Vibrational Interaction Research Articles

Influence of spanwise wall vibration on non-modal perturbations subject to freestream vortical disturbances in hypersonic boundary layers

In this paper, we study the effect of lateral wall vibrations on the excitation and evolution of non-modal perturbations in hypersonic boundary layers subject to low-frequency freestream vortical disturbances (FSVDs). A novel, high-efficiency numerical approach, combining the harmonic weakly nonlinear Navier–Stokes and nonlinear parabolised stability equation approaches, is developed, which is sufficient to accommodate both the rapid distortion of the perturbation in the leading-edge vicinity and the nonlinear development of finite-amplitude high-order harmonics in the downstream region. The boundary-layer response to low-frequency FSVDs shows a longitudinal streaky structure, for which the temperature perturbation shows much greater magnitude than the streamwise velocity perturbation. The lateral vibration induces a Stokes layer solution for the spanwise velocity perturbation, which interacts with the FSVD-induced perturbations and leads to a suppression of the non-modal perturbation and an enhancement of the downstream modal perturbation. The new perturbations excited by the FSVD–vibration interaction strengthen as the vibration intensifies, and they could become comparable with the FSVD-induced perturbations in downstream locations at a high vibration intensity, indicating a remarkable modification of the streaky structure and its instability property. Secondary instability (SI) analyses based on the streaky base flow indicate that the vibration could enhance or suppress the SI modes, depending on their initial phases over the vibration period. Overall, the average effect is that the low-frequency and high-frequency SI modes are stabilised and destabilised by the vibration, respectively. Since the high-frequency SI modes undergo higher amplifications, the subsequent bypass transition is likely to be promoted by relatively strong vibrations.

Solving the Puzzle of the Carbonic Acid Vibrational Spectrum - an Anharmonic Story.

Against the general belief that carbonic acid is too unstable for synthesis, it was possible to synthesize the solid[1,2] as well as gas-phase carbonic acid.[3] It was suggested that solid carbonic acid might exist in Earth's upper troposphere and in the harsh environments of other solar bodies,[4] where it undergoes a cycle of synthesis, decomposition, and dimerization.[5] To provide spectroscopic data for probing the existence of extraterrestrial carbonic acid,[2,6] matrix-isolation infrared (MI-IR) spectroscopy has shown to be essential.[3,4,6-8] However, early assignments within the harmonic approximation using scaling factors impeded a full interpretation of the rather complex MI-IR spectrum of H2CO3. Recently, carbonic acid was detected in the Galactic center molecular cloud,[9] triggering new interest in the anharmonic spectrum.[10] In this regard, we substantially reassign our argon MI-IR spectra based on accurate anharmonic calculations. We calculate a four-mode potential energy surface (PES) at the explicitly correlated coupled-cluster theory using up to triple-zeta basis sets, i. e., CCSD(T)-F12/cc-pVTZ-F12. On this PES, we perform vibrational self-consistent field and configuration interaction (VSCF/VCI) calculations to obtain accurate vibrational transition frequencies and resonance analysis of the fundamentals, first overtones, and combination bands. In total, 12 new bands can be assigned, extending the spectral data for carbonic acid and thus simplifying detection in more complex environments. Furthermore, we clarify disputed assignments between the cc- and ct-conformer.

Analysis of dynamic levitation process of the particle chain in a nonlinear standing wave field.

This research delves into the dynamic behavior of acoustic levitation of the particle chain in a nonlinear standing wave field. Experimental acoustic levitation control tests reveal bifurcation and jump phenomena during dynamic adjustments to resonant cavity height. Employing the 10-particle chain experiments and the COMSOL simulation models, the Sine-Gordon 2D vibration model is established to study the dynamic deformation process of the particle chain. The study uncovers the nonlinear interaction of particle lateral vibrations, horizontal acoustic radiation force, and conical wave fields that generate the jumping standing wave field. Notably, the fourth particle acts as a prominent jumping critical point in the secondary standing wave field, facilitating the derivation of the particle chain's nonlinear levitation dynamics. This discovery provides us with a new method to regulate the particle chain system.

