scholarly journals Computational Micro-Macro Analysis of Impact on Strain-Hardening Cementitious Composites (SHCC) Including Microscopic Inertia

Materials ◽  
2020 ◽  
Vol 13 (21) ◽  
pp. 4934
Author(s):  
Erik Tamsen ◽  
Iurie Curosu ◽  
Viktor Mechtcherine ◽  
Daniel Balzani
Keyword(s):  
Impact Loading ◽  
Fiber Reinforced Concrete ◽  
Material Behavior ◽  
Matrix Cracking ◽  
Fiber Pullout ◽  
Material Models ◽  
Inertia Effects ◽  
Dynamic Framework ◽  
Rate Dependent ◽  
Structural Inertia

This paper presents a numerical two-scale framework for the simulation of fiber reinforced concrete under impact loading. The numerical homogenization framework considers the full balance of linear momentum at the microscale. This allows for the study of microscopic inertia effects affecting the macroscale. After describing the ideas of the dynamic framework and the material models applied at the microscale, the experimental behavior of the fiber and the fiber–matrix bond under varying loading rates are discussed. To capture the most important features, a simplified matrix cracking and a strain rate sensitive fiber pullout model are utilized at the microscale. A split Hopkinson tension bar test is used as an example to present the capabilities of the framework to analyze different sources of dynamic behavior measured at the macroscale. The induced loading wave is studied and the influence of structural inertia on the measured signals within the simulation are verified. Further parameter studies allow the analysis of the macroscopic response resulting from the rate dependent fiber pullout as well as the direct study of the microscale inertia. Even though the material models and the microscale discretization used within this study are simplified, the value of the numerical two-scale framework to study material behavior under impact loading is demonstrated.

scholarly journals Computational Micro-Macro Analysis of Impact on Strain-Hardening Cementitious Composites (SHCC) Including Microscopic Inertia

2020 ◽  
Author(s):  
Erik Tamsen ◽  
Iurie Curosu ◽  
Viktor Mechtcherine ◽  
Daniel Balzani
Keyword(s):  
Impact Loading ◽  
Fiber Reinforced Concrete ◽  
Material Behavior ◽  
Matrix Cracking ◽  
Fiber Pullout ◽  
Material Models ◽  
Inertia Effects ◽  
Dynamic Framework ◽  
Rate Dependent ◽  
Structural Inertia

This paper presents a numerical two-scale framework for the simulation of fiber reinforced concrete under impact loading. The numerical homogenization framework considers the full balance of linear momentum at the microscale. This allows for the study of microscopic inertia effects affecting the macroscale. After describing the ideas of the dynamic framework and the material models applied at the microscale, the experimental behavior of the fiber and the fiber-matrix bond under varying loading rates are discussed. To capture the most important features, a simplified matrix cracking and a strain rate sensitive fiber pullout model are utilized at the microscale. A split Hopkinson bar tension test is used as an example to present the capabilities of the framework to analyze different sources of dynamic behavior measured at the macroscale. The induced loading wave is studied and the influence of structural inertia on the measured signals within the simulation are verified. Further parameter studies allow the analysis of the macroscopic response resulting from the rate dependent fiber pullout as well as the direct study of the microscale inertia. Even though the material models and the microscale discretization used within this study are still simplified, the value of the numerical two-scale framework to study material behavior under impact loading is shown.

scholarly journals An Investigation of The Behavior of Strain-Hardening Cement-Based Composites (SHCC) Obtained in a Split Hopkinson Tension Bar and the Influence of Structural Inertia

2020 ◽  
Author(s):  
Ali A. Heravi ◽  
Joško Ožbolt ◽  
Viktor Mechtcherine
Keyword(s):  
Impact Loading ◽  
High Speed ◽  
Image Correlation ◽  
Analytical Models ◽  
Rate Dependent ◽  
Dependent Behavior ◽  
Structural Inertia ◽  
Split Hopkinson ◽  
Fiber Matrix ◽  
Split Hopkinson Tension Bar

