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Bending and vibration of a discontinuous beam with a curvic coupling under different axial forces

Heng LIU, Jie HONG, Dayi ZHANG

《机械工程前沿(英文)》 2020年 第15卷 第3期   页码 417-429 doi: 10.1007/s11465-019-0584-4

摘要: The transverse stiffness and vibration characteristics of discontinuous beams can significantly differ from those of continuous beams given that an abrupt change in stiffness may occur at the interface of the former. In this study, the equations for the deflection curve and vibration frequencies of a simply supported discontinuous beam under axial loads are derived analytically on the basis of boundary, continuity, and deformation compatibility conditions by using equivalent spring models. The equation for the deflection curve is solved using undetermined coefficient methods. The normal function of the transverse vibration equation is obtained by separating variables. The differential equations for the beam that consider moments of inertia, shearing effects, and gyroscopic moments are investigated using the transfer matrix method. The deflection and vibration frequencies of the discontinuous beam are studied under different axial loads and connection spring stiffness. Results show that deflection decreases and vibration frequencies increase exponentially with increasing connection spring stiffness. Moreover, both variables remain steady when connection spring stiffness reaches a considerable value. Lastly, an experimental study is conducted to investigate the vibration characteristics of a discontinuous beam with a curvic coupling, and the results exhibit a good match with the proposed model.

关键词: discontinuous beam     bending stiffness     transverse vibration     axial loads     gyroscopic moments    

Vibration analysis of a simply supported beam under moving mass based on moving finite element method

Zhuchao YE, Huaihai CHEN,

《机械工程前沿(英文)》 2009年 第4卷 第4期   页码 397-400 doi: 10.1007/s11465-009-0044-7

摘要: In this paper, a moving finite element (MFE) method is proposed to perform the dynamic analysis of a simply supported beam for a moving mass (MM). The MFE method treats the moving mass as a moving part of the entire system, so that the transverse inertial effects caused by the moving mass may easily be taken into account. The solution to the beam’s dynamic behaviors including its displacement is obtained via a Newmark-β method; the effects of the velocity and weight of the MM on the beam’s dynamic behaviors are further discussed. The numerical examples show that the inertial effects of the MM significantly affect the transverse responses of the simply supported beam.

关键词: simply supported beam     moving mass (MM)     transverse vibration     moving finite element (MFE)    

Detection for transverse corner cracks of steel plates’ surface using wavelet

Qiong ZHOU, Qi AN

《机械工程前沿(英文)》 2009年 第4卷 第2期   页码 224-227 doi: 10.1007/s11465-009-0017-x

摘要: An algorithm is presented for detecting transverse corner cracks at a steel plate surface using wavelet transform. According to characteristics of transverse corner crack images, the wavelet transform is used for the multi-scale analysis of detecting the image edges and disintegrating the image into four directions at the same time. The proper threshold value is chosen to segment the image into vertical components to obtain the final detection result. The experiment shows that transverse corner cracks of steel plates can be more effectively extracted by the proposed method than the other two common methods.

关键词: transverse corner cracks     defect detection     multi-scales wavelet analysis    

Effect of axial load and transverse reinforcements on the seismic performance of reinforced concrete

Mounir Ait BELKACEM, Hakim BECHTOULA, Nouredine BOURAHLA, Adel Ait BELKACEM

《结构与土木工程前沿(英文)》 2019年 第13卷 第4期   页码 831-851 doi: 10.1007/s11709-018-0513-3

摘要: The aim of this research is to assess the seismic performance of reinforced concrete columns under different axial load and transverse reinforcement ratios. These two parameters are very important as for the ductility, strength, stiffness, and energy dissipation capacity for a given reinforced concrete column. Effects of variable axial load ratio and transverse reinforcement ratio on the seismic performance of reinforced concrete columns are thoroughly analyzed. The finite element computer program Seismo-Structure was used to perform the analysis of series of reinforced concrete columns tested by the second author and other researchers. In order to reflect the reality and grasp the actual behavior of the specimens, special attention was paid to select the models for concrete, confined concrete, and steel components. Good agreements were obtained between the experimental and the analytical results either for the lateral force-drift relationships or for the damage progress prediction at different stages of the loading.

