Steel-Concrete Bond Deterioration under Repeated Loading for Different Confinement Levels

2012 ◽  
Vol 217-219 ◽  
pp. 188-191 ◽  
Author(s):  
Marco Valente
Keyword(s):  
Cyclic Loading ◽  
Bond Strength ◽  
Three Dimensional ◽  
Experimental Tests ◽  
Experimental Results ◽  
Numerical Analyses ◽  
Repeated Loading ◽  
Loading History ◽  
Steel Rebar ◽  
Bond Deterioration

This paper presents the results of experimental tests and numerical analyses concerning the influence of repeated cyclic loading and reinforcement confinement on bond between steel rebar and concrete. Experimental tests of push-pull type were carried out at the Politecnico di Milano on concrete specimens provided with a steel cage of longitudinal bars and stirrups, and reinforced with a single steel rebar. The experimental tests were conducted under monotonic and repeated loading history. Bond strength degradation was observed due to repeated cyclic loading. Detailed three-dimensional finite element models of the specimens were developed to reproduce laboratory tests and parametric analyses were performed to provide a better understanding of the experimental results. The numerical analyses showed good agreement with the experimental results and confirmed that the applied repeated loading history caused significant bond deterioration. High values of reinforcement confinement enhanced bond strength and delayed the onset of bond deterioration.

Study of Blade Sweep Effects of Compressor

2005 ◽  
Author(s):  
C. Xu ◽  
R. S. Amano
Keyword(s):  
Flow Field ◽  
Turbine Blade ◽  
Experimental Studies ◽  
Three Dimensional ◽  
Experimental Results ◽  
Numerical Analyses ◽  
Blade Design ◽  
3D Flow ◽  
Efficient Manner ◽  
Blade Row

The three dimensional blading had been used for years in the process of turbomachine designs. In need of turbine blade designs in an efficient manner, the current advancement of CFD technologies allows effective 3D predictions of a complex 3D flow field in turbine blade passages, which can improve the turbine blade performances. Since numerous advantages of 3-D CFD usage had been reported in the open literature, many industries already started to use 3D blading in their turbomachines. In addition, a blade lean and a sweep for the blade design had been also implemented to increase the blade row efficiency. Experimental studies have shown some advantages of these lean and sweep features. Most of the experimental results combine many other features together. However, it is difficult to determine what the effects of different features should be. In this study, detailed numerical analyses were developed and these were used to present the results to gain better understanding of different feature of 3D blading for turbine designers and engineers. Throughout this paper performance impacts on different 3D features are presented and the superiority of the present approach is discussed.

Experimental Study on Effects of Fatigue Loading History on Bond Behavior between Steel Bars and Concrete

2016 ◽  
Vol 711 ◽  
pp. 673-680 ◽  
Author(s):  
Zhiwen Ye ◽  
Wei Ping Zhang ◽  
You Hu ◽  
Xiang Lin Gu
Keyword(s):  
Experimental Study ◽  
Bond Strength ◽  
Fatigue Loading ◽  
Critical Value ◽  
Concrete Cover ◽  
Repeated Loading ◽  
Loading History ◽  
Bond Behavior ◽  
Pull Out ◽  
Steel Bars

This paper presents an experimental investigation on the influence of fatigue loading history on bond behavior between steel bars and concrete. Reinforced concrete specimens were subjected to fatigue loadings with different amplitudes and cycles before undergoing eccentric pull-out tests. Tests revealed that all specimens failed with the splitting of the concrete cover. With increased loading cycles, the concrete in front of transverse ribs usually becomes denser at the beginning. Meanwhile, the initial bond stiffness and the bond strength increased, while the slip corresponding to the peak bond stress decreases. With the further increase of loading cycles, the bond strength begins to decrease after it reaches a critical value. This study determined that for specimens subjected to repeated loading with a larger amplitude, fewer cycles are needed for the bond strength to go up to the critical bond strength.

An experimental—numerical investigation of a metal spinning process

2010 ◽  
Vol 225 (3) ◽  
pp. 509-519 ◽  
Author(s):  
H R Beni ◽  
Y T Beni ◽  
F R Biglari
Keyword(s):  
Strain Distribution ◽  
Theoretical Calculations ◽  
Three Dimensional ◽  
Experimental Tests ◽  
Experimental Results ◽  
Explicit Finite Element ◽  
Wide Range ◽  
Spinning Process ◽  
Metal Spinning ◽  
Drawing Method

Spinning process is an advanced plastic working method, which is frequently used for manufacturing of axisymmetric shapes, especially those that cannot be easily produced with deep drawing method. In this article, a three-dimensional explicit finite-element (FE) analysis is employed to simulate the spinning process of an aluminium circular sheet. To achieve a wide range of strain distribution in different directions, a hemispherical cup has been chosen as the final product shape. In addition, a theoretical shear forming as well as a conventional model has been employed to estimate strain distribution in the spinning hemispherical cup. Experimental tests are carried out using a spinning machine and a hemispherical mandrel. Finally, FE and theoretical calculations are compared with the experimental results. A good agreement has been demonstrated between numerical and experimental results but a relative agreement with theoretical calculations.