Effect of Blade Material of Steam Turbine Rotor on Aeroelastic Characteristics

Elements of powerful steam turbines are subjected to significant unsteady loads, in particular the rotor blades of the last stages. These loads, in some cases, can cause self-excited oscillations, which are extremely dangerous and have a negative impact on the efficiency and service life of the blade cascade. Therefore, when designing new or modernizing existing steam turbine stages, it is recommended to study the aeroelastic characteristics of the blades. The conditions for the occurrence of self-excited oscillations are influenced by both the geometric characteristics and the alloy from which the blade is made. To determine the effect of the blade material on the aeroelastic behaviour, a numerical analysis of the aeroelastic characteristics of the last stage blades made of steel and titanium alloy was performed. For the analysis, the method of simultaneous modeling of unsteady gas flow through the blade cascades and elastic vibrations of the blades (coupled problem) was used, which allows obtaining the amplitude-frequency spectrum of the interaction of unsteady loads and blade vibrations. The paper presents the results of numerical analysis for harmonic oscillations with a given amplitude and a given inter-blade phase angle, as well as for the regime of coupled vibration of blades under the action of unsteady aerodynamic forces. The dependences of the aerodamping coefficient on the inter-blade phase angle and the distribution of the coefficient along the blade are presented. The results of modeling the coupled vibration of the blades for the first six natural forms are presented in the form of a time-evolving displacement of the blade peripheral section, as well as forces and moments acting on the peripheral section. The corresponding amplitude-frequency spectra of displacements and loads in the peripheral section are also presented. The analysis of the results showed an insignificant difference in the characteristics of the proposed blade materials. For the first natural form of blade oscillations, the possibility of self-excited oscillations was found, and for the second form, there are conditions for the appearance of stable self-oscillations.

Comparison of curvilinear coordinates within vibrational structure calculations based on automatically generated potential energy surfaces.

For floppy molecules showing internal rotations and/or large amplitude motions, curvilinear internal coordinates are known to be superior to rectilinear normal coordinates within vibrational structure calculations. Due to the myriad definitions of internal coordinates, automated and efficient potential energy surface generators necessitate a high degree of flexibility, supporting the properties arising from these coordinates. Within this work, an approach to deal with these challenges is presented, including key elements, such as the selection of appropriate fit functions, the exploitation of symmetry, the positioning of grid points, or elongation limits for different coordinates. These elements are tested for five definitions of curvilinear coordinates, with three of them being generated in an automated manner. Calculations for semi-rigid molecules, namely H2O, H2CO, CH2F2, and H2CNH, demonstrate the general functionality of the implemented algorithms. Additional calculations for the HOPO molecule highlight the benefits of these curvilinear coordinates for systems with large amplitude motions. This new implementation allowed us to compare the performance of these different coordinate systems with respect to the convergence of the underlying expansion of the potential energy surface and subsequent vibrational configuration interaction calculations.

A compact microfluidic platform for rapid multiplex detection of respiratory viruses via centrifugal polar-absorbance spectroscopy

Nucleic acid detection technology has become a crucial tool in cutting-edge research within the life sciences and clinical diagnosis domains. Its significance is particularly highlighted during the respiratory virus pandemic, where nucleic acid testing plays a pivotal role in accurately detecting the virus. Isothermal amplification technologies have been developed and offer advantages such as rapidity, mild reaction conditions and excellent stability. Among these methods, recombinase polymerase amplification (RPA) has gained significant attention due to its simple primer design and resistance to multiple reaction inhibitors. However, the detection of RPA amplicons hinders the widespread adoption of this technology, leading to a research focus on cost-effective and convenient detection methods for RPA nucleic acid testing. In this study, we propose a novel computational absorption spectrum approach that utilizes the polar GelRed dye to efficiently detect RPA amplicons. By exploiting the asymmetry of GelRed molecules upon binding with DNA, polar electric dipoles are formed, leading to precipitate formation through centrifugal vibration and electrostatic interaction. The quantification of amplicon content is achieved by measuring the residual GelRed concentration in the supernatant. Our proposed portable and integrated microfluidic device successfully detected five respiratory virus genes simultaneously. The optimized linear detection was achieved and the sensitivity for all the targets reached 100 copies/μL. The total experiment could be finished in 27 min. The clinical experiments demonstrated the practicality and accuracy. This cost-effective and convenient detection scheme presents a promising biosensor for rapid virus detection, contributing to the advancement of RPA technology.

Accelerated Electron-Hole Separation at the Organic-Inorganic Anthracene/Janus MoSSe Interface.

