scholarly journals Mesoscale modelling of bond failure behaviour of ribbed steel bar and concrete interface

2021 ◽  
Vol 272 ◽  
pp. 02003
Author(s):  
Mengjia Liu ◽  
Renbo Zhang ◽  
Liu Jin ◽  
Xiuli Du
Keyword(s):  
Frictional Resistance ◽  
Surface Characteristics ◽  
Bond Stress ◽  
Scale Model ◽  
Analysis Method ◽  
Bond Failure ◽  
Bond Behaviour ◽  
Steel Bar ◽  
Friction Component ◽  
Good Agreement

To explore the nonlinear bond behaviour between ribbed bar and concrete, combined with the characteristics of concrete meso-structure and ribbed bar surface characteristics and considering frictional resistance and the mechanical interlocking between rebar and concrete, a meso-scale model is established. Based on the good agreement between the simulation results and experimental results, the failure mechanism of bond between rebar and concrete is discussed, and the distribution characteristics of bond stress of steel bar are analysed. Furthermore, based on the meso numerical analysis method, the influence of friction coefficient between rebar and concrete on the failure mode of concrete and bond stress-slip curve was discussed, and the proportion of friction component in bond strength is obtained.

The Approximate Analytical Solution of the MHD Flow of a Power-Law Fluid

2013 ◽  
Vol 431 ◽  
pp. 198-201
Author(s):  
Jing Zhu ◽  
Lian Cun Zheng
Keyword(s):  
Differential Equations ◽  
Power Law ◽  
Velocity Ratio ◽  
Mhd Flow ◽  
Convergent Series ◽  
Analysis Method ◽  
Governing System ◽  
Homotopy Analysis ◽  
Incompressible Mhd ◽  
Good Agreement

This paper presents a theoretical analysis for the incompressible MHD stagnation-point flows of a Non-Newtonian Fluid over stretching sheets.The governing system of partial differential equations is first transformed into a system of dimensionless ordinary differential equations. By using the homotopy analysis method, a convergent series solution is obtained. The reliability and efficiency of series solutions are illustrated by good agreement with numerical results in the literature.Besides, the effects of the power-law indexthe magnetic field parameter and velocity ratio parameter on the flow are investigated.

NMR Technique for Multiphase Fluid Study Involving Melting Phenomena

1999 ◽  
Author(s):  
Q. Ni ◽  
J. D. King ◽  
Y.-X. Tao
Keyword(s):  
Volume Fraction ◽  
Solid Volume Fraction ◽  
Melting Rate ◽  
Analysis Method ◽  
Image Analysis Method ◽  
Equilibrium Conditions ◽  
Multiphase Fluid ◽  
Physical Phenomena ◽  
Non Destructive ◽  
Good Agreement

Abstract Nuclear magnetic resonance (NMR) sensors are used to determine the time variation of solid mass for a packed ice bed in an experiment of convective melting under non-thermal equilibrium conditions. The paper describes the basic experimental technique for NAFTM apparatus and feasibility for determining the solid volume fraction and ultimately the melting rate. The NMR technique provides an effective, non-destructive method for multiphase fluid study where phase change is one of the important physical phenomena. The results show a good agreement of data obtained by the NMR method with those from image-analysis method.

scholarly journals Homotopy Analysis Solution for Magnetohydrodynamic Squeezing Flow in Porous Medium

2016 ◽  
Vol 2016 ◽  
pp. 1-9 ◽  
Author(s):  
Inayat Ullah ◽  
M. T. Rahim ◽  
Hamid Khan ◽  
Mubashir Qayyum
Keyword(s):  
Porous Medium ◽  
Control Parameter ◽  
Analytical Techniques ◽  
Squeezing Flow ◽  
Analysis Method ◽  
Homotopy Analysis ◽  
Convergence Control ◽  
Flow Through ◽  
Convergence Control Parameter ◽  
Good Agreement

