Scaled Memory Description of Hysteretic Material Behavior

1996 ◽  
Vol 63 (3) ◽  
pp. 750-757 ◽  
Author(s):  
J. P. Bardet
Keyword(s):  
Piecewise Linear ◽  
Material Constant ◽  
Material Behavior ◽  
Linear Distribution ◽  
Nonlinear Variation ◽  
Surface Plasticity ◽  
Material Behaviors ◽  
Pressure Independent ◽  
Single Material ◽  
Tangential Modulus

Herein the concept of scaled memory (SM) is proposed to describe hysteretic material behaviors. SM scales the nonlinear variation of tangential modulus during monotonic loadings into a piecewise linear distribution, which can easily be modified to simulate specific characteristics of material behavior during cyclic loadings. As an example, SM is applied to eliminate artificial ratchetting in bounding surface plasticity, and to produce closed stress-strain loops during cyclic loadings, without introducing a single material constant. SM is generalized to six dimensions in the particular case of pressure-independent materials, and is applied to simulate the hysteretic responses of metals.

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.

Anisotropic and Inhomogeneous Tensile Behavior of the Human Anulus Fibrosus: Experimental Measurement and Material Model Predictions

2000 ◽  
Vol 123 (3) ◽  
pp. 256-263 ◽  
Author(s):  
Dawn M. Elliott ◽  
Lori A. Setton
Keyword(s):  
Tensile Modulus ◽  
Material Model ◽  
Material Behavior ◽  
Anulus Fibrosus ◽  
Linear Region ◽  
Material Behaviors ◽  
Model Predictions ◽  
Complete Set ◽  
Poisson's Ratios ◽  
Poisson’S Ratios

The anulus fibrosus (AF) of the intervertebral disc exhibits spatial variations in structure and composition that give rise to both anisotropy and inhomogeneity in its material behaviors in tension. In this study, the tensile moduli and Poisson’s ratios were measured in samples of human AF along circumferential, axial, and radial directions at inner and outer sites. There was evidence of significant inhomogeneity in the linear-region circumferential tensile modulus (17.4±14.3 MPa versus 5.6±4.7 MPa, outer versus inner sites) and the Poisson’s ratio ν21 (0.67±0.22 versus 1.6±0.7, outer versus inner), but not in the axial modulus (0.8±0.9 MPa) or the Poisson’s ratios ν12 (1.8±1.4) or ν13 (0.6±0.7). These properties were implemented in a linear anisotropic material model of the AF to determine a complete set of model properties and to predict material behaviors for the AF under idealized kinematic states. These predictions demonstrate that interactions between fiber populations in the multilamellae AF significantly contribute to the material behavior, suggesting that a model for the AF as concentric and physically isolated lamellae may not be appropriate.

scholarly journals A hybrid bin scheme to solve the condensation/evaporation equation using a cubic distribution function

2012 ◽  
Vol 12 (2) ◽  
pp. 1003-1011 ◽  
Author(s):  
T. Dinh ◽  
D. R. Durran
Keyword(s):  
Distribution Function ◽  
Efficient Method ◽  
Piecewise Linear ◽  
Computationally Efficient ◽  
Linear Distribution ◽  
Number Distribution ◽  
Cubic Polynomial

Abstract. A computationally efficient method is proposed to replace the piecewise linear number distribution in a hybrid bin scheme with a piecewise cubic polynomial. When the linear distribution is replaced by a cubic, the errors generated in solutions to the condensation/evaporation equation are reduced by a factor of two to three. Alternatively, using the cubic distribution function allows reducing the number of bins by 20 ± 5% when solving the condensation/evaporation problem without sacrificing accuracy.

scholarly journals INVERSION OF ELECTROMAGNETIC LOGGING DATA IN A CLASS OF MODELS WITH A SMOOTH RESISTIVITY DISTRIBUTION

2021 ◽  
Vol 2 (2) ◽  
pp. 196-200
Author(s):  
Vladislav A. Okunev ◽  
Andrey Yu. Sobolev
Keyword(s):  
Electrical Resistivity ◽  
Piecewise Linear ◽  
Linear Distribution ◽  
Geoelectric Model ◽  
Data Inversion

