scholarly journals Nonlocal wrinkling instabilities in bilayered systems using peridynamics

2021 ◽  
Author(s):  
Marie Laurien ◽  
Ali Javili ◽  
Paul Steinmann
Keyword(s):  
Material Model ◽  
Wave Pattern ◽  
Weighting Factor ◽  
Material Behavior ◽  
Critical Conditions ◽  
Local Theory ◽  
Nonlocal Effects ◽  
Material Interface ◽  
First Time ◽  
Quantitative Influence

AbstractWrinkling instabilities occur when a stiff thin film bonded to an elastic substrate undergoes compression. Regardless of the nature of compression, this phenomenon has been extensively studied through local models based on classical continuum mechanics. However, the experimental behavior is not yet fully understood and the influence of nonlocal effects remains largely unexplored. The objective of this paper is to fill this gap from a computational perspective by investigating nonlocal wrinkling instabilities in a bilayered system. Peridynamics (PD), a nonlocal continuum formulation, serves as a tool to model nonlocal material behavior. This manuscript presents a methodology to precisely predict the critical conditions by employing an eigenvalue analysis. Our results approach the local solution when the nonlocality parameter, the horizon size, approaches zero. An experimentally observed influence of the boundaries on the wave pattern is reproduced with PD simulations which suggests nonlocal material behavior as a physical origin. The results suggest that the level of nonlocality of a material model has quantitative influence on the main wrinkling characteristics, while most trends qualitatively coincide with predictions from the local analytical solution. However, a relation between the film thickness and the critical compression is revealed that is not existent in the local theory. Moreover, an approach to determine the peridynamic material parameters across a material interface is established by introducing an interface weighting factor. This paper, for the first time, shows that adding a nonlocal perspective to the analysis of bilayer wrinkling by using PD can significantly advance our understanding of the phenomenon.

scholarly journals Concurrent material and structure optimization of multiphase hierarchical systems within a continuum micromechanics framework

2021 ◽  
Author(s):  
Tarun Gangwar ◽  
Dominik Schillinger
Keyword(s):  
Optimization Problems ◽  
Computational Cost ◽  
Structure Optimization ◽  
Material Behavior ◽  
Hierarchical Systems ◽  
Material Optimization ◽  
Continuum Micromechanics ◽  
Benchmark Tests ◽  
Constraint Optimization Problems ◽  
First Time

AbstractWe present a concurrent material and structure optimization framework for multiphase hierarchical systems that relies on homogenization estimates based on continuum micromechanics to account for material behavior across many different length scales. We show that the analytical nature of these estimates enables material optimization via a series of inexpensive “discretization-free” constraint optimization problems whose computational cost is independent of the number of hierarchical scales involved. To illustrate the strength of this unique property, we define new benchmark tests with several material scales that for the first time become computationally feasible via our framework. We also outline its potential in engineering applications by reproducing self-optimizing mechanisms in the natural hierarchical system of bamboo culm tissue.

A Viscoelastic Correspondence Principle for Plane Membranes Subjected to Lateral Pressure

1983 ◽  
Vol 50 (4a) ◽  
pp. 740-742 ◽  
Author(s):  
B. Stora˚kers
Keyword(s):  
Time Dependence ◽  
Viscoelastic Material ◽  
Lateral Pressure ◽  
Correspondence Principle ◽  
Material Model ◽  
Material Behavior ◽  
Linear Elastic Material ◽  
First Order ◽  
Linear Elastic ◽  
Consistent Approximation

The classical Fo¨ppl equations, governing the deflection of plane membranes, constitute the first-order consistent approximation in the case of linear elastic material behavior. It is shown that despite the static and kinematic nonlinearities present, for arbitrary load histories a correspondence principle for viscoelastic material behavior exists if all relevant relaxation moduli are of uniform time dependence. Application of the principle is illustrated by means of a popular material model.

An accurate double-superposition global–local theory for vibration and bending analyses of cylindrical composite and sandwich shells subjected to thermo-mechanical loads

2011 ◽  
Vol 225 (8) ◽  
pp. 1816-1832 ◽  
Author(s):  
M Shariyat
Keyword(s):  
Vibration Analysis ◽  
Cylindrical Shells ◽  
High Order ◽  
Computational Time ◽  
Local Theory ◽  
Transverse Stress ◽  
Mechanical Loads ◽  
Local Technique ◽  
Sandwich Shells ◽  
First Time

Based on the idea of double superposition, an accurate high-order global–local theoryis proposed for bending and vibration analysis of cylindrical shells subjected to thermo-mechanical loads, for the first time. The theory has many novelties, among them: (1) less computational time due to the use of the global–local technique and matrix formulations; (2) satisfaction of the complete kinematic and transverse stress continuity conditions at the layer interfaces under thermo-mechanical loads; (3) consideration of the transverse flexibility; (4) release of Love–Timoshenko assumption; and (5) capability of investigating the local phenomena. Various comparative examples are included to validate the theory and to examine its accuracy and efficiency.

