Experimental and numerical study on the oblique water-entry impact of a cavitating vehicle with a disk cavitator

Chen, Cheng,Yuan, Xulong,Liu, Xiyan,Dang, Jianjun The Society of Naval Architects of Korea 2019 International Journal of Naval Architecture and Oc Vol.11 No.1

In this paper, the oblique water-entry impact of a vehicle with a disk cavitator is studied experimentally and numerically. The effectiveness and accuracy of the numerical simulation are verified quantitatively by the experiments in this paper and the data available in the literature. Then, the numerical model is used to simulate the hydrodynamic characteristics and flow patterns of the vehicle under different entry conditions, and the axial force is found to be an important parameter. The influences of entry angle, entry speed and cavitator area on the axial force are studied. The variation law of the force coefficient and the dimensionless penetration distance at the peak of the axial force are revealed. The research conclusions are beneficial to engineering calculations on the impact force of a vehicle with a disk cavitator over a wide range of water-entry parameters.

Experimental and numerical analysis of mixed mode I/III fracture of sandstone using three point bending specimens

Yifan Li,Shiming Dong,Martyn J. Pavier 국제구조공학회 2020 Structural Engineering and Mechanics, An Int'l Jou Vol.76 No.6

In this work the mixed mode I/III fracture of sandstone has been studied experimentally and numerically. The experimental work used three-point bending specimens containing pre-existing cracks, machined at various inclination angles so as to achieve varying proportions of mode I to mode III loading. Dimensionless stress intensity factors were calculated using the extended finite element method (XFEM) for and compared with existing results from literature calculated using conventional finite element method. A total of 28 samples were used to conduct the fracture test with 4 specimens for each of 7 different inclination angles. The fracture load and the geometry of the fracture surface were obtained for different mode mixities. Prediction of the fracture loads and the geometry of the fracture surface were made using XFEM coupled with a cohesive zone model (CZM) and showed a good comparison with the experimental results.

Experimental research on free vibration of curved composite box-girders with corrugated steel webs

Yunsheng Li,Qingnian Dai,Chaoxing Liu,Yanling Zhang 국제구조공학회 2021 Steel and Composite Structures, An International J Vol.41 No.1

The curved composite box-girders (CBGs) with corrugated steel webs (CSWs) have been used widely in bridges due to their great advantages and the demand of the road alignment, but the curvature makes both the static and dynamic behaviors more complex. To research the free vibration performance of the curved CBGs with CSWs, 5 simply-supported test girders were designed with the span-to-radius ratio (λ=L/R), the number of the cells of the box section, and the number of the diaphragms as parameters. The natural frequencies and mode shapes were measured in the experiment. The experimental results were compared with the numerical results using ANSYS software, and a satisfying agreement was obtained. The parametric analysis shows that for the curved CBG with CSWs, the vertical mode shapes are combined flexural and torsion, and the contribution of the torsional effects to the mode shapes and frequencies improve with the increase of λ, which leads to a decrease in the vertical and lateral frequencies and increase in the torsional frequency. The corrugated angle of the steel web has little effect on the natural frequencies of the curved CBGs with CSWs. Increasing the thickness of the steel web and the number of the diaphragms can improve the torsional rigidity of the curved CBG with CSWs effectively; while the deck width has a great contribution on the lateral rigidity.

Experimental and numerical assessment of EBF structures with shear links

Silvia Caprili,Nicola Mussini,Walter Salvatore 국제구조공학회 2018 Steel and Composite Structures, An International J Vol.28 No.2

Eccentrically braced frames (EBF) represent an optimal structural solution for seismic prone areas, being able to provide high dissipative capacity and good elastic stiffness, to withstand strong seismic events without significant loss of bearing capacity and to avoid damage to non-structural elements in case of low and moderate earthquakes. The accurate knowledge of the cyclic behaviour of the dissipative links, characterizing the whole performance of EBFs, is required to optimize the structural properties and to refine the design techniques adopted for multi-storey buildings' analysis. Reliable numerical models for the links, at the same time requiring a limited computational effort, are then needed. The present work shows the results of a wide experimental test campaign executed on real-scale one storey/one bay frames with horizontal and vertical links, together with the elaboration of a simple semi-analytical model for the quick representation of the cyclic behaviour of shear links.

Experimental and numerical study on the oblique water-entry impact of a cavitating vehicle with a disk cavitator

Cheng Chen,Xulong Yuan,Xiyan Liu,Jianjun Dang 대한조선학회 2019 International Journal of Naval Architecture and Oc Vol.11 No.1

In this paper, the oblique water-entry impact of a vehicle with a disk cavitator is studied experimentally and numerically. The effectiveness and accuracy of the numerical simulation are verified quantitatively by the experiments in this paper and the data available in the literature. Then, the numerical model is used to simulate the hydrodynamic characteristics and flow patterns of the vehicle under different entry conditions, and the axial force is found to be an important parameter. The influences of entry angle, entry speed and cavitator area on the axial force are studied. The variation law of the force coefficient and the dimensionless penetration distance at the peak of the axial force are revealed. The research conclusions are beneficial to engineering calculations on the impact force of a vehicle with a disk cavitator over a wide range of water-entry parameters.