The article presents an alternative geoelectric model of the near-borehole space for electromagnetic logging data inversion in the class of models with a smooth and piecewise linear distribution of the electrical resistivity. We used ready-made ATLAS MPhM calculation modules, a library for python developed at the IPGG SB RAS.

scholarly journals Finite Cell Method for functionally graded materials based onV-models and homogenized microstructures

2020 ◽  
Author(s):  
Benjamin Wassermann ◽  
Nina Korshunova ◽  
Stefan Kollmannsberger ◽  
Ernst Rank ◽  
Gershon Elber
Keyword(s):  
Functionally Graded Materials ◽  
Large Scale ◽  
Functionally Graded ◽  
Material Behavior ◽  
Geometric Framework ◽  
Graded Materials ◽  
Cell Method ◽  
Complex Shapes ◽  
Large Scale Simulations ◽  
Single Material

Abstract This paper proposes an extension of the nite cell method (FCM) to V-rep models, a novel geometric framework for volumetric representations. This combination of an embedded domain approach (FCM) and a new modelingframework (V-rep) forms the basis for an efficient and accurate simulation of mechanical artifacts, which are not only characterized by complex shapes but also by their non-standard interior structure. These types of objects gain more and more interest in the context of the new design opportunities opened by additive manufacturing, in particular when graded or micro-structured material is applied. Two different types of functionally graded materials (FGM) are considered: The rst one, multi-material FGM is described using the inherent property of V-rep models to assign different properties throughout the interior of a domain. The second, single-material FGM { which is heterogeneously micro-structured { characterizes the effective material behavior of representative volume elements by homogenization and performs large-scale simulations using the embedded domain approach.

Innovative Mechanical Fastening Systems for New Materials: Today’s Situation and Future Perspectives

2005 ◽  
Author(s):  
C. Friedrich ◽  
U. Hoffmann ◽  
T. Bohlender
Keyword(s):  
High Performance ◽  
Operating Conditions ◽  
Material Behavior ◽  
Light Metals ◽  
Automotive Sector ◽  
Future Perspectives ◽  
New Materials ◽  
Component Systems ◽  
Mechanical Fastening ◽  
Single Material

The need for the best material behavior at any location within high performance component systems leads to diversified material combinations. One example is the material mixture in today’s vehicles: steel, aluminum, magnesium, plastics, fibers, glass and other solids. These combinations need new or modified fastening technologies, because traditional techniques like welding or bolting up to now are mainly focused on single material joints. Besides this, the loading level during operation of the components increases continuously, so the behavior of the involved fastening systems under operating conditions also has to be known. Fastening systems with light metals show a significant thermal induced change of clamping/preload. This paper gives an overview with some optimized exemplary fastening systems from the automotive sector which could be partly transferred to other industry branches. The paper also emphasizes that various details of designing fastening systems are decisive for reliability and stability.

scholarly journals A hybrid bin scheme to solve the condensation/evaporation equation using a cubic distribution function

2011 ◽  
Vol 11 (8) ◽  
pp. 21631-21654
Author(s):  
T. Dinh ◽  
D. R. Durran
Keyword(s):  
Distribution Function ◽  
Efficient Method ◽  
Piecewise Linear ◽  
Computationally Efficient ◽  
Linear Distribution ◽  
Number Distribution ◽  
Cubic Polynomial

Abstract. A computationally efficient method is proposed to replace the piecewise linear number distribution in a hybrid bin scheme with a piecewise cubic polynomial. When the linear distribution is replaced by a cubic, the errors generated in solutions to the condensation/evaporation equation are reduced by a factor of two to three. Alternatively, using the cubic distribution function allows reducing the number of bins by 20 ± 5 % when solving the condensation/evaporation problem without sacrificing accuracy.

