Hole In Plate Research Articles

Overstrength and plastic rotation of variable cross-section replaceable link

This paper presents a comprehensive investigation of variable cross-section replaceable links (VRLs) through a combination of experimental and numerical analyses. Two types of specimens were designed: one with circular holes in the web plate (C-VRL) and the other with long holes in the web plate (LC-VRL). The performance of VRL specimens with circular and long holes in the web plate were analyzed, focusing on hysteresis curves, energy dissipation capacity, overstrength coefficient, and failure modes. The results showed that the C-VRL specimen exhibited stable and complete hysteresis loops with substantial plastic development and efficient energy dissipation. On the other hand, the LC-VRL specimen experienced reduced bearing capacity due to tearing around the long holes and sliding of the connection between the web plate and the flange. The C-VRL specimen demonstrated higher bearing capacity compared to the LC-VRL specimen, and both specimens exhibited favorable structural ductility. The numerical analysis involved a validated finite element model, considering various parameters such as the length and height of the energy-dissipation region, variable cross-section slope, and weakening form of the web plate. The energy dissipation capacity increased with the rotation angle for all specimens. The overstrength coefficient of the VRLs exceeded the recommended value, indicating its better load-carrying capacity. Overall, the study findings provide insights into the seismic performance, overstrength coefficient, and design considerations of VRLs in practical engineering applications.

Fatigue response of open hole plates: A finite element simulation investigating the influence of dynamic and static cold expansion processes

Cold Expansion (CE) techniques are extensively used in the aeronautical industry to enhance the fatigue life of open-hole plates. However, the availability of accurate Finite Element (FE) models to simulate the fatigue behavior of this process, particularly Dynamic Cold Expansion (DCE), is limited. This study introduces two novel methods for predicting the fatigue response of DCE and Static Cold Expansion (SCE) open-hole plates. The first method directly estimates the total fatigue life using Continuum Damage Mechanics (CDM) and the Theory of Critical Distance (TCD). The second method separates the prediction of fatigue crack initiation life and propagation life, incorporating CDM, TCD, and the Extended Finite Element Method (XFEM). Moreover, FE models are developed to simulate residual stress, stress under external cyclic loads, and fatigue crack propagation behavior for both DCE and SCE specimens. The proposed methods are evaluated, compared, and the mechanisms behind fatigue life enhancement and fatigue crack propagation modes in CE specimens are discussed. It is found that the prediction accuracy is enhanced by considering stress distributions along the thickness direction and improving the Line Method (LM) in TCD through the introduction of a novel CE parameter. The results demonstrate that both methods achieve good predictive performance, with an average error index within ±30%. Furthermore, it is observed that both DCE and SCE processes primarily improve the fatigue crack initiation life of open-hole plates, with the percentage of crack initiation fatigue life increasing as the expansion size increases. The majority of the fatigue crack propagation life in CE specimens is concentrated in the initial stages of crack propagation. In addition, the effects of DCE and SCE processes on reducing the fatigue crack propagation rate are more pronounced along the thickness direction compared to the width direction, leading to distinct crack propagation modes between CE and non-cold expansion (NCE) specimens.

Evaluation of atomic oxygen fluences by analyzing transmitted light images of polyimide obtained at SLATS/MDM

Expectations for high-resolution observations by very low Earth orbit (VLEO, below 300 km) satellites are growing. However, the density of atomic oxygen (AO) is much higher in VLEO than in LEO (300 km or higher), so severe degradation of materials is a concern due to high-flux AO collisions. To clarify the degradation, we developed and deployed the material degradation monitor (MDM) mission onboard the super-low altitude test satellite (SLATS). In the MDM, several materials were exposed to the environment at 160–560 km from 23 December 2017 to 1 October 2019 and observed optically by a CCD camera. In general, AO fluence is evaluated by measuring the volume or mass loss of a polyimide, but this was difficult to do because the samples could not be returned to the ground in this mission. This study evaluated AO fluences using the CCD images of a polyimide, Vespel. The sample had nine non-penetrating holes with different bottom-plate thicknesses and was monitored by the CCD while being illuminated by LED light from the back. The CCD images reveal the intensity of the light transmitted through the holes in the bottom plate. The erosion depths of the polyimide, corresponding to the AO fluences, can be evaluated from the pixel values at the hole positions on the images. Here, the correlation between the pixel values and thickness was investigated for pristine and AO-exposed Vespel samples using the MDM engineering models. The total green pixel values followed the Beer-Lambert law for the bottom-plate thicknesses, regardless of AO exposure. Applying the correlation to the MDM flight images, we found that the AO fluence increased significantly after the end of March 2019, finally reaching (6.5–9.8) × 1021 atoms/cm2. This optical imaging method would be useful for evaluating the AO effects on the other MDM samples and high AO fluences in future VLEO missions.

