scholarly journals A comparative study of the dynamic fragmentation of non-linear elastic and elasto-plastic rings: the roles of stored elastic energy and plastic dissipation

2020 ◽  
Author(s):  
Jose Rodriguez-Martinez ◽  
Alvaro Vaz-Romero ◽  
Sebastien Mercier ◽  
Alain Molinari
Keyword(s):  
Elastic Energy ◽  
Plastic Material ◽  
Deformation Energy ◽  
Stress Waves ◽  
Uniaxial Tensile ◽  
Linear Elastic ◽  
Commercial Code ◽  
Plastic Dissipation ◽  
Fragmentation Processes ◽  
Elastic Unloading

We develop a comparative analysis of the processes of dynamic necking and fragmentation in elasto-plastic and hyperelastic ductile rings subjected to rapid radial expansion. For that purpose, ?nite element simulationshave been carried out using the commercial code ABAQUS/Explicit. Expanding velocities which range between25 m=s and 600 m=s have been investigated. The elasto-plastic material and the hyperelastic material are modelled with constitutive equations which provide nearly the same stress-strain response during monotonic uniaxial tensile loading, and fracture is assumed to occur at the same level of deformation energy. The computations have revealed that, while the number of necks nucleated in the elasto-plastic and hyperelastic rings is similar, the mechanisms which control their development are significantly different. In the elasto-plastic rings several necks are arrested due to the stress waves which travel the specimen after the localization process has started, and thus the number of fractures in the ring is significantly lower than the number of incepted necks. On the contrary, these stress waves do not stop the development of any neck in the hyperelastic rings. The elastic energy released from the sections of the ring which are unloading during the localization processfuels the development of the necks. Hence, for the whole range of investigated velocities, the proportion of necks that develop into fracture sites is much greater for the hyperelastic rings than for the elasto-plastic ones. The comparison between the numerical results obtained for both materials brings to light the roles of elastic unloading and plastic dissipation in multiple necking and fragmentation processes.

scholarly journals NUMERICAL MODELLING OF THE SOIL BEHAVIOUR BY USING NEWLY DEVELOPED ADVANCED MATERIAL MODEL

2017 ◽  
Vol 57 (1) ◽  
pp. 58-70 ◽  
Author(s):  
Jan Veselý
Keyword(s):  
Numerical Modelling ◽  
Plastic Material ◽  
Material Model ◽  
Small Strain ◽  
Theoretical Background ◽  
Linear Elastic ◽  
In Situ Data ◽  
Modified Cam Clay ◽  
Soil Behaviour

This paper describes a theoretical background, implementation and validation of the newly developed Jardine plastic hardening-softening model (JPHS model), which can be used for numerical modelling of the soils behaviour. Although the JPHS model is based on the elasto-plastic theory, like the Mohr-Coulomb model that is widely used in geotechnics, it contains some improvements, which removes the main disadvantages of the MC model. The presented model is coupled with an isotopically hardening and softening law, non-linear elastic stress-strain law, non-associated elasto-plastic material description and a cap yield surface. The validation of the model is done by comparing the numerical results with real measured data from the laboratory tests and by testing of the model on the real project of the tunnel excavation. The 3D numerical analysis is performed and the comparison between the JPHS, Mohr-Coulomb, Modified Cam-Clay, Hardening small strain model and monitoring in-situ data is done.

Factor of safety of slope stability from deformation energy

2018 ◽  
Vol 55 (2) ◽  
pp. 296-302 ◽  
Author(s):  
Shiguo Xiao ◽  
Wei Dong Guo ◽  
Jinxiu Zeng
Keyword(s):  
Shear Strength ◽  
Factor Of Safety ◽  
Plastic Material ◽  
Limit Equilibrium ◽  
Deformation Energy ◽  
Simple Expression ◽  
Shear Stresses ◽  
Limit Equilibrium Methods ◽  
Coulomb Failure Criterion ◽  
Elastic Plastic Material

The factor of safety of a slope (Fs) is invariably assessed using methods underpinned by moment, force, and (or) shear strength equilibrium concerning slip surfaces. Each method inherently embeds some form of limitations, despite being popularly adopted in practice. In this paper, a new Fs is devised using the ratio of ultimate energy (eu, upon sliding) over accumulated “elastic” energy. The Fs is then reduced to a simple expression of the power to shear stress and shear strength, by taking soil as an elastic–plastic material obeying the Mohr–Coulomb failure criterion. This expression empowers significant efficacy in gaining the factor of safety (without involving energy or directions of shear stresses). The Fs values were calculated for three typical slopes concerning various mechanical properties (dilation, Poisson’s ratio, and shear modulus) and effective computational strategies. All of the Fs values (to a congruous accuracy of available methods) were obtained in less than 1% the time of conventional numerical analyses. The proposed Fs, equally applicable to limit equilibrium methods, may be utilized in practice to expedite slope design.

