A Comparative Study of the Response of Double Shearing and Hypoplastic Models

2002 ◽  
Author(s):  
Huaning Zhu ◽  
Morteza M. Mehrabadi ◽  
Mehrdad Massoudi
Keyword(s):  
Cyclic Loading ◽  
Mechanical Response ◽  
Constitutive Relations ◽  
Constitutive Models ◽  
Shear Loading ◽  
Biaxial Compression ◽  
Finite Element Program ◽  
Cyclic Shear ◽  
Hypoplastic Model ◽  
Element Program

The principal objective of this paper is to compare the mechanical response of a double shearing model with that of a hypoplastic model under biaxial compression and under cyclic shear loading. As the origins and nature of these two models are completely different, it is interesting to compare the predictions of these two models. The constitutive relations of the double shearing and the hypoplastic models are implemented in the finite element program ABACUS/Explicit. It is found that the hypoplastic and the double shearing constitutive models both show strong capability in capturing the essential behavior of granular materials. In particular, under the condition of non-cyclic loading, the stress ratio and void ratio predictions of the double shearing and the hypoplastic models are relatively close, while under the condition of cyclic loading, the predictions of these models are quite different. It is important to note that in the double shearing model employed in this comparison the shear rates on the two slip systems are assumed to be equal. Hence, the conclusions derived in this comparison pertain only to this particular double shearing model. Similarly, the hypoplasticity model considered here is that proposed by Wu, et al. [30] and the conclusions reached here pertain only to this particular hypoplasticity model.

Cyclic loading response of loose air-pluviated Fraser River sand for validation of numerical models simulating centrifuge tests

2005 ◽  
Vol 42 (2) ◽  
pp. 550-561 ◽  
Author(s):  
Dharma Wijewickreme ◽  
Somasundaram Sriskandakumar ◽  
Peter Byrne
Keyword(s):  
Cyclic Loading ◽  
Simple Shear ◽  
Mechanical Response ◽  
Shear Loading ◽  
Shear Stresses ◽  
Fraser River ◽  
River Sand ◽  
Cyclic Shear ◽  
Direct Simple Shear ◽  
Static Shear

Cyclic loading response of loose Fraser River sand was investigated, as input to numerical simulation of centrifuge physical models, using constant-volume direct simple shear tests conducted with and without initial static shear stress condition. Although the observed trends in mechanical response were similar, air-pluviated specimens were more susceptible to liquefaction under cyclic loading than their water-pluviated counterparts. Densification due to increasing confining stress (stress densification) significantly increased the cyclic resistance of loose air-pluviated sand, with strong implications for the interpretation of observations from centrifuge testing. The stress densification effect, however, was not prominent in the case of water-pluviated specimens. The differences arising from the two specimen reconstitution methods can be attributed to the differences in particle structure and highlight the importance of fabric effects in the assessment of the mechanical response of sands. The initial static shear stresses appear to reduce the cyclic shear resistance of loose air-pluviated sand in simple shear loading, in contrast to the increases in resistance reported on the basis of data from triaxial testing. Data from laboratory element tests that closely mimic the soil fabric and loading modes of the centrifuge specimens are essential for meaningful validation of numerical models.Key words: liquefaction of sands, air-pluviation, cyclic loading, direct simple shear testing, specimen preparation, fabric.

scholarly journals Simulation of Cyclic Loading on Pipe Elbows Using Advanced Plane-Stress Elastoplasticity Models1

2020 ◽  
Vol 143 (2) ◽  
Author(s):  
Konstantinos Chatziioannou ◽  
Yuner Huang ◽  
Spyros A. Karamanos
Keyword(s):  
Cyclic Loading ◽  
Large Scale ◽  
Mechanical Response ◽  
Low Cycle Fatigue ◽  
Constitutive Relations ◽  
Cyclic Plasticity ◽  
Integration Scheme ◽  
Repeated Loading ◽  
Finite Element Software ◽  
Hardening Models

