero (-10 ºC), both in distilled water until moisture saturation. Aged specimens absorbed 8.66% and 5.44% moisture in ambient and subzero conditions, respectively. Mechanical testing revealed significant strength reductions in tensile, flexural, impact, and short beam shear tests, with ambient-aged specimens showing the largest decline (up to 31.7% in flexural strength). Vibrational analysis showed reduced natural frequencies, particularly under ambient conditions (27.27%). Sound absorption tests showed that pristine specimens had the highest transmission loss, while moisture-rich ambient-aged specimens had the lowest. SEM analysis confirmed surface degradation, with fiber pull-out and matrix debonding contributing to property loss. This research provides valuable insights into the environmental limitations of basalt fiber composites, emphasizing the need for enhanced durability in eco-friendly materials.

Torsional damper design for diesel engine: theory and application

Abstract Torsional vibration is the primary cause of engine crankshaft failure. Consequently, the reduction of engine vibration is of paramount importance for the enhancement of automotive safety and comfort. However, the lack of comprehensive insight into the damping mechanism of the torsional damper has impeded the effective control of engine torsional vibration. In order to gain insight into the vibration characteristics of the shaft system in an inline six-cylinder diesel engine, an analysis of the system’s behaviour during both free and forced vibration was conducted. A mathematical relationship was deduced between the dimensions, material, operational temperature and damping properties of the silicone oil damper. The objective was to determine the optimal damping and moment of inertia of the damper, with the aim of minimizing the torsional amplitude of the sixth harmonic. The results demonstrate a reduction in the six-harmonic torsional amplitude from 0.32° to 0.14° following the installation of the damper. The mean and relative deviations between the calculated and experimental results are 0.0018° and 0.83%, respectively. To facilitate the design of the silicone oil damper, a software program, Vibsim, was developed based on Visual Studio for the design and torsional vibration analysis of the silicone oil damper. This software is reliable in calculating results and is user-friendly.

Materials and Techniques of the Mural Paintings in the Church-Ossuary of the Rila Monastery, Bulgaria

This presented research examined the wall paintings in the Church-Ossuary Presentation of the Blessed Virgin, part of the most important Rila Monastery complex in Bulgaria, painted by the painters from Mount Athos in 1795. The painting materials used to create the unique murals were studied for the first time by optical microscopy (OM), attenuated total reflectance Fourier transform infrared (ATR–FTIR), scanning electron microscopy energy dispersive X-ray spectroscopy (SEM–EDS), and enzyme-linked immunosorbent assay (ELISA). The vibrational and elemental analysis showed that the color palette of the paintings is composed of pigments traditional for Orthodox church wall paintings such as natural pigments, including yellow ochre, red ochre, green earth, and calcite, as well as other historical pigments of synthetic origin, including smalt, red lead, cinnabar, and verdigris. The analysis of the binders by the ATR–FTIR spectroscopy and enzyme-linked immunosorbent assay (ELISA) analysis implied the use of the post-Byzantine egg tempera technique. Only the blue backgrounds in the murals were painted using a smalt-based paint mixed with a carbohydrate binder. Based on the current analysis and comparison with the successive paintings in the other churches of the Rila Monastery, it could be concluded that the technology of the painting process followed by the Athonite artists during the work in the Church-Ossuary became a point of reference for many Bulgarian icon-painters later.

Fast and Efficient Mitigation of Coupled Axial-Torsional Drillstring Vibrations through State-Feedback Linear-Quadratic-Integral (LQI) Control