Dynamic modeling of vibration behavior and power flow of a plate structure embedded with an ABH indentation

A two-dimensional (2D) semi-analytical model is established for the analyses of vibration behavior and energy transmission of the plate structure with a power-law-profiled thickness variation, referred to as an Acoustic Black Hole (ABH) plate. Under the general Rayleigh-Ritz framework, a modified version of 2D Fourier series is employed as the admissible function of the transverse displacement of the ABH plate featuring a thickness variation. Thanks to such modified Fourier series, a high-order spatial derivative continuity over the entire solution domain is available to express the internal forces and bending moments, further calculating the corresponding structural intensity and power flow within the ABH plate. The proposed model allows an accurate prediction of the modal characteristics and dynamic response, which is verified by the FEM and experiment, respectively. Several numerical analyses are proceeded and the typical dynamic phenomena, including the wave compression and efficient vibrational suppression of the 2D ABH plate are observed. The structural intensity (SI) vector arrows of the ABH plate are given, which represent the magnitude of the vibrational energy and the flowing direction in a visual pattern. The energy transmission behaviors and the manipulation of power flow by the ABH are revealed in an energy perspective. The typical energy focalization and dissipation phenomena of the ABH plate are analyzed in the frequency domain. Finally, the enhancement of the energy transmission by the ABH feature on the plate is explored by the normalized power flow. It is noted that the proposed model offers a visual energy transfer analysis tool for the 2D ABH structures, which may provide a novel perspective in various studies of ABH structures.

The Modeling of Disc-shaped Acoustic Black Hole Plate and Vibration Characteristics

The Acoustic Black Hole (ABH) structure has great potential in vibration and noise control due to the characteristics of high damping and energy accumulation. A dish-shaped two-dimensional acoustic black hole plate is proposed in order to reduce the possibility of the structural damage happened in conventional embedded ABH in the centre of the plate. The dish-shaped acoustic black hole plate only cuts ABH on the edge. The finite element method is often used to establish the model of acoustic black hole plates. However, it is high cost and low efficiency in computation. A semi-analytical theoretical model of the disc-shaped acoustic black hole plate based on Gaussian expansion method is established in order to improve computation efficiency. Meanwhile, the shape function filtering method is proposed to solve the problem of non-convergence when Gaussian expansion method is used to model a non-rectangular plate. A finite element model of the disc-shaped acoustic black hole plate is established and used to verify the accuracy of the proposed semi-analytical theoretical model. The results show that the dish-shaped acoustic black hole plate has excellent energy accumulation effect and can be used further as Dynamic Vibration Absorber (DVA) to reduce the vibration of host structure.

Visualization and Analysis of Temporal and Steady-State Gas Concentration in Process Chamber Using 70-dB SNR 1000 fps Absorption Imaging System

We are developing a 70-dB SNR 1,000 frame-per-second absorption imaging system, and it enables us to visualize gas concentration distribution in a vacuum chamber for semiconductor manufacturing. This article presents the measurement and analysis of temporal and steady-state NO2 gas concentration distribution using this system. In the steady-state gas flow condition which supplied from a shower plate, the spectrometry of NO2 gas shows a good linear relationship between the absorbance and the partial pressure with the system. The system enables the visualization of steady-state of NO2 gas concentration distribution which supplied from one hole of shower plate, and the results are compared with simulation to discuss the reasonability of the measurement. The system also enables to visualize the temporal NO2 gas concentration distribution supplied from a single nozzle, and the advantages of the system’s features of 70-dB and 1,000 fps are discussed.