Abstract This work investigates the response of industrial steel pipe elbows subjected to severe cyclic loading (e.g., seismic or shutdown/startup conditions), associated with the development of significant inelastic strain amplitudes of alternate sign, which may lead to low-cycle fatigue. To model this response, three cyclic-plasticity hardening models are employed for the numerical analysis of large-scale experiments on elbows reported elsewhere. The constitutive relations of the material model follow the context of von Mises cyclic elasto-plasticity, and the hardening models are implemented in a user subroutine, developed by the authors, which employs a robust numerical integration scheme, and is inserted in a general-purpose finite element software. The three hardening models are evaluated in terms of their ability to predict the strain range at critical locations, and in particular, strain accumulation over the load cycles, a phenomenon called “ratcheting.” The overall good comparison between numerical and experimental results demonstrates that the proposed numerical methodology can be used for simulating accurately the mechanical response of pipe elbows under severe inelastic repeated loading. Finally, this paper highlights some limitations of conventional hardening rules in simulating multi-axial material ratcheting.

Computational Modeling of Interaction Between Actions and Action Effects of FPSO Topside Structures Subject to Jet Fire

2010 ◽  
Author(s):  
G. M. Katsaounis ◽  
D. Katsourinis ◽  
M. S. Samuelides ◽  
M. Founti ◽  
Jeom Kee Paik ◽  
...  
Keyword(s):  
Computational Modeling ◽  
Constitutive Relations ◽  
Finite Element Program ◽  
Effect Analysis ◽  
Ansys Cfx ◽  
Commercial Code ◽  
Time Histories ◽  
Element Program ◽  
Computational Fluid Dynamics Cfd ◽  
Nonlinear Elastic

This paper presents a computational modeling of accidental fire actions on the topside structures of a floating, production, storage and offloading (FPSO) unit. According to the assumed scenario, the accident results in a jet fire, which loads the structure by temperature increments and pressures generation on their exposed surfaces. Temperature distributions were obtained by computational fluid dynamics (CFD) simulations, using the ANSYS CFX commercial code. The temperature versus time histories computed were first approximated (idealized) by smoother curves, based on fewer time-points, while retaining the maximum and minimum values. A similar procedure was also followed for the pressure variations. For the consequence (action effect) analysis the LSDYNA nonlinear finite element program was employed and the structures were modeled using shell finite elements with nonlinear (elastic-thermal plastic) constitutive relations. On the structure surfaces non coinciding grids were used for the two kinds of analyses (i.e., the CFD and FEM), in order to accommodate the diverse requirements of the different problems. The procedure of assignment the pressure and temperature loadings directly from the CFD results to the FEM model is described and representative results are given through the application of the methodology to a sample problem.

Numerical Simulations of Pressurized Elbow under Reversed In-Plane Bending

2013 ◽  
Vol 785-786 ◽  
pp. 16-19 ◽  
Author(s):  
Xiao Hui Chen ◽  
Xu Chen
Keyword(s):  
Numerical Simulation ◽  
Finite Element ◽  
Cyclic Loading ◽  
Numerical Simulations ◽  
Prediction Accuracy ◽  
Finite Element Program ◽  
User Subroutine ◽  
Element Program ◽  
Fortran Language ◽  
Plane Bending

The paper compares numerical simulation with experimental results of pressurized elbow piping subjected to reversed in-plane bending in elastoplastic domain. The modified AbdelKarim-Ohno model is implemented into finite element program ANSYS by writing own user subroutine in FORTRAN language. The modified AbdelKarim-Ohno model may improve the prediction accuracy of ratcheting behavior of pressurized elbow under cyclic loading.

