scholarly journals Complex Material and Surface Analysis of Anterolateral Distal Tibial Plate of 1.4441 Steel

Metals ◽  
2021 ◽  
Vol 12 (1) ◽  
pp. 60
Author(s):  
Josef Hlinka ◽  
Kamila Dostalova ◽  
Katerina Peterek Dedkova ◽  
Roman Madeja ◽  
Karel Frydrysek ◽  
...  
Keyword(s):  
Bulk Material ◽  
Austenitic Stainless Steels ◽  
Surface Damage ◽  
Physiological Solution ◽  
Corrosion Products ◽  
Material Behavior ◽  
Excessive Heat ◽  
Real Material ◽  
Tibial Plate ◽  
Evolution Of Microstructure

Nickel-based austenitic stainless steels are still common for manufacture of implants intended for acute hard tissue reinforcement or stabilization, but the risk of negative reactions due to soluble nickel-rich corrosion products must be considered seriously. Corrosion processes may even be accelerated by the evolution of microstructure caused by excessive heat during machining, etc. Therefore, this study also deals with the investigation of microstructure and microhardness changes near the threaded holes of the anterolateral distal tibial plate containing approx. 14wt.% Ni by composition. There were only insignificant changes of microhardness, grain size, or microstructure orientation found close to the area of machining. In addition, wettability measurements of surface energy demonstrated only minor differences for bulk material and areas close to machining. The cyclic potentiodynamic polarization tests were performed in isotonic physiological solution. The first cycle was used for the determination of corrosion characteristics of the implant after chemical passivation, the second cycle was used to simulate real material behavior under the condition of previous surface damage by excessive pitting corrosion occurring during previous polarization. It was found that the damaged and spontaneously repassived surface showed a three-time higher standard corrosion rate than the “as received” chemically passivated surface. One may conclude that previous surface damage may decrease the lifetime of the implant significantly and increase the amount of nickel-based corrosion products distributed into surrounding tissues.

Defects Introduced by Plasma Processing of Silicon

1992 ◽  
Vol 262 ◽  
Author(s):  
J. L. Benton
Keyword(s):  
Bulk Material ◽  
Surface Region ◽  
Surface Damage ◽  
Near Surface ◽  
Enhanced Diffusion ◽  
Interstitial Defect ◽  
Comprehensive Picture ◽  
Reaction Region ◽  
Defect Reactions ◽  
P Type

ABSTRACTThe electrical and optical properties of defects introduced by Reactive Ion Etching (RIE) in the near surface region of Si after dry etching with various gases and plasma conditions is studied with spreading Resistance (SR), photoluminescence (PL), and capacitance-voltage profiling (C-V). Plasma etching in chlorine and fluorine based gases produce donors at the surface in both n-type and p-type, Czochralski and float-zone silicon. Isochronal annealing reveals the presence of two distinct regions of dopant compensation. The surface damage region is confined to 1000 Å and survives heat treatment at 400°C, while the defect reaction region extends ≥ 1 μm in depth and recovers by 250°C. A comprehensive picture of the interstitial defect reactions in RIE silicon is completed. The interstitial defects, Ci and Bi, created in the ion damaged near surface region, undergo recombination enhanced diffusion caused by the presence of ultraviolet light in the plasma, resulting in the long range diffusion into the Si bulk. Subsequently, the interstitial atoms are trapped by the background impurities forming the defect pairs, CiOi, CSCi, or BiOi, which are observed experimentally. The depth of the diffusion-limited trapping and the probability of forming specific pairs depends on the relative concentrations of the reactants, oxygen, carbon or boron, present in the bulk material.

A Subscale Experimental Investigation on the Influence of Sanding on Adhesion and Rolling Contact Fatigue of Wheel/Rail Under Water Condition

2016 ◽  
Vol 139 (1) ◽  
Author(s):  
Wanliang Huang ◽  
Xi Cao ◽  
Zefeng Wen ◽  
Wenjian Wang ◽  
Qiyue Liu ◽  
...  
Keyword(s):  
Feed Rate ◽  
Bulk Material ◽  
Fatigue Cracks ◽  
Rolling Contact Fatigue ◽  
Contact Fatigue ◽  
Particle Diameter ◽  
Surface Damage ◽  
Rolling Contact ◽  
Adhesion Coefficient ◽  
Water Condition

With a subscale rolling-sliding apparatus, the objective of this study is to explore the adhesion and rolling contact fatigue characteristics of wheel/rail rollers with sanding under water condition. Sanding improves adhesion coefficient but aggravates the surface damage of wheel and rail materials. With the particle diameter and feed rate increasing, the adhesion coefficient is further improved. However, the surface damage (spalling and pits) becomes severer as well as the surface roughness. Note that pitting is a special damage type when sanding is used to improve the adhesion. Big pits and fatigue cracks appear on subsurface under larger particle diameter and feed rate conditions. Severe cracks initiate from big pits and develop into material to a depth, which results in bulk material breaking.