Organic light-absorbing materials with two-dimensional semiconductor layers as contact electrodes are promising for efficient and flexible low-cost solar cells. Considering anthracene as an absorber and a MoSSe Janus monolayer, we use non-adiabatic molecular dynamics to show that electron transfer from anthracene to MoSSe is faster on the Se side than the S side. The transfer from anthracene to MoS2 and MoSe2 monolayers takes intermediate times. As a rule, we find that a shorter adsorption distance produces a stronger donor-acceptor coupling. The smaller distance on the Se side is rationalized by the attractive force between the intrinsic dipole moment of the Janus structure and that of the molecule induced due to adsorption. Quantum coherence also affects the transfer time. The study provides detailed insights into adsorption of molecules on Janus structures and the resulting electronic and electron vibrational interactions. The results suggest that the dipole interaction plays an important role in the thermodynamic stability, alignment of electronic levels, and electron vibrational dynamics.

Kylin-V: An open-source package calculating the dynamic and spectroscopic properties of large systems.

Quantum dynamics simulation and computational spectroscopy serve as indispensable tools for the theoretical understanding of various fundamental physical and chemical processes, ranging from charge transfer to photochemical reactions. When simulating realistic systems, the primary challenge stems from the overwhelming number of degrees of freedom and the pronounced many-body correlations. Here, we present Kylin-V, an innovative quantum dynamics package designed for accurate and efficient simulations of dynamics and spectroscopic properties of vibronic Hamiltonians for molecular systems and their aggregates. Kylin-V supports various quantum dynamics and computational spectroscopy methods, such as time-dependent density matrix renormalization group and our recently proposed single-site and hierarchical mapping approaches, as well as vibrational heat-bath configuration interaction. In this paper, we introduce the methodologies implemented in Kylin-V and illustrate their performances through a diverse collection of numerical examples.

Zero-Point-Energy Driven Isotopic Exchange of the [H3O]- anion Probed by Mid-Infrared Action Spectroscopy.

We present the first observation of vibrational transitions in the [H3O]- anion, an intermediate in the anion-molecule reaction of water, H2O, and hydride, H-, using a laser-induced isotopic H/D exchange reaction action spectroscopy scheme applied to anions. The observed bands are assigned as the fundamental and first overtone of the H2O-H- vibrational stretching mode, based on anharmonic calculations within the vibrational perturbation theory and vibrational configuration interaction. Although the D2O·D- species has the lowest energy, our experiments confirm the D2O·H- isotope to be a sink of the H/D exchange reaction. Ab initio calculations corroborate that the formation of D2O·H- is favored, as the zero-point-energy difference is larger between D2 and H2 than between D2O·H- and D2O·D-.

Analysis of vibrational modes and weak interactions in terahertz spectra of γ-aminobutyric acid and its isomer L-2-aminobutyric acid

Aminobutyric acid, a non-proteinogenic amino acid, is present in the human body and influences physiological functions, exhibiting promising pharmaceutical prospects. γ-Aminobutyric Acid (GABA) and its isomer, L-2-Aminobutyric Acid (L-AABA), exhibit unique characteristic absorption peaks in the 0.6 to 2.5 THz range. To elucidate the mechanisms behind these absorption peaks, this study employed Density Functional Theory (DFT) for theoretical simulations of the crystal cell models of L-AABA and GABA, achieving terahertz spectra consistent with experimental results. Additionally, the study utilized Vibrational Mode Automatic Relevance Determination (VMARD) and Interaction Region Indicator (IRI) methodologies to interpret the vibrational modes corresponding to different absorption peaks and to detail the locations and types of intermolecular interactions within the crystals. Research indicates that the combination of terahertz time-domain spectroscopy (THz-TDS) and theoretical calculations can serve as an effective method for identifying isomers of Aminobutyric Acid and detecting intermolecular weak interactions such as hydrogen bonds within these crystals.

Analysis of Vibration Characteristics of Tractor–Rotary Cultivator Combination Based on Time Domain and Frequency Domain