scholarly journals Linear Vibration Analysis of Shells Using a Seven-Parameter Spectral/hp Finite Element Model

2020 ◽  
Vol 10 (15) ◽  
pp. 5102
Author(s):  
Carlos Valencia Murillo ◽  
Miguel Gutierrez Rivera ◽  
Junuthula N. Reddy
Keyword(s):  
Finite Element ◽  
Finite Element Model ◽  
Variable Thickness ◽  
Equations Of Motion ◽  
Shear Deformation Theory ◽  
Element Model ◽  
Linear Elastic ◽  
Commercial Code ◽  
The Finite Element Model ◽  
Hp Finite Element

In this paper, a seven-parameter spectral/hp finite element model to obtain natural frequencies in shell type structures is presented. This model accounts for constant and variable thickness of shell structures. The finite element model is based on a Higher-order Shear Deformation Theory, and the equations of motion are obtained by means of Hamilton’s principle. Analysis is performed for isotropic linear elastic shells. A validation of the formulation is made by comparing the present results with those reported in the literature and with simulations in the commercial code ANSYS. Finally, results for shell like structures with variable thickness are presented, and their behavior for different ratios r/h and L/r is studied.

scholarly journals Anisotropic mechanical behaviour of calendered nonwoven fabrics: Strain-rate dependency

2020 ◽  
pp. 002199832097679
Author(s):  
V Cucumazzo ◽  
E Demirci ◽  
B Pourdeyhimi ◽  
VV Silberschmidt
Keyword(s):  
Strain Rate ◽  
Mechanical Behaviour ◽  
Mechanical Response ◽  
Tensile Tests ◽  
Elastic Response ◽  
Uniaxial Tensile ◽  
Rate Dependency ◽  
Fibrous Matrix ◽  
Nonwoven Fabrics ◽  
Linear Elastic

Calendered nonwovens, formed by polymeric fibres, are three-phase heterogeneous materials, comprising a fibrous matrix, bond-areas and interface regions. As a result, two main factors of anisotropy can be identified. The first one is ascribable to a random fibrous microstructure, with the second one related to orientation of a bond pattern. This paper focuses on the first type of anisotropy in thin and thick nonwovens under uniaxial tensile loading. Individual and combined effects of anisotropy and strain rate were studied by conducting uniaxial tensile tests in various loading directions (0°, 30°, 45°, 60° and 90° with regard to the main fabric’s direction) and strain rate (0.01, 0.1 and 0.5 s−1). Fabrics exhibited an initial linear elastic response, followed by nonlinear strain hardening up to necking and final softening. The studied allowed assessment of the extent the effects of loading direction (anisotropy), planar density and strain rate on the mechanical response of the calendered fabrics. The evidence supported the conclusion that anisotropy is the most crucial factor, also delineating the balance between the fabric’s load-bearing capacity and extension level along various directions. The strain rate produced a marked effect on the fibre’s response, with increased stress at higher strain rate while this effect in the fabric was small. The results demonstrated the differences of the mechanical behaviour of fabrics from that of their constituent fibres.

The Test of Aircraft Material with Performance Parameters

2014 ◽  
Vol 540 ◽  
pp. 48-51
Author(s):  
Xia Ren ◽  
Lian Xiang Ma
Keyword(s):  
Large Scale ◽  
Plastic Material ◽  
Uniaxial Tensile ◽  
Uniaxial Tensile Test ◽  
Performance Parameters ◽  
Analysis Software ◽  
Element Analysis ◽  
Aircraft Material ◽  
Yeoh Model ◽  
Experimental Data Analysis

This paper uses the ABAQUS finite element analysis software for modeling and nonlinear analysis of aircraft tires. Paper H44.5 × 16.5-21 aviation tires, The plastic material of the tire subjected to uniaxial stretching to obtain a rubber such as Young's modulus, Poisson's ratio of the material parameters. Uniaxial tensile test tests the tensile properties of the rubber, the use of large-scale numerical calculations and fitting analysis of the experimental data analysis software Matlab, Yeoh model mechanical parameters.