Evaluation of the transitional inelastic behaviour of unsaturated clay–sand mixtures

2007 ◽  
Vol 44 (4) ◽  
pp. 436-446 ◽  
Author(s):  
James Blatz ◽  
David E.S Anderson ◽  
Greg Siemens
Keyword(s):  
Mechanical Response ◽  
Constitutive Models ◽  
Bentonite Clay ◽  
Shear Loading ◽  
Volume Strain ◽  
Barrier Materials ◽  
Triaxial Cell ◽  
Inelastic Behaviour ◽  
Unsaturated Clay ◽  
Strength And Stiffness

This paper examines and compares the mechanical behaviour of two different unsaturated clay mixtures comprised of bentonite clay (Saskatchewan or Wyoming) and quartz sand. The two mixtures have been proposed as compacted barrier materials for reducing groundwater flow in the vicinity of waste disposal repositories. Triaxial specimens were compacted to consistent properties, and then specified suction conditions were applied to the specimens using the vapour equilibrium technique. Following equilibrium at the specified initial suction, specimens were subjected to isotropic and shear loading in a conventional triaxial cell to measure the mechanical response under selected stress paths. The results are interpreted in terms of the yield, strength, and stiffness behaviour at the various suction levels. Results suggest that the clay component of the mixture dominates the behaviour at suctions less than approximately 30 MPa, and the sand component dominates the behaviour above approximately 30 MPa. The transition from clay- to sand-dominated behaviour is attributed to volume strain during application of the initial suction bringing the sand particles into contact. The discussion highlights how the results can be used to modify constitutive models to incorporate the transitional behaviour in numerical modeling.Key words: inelastic, yielding, unsaturated, stress–strain, triaxial testing.

Nonlinear Analysis of Steel Reinforced High Strength and High Performance Concrete Eccentric Columns

2010 ◽  
Vol 450 ◽  
pp. 223-226 ◽  
Author(s):  
Shan Suo Zheng ◽  
Wei Wang ◽  
Bin Wang ◽  
Lei Li ◽  
Yi Hu
Keyword(s):  
High Performance ◽  
High Performance Concrete ◽  
Numerical Models ◽  
Constitutive Models ◽  
High Strength ◽  
Failure Criteria ◽  
Experimental Results ◽  
Finite Element Program ◽  
Calculation Results ◽  
Element Program

According to experiment of four steel reinforced high strength and high performance concrete(SRHSHPC) columns with different eccentricity, this paper establishes four equally parameter numerical models by finite element program ANSYS. The failure mechanism, failure mode and mechanical behaviors of the SRHSHPC columns with large and small eccentricity can be revealed by comparing the numerical simulation results with the corresponding experimental results. And the approximate plane-section assumption in SRHSHPC eccentric columns is verified by the study of the relationship between load and strain. It is shown that when constitutive models and failure criteria of SRHSHPC and steel are in precise case, the calculation results agree well with the corresponding experimental results.

Modeling Alkali-Silica Reaction Using Image Analysis and Finite Element Analysis

2011 ◽  
Vol 250-253 ◽  
pp. 1050-1053
Author(s):  
Jun Ho Shin ◽  
Nam Yong Jee ◽  
Leslie J. Struble ◽  
R. James Kirkpatrick
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Mechanical Response ◽  
Standard Test ◽  
Alkali Silica Reaction ◽  
Element Analysis ◽  
Finite Element Program ◽  
The Finite Element Analysis ◽  
Element Program ◽  
Element Approach

The objective of this study is to develop a numerical model based on microstructural images of concrete and fundamental material properties of each constituent of concrete subjected to alkali-silica reaction (ASR). A microstructure-based finite element approach is employed directly to analyze the mechanical response of concrete to ASR. The modeling work involves acquiring and processing of microstructural images of specimens suffering from ASR using scanning electron microscopy, and implementing finite element program to analyze the microstructural images. The formulation of this model is based on pressure caused by the ASR product and on properties such as Young’s modulus and Poisson’s ratio. The finite element analysis program used to simulate structural behavior of structures attacked by ASR is object-oriented finite element developed at National Institute of Standards and Technology. The numerical results from this model are compared with experimental data, which have been measured using ASTM standard test C1260. The results show that the development and widening of cracks by formation and swelling of ASR gel cause the majority of expansion of mortar specimens rather than elastic elongation due to gel swelling.