关键词: reinforced concrete columns     axial load     transverse reinforcement     ductility    

Investigating the influence of delamination on the stiffness of composite pipes under compressive transverse

Sattar MALEKI, Roham RAFIEE, Abolfazl HASANNIA, Mohammad Reza HABIBAGAHI

《结构与土木工程前沿(英文)》 2019年 第13卷 第6期   页码 1316-1323 doi: 10.1007/s11709-019-0555-1

摘要: The effect of delamination on the stiffness reduction of composite pipes is studied in this research. The stiffness test of filament wound composite pipes is simulated using cohesive zone method. The modeling is accomplished to study the effect of the geometrical parameters including delamination size and its position with respect to loading direction on stiffness of the composite pipes. At first, finite element results for stiffness test of a perfect pipe without delamination are validated with the experimental results according to ASTM D2412. It is seen that the finite element results agree well with experimental results. Then the finite element model is developed for composite pips with delaminated areas with different primary shapes. Thus, the effect of the size of delaminated region on longitudinal and tangential directions and also its orientation with respect to loading direction on delamination propagation and stiffness reduction of the pipes is assessed.

关键词: delamination     composite pipes     stiffness test     cohesive zone method    

Vibration characteristics and machining performance of a novel perforated ultrasonic vibration platform

《机械工程前沿(英文)》 2023年 第18卷 第1期 doi: 10.1007/s11465-022-0730-2

摘要: Ultrasonic vibration-assisted grinding (UVAG) is an advanced hybrid process for the precision machining of difficult-to-cut materials. The resonator is a critical part of the UVAG system. Its performance considerably influences the vibration amplitude and resonant frequency. In this work, a novel perforated ultrasonic vibration platform resonator was developed for UVAG. The holes were evenly arranged at the top and side surfaces of the vibration platform to improve the vibration characteristics. A modified apparent elasticity method (AEM) was proposed to reveal the influence of holes on the vibration mode. The performance of the vibration platform was evaluated by the vibration tests and UVAG experiments of particulate-reinforced titanium matrix composites. Results indicate that the reasonable distribution of holes helps improve the resonant frequency and vibration mode. The modified AEM, the finite element method, and the vibration tests show a high degree of consistency for developing the perforated ultrasonic vibration platform with a maximum frequency error of 3%. The employment of ultrasonic vibration reduces the grinding force by 36% at most, thereby decreasing the machined surface defects, such as voids, cracks, and burnout.

关键词: ultrasonic vibration-assisted grinding     perforated ultrasonic vibration platform     vibration characteristics     apparent elasticity method     grinding force     surface integrity    

Recent development of vibration utilization engineering

WEN Bangchun

《机械工程前沿(英文)》 2008年 第3卷 第1期   页码 1-9 doi: 10.1007/s11465-008-0017-2

摘要: The utilization of vibration and wave, which was developed during the latter half of the 20th century, is one of the most valueable technology applications and has been rapidly developing recently . Because the technique is closely associated with industry and agriculture, it can create huge social and economical benefits and provide excellent services for society. Thus, due to its necessity in industry and daily life, extensive research has been devoted to vibration utillization engineering. In this paper, vibration utilization is classified into linear or non-linear vibrations, waves, and electric-magnetic oscillations. Their phenomena, patterns, and applications in nature and society are introduced. Some research results about vibration utilization engineering are described.