Higher-Frequency Permeability Measurement by Harmonic Resonance Cavity Perturbation Method

A new combination of electric field antenna and coupling hole plates are introduced to extend the measurable frequency range of rectangular waveguide type harmonic resonator to evaluate complex relative permeability of magnetic composites by perturbation method from 18 GHz to 38 GHz (K/Ka-band). The noise suppression performance parameter ωμ”=2πfμ <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">0</sub> μ <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">r</sub> ” [kΩ/m] is useful to estimate the performance of magnetic powder composite sheets especially beyond 10 GHz range where relative permeability is as small as 0-2. The ωμ” exhibited the maximum of 166 kΩ/m at 27 GHz for a carbonyl iron powder composite sheet, and as high as 510 at 38 GHz for Sendust sheet. These values meet ωμ”≥100 kΩ/m criteria that some commercially available noise suppression sheets exhibit in their recommended frequency range. These performance match Sub-6 GHz band and 28 GHz band used for 5G telecommunication equipment.

Effect of numerous plate holes in a cooling tower on heat transfer optimization

An industry requires a cooling medium to reduce heat in an industrial machine during operation. Companies generally use cooling towers for engine cooling media. The common issue is that heat reduction and heat transfer rate are not significant. Therefore, a new variation is needed to ensure that the cooling tower can effectively lower the temperature of the machinery. The problem statement aims to determine the parameters that can enhance both the heat transfer rate and the heat transfer coefficient in cooling towers. The objective is to determine the heat transfer rate and heat transfer coefficient. The method used is experimental by varying the water inlet in five variations of the cooling tower plates, they are being 48, 60, 80, 120, and 250 holes. The results showed that the highest temperature difference occurs at Tin 80oC with the variation of 250 holes, which is 9.34oC, and the highest heat transfer value reached 1833.17 watts. Meanwhile, the lowest temperature difference occurred at Tin 60oC with a variation of 48 holes, which is 3,98oC, and the lowest heat transfer value reached 787.47 watts. The highest convection coefficient occurs at Tin 70oC with the variation of 250 holes, which is 117.74 W/m²⋅K. The lowest convection coefficient occurs at Tin 80oC with a variation of 48 holes, which is 77.36 W/m²⋅K. This can be concluded that the temperature difference (⧍T), heat transfer rate, and heat transfer coefficient will increase when the number of holes in each plate variation increases.

Experimental study fluidized bed reactor using number hole 8 to see distribution gas fluid pressure

Innovations related to fluidization systems using fluidized bed reactor are still needed to be developed in order to improve the fluidization process services for particle in order to produce the right fluid pressure in certain fluidized bed spaces that are currently operating. In this research, the pressurized fluid in question is air sourced from a compressor which has been arranged in such a way. The aim of the research is to obtain information regarding the characteristics of bubble resulting from the air pressure process pressing fluidized system particle. The research method was carried out by experimenting with testing fluidized bed reactor as test model in the form 8 hole, providing air pressure from compressor then observing the characteristics visually. The results of this visually documented research have been carried out and obtained. By using the number of hole 8 with height silica sand inserted to height of 25 cm, which is measured from the beginning of the hole plate before pressure is applied. After being given high pressure the bed increased to 27.6 cm, the highest bubble diameter was obtained at the input air pressure of 8 bar, which was 3.9 cm, with bed silica sand produced 26.1 cm, where the babble condition began to appear after the 9th second. Other characteristics also obtained reactor temperature of 25.45 °C where this condition is the smallest when compared to other pressure input results, this is because the small input pressure causes the temperature to be low, while the large pressure input temperature becomes higher due to many factor, including friction between silica sand, silica sand collisions, and faster movement of particle material.

Evolution of cold-expanded microstructure with aging temperature and its influence on fatigue performance of hole structure at elevated temperature

A surface-strengthened layer formed by cold expansion (CX) evolves at high temperatures. The evolution of surface integrity and microstructure after a CX-treated superalloy GH4169 center hole plate was investigated in the present study. Aging at 400 ℃ and 600 ℃ took place with a duration of 500 h (CX400 and CX600). In addition, the fatigue properties at 820 MPa/600 ℃/R= 0.1 were investigated. The results show that CX has a smooth surface, a compressive residual stress field with a depth of more than 1.4 mm and a non-improved surface hardness. The statistical fatigue life of the as-received specimens was 7015 cycles, and the fatigue lives after CX and CX400 treatment were 5.27 and 2.86 times higher, respectively, indicating an increase by CX and a decrease by 400 ℃ aging. In contrast, the fatigue life of the original sample decreased to 5576 cycles with 600 ℃ aging, while the corresponding fatigue life of the CX600-treated sample was 7979 cycles, representing a significant decrease in both cases. The transformation of the main strengthening γ″ phase to the δ-phase upon aging at 600 ℃/500 h are the main reasons for the weakening of the fatigue properties, which did not occur upon aging at 400 ℃ (see TEM).

