scholarly journals Modeling Creep Fracture in Rock by Using Kelvin Discretized Virtual Internal Bond

2018 ◽  
Vol 2018 ◽  
pp. 1-8 ◽  
Author(s):  
Wangyang He ◽  
Zhennan Zhang
Keyword(s):  
Finite Number ◽  
Internal Bond ◽  
Fracture Behavior ◽  
Creep Fracture ◽  
A Cell ◽  
Natural Response ◽  
Modeling Creep ◽  
Simulation Results ◽  
Creep Problem ◽  
The Ideal

Discretized virtual internal bond (DVIB) is a lattice model, which is composed of bond cells. Each bond cell has a finite number of bonds. The DVIB is used to model the creep fracture. It is done by introducing a viscous bond to the original hyperelastic DVIB. The hyperelastic bond is parallel coupled with a viscous bond together, forming a hybrid hyperelastic-Kelvin bond. The hyperelastic bond reflects the microfracture mechanism, whereas the viscous bond reflects the creep mechanism. Based on this hyperelastic-Kelvin bond, the constitutive relation of a cell is derived. The microbond parameters are calibrated based on the ideal cell approach. The simulation results suggest that this method can represent the typical features of creep and can simulate the creep fracture. The merit of this method lies in that the complicated 3D macrocreep problem is reduced to the 1D microbond creep problem. No creep law is previously derived. The macrocreep fracture behavior is the natural response of the assembly of the micro hyperelastic-Kelvin bonds.

Criteria and Methods for Reliable Three-Dimensional Image Reconstruction

1974 ◽  
Vol 32 ◽  
pp. 330-331
Author(s):  
R. A. Crowther
Keyword(s):  
Image Reconstruction ◽  
Finite Number ◽  
Density Distribution ◽  
Electron Micrographs ◽  
Mathematical Problem ◽  
Three Dimensional ◽  
Ideal Case ◽  
Dimensional Image ◽  
General Object ◽  
The Ideal

The reconstruction of a three-dimensional image of a specimen from a set of electron micrographs reduces, under certain assumptions about the imaging process in the microscope, to the mathematical problem of reconstructing a density distribution from a set of its plane projections.In the absence of noise we can formulate a purely geometrical criterion, which, for a general object, fixes the resolution attainable from a given finite number of views in terms of the size of the object. For simplicity we take the ideal case of projections collected by a series of m equally spaced tilts about a single axis.

Study on Numerical Simulation Technology Based on ANSYS of Fracture Behavior in Metal Forming Process

2011 ◽  
Vol 130-134 ◽  
pp. 976-979
Author(s):  
Yan Guo Shi ◽  
Bao Jun Yao ◽  
Qing Ling Zhang ◽  
Xin Hua Mei
Keyword(s):  
Metal Forming ◽  
Fracture Process ◽  
Fracture Behavior ◽  
Fracture Criterion ◽  
Secondary Development ◽  
Ansys Software ◽  
Forming Process ◽  
Development Technology ◽  
Metal Forming Process ◽  
Simulation Results

This title use the ANSYS Secondary Development Technology as platform, developed the user101 element that stable for fracture process simulation, and embedded fracture criterion into ANSYS software. Realized the fracture forecast on metal forming process and verified the simulation results through the experiment.

Synthesized ADRC for One-Level Inverted Pendulum System through Combination of Separating and Assembling

2014 ◽  
Vol 490-491 ◽  
pp. 794-797
Author(s):  
Wen Ping Li ◽  
Li Qiang Wu
Keyword(s):  
Nonlinear System ◽  
Inverted Pendulum ◽  
Dynamical Decoupling ◽  
Pendulum System ◽  
Inverted Pendulum System ◽  
Strong Robustness ◽  
Ideal Study ◽  
Simulation Results ◽  
The One ◽  
The Ideal

Inverted pendulum system is the ideal study object of nonlinear system. The ADRC has good estimate for disturbances, strong robustness and using static decoupling instead of dynamical decoupling. The one-level inverted pendulum system can be regarded as composing of the pendulum angel system and the cart position system. The former is faster and the later is slower. The synthesized ADRC for one-level inverted pendulum system is built through combination of separating and assembling to reduce difficulty in optimizing ADRC parameters of the inverted pendulum system. The synthesized controller is simulated by Matlab under different parameters of the inverted pendulum. Simulation results show that the pendulum angle and the cart position are well controlled.

scholarly journals New Improved Fractional Order Differentiator Models Based on Optimized Digital Differentiators

2014 ◽  
Vol 2014 ◽  
pp. 1-11 ◽  
Author(s):  
Maneesha Gupta ◽  
Richa Yadav
Keyword(s):  
Fractional Order ◽  
Differential Operators ◽  
Fitness Function ◽  
Hybrid Optimization ◽  
Nyquist Frequency ◽  
Swarm Optimization ◽  
Optimization Simulation ◽  
Fractional Order Differentiator ◽  
Simulation Results ◽  
The Ideal

