Mechanics

Article Acoustics

Interaction of flutter and forced response in a low pressure turbine rotor with friction damping and mistuning effects

Salvador Rodriguez-Blanco, Javier Gonzalez-Monge, Carlos Martel

Summary: In modern LPT designs, the simultaneous presence of forced response and flutter in different operation regimes is unavoidable. Recent evidence suggests that the traditional linear superposition method may be overly conservative. This study examines the flutter and forced response interaction in a realistic low pressure turbine rotor and confirms that the actual response is much smaller than that predicted by linear superposition.

JOURNAL OF SOUND AND VIBRATION (2024)

Article Acoustics

Effects of number of blades on propeller noise

Kabilan Baskaran, Nur Syafiqah Jamaluddin, Alper Celik, Djamel Rezgui, Mahdi Azarpeyvand

Summary: This study investigates the impact of the number of blades on the aeroacoustic characteristics and aerodynamic performance of propellers used in urban air mobility vehicles. The results show that different blade numbers exhibit distinct noise levels, providing valuable insights for further research on propeller noise and aerodynamic performance.

JOURNAL OF SOUND AND VIBRATION (2024)

Article Acoustics

Three-dimensional analytical solution of free vibrations of a simply supported composite plate in contact with a fluid

Nicco Ulbricht, Alain Boldini, Peng Zhang, Maurizio Porfiri

Summary: The quantification of fluid-structure interactions in marine structures is crucial for their design and optimization. In this study, an analytical solution for the free vibration of a bidirectional composite in contact with a fluid is proposed. By imposing continuity conditions and boundary conditions, the coupled fluid-structure problem is solved and applied to sandwich structures in naval construction, offering insights into the effects of water on mode shapes and through-the-thickness profiles of displacement and stress.

JOURNAL OF SOUND AND VIBRATION (2024)

Article Acoustics

Reliability-based design optimization of tuned mass-damper-inerter for mitigating structural vibration

Yongbo Peng, Peifang Sun

Summary: This study focuses on the reliability-based design optimization (RBDO) of the tuned mass-damper-inerter (TMDI) system under non-stationary excitations. The performance of the optimized TMDI system is evaluated using probability density evolution analysis. The results demonstrate the technical advantages of TMDI, including high vibration mitigation performance, considerable mass reduction, and less stroke demand.

JOURNAL OF SOUND AND VIBRATION (2024)

Article Acoustics

Influence of blades' shape and cutters' arrangement of PDC drill bit on nonlinear vibration of deep drilling system

Pengfei Deng, Xing Tan, He Li

Summary: In this paper, the authors improve the surface morphology method and study the bit-rock interaction model between the rock and the PDC bit, taking into account the impact of blade shape and cutter arrangement. They establish a dynamic model for a deep drilling system equipped with an arbitrary shape PDC bit and propose a stability prediction method. The results show that the shape of the blades and arrangement of the cutters on the PDC bit significantly affect the nonlinear vibration of the drilling system.

JOURNAL OF SOUND AND VIBRATION (2024)

Article Acoustics

Calibration of inverted pendulum pedestrian model for laterally oscillating bridges based on stepping behaviour

Bronislaw Czaplewski, Mateusz Bocian, John H. G. Macdonald

Summary: Despite two decades of study, there is currently no model that can quantitatively explain pedestrian-generated lateral forces. This research proposes a foot placement control law based on empirical data to calibrate and generalize the rigid-leg inverted pendulum model (IPM) for predicting lateral structural stability.

JOURNAL OF SOUND AND VIBRATION (2024)

Article Engineering, Mechanical

Ultra-broadband gaps of a triple-gradient phononic acoustic black hole beam

Yue Bao, Zhengcheng Yao, Yue Zhang, Xueman Hu, Xiandong Liu, Yingchun Shan, Tian He

Summary: This paper proposes a novel triple-gradient phononic acoustic black hole (ABH) beam that strategically manipulates multiple gradients to enhance its performance. The study reveals that the ABH effect is not solely brought about by the thickness gradient, but also extends to the power-law gradients in density and modulus. The synergistic development of three different gradient effects leads to more pronounced and broader bandgaps in PCs.