Summary In the exploitation of subsurface hydrocarbon and geothermal energy, more than 50% of total expenses are typically attributed to drilling and well completion. Coupled triaxial vibrations in the drilling system, excited by various mechanical, hydraulic, and geological sources, are major causes of premature downhole tool failures, excessive bit damage, compromised hole quality, reduced rate of penetration (ROP), and increased nonproductive time. Drillstring dynamic models, shock absorption tools, and controllers have been developed since the 1960s to understand and mitigate detrimental vibrations in the drilling system, aiming for smoother and more efficient operations. With advancements in measurement/logging while drilling technologies, rig equipment, mud pulse/wired pipe telemetry, and the digitalization of drilling engineering, a foundation has been established for proactive drilling vibration detection, analysis, and control to achieve efficient and safe drilling. In this study, a reduced-order axial-torsional drillstring dynamic model with soft string lateral contacts is first developed. Nonlinear drilling boundary conditions and inputs, such as bit-rock interactions (BRIs) with torque-on-bit (TOB) velocity-weakening effects, wellbore-drillstring contacts/friction, drillstring gravity, mud buoyancy, and more, are defined within the modeling framework. Equilibrium states and linearization of the model are derived for any given weight-on-bit (WOB) and rotational speed (RPM) setpoints, 3D well trajectories, and drillstring dimensions. A linear-quadratic-integral (LQI) controller is developed and tested for drillstring vibration suppression using a 6,562 ft (2000 m) drillstring model. In comparison to commercially available controllers for stick/slip mitigation, which are designed based on impedance matching and only address the decoupled drillstring torsional dynamics, the proposed state-feedback LQI controller emphasizes the coupling between the axial and torsional drillstring dynamics by simultaneously controlling WOB and RPM. Simulation results demonstrate that the LQI controller can suppress stick/slip and stabilize downhole WOB within 7 seconds, while a commercial drilling controller takes more than 35 seconds to achieve the same. Additionally, valuable insights and potential future directions for nonlinear drillstring vibration mitigation and drilling controller design are provided. With its fast drilling dysfunction stabilization time, small downhole RPM/WOB overshoots, minimal rig control inputs, robustness against drilling nonlinearities, and high efficiency, the proposed multi-input-multi-output state-feedback drilling controller holds great potential for application in proactive drilling vibration control, drilling automation, and real-time drilling optimization.

Diagnostic significance of the method of computerized joint vibration analysis in studying the functional state of temporomandibular joints

polyetiology, progressive course and high frequency of relapses is one of the urgent problems of modern dentistry. Different conceptual approaches to the analysis of etiological and pathogenetic aspects of the development of dysfunctional TMJ disorders predetermine the increased interest in the search for highly informative diagnostic methods, especially at the stage of preclinical manifestations.Goal. Evaluation of possibilities of computerized joint vibration analysis method in diagnostics of TMJ functional state.Materials and methods. The study involved 42 people of both sexes with physiologic types of bite, preserved tooth rows, no signs of functional disorders in TMJ and masticatory muscles. The patients underwent clinical dental examination, «Hamburg test», selective grinding of teeth, and measurement of mouth opening amplitude. Joint vibration analysis was performed on the hardware-software complex «BioPAK» with registration of TMJ noise oscillations according to the following indices: «Total Integral», «High Integral», «Low Integral», «Ratio». A flow chart (Ishigaki S. et al., 1993) was used to interpret the numerical values. The functional state of TMJ was de-termined according to the flowchart using numerical parameters in accordance with the classification of TMJ disorders (Wilkes С.Н., 1989).Results. In patients with physiologic occlusion, according to joint vibration analysis, Me «Total Integral» of the right TMJ was 11.7 PaHz, left TMJ – 12.6 PaHz, [Q-25; Q-75] – [9.3; 15.1] PaHz and [10.5; 18.3] PaHz respectively, Me «High Integral» of the right TMJ – 1.3 PaHz, left TMJ – 1.4 PaHz, [Q-25; Q-75] – [1.0; 1.8] PaHz and [1.2; 2.1] PaHz respectively, with no statistically significant (p≤0.05) differences in the studied parameters between the right and left TMJ.Conclusions. The diagnosis of «structurally intact» TMJ, corresponding to stage I of the American classification of TMJ disorders (Wilkes S.N., 1989) in people with physiologic types of bite, is confirmed by the numerical values [Q-25; Q-75] of «Total Integral», «High Integral» (block diagram of S. Ishigaki et al., 1993), the degree of maximum mouth opening [43; 50] mm in the absence of pronounced signs of facial asymmetry.

An Improved Conformal Mapping Method for Electromagnetic Vibration Analysis in PMSMs With Rotor Eccentricity

An Improved Conformal Mapping Method for Electromagnetic Vibration Analysis in PMSMs With Rotor Eccentricity

Vibration Analysis of the Bow Bridge With and Without the Soil Foundation

Abstract. Earthquakes can impart the phenomenon of resonance, where the frequencies of seismic waves align with a bridge's natural frequency, causing amplification of vibrations that can lead to structural failures. Aiming to accurately predict potential vulnerabilities posed to the bridge when subjected to earthquakes, this research presents a vibration analysis of the Bow Bridge. Two models, which simulate the Bow Bridge with and without soil foundation, are conducted to investigate the bridges natural frequencies and mode shapes under soilless and soiled conditions. The research result shows that the average vibration frequency in a soiled environment is much lower than that in a non-soil environment, intuitively proving the mitigation of soil environment to bridges vibration frequencies. Based on the agreeable data output, this research demonstrates the feasibility of modeling in the prediction of practical construction.

