Time Interval Effect in Triaxial Discontinuous Cyclic Compression Tests and Simulations for the Residual Stress in Rock Salt

2020 ◽  
Vol 53 (9) ◽  
pp. 4061-4076 ◽  
Author(s):  
Jinyang Fan ◽  
Wei Liu ◽  
Deyi Jiang ◽  
Jie Chen ◽  
William N. Tiedeu ◽  
...  
Keyword(s):  
Residual Stress ◽  
Rock Salt ◽  
Time Interval ◽  
Compression Tests ◽  
Cyclic Compression ◽  
Interval Effect

scholarly journals Energy dissipation of ordinary concrete under discontinuous cyclic compression tests and numerical simulations for the residual stress

2021 ◽  
Author(s):  
Jinyang Fan ◽  
Wenhao Liu ◽  
Deyi JIANG ◽  
Jie CHEN ◽  
William Tiedeu Ngaha
Keyword(s):  
Residual Stress ◽  
Numerical Simulations ◽  
Mechanical Response ◽  
Deformation Modulus ◽  
Dissipated Energy ◽  
Compression Tests ◽  
Ordinary Concrete ◽  
Cyclic Compression ◽  
Unloading Deformation ◽  
Main Material

This paper presents an experimental investigation of ordinary concrete under discontinuous cyclic compression tests and numerical simulations for the residual stress. Stress cycles in discontinuous cyclic compression tests were interrupted by zero or very low loading intervals (ZLIs). Fatigue tests showed that the dissipated energy and the unloading deformation modulus of a cycle after the ZLI ( A cycle) were significantly larger than those of the cycle before the ZLI ( B cycle). The dissipated energy and the unloading deformation modulus both increased with the increase of the stress level. The mechanism of discontinuous fatigue results from the effect of the residual stress which is caused by the uncoordinated mechanical response. Simulations showed that stress concentration occurs on the interface between the aggregate and the main material. The greater the elasticity modulus difference between the aggregate and the main material, the larger the residual stress and plastic deformation.

scholarly journals Research on the Static Recrystallization and Precipitation Behaviors of a V-N Microalloyed Steel

2013 ◽  
Vol 2013 ◽  
pp. 1-7 ◽  
Author(s):  
Baochun Zhao ◽  
Tan Zhao ◽  
Guiyan Li ◽  
Qiang Lu
Keyword(s):  
Static Recrystallization ◽  
Microalloyed Steel ◽  
Time Interval ◽  
Main Role ◽  
Recrystallization Process ◽  
Compression Tests ◽  
Double Compression ◽  
Higher Temperature ◽  
Lower Temperature ◽  
Temperature Strain

Double compression tests were performed on a Gleeble-3800 thermomechanical simulator to study the softening behaviors of deformed austenite in a V-N microalloyed steel. The static recrystallization volume fractions were calculated by stress offset method, and the kinetic model of static recrystallization was constructed. The effects of temperature, strain, and time interval on the softening behaviors were analyzed, and the interactions between precipitation and recrystallization were discussed. The results show that the softening behaviors of the deformed austenite at lower temperature or higher temperature are markedly different. At the temperature of 850°C or 800°C, pinning effects of the precipitates play the main role, and the recrystallization process is inhibited, which leads to the formation of plateaus in the softening curves. An increase in strain promotes the precipitation and recrystallization processes while reduces the inhibition effect of precipitation on recrystallization as well.

scholarly journals EFFECTS OF WELDING PARAMETERS, TIME INTERVAL AND PREHEATING ON RESIDUAL STRESS AND DISTORTION OF JOINING ST52 STIFFENER RING IN AN AISI 4130 TUBULAR SHELL

2020 ◽  
Vol 3 (1) ◽  
pp. 11-15
Author(s):  
Alireza M. Haghighi ◽  
Farhad S. Samani
Keyword(s):  
Residual Stress ◽  
Welding Current ◽  
Welding Parameters ◽  
Time Interval ◽  
Negative Effects ◽  
Short Term ◽  
Welding Line ◽  
Aisi 4130 ◽  
Comparison Of The Results