The performance of a normal-strength SHCC under impact loading was studied using the results obtained from a split Hopkinson tension bar (SHTB). The focus of the investigation is to explain the mechanisms behind the peculiar rate-dependent behavior of SHCC under tensile loading. With the help of frames obtained by high-speed cameras and the subsequent Digital Image Correlation (DIC) analysis, the stress-strain relation of the SHCC obtained in SHTB was analyzed. The investigation of the composite’s behavior was supported by constituent-level experiments on the non-reinforced matrix of the SHCC and on the fiber-matrix bond. In the case of the constituent matrix, the well-known apparent increase in the tensile strength of the cement-based matrix and its influence on the behavior of SHCC was studied. For this purpose, experiments on the SHCC specimens with different geometries were performed in the SHTB. The results obtained from these experiments and those obtained by DIC show that commonly used analytical models, in which the specimen is assumed elastic, cannot capture the effects of structural inertia on the results. Thus, an alternative novel method based on the results of DIC has been used to explain and quantify the contribution of structural inertia. The rate-dependent behavior of the fiber-matrix bond was studied by performing high-speed single fiber pullout tests in a miniaturized split Hopkinson tension bar. This novel experimental technique enabled explanation of the rate-dependent bridging action of the fibers in SHCC. Based on the results, the enhanced behavior of SHCC under impact loading is explained.

scholarly journals Improving the Interpretability of Physics-Based Bias in Material Models

2020 ◽  
Author(s):  
Evan Chodora ◽  
Garrison Flynn ◽  
Trevor Tippetts ◽  
Cetin Unal
Keyword(s):  
Prediction Accuracy ◽  
Systematic Approach ◽  
Experimental Testing ◽  
Material Behavior ◽  
304L Stainless Steel ◽  
Model Bias ◽  
Material Models ◽  
Rate Dependent ◽  
Dynamic Loading Conditions ◽  
Parameter Values

Abstract In order to accurately predict the performance of materials under dynamic loading conditions, models have been developed that describe the rate-dependent material behavior and irrecoverable plastic deformation that occurs at elevated strains and applied loads. Most of these models have roots in empirical fits to data and, thus, require the addition of specific parameters that reflect the properties and response of specific materials. In this work, we present a systematic approach to the problem of calibrating a Johnson-Cook plasticity model for 304L stainless steel using experimental testing in which the parameters are treated as dependent on the state of the material and uncovered using experimental data. The results obtained indicate that the proposed approach can make the presence of a discrepancy term in calibration unnecessary and, at the same time, improve the prediction accuracy of the model into new input domains and provide improved understanding of model bias compared to calibration with stationary parameter values.

Local and nonlocal material models, spatial randomness, and impact loading

2015 ◽  
Vol 86 (1-2) ◽  
pp. 39-58 ◽  
Author(s):  
P. N. Demmie ◽  
M. Ostoja-Starzewski
Keyword(s):  
Impact Loading ◽  
Material Models ◽  
Spatial Randomness

scholarly journals Finite Element Software for Rubber Products Design

2018 ◽  
Vol 3 (1) ◽  
pp. 13-20
Author(s):  
Dávid Huri
Keyword(s):  
Finite Element ◽  
Complex Analysis ◽  
Large Deformations ◽  
Material Behavior ◽  
Nonlinear Material ◽  
Material Models ◽  
Finite Element Software ◽  
Highly Nonlinear ◽  
Wide Range ◽  
Different Types

Automotive rubber products are subjected to large deformations during working conditions, they often contact with other parts and they show highly nonlinear material behavior. Using finite element software for complex analysis of rubber parts can be a good way, although it has to contain special modules. Different types of rubber materials require the curve fitting possibility and the wide range choice of the material models. It is also important to be able to describe the viscoelastic property and the hysteresis. The remeshing possibility can be a useful tool for large deformation and the working circumstances require the contact and self contact ability as well. This article compares some types of the finite element software available on the market based on the above mentioned features.

scholarly journals Experimental and Numerical Characterization of the Cyclic Thermomechanical Behavior of a High Temperature Forming Tool Alloy

2010 ◽  
Vol 132 (5) ◽  
Author(s):  
Sean B. Leen ◽  
Aditya Deshpande ◽  
Thomas H. Hyde
Keyword(s):  
High Temperature ◽  
Life Prediction ◽  
Material Constant ◽  
Superplastic Forming ◽  
Material Model ◽  
Fatigue Tests ◽  
Material Behavior ◽  
Future Application ◽  
Rate Dependent ◽  
Numerical Characterization

This paper describes high temperature cyclic and creep relaxation testing and modeling of a high nickel-chromium material (XN40F) for application to the life prediction of superplastic forming (SPF) tools. An experimental test program to characterize the high temperature cyclic elastic-plastic-creep behavior of the material over a range of temperatures between 20°C and 900°C is described. The objective of the material testing is the development of a high temperature material model for cyclic analyses and life prediction of SPF dies for SPF of titanium aerospace components. A two-layer viscoplasticity model, which combines both creep and combined isotropic-kinematic plasticity, is chosen to represent the material behavior. The process of material constant identification for this model is presented, and the predicted results are compared with the rate-dependent (isothermal) experimental results. The temperature-dependent material model is furthermore applied to simulative thermomechanical fatigue tests, designed to represent the temperature and stress-strain cycling associated with the most damaging phase of the die cycle. The model is shown to give good correlation with the test data, thus vindicating future application of the material model in thermomechanical analyses of SPF dies for distortion and life prediction.