scholarly journals Numerical and Experimental Analysis of Effectors Used in Active Protection Systems

2016 ◽  
Vol 7 (3) ◽  
pp. 113-126
Author(s):  
Robert PANOWICZ ◽  
Tadeusz NIEZGODA ◽  
Marcin KONARZEWSKI
Keyword(s):  
Experimental Analysis ◽  
Direct Contact ◽  
Three Dimensional ◽  
Experimental Tests ◽  
Numerical Analyses ◽  
Explosive Material ◽  
Protection Systems ◽  
Active Protection ◽  
Protected Object ◽  
Three Dimensional Models

The paper presents numerical and experimental analyses of effectors used in active protection systems. In the numerical analyses, the ALE method was used with FSI. Two types of destructors were analysed. The first destructor is a rectangular directed fragmentation warhead which can be mounted on the protected object. The second one is cylindrical and is a component of an antimissile. In both types of destructors we can distinguish several main parts, such as: the case, explosive material and fragmentation liner. The fragmentation liner is built from resin with submerged metallic spheres or cylinders. The fragmentation liner forms a cloud of fragments when the explosive material, located in direct contact with the liner, explodes. In order to perform numerical analyses, three-dimensional models of the destructors were designed in the HyperMesh software. The numerical analyses were performed with the Ls-Dyna software. The results of experimental tests carried out on one of the destructors are also presented in the study.

TIME TO THE END OF PRIMARY CONSOLIDATION (EOP) OF SOFT CLAYEY SOILS: CONCERNING THE EFFECT OF ATTERBERG’S LIMIT AND CYCLIC LOADING HISTORY

2019 ◽  
Vol 128 (2B) ◽  
pp. 29-41
Author(s):  
Trần Thanh Nhàn
Keyword(s):  
Cyclic Loading ◽  
Pore Water ◽  
Pore Water Pressure ◽  
Water Pressure ◽  
Clayey Soils ◽  
Loading History ◽  
Cyclic Shear ◽  
Wide Range ◽  
Primary Consolidation ◽  
Time Required

In order to observe the end of primary consolidation (EOP) of cohesive soils with and without subjecting to cyclic loading, reconstituted specimens of clayey soils at various Atterberg’s limits were used for oedometer test at different loading increments and undrained cyclic shear test followed by drainage with various cyclic shear directions and a wide range of shear strain amplitudes. The pore water pressure and settlement of the soils were measured with time and the time to EOP was then determined by different methods. It is shown from observed results that the time to EOP determined by 3-t method agrees well with the time required for full dissipation of the pore water pressure and being considerably larger than those determined by Log Time method. These observations were then further evaluated in connection with effects of the Atterberg’s limit and the cyclic loading history.

scholarly journals Fatigue Stress-Life Model of RC Beams Based on an Accelerated Fatigue Method

2019 ◽  
Vol 4 (2) ◽  
pp. 16
Author(s):  
Eljufout ◽  
Toutanji ◽  
Al-Qaralleh
Keyword(s):  
Cyclic Loading ◽  
Fatigue Testing ◽  
Three Dimensional ◽  
Rc Beam ◽  
Rc Beams ◽  
Testing Methods ◽  
Load Range ◽  
Fatigue Stress ◽  
Life Model ◽  
Prediction Band

Several standard fatigue testing methods are used to determine the fatigue stress-life prediction model (S-N curve) and the endurance limit of Reinforced Concrete (RC) beams, including the application of constant cyclic tension-tension loads at different stress or strain ranges. The standard fatigue testing methods are time-consuming and expensive to perform, as a large number of specimens is needed to obtain valid results. The purpose of this paper is to examine a fatigue stress-life predication model of RC beams that are developed with an accelerated fatigue approach. This approach is based on the hypothesis of linear accumulative damage of the Palmgren–Miner rule, whereby the applied cyclic load range is linearly increased with respect to the number of cycles until the specimen fails. A three-dimensional RC beam was modeled and validated using ANSYS software. Numerical simulations were performed for the RC beam under linearly increased cyclic loading with different initial loading conditions. A fatigue stress-life model was developed that was based on the analyzed data of three specimens. The accelerated fatigue approach has a higher rate of damage accumulations than the standard testing approach. All of the analyzed specimens failed due to an unstable cracking of concrete. The developed fatigue stress-life model fits the upper 95% prediction band of RC beams that were tested under constant amplitude cyclic loading.

