The effect of the roller profile oncave-in defect in reshaping processby considering nonlinear combine strain hardening

2021 ◽  
pp. 095440542110368
Author(s):  
Siamak Mazdak ◽  
Hassan Moslemi Naeni ◽  
Mohammad Reza Sheykholeslami ◽  
Manabo Kiuchi ◽  
Hesam Validi
Keyword(s):  
Numerical Study ◽  
Contact Model ◽  
Slab Method ◽  
Incremental Method ◽  
Circular Pipes ◽  
Meaningful Relationship ◽  
Numerical Software ◽  
Combined Hardening ◽  
The Common ◽  
Roller Profile

The reshaping process of pipes is an important method in producing non-circular pipes. Desired profile products are produced by passing round pipe through the rotating rollers. Cave-in defect is one of the common defects in the reshaping process. Roller design issues can decrease this kind of defect. In this paper, a method based on the slab method and the incremental plasticity has been presented to the numerical study of a 2D reshaping process. For investigating the Cave-in defect, the contact model has been developed. The concept of element elongation has been introduced to increase the accuracy of the contact model. Based on the presented method, numerical software has been developed to simulate the 2D reshaping process. Elastic-plastic equations for this subject have been driven based on the incremental method, J yielding criterion, and non-linear combined hardening. The effects of the radius of the roller profile on cave-in defects have been investigated by using the presented software (DARF). A set of experiments has been conducted in a forming station to verify the results. Results show that the presented model has higher accuracy than the Abaqus commercial software in predicting the cave-in defect. Based on the results of the model, the local increase of yielding stress directly affects the cave-in defect. Also, a meaningful relationship between the radius of the roller and the amount of the cave-in has been observed.

Numerical Study on Progressive Failure of the Marble Plate Based on the Thin-Layer Tri-Node Jointed Element

2011 ◽  
Vol 255-260 ◽  
pp. 1867-1872
Author(s):  
Jing Hua Qi ◽  
Zhen Nan Zhang ◽  
Xiu Run Ge
Keyword(s):  
Crack Propagation ◽  
Thin Layer ◽  
Numerical Study ◽  
Progressive Failure ◽  
Triangular Element ◽  
Compressive Loads ◽  
Joint Element ◽  
The Common ◽  
Edge Cracks ◽  
Good Agreement

In order to model the mechanical behavior of joints efficiently, a thin-layer tri-node joint element is constructed. The stiffness matrix of the element is derived in the paper. For it shares the common nodes with the original tri-node triangle element, the tri-node joint element can be applied to model the crack propagation without remeshing or mesh adjustment. Another advantage is that the cracked body is meshed without consideration of its geometry integrity and existence of the joints or pre-existed crack in the procedure of mesh generation, and then the triangular element intersected by the crack or joint is automatically transformed into the tri-node joint element to represent pre-existed cracks. These make the numerical simulation of crack propagation highly convenient and efficient. After CZM is chosen to model the crack tip, the mixed- energy simple criterion is used to determine whether the element is intersected by the extended crack or not, the extended crack is located in the model. By modeling the marble plates with two edge cracks subjected to the uniaxial compressive loads, it is shown that the numerical results are in good agreement with the experimental results, which suggests that the present method is valid and feasible in modeling rock crack propagation.

Numerical study and validation of non-Newtonian fluid hammer in circular pipes

2015 ◽  
Author(s):  
Tainan Gabardo Miranda dos Santos ◽  
Gabriel Merhy de Oliveira ◽  
Cezar Otaviano Ribeiro Negrão
Keyword(s):  
Newtonian Fluid ◽  
Numerical Study ◽  
Circular Pipes

Behavior of Geocell-Reinforced Sand under a Vertical Load

2008 ◽  
Vol 2045 (1) ◽  
pp. 95-101 ◽  
Author(s):  
Jie Han ◽  
Xiaoming Yang ◽  
Dov Leshchinsky ◽  
Robert L. Parsons
Keyword(s):  
Bearing Capacity ◽  
Numerical Study ◽  
Three Dimensional ◽  
Numerical Results ◽  
Shear Stresses ◽  
Vertical Load ◽  
Reinforced Sand ◽  
Numerical Software ◽  
Load To Failure ◽  
Test Process

