Simulation of Frictional Sliding Under Impact Shear Loading

2004 ◽  
Author(s):  
Demir Coker ◽  
Alan Needleman ◽  
George Lykotrafitis ◽  
Ares J. Rosakis
Keyword(s):  
Constitutive Relation ◽  
Wave Speed ◽  
Constitutive Relations ◽  
Shear Loading ◽  
Stress And Strain ◽  
Sliding Modes ◽  
Elastic Plates ◽  
Frictional Sliding ◽  
State Dependent ◽  
Dynamic Loading Conditions

Results from recent and ongoing investigations of frictional sliding under dynamic loading conditions are discussed. The configuration analyzed consists of two identical elastic plates with an interface characterized by a rate- and state-dependent frictional law. The calculations are carried out within a framework where two constitutive relations are used: a volumetric constitutive relation between stress and strain and a surface constitutive relation that characterizes the frictional behavior of the interface. The simulations discussed predict a variety of sliding modes including a crack-like mode and several pulse-like modes as well as circumstances where the sliding tip speed can exceed the longitudinal wave speed.

Investigation of PDC Cutter Interface Geometry Using 3D FEM Modelling

2017 ◽  
Vol 29 ◽  
pp. 45-53 ◽  
Author(s):  
Seyed Ali Heydarshahy ◽  
Shivakumar Karekal
Keyword(s):  
Strain Distribution ◽  
High Stress ◽  
Polycrystalline Diamond ◽  
Shear Loading ◽  
Stress And Strain ◽  
3D Fem ◽  
Interface Shear ◽  
Interface Elements ◽  
Premature Failure ◽  
Stress And Strain Distribution

Polycrystalline Diamond Compact (PDC) cutters have been popularly used in recent times due to their resistance against mechanical and thermal wear. This paper was focused on interface geometries between the substrate and the diamond table. Various types of interfaces were designed, to investigate how different interface geometries influence distribution of stress and strain under shear loading. The interface geometries examined in this paper included castle interface, dent interface, honeycomb interface and chase interface. Parallel to the interface, shear loading was applied to the top of diamond table to mimic the shear loading component from the rock cutting. To apply the shear loading, two locations were considered for each of the geometries. These locations differed depending on the interface features. Stress and strain distribution and values across different interface geometries were analysed with the aid of 3D Finite Element Method (FEM). The numerical simulations indicated that stress and strain magnitudes and distribution patterns varied in relation to different geometries. Some substrates showed relatively lower plastic strain representing higher durability of the geometries. Concentration of stress and strain distribution showed the areas where one could expect weakness. It also implies that rotating the PDC cutter assemblies around their cylindrical axis helps avoiding fatigue of interface elements in regions of high stress concentration; and thus, preventing premature failure of interface elements.

scholarly journals Buckling analysis of nano-scale magneto-electro-elastic plates using the nonlocal elasticity theory

2018 ◽  
Vol 10 (8) ◽  
pp. 168781401879333 ◽  
Author(s):  
Weon-Tae Park ◽  
Sung-Cheon Han
Keyword(s):  
Electric Fields ◽  
Constitutive Relations ◽  
Shear Deformation Theory ◽  
Nonlocal Elasticity Theory ◽  
Nonlocal Theory ◽  
Buckling Analysis ◽  
Numerical Results ◽  
Elastic Plates ◽  
Electric Boundary Condition ◽  
Electric Potentials

Buckling analysis of nonlocal magneto-electro-elastic nano-plate is investigated based on the higher-order shear deformation theory. The in-plane magnetic and electric fields can be ignored for magneto-electro-elastic nano-plates. According to magneto-electric boundary condition and Maxwell equation, the variation of magnetic and electric potentials along the thickness direction of the magneto-electro-elastic plate is determined. To reformulate the elastic theory of magneto-electro-elastic nano-plate, the nonlocal differential constitutive relations of Eringen is applied. Using the variational principle, the governing equations of the nonlocal theory are derived. The relations between local and nonlocal theories are studied by numerical results. Also, the effects of nonlocal parameters, in-plane load directions, and aspect ratio on buckling response are investigated. Numerical results show the effects of the electric and magnetic potentials. These numerical results can be useful in the design and analysis of advanced structures constructed from magneto-electro-elastic materials.

Constitutive Relations and Parameter Estimation for Finite Deformations of Viscoelastic Adhesives

2015 ◽  
Vol 82 (2) ◽  
Author(s):  
G. O. Antoine ◽  
R. C. Batra
Keyword(s):  
Constitutive Relation ◽  
Axial Strain ◽  
Constitutive Relations ◽  
Finite Deformations ◽  
Low Velocity Impact ◽  
Uniaxial Tensile ◽  
Strain Rates ◽  
Cauchy Stress ◽  
Peak Strain ◽  
Material Parameters

We propose a constitutive relation for finite deformations of nearly incompressible isotropic viscoelastic rubbery adhesives assuming that the Cauchy stress tensor can be written as the sum of elastic and viscoelastic parts. The former is derived from a stored energy function and the latter from a hereditary type integral. Using Ogden’s expression for the strain energy density and the Prony series for the viscoelastic shear modulus, values of material parameters are estimated by using experimental data for uniaxial tensile and compressive cyclic deformations at different constant engineering axial strain rates. It is found that values of material parameters using the loading part of the first cycle, the complete first cycle, and the complete two loading cycles are quite different. Furthermore, the constitutive relation with values of material parameters determined from the monotonic loading during the first cycle of deformations cannot well predict even deformations during the unloading portion of the first cycle. The developed constitutive relation is used to study low-velocity impact of polymethylmethacrylate (PMMA)/adhesive/polycarbonate (PC) laminate. The three sets of values of material parameters for the adhesive seem to have a negligible effect on the overall deformations of the laminate. It is attributed to the fact that peak strain rates in the severely deforming regions are large, and the corresponding stresses are essentially unaffected by the long time response of the adhesive.

