The acoustic black hole (ABH) can be utilized to achieve aggregation of flexural wave in structures with the feature that the thickness gradually reduced to zero with a power exponent no less than 2. The above characteristics could be applied in vibration reduction, noise attenuation or improving sound insulation. Previous literatures on vibration and acoustic characteristics of ABH structures mainly focus on the structural response under mechanical force excitation, while the transmission loss (TL) of circular plates embedded with two-dimensional ABHs investigated in this paper is a vibro-acoustic coupling procedure under excitation of diffuse sound field. Series of vibro-acoustic coupling finite element models (FEM) for TL analysis of ABH circular plates were established by automatic matched layer (AML) method in this paper and an experimental platform for measuring TLs of ABH circular plates and uniform plates was constructed. The accuracy of the FEM analysis was verified by experimental measurements. To systematically analyze the influence mechanism of parameters of the ABH on TLs of ABH circular plates, the effects of diameter, orientation, number, and truncation thickness of ABHs on TLs of ABH circular plates were further studied. The effect of the damping layer on TLs of circular plates embedded with 1 and 19 ABHs was also analyzed and it reveals that the influence of damping layer mainly concentrates on the first-order resonance frequency and damping-controlled region of the plate, and at some frequencies, the greater the damping layer thickness, the worse the sound insulation performance, despite that the modal damping loss factor has been increased in the whole frequency domain.

Braided corrugated hoses are widely used in displacement compensation and vibration absorption environments due to their excellent flexibility and energy dissipation properties; however, the axial stiffness has rarely been discussed before as an important physical property of braided corrugated hoses. In this paper, the theoretical axial stiffness model for braided corrugated hoses is established based on the energy method and the theory of the curved beam. The influences of the braiding parameters of the metallic braided tube and the structural parameters of the bellows on the axial stiffness are also discussed. Through finite element tensile testing, the axial stiffness curves of the braided corrugated hose under different braiding angles and different wire diameters are obtained. The theoretical axial stiffness model is in good agreement with the simulation experiment, which reflects the nonlinear effects of the braiding angle and wire diameter on the braided corrugated hose. This paper provides an accurate method and basis for the design of braided corrugated hoses in the future.

To explore the mechanical properties of the braided corrugated hose, the space curve parametric equation of the braided tube is deduced, specific to the structural features of the braided tube. On this basis, the equivalent braided tube model is proposed based on the same axial stiffness in order to improve the calculational efficiency. The geometric model and the Finite Element Model of the DN25 braided corrugated hose is established. The numerical simulation results are analyzed, and the distribution of the equivalent stress and frictional stress is discussed. The maximum equivalent stress of the braided corrugated hose occurs at the braided tube, with the value of 903MPa. The maximum equivalent stress of the bellows occurs at the area in contact with the braided tube, with the value of 314MPa. The maximum frictional stress between the bellows and the braided tube is 88.46MPa. The tensile experiment of the DN25 braided corrugated hose is performed. The simulation results are in good agreement with test data, with a maximum error of 9.4%, verifying the rationality of the model. The study is helpful to the research of the axial stiffness of the braided corrugated hose and provides the base for wear and life studies on the braided corrugated hose.

To reveal the temperature rise evolution mechanism of isotropic media subjected to reciprocating motion constant-strength point heat source, various forms of analytical solutions are derived on the basis of differentiated relative scales, and non-dimensionalized parameters are designed to characterize the thermal distribution regularities by utilizing numerical calculations. Temperature rise curves of media subjected to a reciprocating motion point heat source allow similar quasi-steady-state characteristics to appear, which finally achieve a stable state, so that the values of surplus temperature oscillate around the constant time-average quantity. The time to reach quasi-steady state, the time-averaged quantity and the fluctuation amplitude of surplus temperature are comprehensively impacted by the dimensionless distance parameter γ, the convective heat transfer parameter ω and the velocity and travel parameter β. This work discusses influence rules of temperature evolution in various relative-scale media and further enriches the moving heat source theory.