INTERNATIONAL JOURNAL OF MECHANICAL SCIENCES (2024)

Article Engineering, Mechanical

Effective elastic properties of sandwich-structured hierarchical honeycombs: An analytical solution

Omar El-Khatib, S. Kumar, Wesley J. Cantwell, Andreas Schiffer

Summary: Sandwich-structured honeycombs (SSHCs) are hierarchical structures with enhanced mass-specific properties. A model capable of predicting the elastic properties of hexagonal SSHCs is presented, showing superior in-plane elastic and shear moduli compared to traditional honeycombs, while the out-of-plane shear moduli are reduced.

INTERNATIONAL JOURNAL OF MECHANICAL SCIENCES (2024)

Article Engineering, Mechanical

Integrating multiple samples into full-field optimization of yield criteria

Matthias Ryser, Jason Steffen, Bekim Berisha, Markus Bambach

Summary: This study investigates the feasibility of replacing complex experiments with multiple simpler ones to determine the anisotropic yielding behavior of sheet metal. The results show that parameter identifiability and accuracy can be achieved by combining multiple specimen geometries and orientations, enhancing the understanding of the yield behavior.

INTERNATIONAL JOURNAL OF MECHANICAL SCIENCES (2024)

Article Engineering, Mechanical

A conjugated bond-based peridynamic model for laminated composite materials

Shuo Liu, Lu Che, Guodong Fang, Jun Liang

Summary: This study presents a novel lamina conjugated bond-based peridynamic (BB-PD) model that overcomes the limitations of material properties and is applicable to composite laminates with different stacking sequences. The accuracy and applicability of the model are validated through simulations of elastic deformation and progressive damage behavior, providing an explanation of the damage modes and failure mechanisms of laminated composite materials subjected to uniaxial loading.

INTERNATIONAL JOURNAL OF MECHANICAL SCIENCES (2024)

Article Engineering, Mechanical

Analytical probabilistic progressive damage modeling of single composite filaments of material extrusion

E. Polyzos, E. Vereroudakis, S. Malefaki, D. Vlassopoulos, D. Van Hemelrijck, L. Pyl

Summary: This research investigates the elastic and damage characteristics of individual composite beads used in 3D printed composites. A new analytical probabilistic progressive damage model (PPDM) is introduced to capture the elastic and damage attributes of these beads. Experimental results show strong agreement with the model in terms of elastic behavior and ultimate strength and strain.

INTERNATIONAL JOURNAL OF MECHANICAL SCIENCES (2024)

Article Engineering, Mechanical

Multifield asymptotic homogenization for periodic materials in non-standard thermoelasticity

Rosaria Del Toro, Maria Laura De Bellis, Marcello Vasta, Andrea Bacigalupo

Summary: This article presents a multifield asymptotic homogenization scheme for analyzing Bloch wave propagation in non-standard thermoelastic periodic materials. The proposed method derives microscale field equations, solves recursive differential problems within the unit cell, establishes a down-scaling relation, and obtains average field equations. The effectiveness of this approach is validated by comparing dispersion curves with those from the Floquet-Bloch theory.

INTERNATIONAL JOURNAL OF MECHANICAL SCIENCES (2024)

Article Engineering, Mechanical

Oscillation of an ultrasonically driven gas bubble in an asymmetric confined domain

Saman A. Bapir, Kawa M. A. Manmi, Rostam K. Saeed, Abdolrahman Dadvand

Summary: This study numerically investigates the behavior of an ultrasonically driven gas bubble between two parallel rigid circular walls with a cylindrical micro-indentation in one wall. The primary objective is to determine the conditions that facilitate the removal of particulate contamination from the indentation using the bubble jet. The study found that the bubble jet can effectively remove contamination from the indentation for certain ranges of indentation diameter, but becomes less effective for larger indentation diameters.

INTERNATIONAL JOURNAL OF MECHANICAL SCIENCES (2024)

Article Engineering, Mechanical

A novel two-dimensional non-contact platform based on near-field acoustic levitation

Wenjun Li, Pengfei Zhang, Siyong Yang, Shenling Cai, Kai Feng

Summary: This study presents a novel two-dimensional non-contact platform based on Near-field Acoustic Levitation (NFAL), which can realize both one-dimensional and two-dimensional transportation. Numerical and experimental results prove the feasibility and ease of this method.