Modeling of Low Energy, Low Velocity Impact Failure of a Honeycomb Sandwich Material

2014 ◽  
Vol 566 ◽  
pp. 256-261
Author(s):  
M.C. Miron ◽  
Zoltan Major ◽  
Tadaharu Adachi
Keyword(s):  
Brittle Failure ◽  
Plastic Material ◽  
Transverse Isotropy ◽  
Low Velocity Impact ◽  
Honeycomb Core ◽  
Low Velocity ◽  
Material Models ◽  
Linear Elastic ◽  
Honeycomb Sandwich ◽  
Core Components

The current work is aimed at development of a numerical model able to describe complex damage phenomena that occur during an impact event in a sandwich structure having a honeycomb core. The complex material models employed within the research include linear-elastic and elasto-plastic material models having transverse isotropy as well as damage evolution models for both brittle failure and plastic failure. Within this paper remarks concerning the failure of the skins and core components as well as dissipated impact energy and affected regions are done.

Mechanical properties of Precontraint 1202 S2 based on uniaxial tensile and creep tests

2016 ◽  
Vol 36 (4) ◽  
pp. 254-270 ◽  
Author(s):  
Andrzej Ambroziak ◽  
Paweł Kłosowski
Keyword(s):  
Mechanical Properties ◽  
Polyvinyl Chloride ◽  
Viscoelastic Model ◽  
Tensile Tests ◽  
Woven Fabric ◽  
Uniaxial Tensile ◽  
Creep Tests ◽  
Linear Elastic ◽  
Coated Fabric ◽  
Long Time

The purpose of the paper is the estimation of the polyvinyl chloride – polyester-coated fabric (Precontraint 1202 S2) mechanical properties under uniaxial tensile tests as well as short- and long-time creep tests. The uniaxial tests are the basis of non-linear elastic description while the creep tests are used for the evaluation of the stiffness parameters in time and for the identification of the standard viscoelastic model. The paper also includes a short survey of literature concerning the coated woven fabric description.

scholarly journals Research of crack initiation in tension test specimen made of nickel alloy EI961sh

2018 ◽  
Vol 165 ◽  
pp. 22027
Author(s):  
Kamaliddin Karimbaev ◽  
Ivan Pleshcheev ◽  
Elena Bredihina
Keyword(s):  
Cross Sections ◽  
Test Specimen ◽  
Plastic Material ◽  
Tensile Tests ◽  
Deformation Energy ◽  
Experimental Fact ◽  
Conservation Of Energy ◽  
Software Complex ◽  
The Moment ◽  
Cylindrical Test

In this paper method of numerical computations using explicit scheme, implemented in LSDyna (Ansys) software complex, is introduced and verified. Obtained solution explains experimental fact mentioned by P. Ludwik, that cracking in cylindrical test specimen made of plastic material starts in the middle of the smallest cross-section of the specimen. Introduced method allows verifying law, obtained by N.N. Davidenkov during unique experimental research in which he studied logarithmic strain in specimen’s neck by pickling of cross-sections in this zone. Additionally it is possible to estimate amount of heat, generated during rupture of specimen, using obtained solution and law of conservation of energy. For this purpose tensile tests, in which thermal camera was used for temperature measuring, were conducted. It was shown, that all deformation energy apart from elastic and shape-forming energy in volume element, calculated in the moment before rupture is transformed to heat. Also tensile tests with various rate of loading were conducted for more detailed research of rupture process.

Hyperelastic and Elastic-Plastic Approaches for Modelling Uniaxial Tensile Performance of Woven Fabrics

2010 ◽  
Vol 7 (2) ◽  
pp. 31
Author(s):  
Mohamad Faizul Yahya ◽  
Chen Xiaogang
Keyword(s):  
Tensile Stress ◽  
Plastic Material ◽  
Systematic Investigation ◽  
Woven Fabrics ◽  
Woven Fabric ◽  
Uniaxial Tensile ◽  
Elastic Plastic ◽  
Uniaxial Tensile Testing ◽  
Uniaxial Tensile Stress ◽  
Elastic Plastic Material

This article presents thefindings ofexperimental andfinite element simulation warp direction uniaxial tensile testing ofplain 1/1, 2/2 twill and 8 ends satin woven fabrics with respect to a wovenfabric model developed in IGES using UniverFilter. Woven fabrics have been specifically configured as a balanced weave thereby allowing systematic investigation of the effect of uniaxial tensile stress on the weave. Static automatic incrementation of large representative volume elements has enabled characterisation ofthe response oftwo-dimensional woven fabrics under uniaxial tensile stress with respect to hyperelastic and elastic-plastic material properties. Plain 1/1 and 8 ends satin woven fabrics were well-described by the hyperelastic model and the elastic-plastic model predicted extended strain percentages. The modelling indicates that satin woven fabric possesses the lowest strain distribution and compression stress in the unloaded weft direction compared to plain and twill woven fabrics.

Sign in / Sign up

Export Citation Format

Share Document