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.

Effect of Compressive Stress on Longitudinal Wave Speed in Cementitious Material

2002 ◽  
Author(s):  
Mary L. Hughes ◽  
C. Allen Ross ◽  
Voncile L. Ashley
Keyword(s):  
Constitutive Equation ◽  
Longitudinal Wave ◽  
Uniaxial Compression ◽  
Wave Speed ◽  
Constitutive Relations ◽  
Damage Parameter ◽  
Primary Objective ◽  
Compression Tests ◽  
Depth Of Penetration ◽  
Longitudinal Wave Speed

The Air Force has been interested for some time in the development of computer codes that accurately predict the penetrator trajectory created when munitions are fired into concrete and geomaterial targets, as well as the resulting depth of penetration. Recent work has focused on experimental research performed to determine quasistatic, dynamic, unconfined and confined material properties for development of an elastic/viscoplastic constitutive equation. This constitutive equation has shown some promise in predicting stress and strains but lacks a consistent damage parameter to predict damage or fractures exhibited by the target material during experimental impact tests. Current damage level predictors that employ a scalar damage parameter are not sufficient to predict the directional damage or fracture that occurs in simple uniaxial compression tests of concrete and geomaterials. Tensorial or directional damage parameters coupled with constitutive relations are necessary for better understanding and accurate prediction of damage exhibited when munitions impact concrete and geomaterials. The primary objective of the study described herein was to identify, quantify and characterize damage parameters associated with certain constitutive responses of cementitious and geologic materials. To that end, longitudinal wave speed and biaxial strain data were collected simultaneously on a series of grout cubes as they were being loaded to failure in uniaxial compression. The results of these tests, and a comparison to existing related data [1, 2] are presented.

Parameter Estimation of the Mechanical Behavior of the Artery Using a Nonlinear Least Square Method With a Noise Model

2008 ◽  
Author(s):  
Shahrokh Zeinali ◽  
Jongeun Choi ◽  
Seungik Baek
Keyword(s):  
Parameter Estimation ◽  
Blood Vessel ◽  
Mechanical Behavior ◽  
Constitutive Relation ◽  
Environmental Changes ◽  
Constitutive Relations ◽  
Estimation Method ◽  
Least Square ◽  
Noise Model ◽  
Bias Error

Although it is well known that blood vessels adapt and remodel in response to various biomechanical stimuli, quantifying changes in constitutive relation corresponding to environmental changes is still challenging. Especially, when the dimension of blood vessel is small, the uncertainties in experimental measurements become significant and make it difficult to precisely estimate parameters of constitutive relations for mechanical behavior of the blood vessel. Hence without considering measurement error in displacement, a conventional nonlinear least square (NLS) method results in a biased parameter estimation. In this paper, we propose a new parameter estimation method to eliminate such bias error and provide more accurate estimated parameters for a constitutive relation using a weighted nonlinear least square (WNLS) method with a noise model. We first applied the proposed technique to a set of synthesized data with computer generated white noises and compared the fitting results to those of the NLS method without the noise model. We also applied our method to experimental data sets from mechanical tests of rabbit basilar and mouse carotid arteries and studied parameter sensitivity of the constitutive model.

scholarly journals A thermodynamic basis for implicit rate-type constitutive relations describing the inelastic response of solids undergoing finite deformation

2020 ◽  
Vol 25 (12) ◽  
pp. 2222-2230
Author(s):  
David Cichra ◽  
Vít Průša
Keyword(s):  
Constitutive Relation ◽  
Finite Deformation ◽  
Constitutive Relations ◽  
Plastic Response ◽  
Inelastic Response ◽  
Perfectly Plastic ◽  
Novel Approach ◽  
Elastic Perfectly Plastic ◽  
Rate Type ◽  
Thermodynamic Basis

Implicit rate-type constitutive relations utilising discontinuous functions provide a novel approach to the purely phenomenological description of the inelastic response of solids undergoing finite deformation. However, this type of constitutive relation has so far been considered only in the purely mechanical setting, and the complete thermodynamic basis is largely missing. We address this issue, and we develop a thermodynamic basis for such constitutive relations. In particular, we focus on the thermodynamic basis for the classical elastic–perfectly plastic response, but the framework is flexible enough to describe other types of inelastic response as well.

Behavior of Thin-Film-Type Delamination of Layered Composite in Post-Buckling

2013 ◽  
Vol 774-776 ◽  
pp. 1312-1321 ◽  
Author(s):  
Vitalijs Pavelko
Keyword(s):  
Compressive Force ◽  
Layered Composite ◽  
Stress And Strain ◽  
Elastic Plates ◽  
Post Buckling ◽  
Complete Elliptic Integrals ◽  
Analysis Of Stability ◽  
Delamination Propagation ◽  
State Stress ◽  
Buckled State

A revision of the basic assumptions those are usually used in the analysis of stability of thin delaminated layer and delamination propagation in a compressed composite is presented in this paper. For this purpose, the theory of flexible elastic plates with large displacements was used. As a result the compressive force and the total longitudinal strain of sub-laminate are expressed in terms of complete elliptic integrals, which uniquely identify the buckled shape of sub-laminate, the effect of buckling on the compression strain and increment of the compressive force in the buckled state. Stress and strain, as well as the strength of the buckled sub-laminate in the dangerous cross-section were also analyzed. The results of the general analysis of delamination propagation and its compression-bending destruction in the buckled state allow to define the basic regularities of the damage behavior of compressed layered composite.

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