Optimal chordwise stiffness distribution for self-propelled heaving flexible plates

2020 ◽  
Vol 32 (11) ◽  
pp. 111905
Author(s):  
Wenjiang Wang ◽  
Haibo Huang ◽  
Xi-Yun Lu
2017 ◽  
Vol 2 (4) ◽  
pp. 25
Author(s):  
L. A. Montoya ◽  
E. E. Rodríguez ◽  
H. J. Zúñiga ◽  
I. Mejía

Rotating systems components such as rotors, have dynamic characteristics that are of great importance to understand because they may cause failure of turbomachinery. Therefore, it is required to study a dynamic model to predict some vibration characteristics, in this case, the natural frequencies and mode shapes (both of free vibration) of a centrifugal compressor shaft. The peculiarity of the dynamic model proposed is that using frequency and displacements values obtained experimentally, it is possible to calculate the mass and stiffness distribution of the shaft, and then use these values to estimate the theoretical modal parameters. The natural frequencies and mode shapes of the shaft were obtained with experimental modal analysis by using the impact test. The results predicted by the model are in good agreement with the experimental test. The model is also flexible with other geometries and has a great time and computing performance, which can be evaluated with respect to other commercial software in the future.


2021 ◽  
Vol 33 (4) ◽  
pp. 045102
Author(s):  
C. García-Baena ◽  
J. I. Jiménez-González ◽  
C. Martínez-Bazán

2020 ◽  
Vol 37 ◽  
pp. 126-133
Author(s):  
Yuan-Wei Li ◽  
Chao-Nan Wang

Abstract The purpose of this study was to investigate the sound insulation of double-leaf panels. In practice, double-leaf panels require a stud between two surface panels. To simplify the analysis, a stud was modeled as a spring and mass. Studies have indicated that the stiffness of the equivalent spring is not a constant and varies with the frequency of sound. Therefore, a frequency-dependent stiffness curve was used to model the effect of the stud to analyze the sound insulation of a double-leaf panel. First, the sound transmission loss of a panel reported by Halliwell was used to fit the results of this study to determine the stiffness of the distribution curve. With this stiffness distribution of steel stud, some previous proposed panels are also analyzed and are compared to the experimental results in the literature. The agreement is good. Finally, the effects of parameters, such as the thickness and density of the panel, thickness of the stud and spacing of the stud, on the sound insulation of double-leaf panels were analyzed.


Author(s):  
Barış Erdil ◽  
Mücip Tapan ◽  
İsmail Akkaya ◽  
Fuat Korkut

The October 23, 2011 (Mw = 7.2) and November 9, 2011 (Mw = 5.6) earthquakes increased the damage in the minaret of Van Ulu Mosque, an important historical masonry structure built with solid bricks in Eastern Turkey, resulting in significant shear cracks. It was found that since the door and window openings are not symmetrically placed, they result in unsymmetrical stiffness distribution. The contribution of staircase and the core on stiffness is ignorable but its effect on the mass is significant. The pulpit with chamfered corner results in unsymmetrical transverse displacements. Brace wall improves the stiffness however contributes to the unsymmetrical behaviour considerably. The reason for the diagonal cracks can be attributed to the unsymmetrical brace wall and the chamfered pulpit but the effect of brace wall is more pronounced. After introducing the cracks, a new model was created and calibrated according to the results of Operational Modal Analysis. Diagonal cracks were found to be likely to develop under earthquake loading. Drifts are observed to increase significantly upon the introduction of the cracks.


2016 ◽  
Vol 6 (5) ◽  
pp. 141 ◽  
Author(s):  
Dibo Dong ◽  
Weishan Chen ◽  
Shengjun Shi

2016 ◽  
Vol 139 (1) ◽  
Author(s):  
Laurent Dumas ◽  
Tamara El Bouti ◽  
Didier Lucor

Cardiovascular diseases are currently the leading cause of mortality in the population of developed countries, due to the constant increase in cardiovascular risk factors, such as high blood pressure, cholesterol, overweight, tobacco use, lack of physical activity, etc. Numerous prospective and retrospective studies have shown that arterial stiffening is a relevant predictor of these diseases. Unfortunately, the arterial stiffness distribution across the human body is difficult to measure experimentally. We propose a numerical approach to determine the arterial stiffness distribution of an arterial network using a subject-specific one-dimensional model. The proposed approach calibrates the optimal parameters of the reduced-order model, including the arterial stiffness, by solving an inverse problem associated with the noninvasive in vivo measurements. An uncertainty quantification analysis has also been carried out to measure the contribution of the model input parameters variability, alone or by interaction with other inputs, to the variation of clinically relevant hemodynamic indices, here the arterial pulse pressure. The results obtained for a lower limb model, demonstrate that the numerical approach presented here can provide a robust and subject-specific tool to the practitioner, allowing an early and reliable diagnosis of cardiovascular diseases based on a noninvasive clinical examination.


CIRP Annals ◽  
2010 ◽  
Vol 59 (1) ◽  
pp. 387-390 ◽  
Author(s):  
E. Shamoto ◽  
T. Mori ◽  
K. Nishimura ◽  
T. Hiramatsu ◽  
Y. Kurata

Author(s):  
Hui Li ◽  
Di Wang ◽  
Cheng Ming Zhou ◽  
Kaihong Zhang ◽  
Huilong Ren

For ultra large ore carriers, springing response should be analyzed in the design stage since springing is the steady-state resonant vibration and has an important effect on the fatigue strength of hull structure. The springing response of a 550,000 DWT ultra large ore carrier has been studied by using experimental and numerical methods. A flexible ship model composed of nine segments was used in the experiment. The model segments were connected by a backbone with varying section, which can satisfy the request of natural frequency and stiffness distribution. The experiments in regular waves were performed and the motions and wave loads of the ship were measured. The experimental results showed that springing could be excited when the wave encounter frequency coincides with half or one-third the flexural natural frequency of the ship. In this paper, the analysis of the hydroelastic responses of the ultra large ore carrier was also carried out using a 3-D hydroelastic method. Comparisons between experimental and numerical results showed that the 3-D hydroelastic method could predict the motions and the vertical bending moments quite well. Based on this numerical method, the fatigue damage was estimated and the contribution of springing was analyzed.


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