A Material Function of Endochronic Theory and its Application to Test Under Axisymmetrically Cyclic Loading Conditions

2007 ◽  
Vol 23 (2) ◽  
pp. 135-148
Author(s):  
H.-Y. Lin ◽  
W.-C. Yeh ◽  
W.-J. Lee
Keyword(s):  
Cyclic Loading ◽  
Present Model ◽  
Hysteresis Loops ◽  
Cyclic Strain ◽  
Experimental Results ◽  
Material Function ◽  
Deformation History ◽  
Cyclic Loading Condition ◽  
Endochronic Theory ◽  
Good Agreement

AbstractA material function of endochronic theory is proposed for investigating the plastic behaviors of material. Depending on the material parameters properly chosen, the present model can be classified into four categories, and is appropriate for describing various materials behaving cyclic strain hardening inherently with respect to the deformation history. Experimental verification of the theory was demonstrated using the experimental results of Shiao [1] and Lamba and Sidebottom [2]. The theory is in good agreement with experimental results obtained by Shiao [1] through comparing the stress-strain hysteresis loops of SAE 4340 steel under axisymmetrically cyclic loading condition with various amplitudes. In addition, the present model is shown to be capable of describing the behavior of erasure of memory of materials, as experimentally observed by Lamba and Sidebottom [2].

Unresolved Issues With Regard to Creep and Creep Fatigue Life Prediction

2002 ◽  
Author(s):  
J. Oh ◽  
N. Katsube ◽  
F. W. Brust
Keyword(s):  
Cyclic Loading ◽  
Damage Evolution ◽  
Life Prediction ◽  
Loading Condition ◽  
Cyclic Strain ◽  
Rupture Process ◽  
Steady State Creep ◽  
Creep Failure ◽  
Cyclic Loading Condition ◽  
Creep Fatigue

This paper studies intergranular creep failure of high temperature service material under a stress-controlled unbalanced cyclic loading condition. The grain boundary rupture process was numerically analyzed using Tvergaard’s axisymetric model. The present numerical model incorporated the experimentally verified Murakami-Ohno cyclic strain hardening creep law and Norton’s creep law. The numerical results show that void growth accelerates under cyclic loading condition. Also, analysis shows that a steady state creep law is not sufficient to analyze damage evolution under cyclic loading conditions.

scholarly journals Research on Ceramic Spindle Loss Based on Ceramic Reverse Magnetic Effect

2020 ◽  
Vol 2020 ◽  
pp. 1-14
Author(s):  
Ke Zhang ◽  
Zinan Wang ◽  
Xiaotian Bai ◽  
Huaitao Shi ◽  
Songhua Li
Keyword(s):  
Working Conditions ◽  
Present Model ◽  
Magnetic Effect ◽  
Experimental Results ◽  
Magnetic Characteristics ◽  
Motorized Spindle ◽  
Coupling System ◽  
Average Loss ◽  
Park Transformation ◽  
Good Agreement

Ceramic motorized spindle is a multifield, nonlinear, and strong coupling system. The present model ignores the reverse magnetic effect and has a poor accuracy on the loss of the spindle system. In the paper, Park transformation was used to establish the electromagnetic physical model of ceramic motorized spindle. By combining with the Jiles–Atherton theory, an eccentric magnetization model of a ceramic motorized spindle considering reverse magnetic properties was established. Energy consumption parameters were calculated under various working conditions. The influence of ceramic reverse magnetic characteristics on the motorized spindle loss was analyzed and verified by experiments. The results show that the simulation of the ceramic motorized spindle loss model is in good agreement with the experimental results. Compared with the experimental results, the average loss error was 2.1%. Due to the reverse magnetic characteristics, the application of ceramic motorized spindle can help reduce the system loss. The ceramic motorized spindle model provides a theoretical basis for the development of ceramic spindle energy loss and efficiency.

scholarly journals Damage Detection of Concrete-Filled Square Steel Tube (CFSST) Column Joints under Cyclic Loading Using Piezoceramic Transducers

Sensors ◽  
2018 ◽  
Vol 18 (10) ◽  
pp. 3266 ◽  
Author(s):  
Juan Zhang ◽  
Jindong Xu ◽  
Wenqiang Guan ◽  
Guofeng Du
Keyword(s):  
Cyclic Loading ◽  
Damage Detection ◽  
Health Monitoring ◽  
Hysteresis Loops ◽  
Steel Tube ◽  
Experimental Results ◽  
Frame Structures ◽  
Seismic Loads ◽  
Square Steel Tube ◽  
Core Concrete

Concrete-filled square steel tube column (CFSSTC) joints are the most important parts of concrete-filled steel tube frame structures. It is of great significance to study the damage of CFSSTC joints under the seismic loads. In this paper, embedded piezoceramic transducers are used to monitor the damage of core concrete of CFSSTC joints under cyclic loading and surface-bonded piezoceramic disks are used to monitor the debonding damage of the steel tube and core concrete of two specimens. The damages of the joints under different loading levels and different loading cycles are evaluated by the received signal of the piezoceramic transducers. The experimental results show that the amplitude of the signal attenuates obviously with the appearance of damage in the joints, and the degree of attenuation increases with the development of the damage. The monitoring results from piezoceramic transducers are basically consistent with the hysteresis loops and skeleton curves of the CFSSTC joints during the cyclic loading. The effectiveness of the piezoceramic transducers are verified by the experimental results in structural health monitoring of the CFSSTC joint under cyclic loading.