Yaw Galloping of a TLWP Platform Under High Speed Currents by Analytical Methods and its Comparison With Experimental Results

2017 ◽  
Author(s):  
Francisco Lamas ◽  
Miguel A. M. Ramirez ◽  
Antonio Carlos Fernandes
Keyword(s):  
High Speed ◽  
Production Systems ◽  
Experimental Tests ◽  
Experimental Results ◽  
Analytical Methodology ◽  
New Approach ◽  
Laboratory Facilities ◽  
Polynomial Curve ◽  
Computational Fluid Dynamics Cfd ◽  
Cfd Analyses

Flow Induced Motions are always an important subject during both design and operational phases of an offshore platform life. These motions could significantly affect the performance of the platform, including its mooring and oil production systems. These kind of analyses are performed using basically two different approaches: experimental tests with reduced models and, more recently, with Computational Fluid Dynamics (CFD) dynamic analysis. The main objective of this work is to present a new approach, based on an analytical methodology using static CFD analyses to estimate the response on yaw motions of a Tension Leg Wellhead Platform on one of the several types of motions that can be classified as flow-induced motions, known as galloping. The first step is to review the equations that govern the yaw motions of an ocean platform when subjected to currents from different angles of attack. The yaw moment coefficients will be obtained using CFD steady-state analysis, on which the yaw moments will be calculated for several angles of attack, placed around the central angle where the analysis is being carried out. Having the force coefficients plotted against the angle values, we can adjust a polynomial curve around each analysis point in order to evaluate the amplitude of the yaw motion using a limit cycle approach. Other properties of the system which are flow-dependent, such as damping and added mass, will also be estimated using CFD. The last part of this work consists in comparing the analytical results with experimental results obtained at the LOC/COPPE-UFRJ laboratory facilities.

scholarly journals Early-Age Tensile Bond Characteristics of Epoxy Coatings for Underwater Applications

Coatings ◽  
2019 ◽  
Vol 9 (11) ◽  
pp. 757 ◽  
Author(s):  
Kim ◽  
Hong ◽  
Han ◽  
Kim
Keyword(s):  
Bond Strength ◽  
Surface Treatment ◽  
Epoxy Resin ◽  
Coating Thickness ◽  
Experimental Results ◽  
Early Age ◽  
Curing Time ◽  
Bond Performance ◽  
Coating Type ◽  
Bond Characteristics

In this study, coating equipment for the effective underwater repair of submerged structures was developed. The tensile bond characteristics of selected epoxy resin coatings were investigated by coating the surface of a specimen using each of the four types of equipment. Using the experimental results, the tensile bond strength and the coating thickness were analyzed according to the type of equipment, coating, and curing time. The results show that the type of coating equipment used had the greatest effect on the measured bond strength and coating thickness of the selected coatings. However, the effect of coating type and curing time on the bond strength and the thickness was observed to be insignificant. Compared with the developed equipment, the surface treatment of the coating was observed to be more effective when using the pre-existing equipment, and thus the bond performance of the coating was improved compared to using the pre-existing equipment. Based on the experimental results, improvements and needs involving the equipment for further research were discussed.

scholarly journals Investigation of Pressure Oscillation and Cavitation Characteristics for Submerged Self-Resonating Waterjet

2021 ◽  
Vol 11 (15) ◽  
pp. 6972
Author(s):  
Lihua Cui ◽  
Fei Ma ◽  
Tengfei Cai
Keyword(s):  
Sudden Change ◽  
Three Dimensional ◽  
Pressure Oscillation ◽  
Experimental Tests ◽  
Low Pressure ◽  
The Self ◽  
Two Phase ◽  
Cavitation Phenomenon ◽  
Pressure Zone ◽  
Unsteady Characteristics

The cavitation phenomenon of the self-resonating waterjet for the modulation of erosion characteristics is investigated in this paper. A three-dimensional computational fluid dynamics (CFD) model was developed to analyze the unsteady characteristics of the self-resonating jet. The numerical model employs the mixture two-phase model, coupling the realizable turbulence model and Schnerr–Sauer cavitation model. Collected data from experimental tests were used to validate the model. Results of numerical simulations and experimental data frequency bands obtained by the Fast Fourier transform (FFT) method were in very good agreement. For better understanding the physical phenomena, the velocity, the pressure distributions, and the cavitation characteristics were investigated. The obtained results show that the sudden change of the flow velocity at the outlet of the nozzle leads to the forms of the low-pressure zone. When the pressure at the low-pressure zone is lower than the vapor pressure, the cavitation occurs. The flow field structure of the waterjet can be directly perceived through simulation, which can provide theoretical support for realizing the modulation of the erosion characteristics, optimizing nozzle structure.

Conical SNA using fuzzy k-medoids based on user experience

2021 ◽  
pp. 002072092098849
Author(s):  
Poonam Rani ◽  
MPS Bhatia ◽  
Devendra K Tayal
Keyword(s):  
Social Networks ◽  
Social Network ◽  
User Experience ◽  
Three Dimensional ◽  
Experimental Results ◽  
Dynamic Parameters ◽  
Clustering Method ◽  
Cone Model ◽  
Intelligent Approach ◽  
Conical Model

The paper presents an intelligent approach for the comparison of social networks through a cone model by using the fuzzy k-medoids clustering method. It makes use of a geometrical three-dimensional conical model, which astutely represents the user experience views. It uses both the static as well as the dynamic parameters of social networks. In this, we propose an algorithm that investigates which social network is more fruitful. For the experimental results, the proposed work is employed on the data collected from students from different universities through the Google forms, where students are required to rate their experience of using different social networks on different scales.

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