The aim of the present work is to analyze the magnetohydrodynamic (MHD) squeezing flow through porous medium using homotopy analysis method (HAM). Fourth-order boundary value problem is modeled through stream functionψ(r,z)and transformationψ(r,z)=r2f(z). Absolute residuals are used to check the efficiency and consistency of HAM. Other analytical techniques are compared with the present work. It is shown that results of good agreement can be obtained by choosing a suitable value of convergence control parameterhin the valid regionRh. The influence of different parameters on the flow is argued theoretically as well as graphically.

scholarly journals A Useful Manufacturing Guide for Rotary Piercing Seamless Pipe by ALE Method

2020 ◽  
Vol 8 (10) ◽  
pp. 756
Author(s):  
Ameen Topa ◽  
Burak Can Cerik ◽  
Do Kyun Kim
Keyword(s):  
Numerical Simulations ◽  
Maximum Stress ◽  
Three Dimensional ◽  
Material Model ◽  
Manufacturing Processes ◽  
Arbitrary Lagrangian Eulerian ◽  
Analysis Method ◽  
Seamless Pipe ◽  
Ale Formulation ◽  
Good Agreement

The development of numerical simulations is potentially useful in predicting the most suitable manufacturing processes and ultimately improving product quality. Seamless pipes are manufactured by a rotary piercing process in which round billets (workpiece) are fed between two rolls and pierced by a stationary plug. During this process, the material undergoes severe deformation which renders it impractical to be modelled and analysed with conventional finite element methods. In this paper, three-dimensional numerical simulations of the piercing process are performed with an arbitrary Lagrangian–Eulerian (ALE) formulation in LS-DYNA software. Details about the material model as well as the elements’ formulations are elaborated here, and mesh sensitivity analysis was performed. The results of the numerical simulations are in good agreement with experimental data found in the literature and the validity of the analysis method is confirmed. The effects of varying workpiece velocity, process temperature, and wall thickness on the maximum stress levels of the product material/pipes are investigated by performing simulations of sixty scenarios. Three-dimensional surface plots are generated which can be utilized to predict the maximum stress value at any given combination of the three parameters.

scholarly journals Experimental study on the effect of concrete strength and corrosion level on bond between steel bar and concrete

2021 ◽  
Vol 72 (4) ◽  
pp. 498-509
Author(s):  
Vuong Doan Dinh Thien ◽  
Hung Nguyen Thanh ◽  
Hung Nguyen Dinh
Keyword(s):  
Compressive Strength ◽  
Bond Strength ◽  
Concrete Strength ◽  
Concrete Block ◽  
Bond Stress ◽  
Concrete Compressive Strength ◽  
Pull Out ◽  
Steel Bar ◽  
Stress Degradation ◽  
Slip Displacement

Corrosion of the steel reinforcement bars reduces the area of the steel bar and the bond stress between the steel bars and around concrete that decreases the capacity of concrete structures. In this study, the bond stress between steel bar with a diameter of 12mm and concrete was examined with the effect of different corrosion levels and different concrete grades. A steel bar was inserted in a concrete block with a size of 20×20×20cm. The compressive strength of concrete was 25.6MPa, 35.1MPa, and 44.1MPa. These specimens were soaked into solution NaCl 3.5% to accelerate the corrosion process with different corrosion levels in the length of 60mm. The pull-out test was conducted. Results showed that the bond strength of the corroded steel bar was higher than that predicted from CEB-FIP. Slip displacement and the range of slip displacement at the bond strength were reduced when the concrete compressive strength was increased. The rate of bond stress degradation occurred faster with the increment of the corrosion level when the concrete compressive strength was increased.

scholarly journals Finite element modelling of monotonic pull-out test of deformed steel rebar embedded in well-confined concrete

2021 ◽  
Vol 331 ◽  
pp. 05012
Author(s):  
Patria Kusumaningrum ◽  
Gigih Muslim Prayogo ◽  
Sri Tudjono
Keyword(s):  
Finite Element ◽  
Finite Element Modelling ◽  
Empirical Equation ◽  
Bond Stress ◽  
Confined Concrete ◽  
Bond Slip ◽  
Steel Rebar ◽  
Bond Model ◽  
Pull Out ◽  
Good Agreement