Estimation of Residual Stress Change due to Cyclic Loading by Classical Elastoplasticity Model and Subloading Surface Model

2016 ◽  
Vol 725 ◽  
pp. 281-286 ◽  
Author(s):  
Ryota Higuchi ◽  
Kazuo Okamura
Keyword(s):  
Residual Stress ◽  
Cyclic Loading ◽  
Stress Measurement ◽  
Kinematic Hardening ◽  
Bending Test ◽  
Surface Model ◽  
Material Function ◽  
X Ray ◽  
Before And After ◽  
Good Agreement

The subloading surface model has been formulated and applied to the prediction of cyclic loading behavior. The material function prescribing elastic-plastic transition in the original subloading surface model has been extended so as to describe the inverse and reloading behavior and the strain accumulation in cyclic loading more accurately for steel. In the present paper, the extended subloading surface model was applied to the prediction of the change of the residual stress due to cyclic loading. The four-point cyclic bending test was performed for the specimen that had initial residual stress. The distributions of the residual stress before and after cyclic loading were measured by the X-ray stress measurement method. The simulation to the experiment was performed by the extended subloading surface model. The stress distribution after cyclic loading simulated by the extended subloading surface model was in good agreement with measured one, and was more accurate than that by the nonlinear isotropic/kinematic hardening model.

The Endochronic Approach for Structural Steel Subjected to Cyclic Loading

2001 ◽  
Vol 17 (1) ◽  
pp. 49-54
Author(s):  
Jun-Kai Lu ◽  
Nai-Kuan Ji
Keyword(s):  
Cyclic Loading ◽  
Structural Steel ◽  
Present Model ◽  
Cyclic Strain ◽  
Induced Anisotropy ◽  
Mechanical Behaviors ◽  
Strain Paths ◽  
Loading And Unloading ◽  
Definition Of ◽  
Theoretical Results

ABSTRACTThe A36 structural steel shows significant Baushinger effect under cyclic loading. Present paper modifies the anisotropic endochronic model to describe the behaviors of the A36 structural steel subjected to cyclic loading. The deformation induced anisotropy has been considered to modify the definition of the intrinsic time. Also, the different hardening functions are used with respect to the mechanical behavior under loading and unloading condition, respectively. Then, the presented constitutive equations are used to describe the mechanical behaviors of the A36 structural steel under different cyclic strain paths. The theoretical results are compared with the experimental data. The test investigated includes several different cyclic uniaxial and axial-torsional loading experiments from Hong and his co-workers. It is shown that the present model is capable of describing the anisotropic behaviors of A36 structural steel well.

Inducing Frictional Force to Enhance the Transient Response in Beams

2019 ◽  
Vol 22 (2) ◽  
pp. 88-93
Author(s):  
Hamed Khanger Mina ◽  
Waleed K. Al-Ashtrai
Keyword(s):  
Numerical Analysis ◽  
Transient Response ◽  
Frictional Force ◽  
Damping Ratio ◽  
Experimental Results ◽  
Damping Capacity ◽  
Tightening Force ◽  
Contact Areas ◽  
Good Agreement ◽  
Ansys Workbench

This paper studies the effect of contact areas on the transient response of mechanical structures. Precisely, it investigates replacing the ordinary beam of a structure by two beams of half the thickness, which are joined by bolts. The response of these beams is controlled by adjusting the tightening of the connecting bolts and hence changing the magnitude of the induced frictional force between the two beams which affect the beams damping capacity. A cantilever of two beams joined together by bolts has been investigated numerically and experimentally. The numerical analysis was performed using ANSYS-Workbench version 17.2. A good agreement between the numerical and experimental results has been obtained. In general, results showed that the two beams vibrate independently when the bolts were loosed and the structure stiffness is about 20 N/m and the damping ratio is about 0.008. With increasing the bolts tightening, the stiffness and the damping ratio of the structure were also increased till they reach their maximum values when the tightening force equals to 8330 N, where the structure now has stiffness equals to 88 N/m and the damping ratio is about 0.062. Beyond this force value, increasing the bolts tightening has no effect on stiffness of the structure while the damping ratio is decreased until it returned to 0.008 when the bolts tightening becomes immense and the beams behave as one beam of double thickness.