Geocells have a three-dimensional cellular structure, which can be used to stabilize foundations by increasing bearing capacity and reducing settlements. However, a considerable gap exists between the applications and the theories for the mechanisms of geocell-reinforced foundations. An experimental and numerical study on the behavior of geocell-reinforced sand under a vertical load is presented. A single geocell was filled with sand and subjected to a vertical load to failure. This test process was modeled by using the FLAC3D numerical software to investigate the mechanisms of geocell and sand interactions. Experimental and numerical results both demonstrated that the geocell increased the ultimate bearing capacity and the modulus of the sand. The numerical results include the distributions of displacements in the sand and geocell walls and the distributions of tensile stresses and shear stresses acting on the geocell walls. The numerical results for geocell-reinforced sand are compared to those for sand without geocell.

Stability of a Beam on an Elastic Foundation Subjected to a Nonconservative Load

1980 ◽  
Vol 47 (1) ◽  
pp. 116-120 ◽  
Author(s):  
Z. Celep
Keyword(s):  
Approximate Solution ◽  
Numerical Calculation ◽  
Elastic Foundation ◽  
Cantilever Beam ◽  
Numerical Study ◽  
Galerkin’S Method ◽  
Galerkin's Method ◽  
The Common ◽  
The Stability

In this investigation, the influence of a Winkler type of elastic foundation on the stability of the cantilever beam subjected to a nonconservative load which consists of a vertical and a follower components is studied. In addition to the common transverse foundation modulus, a rotatory foundation modulus is considered. Approximate solution is obtained by using Galerkin’s method. Numerical calculation are reported and displayed for various combinations of the nonconservativeness parameter, transverse and rotatory modulus of the foundation, distance of the point of application of the load and that of the transverse spring. As a result of the numerical study unexpected feature of stability of the cantilever beam in contrast to the behavior of the column is identified.

scholarly journals An efficient optimization method for structures with local non-linearity

2016 ◽  
Vol 20 (suppl. 3) ◽  
pp. 879-886
Author(s):  
Zhao-Li Zheng ◽  
Yu-Qi Wang ◽  
Di Zhang
Keyword(s):  
Turbine Blade ◽  
Degrees Of Freedom ◽  
Fractal Theory ◽  
Linear Part ◽  
Equivalent Stress ◽  
Iteration Process ◽  
Optimization Method ◽  
Contact Model ◽  
Maximum Equivalent Stress ◽  
The Common

During the operation of turbines, one of the common accidents is due to the structure failure of blades. The contact model with strong non-linearity and time variation makes it difficult to be analyzed. In this paper, firstly, the contact model is described by using fractal theory. Secondly, the new method for the optimization of turbine blade is proposed, which is a kind of structure with local nonlinearity and multi degree of freedom. The method reduces the number of degrees of freedom by forming a new super element, which makes the linear part of turbine blade without repeated calculation in the non-linear iteration process. Therefore, it can shorten the calculation time and reduce the demand for computing resources. Finally, an optimization of the turbine blade is carried out, and the maximum equivalent stress reduces by 13.19%, which proves the effectiveness of the new optimization method.

scholarly journals Numerical Study of the In-Plane Seismic Response of RC Infilled Frames

2021 ◽  
Vol 1 (1) ◽  
pp. 82-94
Author(s):  
Matteo Bagnoli ◽  
Ernesto Grande ◽  
Gabriele Milani
Keyword(s):  
Seismic Vulnerability ◽  
Numerical Study ◽  
Pushover Analysis ◽  
Experimental Tests ◽  
Economic Losses ◽  
Rc Buildings ◽  
Infilled Frames ◽  
Masonry Infills ◽  
Reliable Model ◽  
The Common