Non-linear vibration analysis of hard rock TBMs with multiple state-dependent delays and stick–slip effects

Non-linear vibration analysis of hard rock TBMs with multiple state-dependent delays and stick–slip effects

A comprehensive study of beam modal functions in the free vibration analysis of cylindrical shells: critical examination on the applicability to the clamped-free boundary condition

Over the past few decades, approximate methods that can provide solutions of sufficient accuracy have received considerable attention in the free vibration analysis of cylindrical shells, where a great deal of studies adopted the beam modal functions as the trial functions for the axial mode shapes of cylindrical shells. Nevertheless, most studies were restricted to the application of single term beam modal function and failed to simulate elastic boundary conditions of cylindrical shells, while the accuracy of the corresponding methods has recently sparked significant controversy, especially for cylindrical shells under the clamped-free boundary condition. This paper presents a comparative study of three forms of beam modal functions in the free vibration analysis of cylindrical shells, one of which is proposed for the first time to simulate elastic boundary conditions of cylindrical shells. A unified model is developed using the general Rayleigh-Ritz method, incorporating the breathing modes with circumferential orders being zero, and four types of commonly used thin shell theories, namely the Donnell, Reissner, Love, and Sanders theories. From both perspectives of natural frequencies and mode shapes, numerical results are validated by comparison with those existing in the literature and those calculated from the finite element method (FEM). The results not only clarify the distinction of different forms of beam modal functions used in the Rayleigh-Ritz method, but also provide explanations for the controversy raised in recent studies. Furthermore, the unified formulations can be extended to vibration analysis of various forms of shell structures, and can also be helpful to the vibration analysis of beams and plates with elastic boundary conditions.

Development of Wear and Pitting Curves with Vibration Analysis for Lubricating Grease under Contamination Conditions

Development of Wear and Pitting Curves with Vibration Analysis for Lubricating Grease under Contamination Conditions

Detecting damage on engine mounts using hilbert-huang transform vibration analysis

Engine mounts, which are usually composed of elastomeric materials like rubber that can absorb excessive vibrations, are built to withstand vibration sources from engines. Engine mounts may eventually degrade from extended use. When rubber products age or sustain damage, they may grow harder and crack. Engine mounts need to be maintained regularly to ensure optimal performance. Visual examinations and the detection of excessive vibrations can be used to accomplish this. Vibration sensors are mounted on the engine mount in axial, vertical, and horizontal orientations using a vibration detection technique utilizing the Hilbert-Huang Transform (HHT) methodology. Matlab is used to examine the data that is gathered at three distinct rotational speeds: 750 rpm, 2000 rpm, and 3000 rpm. The HHT approach combines two key components: the Hilbert Transform, which analyzes the time-frequency signal of the first decomposition until only residuals remain, and Empirical Mode Decomposition (EMD), which breaks down the signal into Intrinsic Mode Functions (IMFs). According to test data, a damaged mount had an amplitude of 0.00005212 m/s² and a frequency of 8 Hz. On the other hand, in typical circumstances, the highest frequency was 7 Hz with the same amplitude. Five frequency increases were made in the damaged mount throughout this operation. In the damaged mount, the Hilbert Transform showed a frequency of 2124 Hz with an amplitude of 0.007594 m/s², indicating a significant resonance. This illustrates how the Hilbert-Huang Transform's capacity to handle non-stationary and nonlinear signal forms allows it to detect damage in components efficiently

Analysis of the impact of misfiring on the throttle body in ayla vehicles using the fast fourier transform method