关键词: utilization engineering     non-linear     vibration     vibration utillization     utillization engineering    

Application of python-based Abaqus preprocess and postprocess technique in analysis of gearbox vibration

Guilian YI, Yunkang SUI, Jiazheng DU

《机械工程前沿(英文)》 2011年 第6卷 第2期   页码 229-234 doi: 10.1007/s11465-011-0128-z

摘要:

To reduce vibration and noise, a damping layer and constraint layer are usually pasted on the inner surface of a gearbox thin shell, and their thicknesses are the main parameters in the vibration and noise reduction design. The normal acceleration of the point on the gearbox surface is the main index that can reflect the vibration and noise of that point, and the normal accelerations of different points can reflect the degree of the vibration and noise of the whole structure. The K-S function is adopted to process many points’ normal accelerations as the comprehensive index of the vibration characteristics of the whole structure, and the vibration acceleration level is adopted to measure the degree of the vibration and noise. Secondary development of the Abaqus preprocess and postprocess on the basis of the Python scripting programming automatically modifies the model parameters, submits the job, and restarts the analysis totally, which avoids the tedious work of returning to the Abaqus/CAE for modifying and resubmitting and improves the speed of the preprocess and postprocess and the computational efficiency.

关键词: Abaqus secondary development     Python language     vibration and noise reduction     K-S function     vibration acceleration level    

Similitude design for the vibration problems of plates and shells: A review

Yunpeng ZHU, You WANG, Zhong LUO, Qingkai HAN, Deyou WANG

《机械工程前沿(英文)》 2017年 第12卷 第2期   页码 253-264 doi: 10.1007/s11465-017-0418-1

摘要:

Similitude design plays a vital role in the analysis of vibration and shock problems encountered in large engineering equipment. Similitude design, including dimensional analysis and governing equation method, is founded on the dynamic similitude theory. This study reviews the application of similitude design methods in engineering practice and summarizes the major achievements of the dynamic similitude theory in structural vibration and shock problems in different fields, including marine structures, civil engineering structures, and large power equipment. This study also reviews the dynamic similitude design methods for thin-walled and composite material plates and shells, including the most recent work published by the authors. Structure sensitivity analysis is used to evaluate the scaling factors to attain accurate distorted scaling laws. Finally, this study discusses the existing problems and the potential of the dynamic similitude theory for the analysis of vibration and shock problems of structures.

关键词: review     dynamic     similitude     vibration     model test    

Multi-harmonic forced vibration and resonance of simple beams to moving vehicles

《结构与土木工程前沿(英文)》   页码 981-993 doi: 10.1007/s11709-023-0979-5

摘要: This study modeled the moving-vehicle-induced forcing excitation on a single-span prismatic bridge as a multiple frequency-multiplication harmonic load on the modal coordinates of a linear elastic simple Euler–Bernoulli beam, and investigated the forced modal oscillation and resonance behavior of this type of dynamic system. The forced modal responses consist of multiple frequency-multiplication steady-state harmonics and one damped mono-frequency complementary harmonic. The analysis revealed that a moving load induces high-harmonic forced resonance amplification when the moving speed is low. To verify the occurrence of high-harmonic forced resonance, numerical tests were conducted on single-span simple beams based on structural modeling using the finite element method (FEM) and a moving sprung-mass oscillator vehicle model. The forced resonance amplification characteristics of the fundamental mode for beam response estimation are presented with consideration to different end restraint conditions. The results reveal that the high-harmonic forced resonance may be significant for the investigated beams subjected to vehicle loads moving at specific low speeds. For the investigated single-span simple beams, the moving vehicle carriage heaving oscillation modulates the beam modal frequency, but does not induce notable variation of the modal oscillation harmonic structure for the cases that vehicle of small mass moves in low speed.

关键词: forced vibration     linear Euler beam     moving load     harmonic structure     frequency modulation     end restraints    

Analytical and numerical investigation into the longitudinal vibration of uniform nanotubes

null

《机械工程前沿(英文)》 2014年 第9卷 第2期   页码 142-149 doi: 10.1007/s11465-014-0292-z

摘要:

In recent years, prediction of the behaviors of micro and nanostructures is going to be a matter of increasing concern considering their developments and uses in various engineering fields. Since carbon nanotubes show the specific properties such as strength and special electrical behaviors, they have become the main subject in nanotechnology researches. On the grounds that the classical continuum theory cannot accurately predict the mechanical behavior of nanostructures, nonlocal elasticity theory is used to model the nanoscaled systems. In this paper, a nonlocal model for nanorods is developed, and it is used to model the carbon nanotubes with the aim of the investigating into their longitudinal vibration. Following the derivation of governing equation of nanorods and estimation of nondimensional frequencies, the effect of nonlocal parameter and the length of the nanotube on the obtained frequencies are studied. Furthermore, differential quadrature method, as a numerical solution technique, is used to study the effect of these parameters on estimated frequencies for both classical and nonlocal theories.