Study of Plasma Arc Underwater Penetration Processes in Steel Structures Covered with Non-conductive Materials

Recently, plenty of offshore platforms have faced decommissioning. Offshore steel structures covered with rust, mud, and barnacles require suitable cutting methods for their removal. The non-transferred plasma arc is highly efficient in cutting both conductive and non-conductive materials and is expected to play an important role in offshore demolition operations. This work aims to investigate the underwater penetration process of non-transferred plasma arcs on steel structures covered with non-conductive substances. The workpiece consisted of a 5 mm cement layer and a 10 mm steel plate, whose removal mass and hole morphology were recorded at several moments. It was found that the hole of the cement layer was larger than that of the steel plate, while the mass removal rate of the steel plate was much higher than that of the cement layer. The hole in the cement layer gradually changes from an inverted cone to a drum, and the hole in the steel plate is always an inverted cone. A combined heat source model with time variation is proposed based on the experimental results, and a 2D axisymmetric simulation model is developed. The error between the simulated and experimental hole dimensions was within 3.1%, proving that the proposed heat source model can reflect the heat process of the workpiece well.

Analyzing Stress Concentration Factor in Finite Plate with Different Polygonal Discontinuities Under Uniaxial Compression Using FEM

A geometric, or theoretical, stress-concentration factor is the ratio of the actual maximum stress at the discontinuity to the nominal stress. Stress concentrations occur when there are irregularities in the geometry or material of a structural component that cause an interruption to the flow of stress. This arises from such details as holes, grooves, notches, and fillets. A detailed understanding of the stress concentration around the hole is essential for optimal design and resilience to mechanical failure. Therefore, in the design of structures, it is essential to study the effects of polygonal discontinuities in structures to achieve convenient and efficient designs. The current paper investigated the stress concentration factor around the polygonal holes in the finite structural steel plate, assuming a plane stress state and uniaxial compression loading. The present study provides a complete finite element analysis of stress concentrations in structural steel plates with polygonal cutouts (triangular, square, pentagonal, and hexagonal), in contrast to the side ratio of a polygonal hole, and the length, and height ratio of a square hole. The increasing order of stresses and SCF are square, triangular, pentagonal, and hexagonal. Due to the more edges of polygonal shapes parallel to the loading direction and minimum corners positioned in the direction of loading, a square-shaped hole produces 40% less SCF than a hexagonal-shaped hole.

Damage Propagation and Residual Strength of Simple Block-Loaded CFRP Plates with Circular Holes under Tension–Tension Fatigue Conditions

Holes and their effects on the fatigue behavior and damage propagation of thin-walled structural components remain objects of research. In this paper, the previously untreated effect of round holes in thin plain-woven carbon fiber-reinforced plastic plates subjected to simple block loading is examined, and the implication on both damage propagation and residual tensile strength is investigated. Using three-dimensional digital image correlation, the damage propagation in the performed experimental tests is acquired, and the damage size is quantified. The evaluations reveal a relationship between the damage propagation and applied load level, for which an empirical model has been previously established by the authors. As the number of cycles increases, a saturation behavior is found. Once the increased load is imposed on the plate, damage propagation resumes, leading to further damage propagation that can be described with the same empirical model as the initial damage propagation, including renewed saturation behavior. The subsequent experimental tests to determine the residual tensile strength reveal a positive effect of the existing damage size, as the ultimate load significantly exceeds the ultimate load of the non-damaged plate.