INTERNATIONAL JOURNAL OF MECHANICAL SCIENCES (2024)

Article Engineering, Mechanical

Energy-based performance prediction for metals in powder bed fusion

Zhi-Jian Li, Hong-Liang Dai, Yuan Yao, Jing-Ling Liu

Summary: This paper proposes a process-performance prediction model for estimating the yield strength and ultimate tensile strength of metallic parts fabricated by powder bed fusion additive manufacturing. The effect of main process variables on the mechanical performance of printed metallic parts is analyzed and the results can serve as a guideline for improvement. The accuracy of the proposed model is validated by comparison with literature.

INTERNATIONAL JOURNAL OF MECHANICAL SCIENCES (2024)

Article Thermodynamics

High thermal conductivity and ultralow friction of two-dimensional ice by molecular dynamics simulations

Hongyi Zou, Lijun Yang, Zhiyuan Huang, Yuan Dong, Ruo-Yu Dong

Summary: In this study, the thermal and mechanical properties of two-dimensional ice (2D ice) were systematically studied using molecular dynamics simulations. The results showed that the thermal conductivity of 2D ice depends on its length and can be increased by decreasing temperature or applying mechanical strains. Additionally, 2D ice exhibited a very low friction and the friction coefficient decreased with decreasing temperature or increasing normal load.

INTERNATIONAL JOURNAL OF HEAT AND MASS TRANSFER (2024)

Article Thermodynamics

Study of flow pattern transition criterion and heat transfer characteristics in vertical rectangular narrow channel for steam heating

Shengjie Gu, Leren Tao, Cheng Jin, Yiwei Ju, Xiefei Zhao

Summary: This study clarifies the heat transfer characteristics of flow boiling in a narrow vertical rectangular channel and proposes a corresponding heat transfer correlation equation. The results show that an increase in inlet temperature has a positive effect on the nucleate boiling section, while an increase in mass flux has a negative effect on the nuclear state boiling stage. Furthermore, the peak of the local heat transfer coefficient tends to shift to the left as the heating power increases.

INTERNATIONAL JOURNAL OF HEAT AND MASS TRANSFER (2024)

Article Mechanics

Effect of radius ratio on the instabilities in a vaneless diffuser

Meng Fan, Antoine Dazin, Gerard Bois, Francesco Romano

Summary: This study investigates the prominent features of the primary instabilities of a turbulent source flow between finite-span parallel rings with spatially modulated inflow conditions rotating at angular rate n. Two different two-dimensional instabilities that occur at large and low flow rates have been traced back to two different physical mechanisms related to jet-wake and mean-core flow, respectively. The effect of the radial aspect ratios on the instability characteristics of the flow between parallel rings is also considered.

EUROPEAN JOURNAL OF MECHANICS B-FLUIDS (2024)

Article Mathematics, Applied

Non-autonomous inverse Jacobi multipliers and periodic orbits of planar vector fields

Isaac A. Garcia, Susanna Maza

Summary: This paper analyzes the role of non-autonomous inverse Jacobi multipliers in the problem of nonexistence, existence, localization, and hyperbolic nature of periodic orbits of planar vector fields. It extends and generalizes previous results that focused only on the autonomous or periodic case, providing novel applications of inverse Jacobi multipliers.

COMMUNICATIONS IN NONLINEAR SCIENCE AND NUMERICAL SIMULATION (2024)

Article Thermodynamics

Structural gradient optimization of diffusion layer based on finite data mapping method for PEMFC performance improvement

Junhong Hao, Tengyu Ma, Jinglong Zhou, Huimin Wei, Yanqiang Kong, Xiaoze Du

Summary: This paper focuses on optimizing the design of proton exchange membrane fuel cells (PEMFCs). A three-dimensional mathematical model of PEMFC is established and simulation data under different structural parameters are collected. By analyzing the simulation data, a mapping relationship between the thickness of the diffusion layer and the output power is derived using response surface analysis. The optimal structural parameters are obtained through the BP neural network. The results show that the fuel cell using a gradient diffusion layer has improved performance compared to using a conventional diffusion layer, including increased average power, overall heat transfer capacity, and oxygen utilization. Furthermore, the paper finds that the fuel cell with a tapered diffusion layer has better synergistic performance in temperature and concentration fields, as well as temperature and velocity fields.

INTERNATIONAL JOURNAL OF HEAT AND MASS TRANSFER (2024)