A good planting bed is a prerequisite for improving planting quality, while complex ground excitation often leads to machine bouncing and operation vibration, which then affects the operation effect. In order to improve the quality of rotary tillage operations, it is necessary to study the effects of various vibration excitations on the unit during tractor rotary tillage operations and analyze the vibration interaction relationship among the tractor, the three-point suspension mechanism, and the rotary tiller. For this purpose, multiple three-way acceleration sensors were installed at different positions on the rotary tiller unit of a Lexing LS1004 tractor(Lexing Agricultural Equipment Co. Ltd., Qingdao, China) to collect vibration data at different operating speeds and conduct vibration characteristic analysis between different components. The test results showed that when the unit moved forward at 2.1 km/h, 3.6 km/h, and 4.5 km/h, respectively, the vibration acceleration of the tractor, the three-point suspension mechanism, and the rotary tiller increased with the increase in speed, and there was indeed interaction between them. The vertical acceleration change during the test in the three-point suspension mechanism was the most significant (5.914 m/s2) and was related to the increase in the speed of the vehicle and the vibration transfer of the rotary tiller. Meanwhile, the vertical vibration acceleration of the tractor’s symmetrical structure was not similar, suggesting the existence of structural assembly problems. From the perspective of frequency domain analysis, the resonant frequency at the cab of the tractor was reduced in a vertical vibration environment, with relatively low frequencies (0~80 Hz) and small magnitudes, which might be beneficial to the driver’s health. The rotary tillage group resonated around 350 Hz, and this characteristic can be used to appropriately increase the vibration of the rotary tiller to reduce resistance. The tractor cab resonated around 280 Hz, which must be avoided during field operations to ensure driver health and reduce machine wear. The research results can provide a reference for reducing vibration and resistance during tractor rotary tillage operations, as well as optimizing and improving the structure of rotary tillers and tractors.

Enhancement in Heat Transfer Performance of Water Vapor Condensation on Graphene-Coated Copper Surfaces: A Molecular Dynamics Study.

The condensation of water vapor plays a crucial role in various applications, including combating water scarcity. In this study, by employing molecular dynamics simulations, we delved into the impact of graphene coatings on water vapor condensation on copper surfaces. Unique to this work was the exploration of various levels of graphene coverage and distribution, a facet largely unexplored in prior investigations. The findings demonstrated a notable increase in the rate of water vapor condensation and heat transfer performance as the graphene coverage was reduced. Using graphene coverages of 84%, 68%, and 52%, the numbers of condensed water molecules were 664, 735, and 880 molecules/ns, respectively. One of the most important findings was that when using the same graphene coverage of 68%, the rate of water vapor condensation and heat transfer performance increased as the graphene coating became more distributed. The overall performance of the water condensation correlated well with the energy and vibrational interaction between the graphene and the copper. This phenomenon suggests how a hybrid surface can enhance the nucleation and growth of a droplet, which might be beneficial for tailoring graphene-coated copper surfaces for applications demanding efficient water vapor condensation.

VSCF/VCI theory based on the Podolsky Hamiltonian.

While the vibrational spectra of semi-rigid molecules can be computed on approaches relying on the Watson Hamiltonian, floppy molecules or molecular clusters are better described by Hamiltonians, which are capable of dealing with any curvilinear coordinates. It is the kinetic energy operator (KEO) of these Hamiltonians, which render the correlated calculations relying on them rather costly. Novel implementation of vibrational self-consistent field theory and vibrational configuration interaction theory on the basis of the Podolsky Hamiltonian are reported, in which the inverse of the metric tensor, i.e., the G matrix, is represented by an n-mode expansion expressed in terms of polynomials. An analysis of the importance of the individual terms of the KEO with respect to the truncation orders of the n-mode expansion is provided. Benchmark calculations have been performed for the cis-HOPO and methanimine, H2CNH, molecules and are compared to experimental data and to calculations based on the Watson Hamiltonian and the internal coordinate path Hamiltonian.

Theoretical Insights into the Vibrational Structure of Carbon Dioxide Rare-Gas Complexes.

Two new flexible-monomer two-body ab initio potential energy surfaces (PESs) for the neon and krypton van der Waals complexes with carbon dioxide were developed, extending our previous work on the Ar-CO2 molecule. The accuracy of the PESs was validated by their agreement with the vibrational spectrum of the rare-gas complexes. The intermolecular and intramolecular vibrational excitation energies were computed at the vibrational self-consistent field and vibrational configuration interaction levels of theory. Overall, the agreement between theory and experiment is excellent throughout the vibrational spectra. The observed slight splitting of the bending modes, resulting from their nondegeneracy in the complexes, is confirmed by our computations, and the results qualitatively agree with the experiment. The splitting increases with increasing polarizability of the rare-gas atom. Additionally, we explain a discrepancy in the mode assignment in the intermolecular region of the neon complex with our VCI character assignment.

A novel non-adiabatic spin relaxation mechanism in molecular qubits.