The Influence of Rib Distortion on the fatigue resistance of orthotropic plated bridge decks

AbstractOrthotropic bridge decks contain many places that are prone to fatigue damage due to the crossing of wheel loads of vehicles. Most research has focused on the rib to deck plate detail that has limited fatigue strength, especially due to the joint weld between these two parts. Less attention has been given to the effect of the alternating distortion stresses in the web plate of closed ribs. This distortion occurs as the rib passes through the web plate of the cross beams and is particularly pronounced if there is a high cope hole in that web plate. Experiments have been carried out in on this distortion effect at Ghent University. During 2 series of tests, similar results for the vertical rib web stress were found. However, these stresses due to distortion combine with longitudinal bending stress of the rib web and with shear. The corresponding strains were found from rosette measurements. These stress variations must be combined for fatigue assessment. This requires to use hot spot stress. In theory, the variation of the principal stress should be compared with the hot spot stress limit. This limit value is of course different for the 2 principal directions of the stress variations. This type of multi‐directional stress variations is addressed in codes, yet not exactly applicable in the present problem. Therefore, the modified critical plane offers a solution and gives more favourable results with longer fatigue endurance. In particular the Findley criterion that uses normal stress instead of shear, proves to be efficient in this type of problem. In order to link the results to simpler calculations, an attempt has been made to constitute a graph, which should allow a quick approximation for a first design.

Influence of plate thickness on the results of residual stresses determination by through hole drilling in orthotropic composites of different fiber orientation

The main objective of this study is to characterize residual stress in composite orthotropic plates using hole drilling method. The values of hole diameter increment in the principal anisotropic directions, which were obtained from electronic speckle-pattern interferometry on the external surface of the specimen, serve as the initial experimental information. The theoretical foundation of the approach is based on S. G. Lekhnitsky's analytical solution, which describes a stress concentration along the edge of the central open hole in a rectangular orthotropic plate under tension in principal anisotropy directions. The transitional model, that is essential link for deriving residual stress components from initial experimental data, provides the unequivocally solution to the properly posed inverse problem. Firstly, the validation of the transitional model regarding prescription of residual stress values for specific plies within a specimen’s thickness is based on calibration experiments. These experiments yield data for unidirectional and cross-ply composite plates of three different thicknesses. The results demonstrate that the values of principal residual stress components for cross-ply composite material are independent of plate thickness. This means that the transition model, based on the measurements of deformation responses to through hole drilling on the external plate face, can be reliably implemented to characterize the maximal residual stress values present in the middle plane of the composite plate. An investigation into the effect of hole diamter values on the determination of residual stress is conducted for cross-ply and angle-cross-ply composites. It is shown that a hole of diameter of 3.2 mm provides the most reliable results.

Reducing the taper and the heat-affected zone of CFRP plate by Micro fluid assisted laser induced plasma micro-drilling

Carbon Fiber Reinforced Plastics (CFRP) with superior mechanical properties are widely used in aerospace, automotive, and medical fields. The characteristics of CFRP with anisotropy and inhomogeneous result in poor machining performances by conventional drilling techniques. Laser drilling is a non-contact high precision machining technique without tool wear but leads to a large heat-affected zone (HAZ) and taper. Although underwater laser drilling could reduce thermal damage on CFRP surface, bubbles produced in the machining process severely affect the machining stability and surface quality. In this study, a micro fluid-assisted laser-induced plasma drilling (MFA-LIPMD) method was proposed to relieve the negative effect of bubbles as well as reduce the taper and HAZ. A comprehensive analysis of hole surface quality, HAZ, taper, and mechanical properties was conducted, and MFA-LIPMD performed more advantages over laser in the air (LIA) and laser-induced plasma drilling (LIPMD). It was found that the taper of micro-holes was reduced by 42.8%–51.78%, and the thermal damage rate of micro holes processed by the MFA-LIPMD process was reduced by 65.3%–68.1% compared with the LIPMD process, and the maximum tensile load of samples was increased by about 7.68%. Therefore, MFA-LIPMD has great potential for machining high-quality micro holes of CFRP plates.

Experimental Investigation of Temperature Distribution in a Laminar Boundary Layer over a Heated Flat Plate with Localized Transverse Cold Air Injections

This study presents an experimental investigation focused on the interaction between a transverse injection of cold air (blowing) and the boundary layer over a heated flat plate. The flat plate was equipped with a cylindrical coil heater positioned at its center along the flow direction. The constant heat flux was maintained using a variable resistance potentiometer. The flat plate with the heater was mounted inside a subsonic wind tunnel to sustain a constant laminar air flow. The primary objective of this research was to examine the effects of cold air injections through localized holes in the flat plate near the trailing edge on the thermal boundary layer thickness δt(x,Rex,Pr). The thermal boundary layer thickness was measured using K-type thermocouples and PT-100 RTD sensors, which are made to move precise, small distances using a specially constructed traversing mechanism. Cold air was injected using purposefully fabricated metal capillary tubes force-fitted into holes through the hot flat plate. The metal tubes were thermally insulated using class-F insulation, which is used in electric motor windings. The presented work focused on a fixed free-stream velocity and a fixed cold-injection velocity less than the free-stream velocity but for two-variable heat fluxes. The results show that the thermal boundary layer thickness generally increased due to the secondary cold flow.