Stiffener rings and stringers are used commonly in offshore and aerospace structures. Welding the stiffener to the structure causes the appearance of residual stress and distortion that leads to short-term and long-term negative effects. Residual stress and distortion of welding have destructive effects such as deformation, brittle fracture, and fatigue of the welded structures. This paper aims to investigate the effects of preheating, time interval and welding parameters such as welding current and speed on residual stress and distortion of joining an ST52-3N (DIN 1.0570) T-shape stiffener ring to an AISI 4130 (DIN 1.7218) thin-walled tubular shell by eleven pairs of welding line in both sides of the ring by means of finite element method (FEM). Results in tangent (longitudinal), axial and radial directions have been compared and the best welding methods proposed. After the comparison of the results, simultaneous welding both sides of the ring with preheating presented as the best method with less distortion and residual stresses among the studied conditions. The correctness of the FEM confirmed by the validation of the results.

scholarly journals Finite Difference Modeling of the Interstand Evolutions of Profile and Residual Stress during Hot Strip Rolling

Metals ◽  
2020 ◽  
Vol 10 (11) ◽  
pp. 1417
Author(s):  
Chihuan Yao ◽  
Anrui He ◽  
Jian Shao ◽  
Jianwei Zhao ◽  
Guanyu Zhou ◽  
...  
Keyword(s):  
Residual Stress ◽  
Stress Relaxation ◽  
Finite Difference ◽  
Hot Rolling ◽  
Shape Control ◽  
Elastic Recovery ◽  
Compression Tests ◽  
Hot Strip Rolling ◽  
New Model ◽  
Roll Bite

Elastic recovery and viscoplastic stress relaxation occur in the interstand of hot rolling, impacting the evolutions of strip profile and residual stress, which are major concerns for obtaining high-quality flat products. A better understanding of the evolutionary mechanisms would help develop shape control strategies. Therefore, a quasi-3D steady-state elasto-viscoplastic rolling model is developed based on the finite difference method. Predictions of spread, profile, and residual stress are validated through comparisons with a two-stand finite element model. The new model is also complemented with a roll stack model and with a viscoplastic constitutive model calibrated by hot compression tests to simulate a seven-stand hot rolling industrial experiment with low carbon steel. Comparisons between the predicted and measured profiles show a satisfactory accuracy. The simulation costs approximately a minute of CPU time, enabling the new model to run massive parametric campaigns for process optimization. It is found that during the interstand elastic recovery, the transverse compressive stress releases and the strip velocity tends to be uniform, revealing residual stress after a significant change of stress pattern. The stress relaxation mainly occurs at the edge near the roll bite and therefore increases the edge drop of the profile; it also decreases the center crown by changing the distribution of the rolling pressure in the roll bite.

Modelling and Simulation of Temperature and Stress Analysis in TIG Welding Process

2015 ◽  
Vol 830-831 ◽  
pp. 294-297
Author(s):  
Nayan Chandak ◽  
Mohan Kumar Pradhan ◽  
Lokesh Boriwal
Keyword(s):  
Residual Stress ◽  
Structural Analysis ◽  
Strain State ◽  
Processing Time ◽  
Welding Process ◽  
Time Interval ◽  
Coarse Mesh ◽  
Ansys Software ◽  
Fine Mesh ◽  
Material Conditions

In this study, the welding process is modelled and analysed using ANSYS software. The temperature and residual stress produced during the process is depicted. During heating, the material conditions, parts affected by residual stress and the stress–strain state at different time interval is recorded and a subsequent structural analysis is used for the analysis, the same is used in the analysis where thermal and structural results are investigated. Subsequently, with sensitivity analysis the results are evaluated. Non-uniform meshing is used to entrap the result with fine mesh in the heat affected zone and coarse mesh away from it to save processing time. The results from the thermal structural analysis are presented to understand the process deeply and comparison of the graph plot between temperature and time is explained.