The interaction of electronic spin and molecular vibrations mediated by spin-orbit coupling governs spin relaxation in molecular qubits. We derive an extended molecular spin Hamiltonian that includes both adiabatic and non-adiabatic spin-dependent interactions, and we implement the computation of its matrix elements using state-of-the-art density functional theory. The new molecular spin Hamiltonian contains a novel spin-vibrational orbit interaction with a non-adiabatic origin, together with the traditional molecular Zeeman and zero-field splitting interactions with an adiabatic origin. The spin-vibrational orbit interaction represents a non-Abelian Berry curvature on the ground-state electronic manifold and corresponds to an effective magnetic field in the electronic spin dynamics. We further develop a spin relaxation rate model that estimates the spin relaxation time via the two-phonon Raman process. An application of the extended molecular spin Hamiltonian together with the spin relaxation rate model to Cu(II) porphyrin, a prototypical S = 1/2 molecular qubit, demonstrates that the spin relaxation time at elevated temperatures is dominated by the non-adiabatic spin-vibrational orbit interaction. The computed spin relaxation rate and its magnetic field orientation dependence are in excellent agreement with experimental measurements.

Vibrational ADAPT-VQE: Critical points lead to problematic convergence.

Quantum chemistry is one of the most promising applications for which quantum computing is expected to have a significant impact. Despite considerable research in the field of electronic structure, calculating the vibrational properties of molecules on quantum computers remains a relatively unexplored field. In this work, we develop a vibrational Adaptive Derivative-Assembled Pseudo-Trotter Variational Quantum Eigensolver (vADAPT-VQE) formalism based on an infinite product representation (IPR) of anti-Hermitian excitation operators of the Full Vibrational Configuration Interaction (FVCI) wavefunction, which allows for preparing eigenstates of vibrational Hamiltonians on quantum computers. In order to establish the vADAPT-VQE algorithm using the IPR, we study the exactness of disentangled Unitary Vibrational Coupled Cluster (dUVCC) theory and show that dUVCC can formally represent the FVCI wavefunction in an infinite expansion. To investigate the performance of the vADAPT-VQE algorithm, we numerically study whether the vADAPT-VQE algorithm generates a sequence of operators that may represent the FVCI wavefunction. Our numerical results indicate frequent appearance of critical points in the wavefunction preparation using vADAPT-VQE. These results imply that one may encounter diminishing usefulness when preparing vibrational wavefunctions on quantum computers using vADAPT-VQE and that additional studies are required to find methods that can circumvent this behavior.

Theoretical prediction of molar entropy of modified shifted Morse potential for gaseous molecules

The modified shifted Morse potential is a molecular potential that describes the molecular vibration and atomic interaction. This potential has not received much report as one of the useful potential function. In this study, the molar entropy of a modified shifted Morse is obtained via the vibrational partition function, rotational partition function and translational partition function. Numerical results are obtained for iodine molecule (I2), silicon carbide (SiC), carbon phosphide (CP) and fluorine molecule (F2) for temperatures of 200 K to 6000 K. The predicted results are compared with the experimental results obtained from the National Institute of Standards and Technology (NIST) data base. The predicted values aligned with the experimental results for the four molecules. The average absolute percentage deviation obtained for each molecule is less than one, which shows a good representation of the modified shifted Morse potential for thermodynamic functions.

Optimal Vibration Fields in Problems of Modeling Dynamic States of Technical Objects

Introduction. Vibration interaction control is timely in production processes related to liquid and bulk media, systems of solids experiencing kinematic or force disturbances. At the same time, there is no single methodological basis for the formation of vibrational interactions. The issues of constructing optimal vibration fields of technical objects have not been addressed. The objective of the study is to develop a structural approach to the development of mathematical models in the problems of formation, evaluation, and correction of vibration fields of technical objects under conditions of intense force and kinematic loads. The task is to build vibration fields that are optimal in terms of the set of requirements, with the possibility of selecting the criterion of optimality of the vibration field of a technical object.Materials and Methods. A structural approach was used as the basic methodology. It was based on a comparison of mechanical vibratory systems used as computational schemes of technical objects, and structural schemes of automatic control systems, which are equivalent in dynamic terms. Lagrange formalism, elements of operational calculus based on Laplace integral transformations, sections of vibration theories, algebraic methods, and the theory of spline functions were used for structural mathematical modeling.Results. An approach to the selection of criteria for the optimality of vibration fields based on minimizing the residual of vibration fields for various required conditions was proposed. The problem was considered within the framework of a mechanical vibratory system formed by solids. It was shown that the optimal vibration field was determined by an external disturbance and was to satisfy condition Ay̅ = b. There, A — matrix mapping the operator of conditions to the shape of the vibration field at control points; b — vector of values of vibration field characteristics; “–” above y meant the vibration amplitude of the steady-state component of the coordinate. To evaluate the field with account for noisy or unreliable requirements for dynamic characteristics, the smoothing parameter was used, indicating the priority of the criterion of optimality of the vibration field shape. The construction of a field for a mechanical vibratory system showed that the value of the vibration amplitudes of generalized coordinates remained constant when the frequency of external kinematic disturbances changed. Two approaches to the correction of the field optimality criteria were considered: equalization of the vibration amplitudes of the coordinates of a technical object and the selection of an energy operator.Discussion and Conclusion. The development of the applied theory of optimal vibration fields involved, firstly, the correlation of the energy operator and the operator of the requirements for the shape of the vibration field in the theory of abstract splines. The second pair of comparable elements was the criterion of optimality of the vibration field and a system of requirements for the characteristics of the field at control points. The structural theory of optimal vibration fields improved in this way will find application in various industries. Accurate calculations in the formation, assessment, and correction of the states of systems under vibration loading are required in the tasks of increasing the durability of structures, improving measurements in complex vibratory systems, and developing new technologies and materials.