Different evolutionary algorithms (EAs), namely, particle swarm optimization (PSO), genetic algorithm (GA), and PSO-GA hybrid optimization, have been used to optimize digital differential operators so that these can be better fitted to exemplify their new improved fractional order differentiator counterparts. First, the paper aims to provide efficient 2nd and 3rd order operators in connection with process of minimization of error fitness function by registering mean, median, and standard deviation values in different random iterations to ascertain the best results among them, using all the abovementioned EAs. Later, these optimized operators are discretized for half differentiator models for utilizing their restored qualities inhibited from their optimization. Simulation results present the comparisons of the proposed half differentiators with the existing and amongst different models based on 2nd and 3rd order optimized operators. Proposed half differentiators have been observed to approximate the ideal half differentiator and also outperform the existing ones reasonably well in complete range of Nyquist frequency.

The Investigation of Creep Behavior for NiAl-28Cr-5.5Mo-0.5Hf-0.02wt.%P Alloy at High Temperature

2011 ◽  
Vol 279 ◽  
pp. 28-32
Author(s):  
Guang Ye Zhang ◽  
Dong Wen Ye ◽  
Jin Lin Wang ◽  
You Ming Chen ◽  
Long Fei Liu ◽  
...  
Keyword(s):  
Steady State ◽  
High Temperature ◽  
Creep Behavior ◽  
Fracture Behavior ◽  
Primary Creep ◽  
Dislocation Climb ◽  
Steady State Creep ◽  
Creep Fracture ◽  
Creep Mechanisms ◽  
Higher Temperature

The Microstructure and creep behavior for NiAl-28Cr-5.5Mo-0.5Hf-0.02wt.%P alloy at high temperature have been investigated in this paper. The results reveal that the high temperature creep behavior of the NiAl-28Cr-5.5Mo-0.5Hf-0.02wt.%P alloy is characterized by transient primary creep and dominant steady-state creep as well as ternary creep behavior. The primary creep can be described by Garofalo equation and the steady-state creep can be depicted by Dorn equation. The creep mechanisms are viscous glide of dislocations at lower and middle testing temperatures and dislocation climb at higher temperature. No change of the microstructure for the testing alloy indicates that the creep fracture is controlled by the formation and propagation of cavities and cracks, and the creep fracture behavior obeys Monk man-Grant relationship.

Electric Servo Loading System Applied to Flight Simulator

2013 ◽  
Vol 380-384 ◽  
pp. 572-575
Author(s):  
Liu Hong
Keyword(s):  
Digital Control ◽  
Flight Simulator ◽  
Loading System ◽  
Control Load ◽  
Working Principle ◽  
Simulation Results ◽  
The Ideal

Flight simulator control loading system is an important part of the flight simulator, and it provides operating force people feeling system for Pilots. This paper introduces the working principle of digital control load system, and describes in detail the simulation and application of the electric servo loading system in the flight simulator. After tested the system has reached the ideal simulation results.

Creep fracture behavior of dissimilar weld joints between T92 martensitic and HR3C austenitic steels

2011 ◽  
Vol 88 (2-3) ◽  
pp. 94-98 ◽  
Author(s):  
Jian Cao ◽  
Yi Gong ◽  
Zhen-Guo Yang ◽  
Xiao-Ming Luo ◽  
Fu-Ming Gu ◽  
...  
Keyword(s):  
Fracture Behavior ◽  
Austenitic Steels ◽  
Creep Fracture ◽  
Dissimilar Weld ◽  
Weld Joints

Study on Fracture Behavior of Steel Strip under Cold Rolling Forming Process Based on GTN Damage Model

2013 ◽  
Vol 779-780 ◽  
pp. 126-129
Author(s):  
Jian Jun Chen ◽  
Yu Xi Yan ◽  
Quan Sun ◽  
Hong Liang Pan
Keyword(s):  
Crack Propagation ◽  
Fracture Behavior ◽  
Steel Strip ◽  
Damage Model ◽  
Forming Process ◽  
Strip Steel ◽  
Initiation And Propagation ◽  
Gtn Damage Model ◽  
Edge Cracks ◽  
Simulation Results

In this paper the behavior of crack propagation of the strip steel is investigated by using the Gurson-Tvergaard-Needleman (GTN) damage model. The damage parameters used in the damage model are determined by tension experiments and SEM observation. With the aid of finite element method the influences of rolling ruduction and tension on crack propagation are systematically analyzed. The numerical results show that the GTN damage model is available to prediction the initiation and propagation of edge cracks during rolling forming process and the simulation results agrees well with the experimental results.

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