scholarly journals Behavior of Mortarless Wall Subjected to In-Plane Combine Loading

2011 ◽  
Vol 264-265 ◽  
pp. 1746-1751 ◽  
Author(s):  
N.A. Safiee ◽  
M.S. Jaafar ◽  
Jamal Noorzaei
Keyword(s):  
Finite Element ◽  
Shear Loading ◽  
Combined Loading ◽  
Combine Loading ◽  
Interface Element ◽  
Structural Behaviour ◽  
Element Analysis ◽  
Finite Element Program ◽  
Plane Element ◽  
Element Program

The ability of mortarless wall to restrain/sustain lateral load become important aspect to be consider in the design of wall. Therefore, this paper presents analyses of mortarless wall subjected to in-plane combined loading using finite element programs. The developed 2D finite element program is used in this research. The finite element models are developed based on micro modelling approach where each constituent of masonry (block and dry joint) connected each other by joints at their actual position. Eight nodded isoparametric plane element and six nodded zero thickness isoparametric interface element are used to represent block unit and dry joint respectively. The developed models are analysed under nonlinear environment. The most relevant results concern the strength response of the dry joint masonry walls subjected to in-plane combined compressive and shear loading. The results of finite element analysis compared with corresponding experimental results and its show good agreement. Parametric study also performed to consider the important parameters that effect the design of wall under combined loading. Significant features of the structural behaviour, ultimate capacity and observed failure mechanisms are addressed and discussed.

Behaviour of Marine Clay Under Wave Type of Cyclic Loading

2003 ◽  
Author(s):  
S. Narasimha Rao ◽  
G. Gerald Moses
Keyword(s):  
Cyclic Loading ◽  
Deformation Behaviour ◽  
Cyclic Stress ◽  
Shear Loading ◽  
Load Level ◽  
Marine Clay ◽  
Cyclic Shear ◽  
Coastal Marine ◽  
Storm Wave ◽  
Stress Ratios

This paper presents the results of two series of cyclic triaxial shear tests carried out under both uniform and Varied cyclic shear loading and these bring out the influence of load cycles on strain and undrained strength of a cemented marine clay from East coast of India. The undrained shear strength and deformation behaviour of Indian coastal marine clay have been established through a detailed shear testing carried out. In order to estimate the effect brought in by varied cyclic loading, it becomes necessary to conduct reference standard tests under uniform cyclic loading at various cyclic stress ratios (CSR) on identical soil specimens and these stress levels are chosen in such a way that there is no failure taking place during testing. In field situations, storm wave loading is considered to be irregular cyclic loading in which there is a continuous variation in the load level from one cycle to the other. The results obtained from tests under uniform cyclic loading are compared with the results obtained from tests under varied cyclic loading.

An Experimental and Modeling Study of Thermal Cyclic Behavior of Sn-Cu and Sn-Pb Solder Joints

1993 ◽  
Vol 323 ◽  
Author(s):  
Y.-H. Pao ◽  
S. Badgley ◽  
R. Govila ◽  
E. Jah
Keyword(s):  
Solder Joints ◽  
Cyclic Behavior ◽  
Temperature Cycle ◽  
Beam Specimen ◽  
Finite Element Program ◽  
Creep Properties ◽  
Cyclic Shear ◽  
Double Beam ◽  
Element Program ◽  
Hysteresis Response

AbstractThermal cyclic shear stress/strain hysteresis response of 97Sn-2Cu-0.8Sb-0.2Ag, 95.5Sn-4Cu-0.5Ag, 63Sn-37Pb, and 62Sn-36Pb-2Ag solder joints have been determined using a double beam specimen. The temperature cycle had a period of 40 minutes and extreme temperatures of 40°C and 140°C.The steady state creep properties of these solders were determined, and the associated Norton's law was implemented in a finite element program to simulate the experiment. The fatigue life of these solders joints and failure mechanism are also discussed.

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