Towards the Mastering of the Free Surface Position in Roll Coating

2007 ◽  
Vol 344 ◽  
pp. 955-962
Author(s):  
E. Szczurek ◽  
M. Dubar ◽  
R. Deltombe ◽  
A. Dubois ◽  
L. Dubar
Keyword(s):  
Numerical Simulation ◽  
Free Surface ◽  
Compression Tests ◽  
Contact Conditions ◽  
Roll Coating ◽  
Real Contact ◽  
Cyclic Compression ◽  
Viscoelastic Parameters ◽  
Element Simulation ◽  
Behaviour Law

This paper deals with an industrial three rolls coater. The behaviour law of the elastomer roll cover in different environments is first established in order to be taken into account in the numerical simulation of the process. Cyclic compression tests are performed and compared to the corresponding numerical simulation to precisely determine the viscoelastic parameters. With the identified parameters, a finite element simulation of the process is then performed to evaluate the meniscus stability in real contact conditions. The influence of the determined elastomer behaviour laws on the free surface position is discussed.

scholarly journals Mechanical characterization and numerical modeling of laser-sintered TPE lattice structures

2021 ◽  
Author(s):  
Christina Kummert ◽  
Hans-Joachim Schmid ◽  
Lena Risse ◽  
Gunter Kullmer
Keyword(s):  
Numerical Modeling ◽  
Thermoplastic Elastomer ◽  
Experimental Investigations ◽  
Lattice Structures ◽  
Sintering Process ◽  
Compression Tests ◽  
Plastic Properties ◽  
Cell Parameters ◽  
Cyclic Compression

Abstract Additive Manufacturing provides the opportunity to produce tailored and complex structures economically. The use of lattice structures in combination with a thermoplastic elastomer enables the generation of structures with configurable properties by varying the cell parameters. Since there is only little knowledge about the producibility of lattice structures made of TPE in the laser sintering process and the resulting mechanical properties, different kinds of lattice structures are investigated within this work. The cell type, cell size and strut thickness of these structures are varied and analyzed. Within the experimental characterization of Dodecahedron-cell static and cyclic compression tests of sandwich structures are focused. The material exhibits hyperelastic and plastic properties and also the Mullins-Effect. For the later design of real TPE structures, the use of numerical methods helps to reduce time and costs. The preceding experimental investigations are used to develop a concept for the numerical modeling of TPE lattice structures. Graphic abstract

scholarly journals Stress-Strain Response of Cylindrical Rubber Fender under Monotonic and Cyclic Compression

Materials ◽  
2019 ◽  
Vol 12 (2) ◽  
pp. 282 ◽  
Author(s):  
Chia-Chin Wu ◽  
Yung-Chuan Chiou
Keyword(s):  
Energy Density ◽  
Strain Energy Density ◽  
Strain Energy ◽  
Polynomial Function ◽  
Compressive Strain ◽  
Strain Curve ◽  
Strain Range ◽  
Compression Tests ◽  
Cyclic Compression ◽  
The Relationship

The study was devoted to the observation and modeling the mechanical behaviors of a hybrid SBR/NR (Styrene-Butadiene/Natural Rubber) hybrid vulcanized rubber fender under monotonic/cyclic compression. In experimental observations of the monotonic compression tests, it was found that lateral deformation occurred on the tested fender and was more significant with increasing the extent of the compressive strain. The relationship between the transmission stress S c and the compressive strain e c was nonlinear and the absorbed strain-energy-density was increased monotonically with the increment of the compressive strain. Among all cyclic compression tests with strain controlled, the reductions in both the stress range and the absorbed strain-energy-density up to the ten-thousandth cycle were found and then both of the cyclic properties remain approximately constant in the following compression cycles. Two new properties, the softening factor and the energy reduction factor, were introduced to quantify the effect of the strain range on the extent of the reduction in stress range and that on the absorbed strain-energy-density, respectively. It was found that both of the calculated values of the new properties increase with the increment of strain range. In mathematical modeling of the relationship between the transmission stress and the compressive strain, a new approach based on energy-polynomial-function E s ( e c ) was presented and was successfully used to simulate the monotonic curve and the stable hysteresis loop curves of the tested rubber fender in compression. Essentially, the energy-polynomial-function E s ( e c ) was obtained by performing a polynomial regression on a large amount of ( e c , E s ) data. Moreover, the least-square approach was applied to determine the corresponding regression coefficients in E s ( e c ) . Clearly, the stress-polynomial-function in modeling the S c − e c curve could be obtained from the differentiation of the energy-polynomial-function with respect to the compressive strain. In addition, to provide an adequate estimation of the mechanical properties of the cylindrical rubber fender under compression, the named cyclic stress-strain curve and cyclic energy-strain curve were developed and also modeled in this study.

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