scholarly journals On the Plastic Strain Accumulation in Notched Bars During High-Temperature Creep Dwell

2020 ◽  
Vol 36 (2) ◽  
pp. 167-176 ◽  
Author(s):  
Daniele Barbera ◽  
Haofeng Chen
Keyword(s):  
High Temperature ◽  
Cyclic Loading ◽  
Plastic Strain ◽  
Kinematic Hardening ◽  
High Temperature Creep ◽  
Strain Accumulation ◽  
Material Models ◽  
Cyclic Loading Condition ◽  
Hardening Material ◽  
Temperature Creep

ABSTRACTStructural integrity plays an important role in any industrial activity, due to its capability of assessing complex systems against sudden and unpredicted failures. The work here presented investigates an unexpected new mechanism occurring in structures subjected to monotonic and cyclic loading at high temperature creep condition. An unexpected accumulation of plastic strain is observed to occur, within the high-temperature creep dwell. This phenomenon has been observed during several full inelastic finite element analyses. In order to understand which parameters make possible such behaviour, an extensive numerical study has been undertaken on two different notched bars. The notched bar has been selected due to its capability of representing a multiaxial stress state, which is a practical situation in real components. Two numerical examples consisting of an axisymmetric v-notch bar and a semi-circular notched bar are considered, in order to investigate different notches severity. Two material models have been considered for the plastic response, which is modelled by both Elastic-Perfectly Plastic and Armstrong-Frederick kinematic hardening material models. The high-temperature creep behaviour is introduced using the time hardening law. To study the problem several results are presented, as the effect of the material model on the plastic strain accumulation, the effect of the notch severity and the mesh element type and sensitivity. All the findings further confirm that the phenomenon observed is not an artefact but a real mechanism, which needs to be considered when assessing off-design condition. Moreover, it might be extremely dangerous if the cyclic loading condition occurs at such a high loading level.

PHOTOINDUCED NONLINEAR OCTUPOLAR POLARIZATION: TRANSIENT AND PERMANENT REGIMES

1996 ◽  
Vol 05 (04) ◽  
pp. 653-670 ◽  
Author(s):  
CÉLINE FIORINI ◽  
JEAN-MICHEL NUNZI ◽  
FABRICE CHARRA ◽  
IFOR D.W. SAMUEL ◽  
JOSEPH ZYSS
Keyword(s):  
Theoretical Analysis ◽  
Second Harmonic ◽  
Experimental Results ◽  
Polar Field ◽  
Rotational Spectrum ◽  
Dual Frequency ◽  
One Dimensional ◽  
Ethyl Violet ◽  
Disperse Red 1 ◽  
Good Agreement

An original poling method using purely optical means and based on a dual-frequency interference process is presented. We show that the coherent superposition of two beams at fundamental and second-harmonic frequencies results in a polar field with an irreducible rotational spectrum containing both a vector and an octupolar component. This enables the method to be applied even to molecules without a permanent dipole such as octupolar molecules. After a theoretical analysis of the process, we describe different experiments aiming at light-induced noncentrosymmetry performed respectively on one-dimensional Disperse Red 1 and octupolar Ethyl Violet molecules. Macroscopic octupolar patterning of the induced order is demonstrated in both transient and permanent regimes. Experimental results show good agreement with theory.

scholarly journals Comparison of Experimental and Numerical Transient Drop Deformation during Transition through Orifices in High-Pressure Homogenizers

2021 ◽  
Vol 5 (3) ◽  
pp. 32
Author(s):  
Benedikt Mutsch ◽  
Peter Walzel ◽  
Christian J. Kähler
Keyword(s):  
High Pressure ◽  
Visual Analysis ◽  
Imaging Technique ◽  
Extensional Flow ◽  
Droplet Breakup ◽  
Experimental Results ◽  
Drop Deformation ◽  
Droplet Deformation ◽  
Shadow Imaging ◽  
Good Agreement

The droplet deformation in dispersing units of high-pressure homogenizers (HPH) is examined experimentally and numerically. Due to the small size of common homogenizer nozzles, the visual analysis of the transient droplet generation is usually not possible. Therefore, a scaled setup was used. The droplet deformation was determined quantitatively by using a shadow imaging technique. It is shown that the influence of transient stresses on the droplets caused by laminar extensional flow upstream the orifice is highly relevant for the droplet breakup behind the nozzle. Classical approaches based on an equilibrium assumption on the other side are not adequate to explain the observed droplet distributions. Based on the experimental results, a relationship from the literature with numerical simulations adopting different models are used to determine the transient droplet deformation during transition through orifices. It is shown that numerical and experimental results are in fairly good agreement at limited settings. It can be concluded that a scaled apparatus is well suited to estimate the transient droplet formation up to the outlet of the orifice.

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