关键词: continuum theory     differential quadrature method     nanorod     longitudinal vibration    

Design of ultrasonic elliptical vibration cutting system for tungsten heavy alloy

《机械工程前沿(英文)》 2022年 第17卷 第4期 doi: 10.1007/s11465-022-0715-1

摘要: Nanoscale surface roughness of tungsten heavy alloy components is required in the nuclear industry and precision instruments. In this study, a high-performance ultrasonic elliptical vibration cutting (UEVC) system is developed to solve the precision machining problem of tungsten heavy alloy. A new design method of stepped bending vibration horn based on Timoshenko’s theory is first proposed, and its design process is greatly simplified. The arrangement and working principle of piezoelectric transducers on the ultrasonic vibrator using the fifth resonant mode of bending are analyzed to realize the dual-bending vibration modes. A cutting tool is installed at the end of the ultrasonic vibration unit to output the ultrasonic elliptical vibration locus, which is verified by finite element method. The vibration unit can display different three-degree-of-freedom (3-DOF) UEVC characteristics by adjusting the corresponding position of the unit and workpiece. A dual-channel ultrasonic power supply is developed to excite the ultrasonic vibration unit, which makes the UEVC system present the resonant frequency of 41 kHz and the maximum amplitude of 14.2 μm. Different microtopography and surface roughness are obtained by the cutting experiments of tungsten heavy alloy hemispherical workpiece with the UEVC system, which validates the proposed design’s technical capability and provides optimization basis for further improving the machining quality of the curved surface components of tungsten heavy alloy.

关键词: tungsten heavy alloy     ultrasonic elliptical vibration cutting     Timoshenko’s theory     resonant mode of bending     finite element method    

Conformal analysis of fundamental frequency of vibration of elastic clamped plates

QI Hongyuan, ZHU Hengjun

《机械工程前沿(英文)》 2007年 第2卷 第4期   页码 429-432 doi: 10.1007/s11465-007-0073-z

摘要: To calculate the fundamental frequency of vibration of special-shaped and elastic clamped plates, the conformal mapping theory is adopted to separate the interpolating points of a complicated boundary into odd and even sequences, both of which can be mutually iterated, so that the conformal mapping function between the complicated region and the unit dish region is established. Trigonometric interpolation and convergence along the normal direction methods are provided, and the complex coefficients of the conformal mapping function are calculated. Galerkin method is used to obtain the solution of fundamental frequency in the vibrating differential function of the complicated vibrating region. Finally, taking ellipse elastic clamped plates as an example, the effects on fundamental frequency coefficient caused by eccentric ratio and area size are analyzed.

关键词: direction     theory     vibration     odd     complicated boundary    

Weakening behavior of waterproof performance in joints of shield tunnels under adjacent constructions