Accuracy of incidental dynamic analysis of mobile elevating work platforms

Miomir LJ. Jovanović,Goran N. Radoičić,Vladimir S. Stojanović 국제구조공학회 2019 Structural Engineering and Mechanics, An Int'l Jou Vol.71 No.5

This paper presents the results of a study into the dynamic behaviour of a support structure of a mobile elevating work platform. The vibrations of the mechanical system of the observed structure are examined analytically, numerically, and experimentally. Within the analytical examination, a simple mathematical model is developed to describe free and forced vibrations. The dynamic analysis of the mechanical system is conducted using a discrete dynamic model with a reduced number of vibrational degrees of freedom. On the basis of the expression for the system energy, and by applying Lagrange's equations of the second kind, differential equations are derived for system vibrations, frequencies are determined, and the laws of forced platform vibration are established. At the same time, a nonlinear FEM model is developed and the laws of free and forced vibration are determined. The experimental and numerical part of the study deal with the examination of the real structure in extreme conditions, taking into account: the lowest eigenfrequency, forced actions that could endanger the general stability, the maximal amplitudes, and the acceleration of the work platform. The obtained analytical and numerical results are compared with the experiments. The experimental verification points to the adverse behaviour of the platform in excitation cases – swaying. In such a situation, even a relatively small physical force can lead to unacceptably high amplitudes of displacement and acceleration – exceeding the usual work values.

Numerical Analysis and Experiment Study of Magnetic Fluid Boundary in Seals

Yibiao Chen,Decai Li,Yanjuan Zhang,Anmin Xi 한국자기학회 2018 Journal of Magnetics Vol.23 No.2

Magnetic fluid seals are widely used technical applications of magnetic fluid. This paper presents a numerical simulation model to obtain the boundary of magnetic fluid in seals. The magnetic field in the seal is solved by finite element method, and the boundary is calculated by using Navier-Stokes equations in magnetic fluid. In order to observe the surface and obtain the seal capacity, the plane magnetic fluid seal experiment is carried out. The relationship between the seal capacity and the magnetic fluid volume is presented. The seal capacity which is obtained by the theoretical analysis has well congruence with the result of the experiment. The displacement of boundary with the pressure difference is quantitatively depicted.

Experimental and numerical analyses of RC beams strengthened in compression with UHPFRC

Thomaz E.T. Buttignol,Eduardo C. Granato,Túlio N. Bittencourt,Luís A.G. Bitencourt Jr. 국제구조공학회 2023 Structural Engineering and Mechanics, An Int'l Jou Vol.85 No.4

This paper aims to better understand the bonding behavior in Reinforced Concrete beams strengthened with an Ultra- High Performance Fiber Reinforced Concrete (RCUHPFRC) layer on the compression side using experimental tests and numerical analyses. The UHPFRC mix design was obtained through an optimization procedure, and the characterization of the materials included compression and slant shear tests. Flexural tests were carried out in RC beams and RC-UHPFRC beams. The tests demonstrated a debonding of the UHPFRC layer. In addition, 3D finite element analyses were carried out in the Abaqus CAE program, in which the interface is modeled considering a zero-thickness cohesive-contact approach. The cohesive parameters are investigated, aiming to calibrate the numerical models, and a sensitivity analysis is performed to check the reliability of the assumed cohesive parameters and the mesh size. Finally, the experimental and numerical values are compared, showing a good approximation for both the RC beams and the RC strengthened beams.

Nonlinear analysis of reinforced concrete frame under lateral load

Salihovic, Amir,Ademovic, Naida Techno-Press 2018 Coupled systems mechanics Vol.7 No.3

This study aims to investigate the capacity of different models to reproduce the nonlinear behavior of reinforced concrete framed structures. To accomplish this goal, a combined experimental and analytical research program was carried out on a large scaled reinforced concrete frame. Analyses were performed by SAP2000 and compared to experimental and VecTor2 results. Models made in SAP2000 differ in the simulation of the plasticity and the type of the frame elements used to discretize the frame structure. The results obtained allow a better understanding of the characteristics of all numerical models, helping the users to choose the best approach to perform nonlinear analysis.

Nonlinear analysis of reinforced concrete frame under lateral load

Salihovic, Amir,Ademovic, Naida Techno-Press 2017 Coupled systems mechanics Vol.6 No.4

This study aims to investigate the capacity of different models to reproduce the nonlinear behavior of reinforced concrete framed structures. To accomplish this goal, a combined experimental and analytical research program was carried out on a large scaled reinforced concrete frame. Analyses were performed by SAP2000 and compared to experimental and VecTor2 results. Models made in SAP2000 differ in the simulation of the plasticity and the type of the frame elements used to discretize the frame structure. The results obtained allow a better understanding of the characteristics of all numerical models, helping the users to choose the best approach to perform nonlinear analysis.