A Microstructure-Level Material Model for Simulating the Machining of Carbon Nanotube Reinforced Polymer Composites

2008 ◽  
Vol 130 (3) ◽  
Author(s):  
Ashutosh Dikshit ◽  
Johnson Samuel ◽  
Richard E. DeVor ◽  
Shiv G. Kapoor
Keyword(s):  
Carbon Nanotube ◽  
Weight Fraction ◽  
Material Model ◽  
Material Behavior ◽  
Compression Tests ◽  
Linear Elastic ◽  
Rate Dependent ◽  
Wide Range ◽  
Parametrization Scheme ◽  
Fraction Length

A continuum-based microstructure-level material model for simulation of polycarbonate carbon nanotube (CNT) composite machining has been developed wherein polycarbonate and CNT phases are modeled separately. A parametrization scheme is developed to characterize the microstructure of composites having different loadings of carbon nanotubes. The Mulliken and Boyce constitutive model [2006, “Mechanics of the Rate Dependent Elastic Plastic Deformation of Glassy Polymers from Low to High Strair Rates,” Int. J. Solids Struct., 43(5), pp. 1331–1356] for polycarbonate has been modified and implemented to capture thermal effects. The CNT phase is modeled as a linear elastic material. Dynamic mechanical analyzer tests are conducted on the polycarbonate phase to capture the changes in material behavior with temperature and strain rate. Compression tests are performed over a wide range of strain rates for model validation. The model predictions for yield stress are seen to be within 10% of the experimental results for all the materials tested. The model is used to study the effect of weight fraction, length, and orientation of CNTs on the mechanical behavior of the composites.

Input Data Determination for Large Strain Simulations

2015 ◽  
Vol 751 ◽  
pp. 124-130
Author(s):  
Jan Džugan ◽  
Martina Maresova ◽  
Jan Nachazel
Keyword(s):  
Numerical Simulations ◽  
Input Data ◽  
Large Strain ◽  
Fem Simulation ◽  
Material Behavior ◽  
Production Costs ◽  
Image Correlation ◽  
Compression Tests ◽  
Material Models ◽  
Strain Measurements

Numerical simulations are widely used for forming processes optimizations nowadays. They significantly contribute to improvement of forgings quality and production costs reduction. The crucial points of the numerical simulations are material input data and implemented material models. The paper is dealing with overview of methods for the input data measurement. There are discussed tests with various options of strain measurements as well as modifications of compression tests. Part of the paper is dealing with 3D strain measurements by Digital Image Correlation (DIC) enabling local strains measurements. DIC enables direct comparison of strains experimentally measured and strains obtained by numerical simulations, which is going to be presented. Finally, possibilities of complex material description considering plastic damage are presented. The last approach is the most accurate providing the most information on material behavior for FEM simulation, the procedure includes measurements on samples of various geometries with various stress strain conditions. Examples of sample sets for these measurements are shown here together with material models describing multiaxial plastic flow and damage.

Methods of Evaluating the Performance of Fiber-Reinforced Concrete

1990 ◽  
Vol 211 ◽  
Author(s):  
Colin D. Johnston
Keyword(s):  
Reinforced Concrete ◽  
Fiber Reinforced Concrete ◽  
Material Behavior ◽  
Fiber Reinforced ◽  
Thermal Change ◽  
Advantages And Disadvantages ◽  
Concrete Quality ◽  
Predetermined Level ◽  
Loading Tests ◽  
Crack Widths

AbstractThree of the most important properties of fiber-reinforced concrete (FRC) are strength, toughness and resistance to cracking. The various methods of evaluating them are compared in terms of underlying rationale, ability to characterize composite material behavior in a readily understandable manner minimally affected by testing variables, and suitability for routine use in specifying and controlling concrete quality. The scope includes dynamic loading tests, slow-rate (static) loading tests, and tests to evaluate cracking induced directly by load or indirectly by restraint during shrinkage or thermal change.Consideration of the advantages and disadvantages of the various alternatives shows that slow flexure testing in accordance with the rationale developed by the writer and incorporated into ASTM standard C1018 effectively characterizes the FRC in terms of first-crack strength, toughness, and residual strength after first crack up to any predetermined level of serviceability expressed in terms of maximum permissible deflection. Although not part of the standard, resistance to cracking under load may also be assessed by measuring crack widths at appropriate deflections.

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