An essential component of an automobile's air intake system, the throttle body controls airflow during combustion by acting as an idle speed control mechanism. Making ensuring the throttle body is operating properly is crucial to keeping the engine running at its best. The Fast Fourier Transform vibration analysis is one technique used for this (FFT). A an LCGC Ayla 1000 cc vehicle's throttle body and engine underwent vibration testing with rotational rates set to 750 rpm, 1000 rpm, 1500 rpm, and 2000 rpm. Vibration responses were measured using an accelerometer sensor coupled to an FFT analyzer, and Matlab was used for analysis. The throttle body had anomalous frequency readings at 1977 Hz with an amplitude of 0.03171 m/s2, according to the test results. On the other hand, the frequency value at 1410 Hz with an amplitude of 0.03435 m/s2 was observed under normal circumstances. Similar to this, abnormal frequency values with an amplitude of 0.02378 m/s2 were found on the engine at 1493 Hz, whereas normal frequency values with the same amplitude were found at 1712 Hz. These results point to incomplete combustion as the cause of the increased vibration

Modeling of drilling tool vibration in the process of drilling blast wells

Purpose. To determine the characteristic features and model bit vibration during its interaction with rock in the process of drilling technical (blast) wells in open pit mines. Methodology. The following methods were used in the work: analysis of scientific and practical solutions; statistical methods for processing the results of experimental studies; methods of analytical synthesis; computer modeling methods for synthesis and analysis of mathematical models. Findings. The process of interaction between a drill bit and a rock was analyzed. The conditions and causes of vibration of drilling equipment are determined. The spectral analysis of the vibration signal, the formation and analysis of the map of the order of rotation of the rotating parts of the drilling rig during the drilling of technical (blast) wells were performed to identify the bit in the frequency domain of the measured concomitant integrated vibration signal as a source of high-amplitude vibration. The modulated signal measured in the time domain at the specified frequency carries information about the physical and mechanical characteristics of the drilled rock and the state of the bit. The analysis of the experimental studies and modeling of the process of interaction of the bit with the rock allows us to conclude that the obtained statistical indicators of the accompanying vibration signal really adequately characterize the process of well drilling. Originality. A method for determining the characteristics of the interaction of a drill bit with rock in the process of drilling technical (blast) wells based on measuring the parameters of the accompanying vibration signal is proposed. The method differs from the known ones in the fact that in the process of changing the operating mode of the drive of the rotating parts of the drilling rig, an order map is formed over the entire range of its revolutions, the frequency of high-amplitude vibration of the bit is determined, which corresponds to a certain peak order of revolutions, and at this frequency the statistical parameters of changes are measured. Practical value. This approach to the process of drilling wells in open pit mines makes it possible to quickly determine the physical and mechanical characteristics of the drilled rock and adjust the process parameters accordingly to increase its productivity and energy saving.

Free Vibration Analysis for Polyester/Graphene Nanocomposites Multilayer Functionally Graded Plates

In the current work, an FGM nanocomposite made of multi-layers of graphene nanoparticles and a polyester-based matrix was constructed using the molds with a hand lay-up technique to attain an accurate shape and reduce defects in the final product. The desired models have four, six, and 11 layers and different volume fractions of nanoparticles (0.5, 1, 2, 3, 4, and 5%). This study conducted various experimental tests to analyze the free vibration characteristics of functionally graded composite sandwich rectangular structures with simply supported boundary conditions to evaluate the significance of hole number and cutout location in fundamental frequencies. For holes, three types are used (2, 4, and 6) holes with a 10 mm diameter, while for cutouts, three geometrical designs are used (circular, rectangular, and triangular) with various aspect ratios (r = 1, 1.5, 2, and 2.5). A numerical study was carried out to validate the experimental solution, employing modal analysis and finite element analysis (FEA) using ABAQUS software tools. From the findings, the experimental findings and numerical calculations exhibit a satisfactory level of concurrence, displaying a maximum discrepancy of 9.5%. The results show that the fundamental frequency decreases by increasing the cutouts' aspect ratio (r=a/b). There is minimal variation between r =1 and r= 1.5, but a noticeable decrease is observed at an aspect ratio of r= 2.5. This difference is primarily influenced by the type of material gradient and the number of holes, specifically for a given thickness of the functionally graded (FG) plates.