Development of methods and means to improve environmental, radiation and industrial safety of NPPs with WWER-1200

The introduction provides an overview of scientific research on the sources of generation, characteristics and classification of infrasound. It is noted that infrasound has a number of features related to the low oscillation frequency of the elastic medium and the diffraction property. Infrasound has harmful effects on hearing, breathing, vision, gastrointestinal tract, nervous and cardiovascular systems, brain and vestibular apparatus, leading to decreased performance, general malaise and premature aging of the human body. The methodology of theoretical substantiation of methods for detecting previously unknown sources of infrasound, improving the environmental, radiation and industrial safety of nuclear power plants with WWER-1200 is based on the use of digital acoustic models of primary circuit equipment responsible for operational safety developed under the guidance of K.N. Proskuryakov. The methodology of practical confirmation of the results of computational and theoretical forecasting of acoustic parameters of previously unknown infrasound sources is presented in the form of two stages: a) development of a methodology for verifying forecasting results and selection of power units No. 1, 2 of Novovoronezh NPP-2 in the form of objects; b) investigation of the conditions for the occurrence of vibro-infrasound resonances in the first circuit. The developed method for investigating infrasound sources has been verified at the WWER-1200 reactor plant. When discussing the results of the conducted research, previously unknown sources of infrasound were identified. Innovative methods of analysis and damping of infrasound sources have been developed and a patent for invention No. 2803181 «A method for preventing resonant interaction of vibrations of water-water power reactor equipment with acoustically standing waves and a device for its implementation» has been obtained. The errors of the chief designer of reactor installations with WWER in the regulations for the launch of new power units are noted; their negative consequences for the health of personnel and the condition of equipment responsible for environmental, radiation and industrial safety of nuclear power plants with WWER are indicated

Study on failure mechanism of suspension lug elbow in an ethylene cracking pyrolyzer

The cracking of a suspension lug elbow caused a shutdown in a certain petrochemical enterprise. In this study, the authors conducted physical and chemical analysis to investigate the cracking mechanism. Macroscopic observations indicated no signs of corrosion or thinning on the inner and outer surfaces of the head, and the cracks were distributed in the body of the head and the ear. Chemical composition analysis revealed that the main chemical components of the failed elbow met the standard requirements. Metallographic observations showed significant creep damage in the substrate material, and after long-term high-temperature service, both the room temperature and high-temperature mechanical properties of the failed elbow significantly deteriorated. The failure sample exhibit a fracture elongation of 0 %, and the high-temperature creep performance of the head material was only 6.868 h, both lower than the standard requirement of a fracture elongation of 4 % and 120 h of high-temperature creep performance. Fracture surface observation revealed obvious creep voids and fatigue striations, indicating severe creep damage and the influence of alternating loads on the head. Field observations indicated that the head experienced significant shaking inside the furnace. Therefore, simulation analysis suggested that the maximum stress coincided with the crack location, ranging from 121 MPa to 131 MPa, far exceeding the tensile strength at the operating temperature when the elbow was subjected to alternating loads generated by left–right and back-forth swinging. In conclusion, the failure of the suspension lug elbow was caused by creep-fatigue cracking. This study reveals that, even when the internal medium is in single gaseous phase, elbows are still susceptible to cracking under the combined effects of high temperature vibration and creep interaction. To avoid future failures, strengthening the monitoring of the cracking furnace operation, controlling the load appropriately, and preventing severe vibration and shaking of the furnace tube are recommended.