A General Solution to the Two-Surface Plasticity Theory

1997 ◽  
Vol 119 (1) ◽  
pp. 20-25 ◽  
Author(s):  
Wei Jiang
Keyword(s):  
General Solution ◽  
Constitutive Modeling ◽  
Maximum Size ◽  
Stress Path ◽  
Plasticity Theory ◽  
Material Behavior ◽  
Surface Model ◽  
Surface Plasticity ◽  
Line Parallel ◽  
Linear Loading

This paper obtains a closed-form general solution to the two-surface plasticity theory for linear stress paths. The simple two-surface model is discussed first. It is shown that according to this model, the response of the material stabilizes immediately during the first loading cycle. That is, the memory surface reaches its maximum size with a radius equal to the maximum effective stress and then remains unchanged thereafter, while the yield center translates along a line parallel to the stress path, thus always leading to a constant plastic strain growth rate. As a result, the model predicts that under any cyclic linear loading conditions, the material response can always be ratchetting, with no possibility of shakedown of any kinds, which violates those aspects of material behavior that are generally deemed essential in constitutive modeling. The general two-surface theory is also discussed in this paper, and some comments are made.

Ramberg–Osgood material behavior expression and large deflections of Euler beams

2020 ◽  
pp. 108128652093236
Author(s):  
Ronald J Giardina ◽  
Dongming Wei
Keyword(s):  
Cross Sections ◽  
Nonlinear Behavior ◽  
Material Model ◽  
Material Behavior ◽  
Combined Loading ◽  
Elastic Behavior ◽  
Large Deflections ◽  
Euler Beam ◽  
Special Cases ◽  
Material Behaviors

Several assumptions are commonly made throughout the literature with regard to the mechanical expression of material behavior under a Ramberg–Osgood material model; specifically, the negligible effects of nonlinearity on the elastic behavior of the material. These assumptions do not reflect the complicated nonlinearity implied by the Ramberg–Osgood expression, which can lead to significant differences in the member model response from the true material behavior curve. With the proposed approach, new explicit results for Ramberg–Osgood materials are achieved without relying on these assumptions of material and model expression. The only assumptions present within the proposed model are the standard mechanical assumptions of an Euler beam. A general nonlinear moment–curvature relationship for monotone material behaviors is constructed. Large deflections of cantilever Euler beams with rectangular cross-sections under a combined loading are modeled. Numerical validation of this new method against results already given in the literature for the special cases of linear and power-law material behaviors are provided. An analysis is presented for three common material behavior relationships, with a focus on how these relationships are expressed through the deflection of members under the application of force within the model; this analysis clearly demonstrates that the sub-yield nonlinear behavior of the Ramberg–Osgood expression can be significant. The distinctions between material behavior expression demonstrated in this analysis have been long overlooked within the literature. This work addresses a gap between the modeling of Ramberg–Osgood material behaviors and the implementation of that model in mechanics.

A Springback Prediction of 1.5 GPa Grade Steel in Roll Forming Process for Automotive Sill-Side Inner Component

2019 ◽  
Vol 794 ◽  
pp. 267-274 ◽  
Author(s):  
Hyun Sung Choi ◽  
Jeong Whan Yoon ◽  
Jong Sup Lee ◽  
Geun Ho Kim
Keyword(s):  
Steel Sheet ◽  
Kinematic Hardening ◽  
Piecewise Linear ◽  
Material Behavior ◽  
Roll Forming ◽  
Isotropic Hardening ◽  
Forming Process ◽  
Springback Prediction ◽  
Roll Forming Process ◽  
Grade Steel

Roll forming has been widely used to produce steel sheet with low formability such as Ultra High Strength Steel (UHSS). It allows the steel sheet to be formed through successive bending process into a desired shape which even cannot be formed by press brake forming. Although the process effectively improves the formability of UHSS, there still the remains accuracy issue such as springback, flair, bow and so on. Especially, springback of UHSS is one of the major challenges in roll forming process as much as press forming process. In this paper, the springback of 1.5 GPa grade steel in roll forming process was numerically investigated for automotive sill-side inner component. The material behavior was described by using the selected hardening models: isotropic hardening (Piecewise linear model), linear kinematic hardening (Prager model [6]), nonlinear kinematic hardening model (Yoshida-Uemori model [7]). A commercial software LS-DYNA was utilized for the analysis. Eighteen successive roll stages were modelled for the simulation. From the results, it was found that the springback prediction during roll forming process could be successfully achieved when the complicated material behaviors including Bauschinger effect, nonlinear transient hardening, and changeable unloading modulus are taken into account for the Finite Element (FE) simulation.

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