A finite element study carried out using LS DYNA and aimed to simulate the monotonic pull-out test of deformed steel rebar embedded in concrete is presented in this paper. Three models of the interface between deformed steel rebar and well-confined concrete, i.e. perfect bond model and two bond-slip models are observed and compared. Bond stress-slip response and rebar stress-slip response obtained numerically are validated with experimental data and empirical equations available from the literature. The full bond model overestimates the response, providing higher rebar stress. In the bond-slip models, good agreement is observed between numerical and experimental bond stress and rebar Stress–slip responses. The empirical equation of bond-slip proposed by Murcia-Delso and Shing (2014) is found to overestimate the peak bond stress.

scholarly journals PENGARUH DIAMETER TIANG TERHADAP TAHANAN GESEK TIANG DALAM TANAH LEMPUNG

2019 ◽  
Vol 1 (3) ◽  
pp. 219-224
Author(s):  
Andikanoza Pradiptiya ◽  
A’isyah Salimah
Keyword(s):  
Pile Foundation ◽  
Structural Damage ◽  
Tensile Load ◽  
Frictional Resistance ◽  
Test Method ◽  
Scale Model ◽  
Friction Resistance ◽  
Average Value ◽  
Constant Rate ◽  
Pile Model

AbstractSome buildings impose limits on the foundation displacement that occur with relatively small values so as not to cause structural damage. The test method used was to make a model test box as a testing medium by simulating the actual model into the form of a scale model. The study was conducted using a single pile foundation with reduced scale, made of concrete with a diameter of 0.02 m, 0.03 m, 0.04 m and the length of each pile was 0.4 m. The pile model was mounted by pressing into the clay that had been compacted in the test box and then given a tensile load which refers to ASTM D3689-07 procedure E (Constant Rate of Uplift Test). Mobilization of pile friction resistance at critical displacement determined the frictional resistance of the ultimate pile units. The test results showed that the greater the diameter of the pile, the frictional resistance of the ultimate pile units would increase. The increase in frictional resistance of the ultimate pile units showed an average value of around 17.1%.Keywords : Pile foundation, Pile diameter, Friction resistance.AbstrakMeningkatnya pembangunan hunian mengakibatkan naiknya permintaan akan batako, hal ini tentunya Beberapa konstruksi bangunan memberikan batasan kepada perpindahan tiang yang terjadi dengan nilai yang relatif kecil supaya tidak menyebabkan kerusakan struktur. Metode uji yang dipakai adalah membuat box uji model sebagai media pengujian, dengan mensimulasikan model yang sebenarnya ke dalam bentuk model skala. Penelitian dilakukan menggunakan model pondasi tiang tunggal penampang lingkaran lingkaran skala tereduksi yang terbuat dari beton dengan diameter 0,02 m, 0,03 m, 0,04 m dan panjang  masing-masing tiang adalah 0,4 m. Model tiang dipasang dengan cara ditekan pada tanah lempung yang sudah dipadatkan dalam box uji kemudian diberikan beban tarik yang mengacu pada ASTM D3689-07 prosedur E (Constant Rate of Uplift Test). Mobilisasi tahanan gesek tiang pada perpindahan tiang kritis menetukan tahanan gesek satuan ultimit. Hasil uji memperlihatkan bahwa semakin besar diameter tiang, tahanan gesek satuan ultimit tiang akan bertambah. Peningkatan tahanan gesek satuan ultimit tiang menunjukkan rata-rata sekitar 17,1 %.Kata kunci : Pondasi Tiang, Diameter Tiang, Tahanan Gesek Tiang.