Reinforced Concrete (RC) buildings with masonry infills are a very common structural typology worldwide for civil, strategic, or productive use. Damage to infills may cause danger for human lives and strongly affects economic losses, as shown during past earthquakes. In the current literature, different approaches are available for modeling the in-plane response of infilled frames and different constitutive laws generally calibrated on experimental tests. On the contrary, few and recent studies proposed formulas that account for the main properties of infills influencing their in-plane behavior to lateral forces. This paper presents a study finalized to derive a reliable model that is able to predict the monotonic and cyclic response of RC infilled masonry frames. To this end, after a critical analysis of the available literature, the authors combine among them two models, one for the monotonic response and the other for the cyclic one, by showing their reliability with reference to different experimental cases. Then, at the end of the paper, the derived models are employed to assess the seismic vulnerability of infills throughout a proposed procedure based on the common pushover analysis approach.

scholarly journals Numerical Study of Heat Transfer Intensification in a Circular Tube Using a Thin, Radiation-Absorbing Insert. Part 2: Thermal Performance

Energies ◽  
2021 ◽  
Vol 14 (15) ◽  
pp. 4533
Author(s):  
Piotr Bogusław Jasiński
Keyword(s):  
Heat Transfer ◽  
Thermal Performance ◽  
Thermal Efficiency ◽  
Circular Tube ◽  
Numerical Study ◽  
Radiation Absorption ◽  
Channel Diameter ◽  
Heat Transfer Intensification ◽  
Pressure Drops ◽  
The Common

This article is the second part of the work under the same title, which is based on the results of the research presented in the previous article: “Numerical study of heat transfer intensification in a circular tube using a thin, radiation-absorbing insert. Part 1: Thermo-hydraulic characteristics”. Part 1 presents an analysis of pressure drops and heat transfer intensification in a round tube with an insert, using the phenomenon of radiation absorption. In this paper, an analysis of the tested insert’s thermal performance (PEC) is presented, taking into account the criterion of equal pumping power. The tests were carried out for the range of Re = 5000–100,000 numbers, for various insert diameters (from 20% to 90% of the pipe diameter) and a constant temperature difference between the wall and the gas ∆T = 100 °C. The highest Nu numbers were observed for inserts with dimensionless diameters of 0.3 and 0.4, while the highest flow resistance was observed for inserts with diameters of 0.6 and 0.7 of the channel diameter. The thermal efficiency was calculated in two ways, as was the associated Nu number. These results significantly differed from each other: the maximum PEC values for method (I) reached 2, and for method (II) to 8. The common feature for both calculation methods was the fact that the maximum values of the Nu number and the thermal efficiency were observed for small Re numbers; however, as the Re number increases, PEC and Nu number decrease strongly.

Self-Selected Task Allocation

2020 ◽  
Author(s):  
Refael Hassin ◽  
Adam Nathaniel
Keyword(s):  
Task Allocation ◽  
Numerical Study ◽  
Fixed Number ◽  
Problem Definition ◽  
Independent Random Variables ◽  
Taxi Drivers ◽  
Closed Form Solutions ◽  
Allocation Method ◽  
Managerial Implications ◽  
The Common

Problem definition: Tasks sequentially arrive, and their values to the workers who are going to perform them are independent random variables. The common way to allocate tasks to workers is according to the first-in, first-out order. But this method both is inefficient and seems unfair to those who receive a low-valued task after a long wait. We are looking for a better allocation method. Academic/practical relevance: Finding a fair and efficient task allocation method is an aspiration of manpower firms that employ a pool of workers, such as salespersons, technicians, emergency medical stuff, nurses, or taxi drivers. We present many more implementations, such as turn taking and load management. Methodology: We propose a self-selected task allocation method and discuss its importance and implementations. The proposed method is defined as a cyclic queueing game with a fixed number of players. Every unit of time a prize with a random value is offered to the players according to their order in the queue, and a player who accepts a prize moves to the end of the queue. The process of choosing which prizes to accept in each position is presented as a noncooperative multiplayer game. We analyze strategies and symmetric equilibria for three variations. Results: We provide closed-form solutions and suggest a novel intuitive interpretation to find equilibria via calculating maximum-profit strategies. We complement the theoretical results by conducting a numerical study. Managerial implications: The proposed method is natural and easy to implement, its outcome is better than the common allocation by seniority, and the ratio of the expected value obtained under the two methods is unbounded.

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