Hyperelastic Muscle Simulation

2007 ◽  
Vol 345-346 ◽  
pp. 1241-1244 ◽  
Author(s):  
Mohd. Zahid Ansari ◽  
Sang Kyo Lee ◽  
Chong Du Cho
Keyword(s):  
Skeletal Muscle ◽  
Silicone Rubber ◽  
Soft Tissues ◽  
Material Model ◽  
Incompressible Material ◽  
Material Behavior ◽  
Rubber Tube ◽  
Stress Strain ◽  
Element Analysis ◽  
Strain Behavior

Biological soft tissues like muscles and cartilages are anisotropic, inhomogeneous, and nearly incompressible. The incompressible material behavior may lead to some difficulties in numerical simulation, such as volumetric locking and solution divergence. Mixed u-P formulations can be used to overcome incompressible material problems. The hyperelastic materials can be used to describe the biological skeletal muscle behavior. In this study, experiments are conducted to obtain the stress-strain behavior of a solid silicone rubber tube. It is used to emulate the skeletal muscle tensile behavior. The stress-strain behavior of silicone is compared with that of muscles. A commercial finite element analysis package ABAQUS is used to simulate the stress-strain behavior of silicone rubber. Results show that mixed u-P formulations with hyperelastic material model can be used to successfully simulate the muscle material behavior. Such an analysis can be used to simulate and analyze other soft tissues that show similar behavior.

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.

Prediction of Cutting Force in Bone Cutting Using Finite Element Analysis

2021 ◽  
Author(s):  
Varatharajan Prasannavenkadesan ◽  
Ponnusamy Pandithevan
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Cutting Force ◽  
Material Model ◽  
Tensile Tests ◽  
Bovine Bone ◽  
Element Analysis ◽  
Cutting Processes ◽  
Parameter Values ◽  
First Time

Abstract In orthopedic surgery, bone cutting is an indispensable procedure followed by the surgeons to treat the fractured and fragmented bones. Because of the unsuitable parameter values used in the cutting processes, micro crack, fragmentation, and thermal osteonecrosis of bone are observed. Therefore, prediction of suitable cutting force is essential to subtract the bone without any adverse effect. In this study, the Cowper-Symonds model for bovine bone was developed for the first time. Then the developed model was coupled with the finite element analysis to predict the cutting force. To determine the model constants, tensile tests with different strain rates (10−5/s, 10−4/s, 10−3/s, and 1/s) were conducted on the cortical bone specimens. The developed material model was implemented in the bone cutting simulation and validated with the experiments.

A Continued Evaluation of the Role of Material Hardening Behavior for the NeT TG1 and TG4 Specimens

2014 ◽  
Author(s):  
David J. Dewees ◽  
Phillip E. Prueter ◽  
Seetha Ramudu Kummari
Keyword(s):  
Structural Integrity ◽  
Plastic Material ◽  
Critical Factor ◽  
Material Model ◽  
Standard Test ◽  
Material Behavior ◽  
Weld Residual Stress ◽  
Hardening Models ◽  
Elastic Plastic Material

Modeling of cyclic elastic-plastic material behavior (hardening) has been widely identified as a critical factor in the finite element (FE) simulation of weld residual stresses. The European Network on Neutron Techniques Standardization for Structural Integrity (NeT) Project has provided in recent years both standard test cases for simulation and measurement, as well as comprehensive material characterization. This has allowed the role of hardening in simulation predictions to be isolated and critically evaluated as never before possible. The material testing information is reviewed, and isotropic, nonlinear kinematic and combined hardening models are formulated and tested. Particular emphasis is placed on material model selection for general fitness-for-service assessments, as it relates to the guidance for weld residual stress (WRS) in flaw assessments of in-service equipment in Annex E of the FFS standard, API 579-1/ASME FFS-1.

Inelastic material behavior of polymers – Experimental characterization, formulation and implementation of a material model

2012 ◽  
Vol 52 ◽  
pp. 40-57 ◽  
Author(s):  
Markus Kästner ◽  
Martin Obst ◽  
Jörg Brummund ◽  
Karin Thielsch ◽  
Volker Ulbricht
Keyword(s):  
Material Model ◽  
Material Behavior ◽  
Experimental Characterization ◽  
Inelastic Material

A new analytical model for reliability analysis of a launch vehicle system with limited test data

2018 ◽  
Vol 233 (9) ◽  
pp. 3482-3495
Author(s):  
V Murugesan ◽  
Sreejith Plappillimadam ◽  
VJ Saji ◽  
SS Maruthi ◽  
AK Anilkumar
Keyword(s):  
Reliability Analysis ◽  
Analytical Model ◽  
Test Data ◽  
Weighting Factor ◽  
Design Parameters ◽  
Launch Vehicles ◽  
Minimum Number ◽  
First Time ◽  
Propellant Rocket

Reliability is one of the critical design parameters for the launch vehicles and its systems. When the systems are ready to fly the first time, only limited test data are available and accordingly reliability assessed will be very low. However, in most cases, the new systems are derived and developed using the knowledge and experience gained from the heritage systems to meet the fresh challenges. Hence, the reliability assessed with the minimum number of tests done on the new system does not truly reflect the inherent reliability of the system. In this paper, an approach and a new analytical model are developed for the reliability assessment of systems with limited test data, giving an accurate weighting for the tests and flight experiences with similar systems. The method gives a systematic procedure for arriving at the weighting factor for test data of the pedigree system, with due consideration of the similarities between the systems and various factors influencing system reliability. The method is illustrated with a case study of a newly developed liquid propellant rocket system. The model is validated using the available test and flight data of two propulsion systems with adequate flight experience. The analytical model is generic in nature and can be applied to reliability analysis of any system, which has considerable similarities with a pedigree system.

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