《结构与土木工程前沿(英文)》   页码 884-900 doi: 10.1007/s11709-022-0912-3

摘要: Groundwater leakage in shield tunnels poses a threat to the safety and durability of tunnel structures. Disturbance of adjacent constructions during the operation of shield tunnels frequently occurs in China, leading to deformation of tunnel lining and leakage in joints. Understanding the impact of adjacent constructions on the waterproofing performance of the lining is critical for the protection of shield tunnels. In this study, the weakening behavior of waterproof performance was investigated in the joints of shield tunnels under transverse deformation induced by adjacent construction. First, the relationship between the joint opening and transverse deformation under three typical adjacent constructions (upper loading, upper excavation, and side excavation) was investigated via elaborate numerical simulations. Subsequently, the evolution of the waterproof performance of a common gasket with a joint opening was examined by establishing a coupled Eulerian–Lagrangian model of joint seepage, and a formula describing the relationship between waterproof performance and joint opening was proposed. Finally, the weakening law of waterproofing performance was investigated based on the results of the aforementioned studies. It was determined that the joints with the greatest decline in waterproof performance were located at the tunnel shoulder in the upper loading case, tunnel crown in the upper excavation case, and tunnel shoulder in the side excavation case. When the waterproof performance of these joints decreased to 50% and 30%, the transverse deformations were 60 and 90 mm under upper loading, 90 and 140 mm under upper excavation, and 45 and 70 mm under side excavation, respectively. The results provide a straightforward reference for setting a controlled deformation standard considering the waterproof performance.

关键词: shield tunnel     waterproof performance     horizontal transverse deformation     joint opening     weakening behavior    

An investigation into the vibration of harmonic drive systems

M. Masoumi, H. Alimohammadi

《机械工程前沿(英文)》 2013年 第8卷 第4期   页码 409-419 doi: 10.1007/s11465-013-0275-5

摘要:

Harmonic drive systems are precise and specific transmission gear systems which are beneficial in terms of the high transmission ratio and almost zero backlash. These inherent and spectacular properties result in using this mechanism in robotic and space sciences where the precision and lightwieght play an important role. This paper presents a vibration analysis of harmonic drive systems using the shell theory. Equations of vibration for the flexspline and the circular spline of the system are derived and used to find the natural frequencies for both parts and, moreover, vibration response of the system under the operating condition is calculated. Also, obtained vibration equations are utilized to study the effects of different involved parameters such as the geometry of the flexspline and its gear tooth, eccentricity, and unbalancing on the vibrational behavior of the system.

关键词: harmonic drive system     strain wave gearing mechanism     vibration analysis     natural frequencies    

标题 作者 时间 类型 操作

Bending and vibration of a discontinuous beam with a curvic coupling under different axial forces

Heng LIU, Jie HONG, Dayi ZHANG

期刊论文

Vibration analysis of a simply supported beam under moving mass based on moving finite element method

Zhuchao YE, Huaihai CHEN,

期刊论文

Detection for transverse corner cracks of steel plates’ surface using wavelet

Qiong ZHOU, Qi AN

期刊论文

Effect of axial load and transverse reinforcements on the seismic performance of reinforced concrete

Mounir Ait BELKACEM, Hakim BECHTOULA, Nouredine BOURAHLA, Adel Ait BELKACEM

期刊论文

Investigating the influence of delamination on the stiffness of composite pipes under compressive transverse

Sattar MALEKI, Roham RAFIEE, Abolfazl HASANNIA, Mohammad Reza HABIBAGAHI

期刊论文

Vibration characteristics and machining performance of a novel perforated ultrasonic vibration platform

期刊论文

Recent development of vibration utilization engineering

WEN Bangchun

期刊论文

Application of python-based Abaqus preprocess and postprocess technique in analysis of gearbox vibration

Guilian YI, Yunkang SUI, Jiazheng DU

期刊论文

Similitude design for the vibration problems of plates and shells: A review

Yunpeng ZHU, You WANG, Zhong LUO, Qingkai HAN, Deyou WANG

期刊论文

Multi-harmonic forced vibration and resonance of simple beams to moving vehicles

期刊论文

Analytical and numerical investigation into the longitudinal vibration of uniform nanotubes

null

期刊论文

Design of ultrasonic elliptical vibration cutting system for tungsten heavy alloy

期刊论文

Conformal analysis of fundamental frequency of vibration of elastic clamped plates

QI Hongyuan, ZHU Hengjun

期刊论文

Weakening behavior of waterproof performance in joints of shield tunnels under adjacent constructions

期刊论文

An investigation into the vibration of harmonic drive systems

M. Masoumi, H. Alimohammadi

期刊论文