Dynamic Characteristics of TEHD Tilt Pad Journal Bearing Simulation Including Multiple Mode Pad Flexibility Model

1993 ◽  
Author(s):  
Jinsang Kim ◽  
Alan Palazzolo
Keyword(s):  
Heat Transfer ◽  
Elastic Deformation ◽  
Degrees Of Freedom ◽  
Journal Bearing ◽  
Variable Viscosity ◽  
Global Analysis ◽  
Analysis Method ◽  
Stiffness And Damping ◽  
Modal Coordinates ◽  
Good Agreement

Abstract An approach for incorporating the heat transfer and elastic deformation effects into dynamic coefficient calculation is presented. A global analysis method is used, which finds the equilibrium pad tilt angles at each eccentricity position and includes cross-film variable viscosity, heat transfer effects in the lubricant, elastic deformation, heat conduction effects in the pads, and elastic deformation effect in the pivots. Deflection modes are used to approximate deformation of the top surface of the pads. The dynamic coefficients of a single pad are calculated at the equilibrium state of the bearing, based on numerical perturbation with respect to the bearing degrees of freedom. These include journal position, pad rotation, pivot deformation, and modal coordinates. The stiffness and damping coefficients are calculated and show very good agreement with experimental and numerical results from the existing literature.

scholarly journals A Comparison of Surface Characteristics, Coating Stability and Friction Coefficients of Esthetic Archwires: A Comparative Study

2020 ◽  
pp. 030157422095988
Author(s):  
Harshal Jejurikar ◽  
Taabish Contractor ◽  
Salil Nene ◽  
Ajit Kalia ◽  
Wasu Patil ◽  
...  
Keyword(s):  
Friction Coefficient ◽  
Frictional Resistance ◽  
Surface Characteristics ◽  
Group 4 ◽  
Oral Environment ◽  
Surface Irregularities ◽  
Group 3 ◽  
Bonferroni Test ◽  
Coating Stability ◽  
Group 2

Aim: The aim of this article is to evaluate coated orthodontic aligning archwires for surface characteristics, coating stability, and associated dynamic frictional resistance and to compare and relate these results to each other. Materials and Methods: The archwire investigated were (1) group 1: American orthodontics (0.016 NiTi) (AO); (2) group 2: G and H Wire Company, USA (0.016) (G and H); (3) group 3: Orthosystems (0.016) (OS); and (4) group 4: Forestadent, Bio Cosmetic (0.017) (BC) Surface roughness (ESEM), coating stability, and frictional resistance were tested. Analysis of variance and Bonferroni test were used for analysis. Results: Frictional resistance from low to high—BC, AO, OS, G, and H. Coating stability from low to high—BC, AO, G and H, and OS. Surface characteristics from low to high—BC, OS, AO, G, and H. Conclusions: The study showed that BC has least friction coefficient, best coating stability, and less surface irregularities. Surface characteristics, friction coefficient, and coating stability may have correlation but are not statistically significant because of multifactorial conditions in the oral environment.

scholarly journals Numerical and Experimental Investigation on a Moonpool-Buoy Wave Energy Converter

Energies ◽  
2020 ◽  
Vol 13 (9) ◽  
pp. 2364 ◽  
Author(s):  
Hengxu Liu ◽  
Feng Yan ◽  
Fengmei Jing ◽  
Jingtao Ao ◽  
Zhaoliang Han ◽  
...  
Keyword(s):  
Numerical Model ◽  
Wave Energy ◽  
Wave Energy Converter ◽  
Scale Model ◽  
Energy Converter ◽  
Point Absorber ◽  
Motion Responses ◽  
Computational Fluid Dynamics Cfd ◽  
The Time Domain ◽  
Good Agreement

This paper introduces a new point-absorber wave energy converter (WEC) with a moonpool buoy—the moonpool platform wave energy converter (MPWEC). The MPWEC structure includes a cylinder buoy and a moonpool buoy and a Power Take-off (PTO) system, where the relative movement between the cylindrical buoy and the moonpool buoy is exploited by the PTO system to generate energy. A 1:10 scale model was physically tested to validate the numerical model and further prove the feasibility of the proposed system. The motion responses of and the power absorbed by the MPWEC studied in the wave tank experiments were also numerically analyzed, with a potential approach in the frequency domain, and a computational fluid dynamics (CFD) code in the time domain. The good agreement between the experimental and the numerical results showed that the present numerical model is accurate enough, and therefore considering only the heave degree of freedom is acceptable to estimate the motion responses and power absorption. The study shows that the MPWEC optimum power extractions is realized over a range of wave frequencies between 1.7 and 2.5 rad/s.

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