Vibration analysis of rotating functionally graded refined shear deformable microbeams with initial geometric imperfections

Vibration analysis of rotating functionally graded refined shear deformable microbeams with initial geometric imperfections

Numerical model and coupled vibration analysis of transmission shaft with spatial angle misalignment

Numerical model and coupled vibration analysis of transmission shaft with spatial angle misalignment

Characterization of Three-Mode Combination Internal Resonances in Electrostatically Actuated Flexible–Flexible Microbeams

Abstract Nonlinear intermodal coupling based on internal resonances in MEMS resonators has advanced significantly over the past two decades for various real-world applications. In this study, we demonstrate the existence of various three-mode combination internal resonances between the first five flexural modes of electrostatically actuated flexible–flexible beams and dynamic modal interaction between three modes via internal resonance. We first calculate the natural frequencies of the beam as a function of the stiffnesses of the transverse and rotational springs of the flexible supports, utilizing both analytical formulation and finite element analysis (FEA). Following this, we identify six combination internal resonances among the first five modes and use applied DC voltage to validate the exactness of one commensurable internal resonance condition (ω2=ω5−ω4). Subsequently, we studied a detailed forced vibration analysis corresponding to this resonance condition by solving the five-mode coupled governing equations through numerical time integration and the method of multiple scales. The results compellingly exhibit three-mode intermodal coupling among the second, fourth, and fifth modes as a function of excitation amplitude and frequency. Alongside this, intriguing nonlinear phenomena such as threshold behavior, saturation phenomena, and autoparametric instability are observed. Finally, this paper provides a systematic methodology for investigating three-mode combination internal resonances and related nonlinear dynamics, offering significant insights that could be used in observing phonon or mechanical lasing phenomena in MEMS resonators.

Nonlinear vibration analysis of multi-support oil-tank system in aero-engine based on asymptotic methods

This article is primarily focused on the complicated nonlinear vibration behavior of an aero-engine lubricating oil-tank system with multiple nonlinear pedestals. First, the rubber damping ring’s nonlinear factors are introduced into a cubic nonlinear dynamic model of lubricating oil-tank system. The nonlinear system parameters are identified by testing a simplified aero-engine lubricating oil-tank structure. Then, the nonlinear dynamic model is solved via asymptotic approach, and results are confirmed using Runge-Kutta numerical analysis approach. The system’s vibration responses and amplitude-frequency curves are also acquired, and influence of system parameters on nonlinearity is analyzed. Finally, an experimental investigation on the simplified oil-tank is performed. The nonlinear vibration characteristics of the rubber damping ring and its vibration reduction mechanism are verified using vibration transmissibility. The experimental results are consistent with numerical results. This paper’s recommended analysis approach has engineering significance for vibration and noise reduction design of aero-engine components.

Molecular docking, DFT and antiproliferative properties of 4-(3,4-dimethoxyphenyl)-3-(4-methoxyphenyl)-1-phenyl-1H-pyrazolo[3,4-b]pyridine as potent anticancer agent with CDK2 and PIM1 inhibition potency.

Due to the limited effeteness and safety concerns associated with current cancer treatments, there is a pressing need to develop novel therapeutic agents. 4-(3,4-Dimethoxyphenyl)-3-(4-methoxyphenyl)-1-phenyl-1H-pyrazolo[3,4-b]pyridine (3) was synthesized and Initially screened on 59 cancer cell lines showed promising anticancer activity, so, it was chosen for a 5-dose experiment by the NCI/USA. The GI50 values ranged from 1.04 to 8.02 μM on the entire nine panels (57 cell lines), with a GI50 of 2.70 μM for (MG-MID) panel, indicating an encouraging action. To further explore the molecular attributes of compound 3, we optimized its structure using DFT with the B3LYP/6-31 + + G(d,p) basis set. We have considered vibrational analysis, bond lengths and angles, FMOs, and MEP for the structure. Additionally, pharmacokinetic assessments were conducted using various in-silico platforms to evaluate the compound safety. A molecular modeling study created a kinase profile on 44 different kinases. This allowed us to study our compound's binding affinity to these kinases and compare it to the co-crystallized one. Our findings revealed compound 3 exhibited better binding for half of the tested kinases, suggesting its potential as a multi-kinase inhibitor. To further validate our computational results, we tested compound 3 for its inhibitory effects on CDK2 and PIM1. Compound 3 exhibited an IC50 of 0.30 µM for CDK2 inhibition, making it five times less active than Roscovitine, which has an IC50 of 0.06 µM. However, compound 3 demonstrated slightly better inhibition of PIM1 compared to Staurosporine. These findings suggest that compound 3 is a promising anticancer agent with the potential for further development into a highly active compound.