Ефективність суднових енергетичних установок з теплообмінними апаратами з трубних пучків з лунковими системами

The direction of increasing the efficiency of marine power plants by using heat exchange elements that implement intensive methods of heat transfer, which are characterized by a predominant increase in heat transfer over aerodynamic resistance, is considered. The research method is mathematical modeling of processes in power plants at the level of their individual elements – heat engine, power, and technological heat exchangers. The adequacy of the mathematical model for research the efficiency of power plants is justified by the results of verification and validation by comparing the results of calculations with the results of a physical experiment that have a discrepancy not exceeding 9.3 %. The goal of the research is to improve the economic, environmental, resource and weight-size parameters of power plants by using heat exchange elements with the intensification of the processes of convective transfer of heat and mass by using finned surfaces with dimples. Thanks to the performance of dimple systems on the edges of round pipes with spiral-ribbon finning and elliptical pipes with lamellar finning, it is possible to increase the heat transfer coefficient up to 36 %, while the resistance coefficient of the beam remains unchanged. The use of heat exchangers with the proposed heat transfer elements as part of ship power plants with low-speed engines and gas-and-steam turbine units allows to improve their economic and environmental characteristics. It was obtained that for tankers of the PANAMAX type, the increase in the efficiency of the ship's power plant is 1.3 % due to the use of elliptical surfaces with plate finning and hole systems on the ribs in the utilization boiler. The ship's EEDI index decreased by 1.7 %. For container ships with a deadweight of more than 100,000 tons, the change in these indexes was 2.5 and 2.7 %, respectively. For a marine gas-and-steam turbine plant, the efficiency increase was 2.4 %. The presented mathematical model of the power plant is characterized by positive results of approbation for constructive and verification calculations of power plants in marine energy, transport, and industry.

Mechanical evaluation of different sagittal osteotomy fixation techniques used in minimally invasive surgery

Minimally invasive orthognathic surgery has advantages such as faster recovery, less paresthesia, and lower morbidity in the immediate postoperative period. However, there is no consensus regarding which fixation method is safer. The aim of the present study is to compare different methods of fixation of the short sagittal osteotomy like the Cordier G modification performed in minimally invasive surgery. An in vitro study was performed, consisting of 54 standardized polyurethane synthetic hemimandibles with Short sagittal osteotomy divided into 6 groups comprising 09 hemimandibles each. The groups consisted of bicortical screws, 4-hole straight plates, 0.8 mm and 1.0 mm thick curved plates, and 0.8 mm thick double Y and 1.0 mm thick double Y plates. All groups are System 2.0 and trademark Artfix®. The loading test was carried out, at a speed of 1mm/min, with a 50 Kgf load note for progressive load application on the system. Peak load (Kgf) and peak displacement (mm) were evaluated. Greater load resistance was found in the groups that received bicortical screws and 0.8mm and 1.0mm thick double Y plates.

A composite acoustic black hole for ultra-low-frequency and ultra-broad-band sound wave control

Achieving ultra-low and ultra-broad-band sound absorption and full-band sound insulation is a major challenge. Here, we propose a composite structure of a multilayer micro-perforated plate and acoustic black holes to achieve this purpose. Combining the stable sound absorption effect of the multilayer micro-perforated plate in the full frequency band and the sound insulation effect of the acoustic black hole in the low frequency and the excellent sound absorption effect in the high frequency, the excellent sound control effect of 600–3150 Hz absorption coefficient greater than 0.8 and 100–3150 Hz sound transmission loss greater than 50 dB is achieved. The acoustic properties of different components and different acoustic black hole outlet were evaluated by finite element method, and the principles of sound absorption and insulation of the composite structure were elaborated. Finally, the results of finite element method are verified by impedance tube experiments. This work can make further progress in elucidating the acoustic properties of the ABH and open up new avenues in the control of ultra-low and ultra-wide frequency acoustic waves.