Material Modeling for Autofrettage Stress Analysis Including the “Single Effective Material”

2008 ◽  
Author(s):  
Anthony P. Parker ◽  
Michael C. Gibson ◽  
Amer Hameed ◽  
Edward Troiano ◽  
John G. Hetherington
Keyword(s):  
Stress Analysis ◽  
Numerical Solutions ◽  
Material Behavior ◽  
Material Modeling ◽  
Equivalent Material ◽  
Element Analysis ◽  
Adjustment Procedure ◽  
Analysis Process ◽  
Real Material ◽  
Accurate Procedure

Analytical and numerical stress analysis of the autofrettage process has made great strides in the last few years. The major challenge is no longer the stress analysis process but the incorporation of ‘real’ material behavior, including Bauschinger effect. This means that material properties may vary at every radial location within the tube. In this paper it is demonstrated that Finite Element Analysis (FEA) may be accomplished using a ‘user programmable feature’ within a non-linear FEA or, more simply using an elastic modulus and Poisson’s ratio adjustment procedure within a linear-elastic FEA. The results of these two methods are shown to be in agreement with each other and with an independent numerical analysis. It is further demonstrated that numerical solutions may be obtained using a single ‘fictitious’ material. This is called a ‘single equivalent material’ (SEMAT). Whilst this requires a very small number of iterations for accurate convergence, it dramatically reduces the material-modeling challenges. Furthermore, SEMAT may be implemented into an analytical procedure thereby permitting highly accurate modeling of a real material whose unloading behavior varies with radius. Comparisons indicate that this is a robust, accurate procedure.

scholarly journals Constitutive Modelling of Laser Based Powder Bed Fusion Melted Inconel 718 Superalloy over a Wide Range of Strain Rates

2021 ◽  
Author(s):  
Laura Delcuse ◽  
Slim Bahi ◽  
Urvashi Gunputh ◽  
Paul Wood ◽  
Alexis Rusinek
Keyword(s):  
Inconel 718 ◽  
Bulk Material ◽  
Constitutive Modelling ◽  
Material Behavior ◽  
Vertical Position ◽  
Strain Rates ◽  
Powder Bed Fusion ◽  
Compression Tests ◽  
Powder Bed ◽  
The Difference

The aim of this paper is to determine the material parameters of the Inconel 718 manufactured by Laser Powder Bed Fusion, using the Johnson-Cook model. Different compression tests in quasi-static and dynamic domains were performed under various strain rates, in range of 10-3 s-1 to 2500 s-1 at the room temperature. The difference between the two building directions XY and ZX, horizontal and vertical position from the substrate, was investigated to highlight the influence of the process parameter on the bulk material behavior. Finally, the identified parameters were implemented into a numerical model, describing the behavior of auxetic structure under compression test, and validated using experimental data.

Mesoscale Analysis of Porous Shape Memory Alloys

2000 ◽  
Author(s):  
Virginia G. DeGiorgi ◽  
Muhammad A. Qidwai
Keyword(s):  
Shape Memory Alloys ◽  
Shape Memory ◽  
Dynamic Loading ◽  
Smart Materials ◽  
Bulk Material ◽  
Material Behavior ◽  
Loading Conditions ◽  
Shape Variation ◽  
Energy Absorbing ◽  
Dynamic Loading Conditions

Abstract Shape memory alloys are frequently used in smart materials and structures as the active component. Their ability to provide high force and large displacements has been used to the advantage in many applications. The majority of applications to date utilize solid shape memory alloy materials in quasi-static loading conditions. Recent work has proposed the use of porous SMAs as an energy absorbing material under dynamic loading conditions. The use of porous SMAs under dynamic loading will require advancements in the understanding of SMA behavior both in the dense or solid form and in the porous form. The current work examines the quasi-static behavior of porous SMA as a first step. The material behavior is modeled on a mesoscale level allowing for the examination of pore size and shape variation effects. Bulk material response is estimated and compared with micromechanical periodic unit cell predictions.

Analysis of the Macroscopic Behaviour of PMI Foam

2019 ◽  
Vol 809 ◽  
pp. 285-290
Author(s):  
Michaela Nagler ◽  
Michael Thor ◽  
Peter Peyrer ◽  
Gernot Schneiderbauer ◽  
Franz M. Sendner ◽  
...  
Keyword(s):  
Finite Element Modelling ◽  
Bulk Material ◽  
Material Model ◽  
Material Behavior ◽  
Nonlinear Behaviour ◽  
Foam Core ◽  
Macroscopic Scale ◽  
Element Modelling ◽  
Hyperelastic Materials ◽  
Scanning Electron

o accurately simulate the foam core in composite parts on a macroscopic scale the morphology, the characterisation, and the nonlinear behaviour of thefoam must be understood properly. Accounting for the heterogeneity and the mechanical properties of the foam core affects the dimensioning of the final part.In the present study the microstructure of the foam samples were characterized using scanning electron microscopy. To determine the bulk material behavior and the strength limitations of the nonlinear foam, shear and compressions tests are performed. All numerical calculations were carried out on the macroscopic level.A basic challenge in the finite element modelling of hyperelastic materials by means of test data is the identification of material model coefficients which are appropriate to describe the behaviour of the considered foam.

scholarly journals Development of a Microscopic Damage Model for Low Stress Triaxiality

2011 ◽  
Vol 473 ◽  
pp. 460-467 ◽  
Author(s):  
Mohamed Achouri ◽  
Guenael Germain ◽  
Phillippe dal Santo ◽  
Serge Boude ◽  
Jean Lou Lebrun ◽  
...  
Keyword(s):  
Hsla Steel ◽  
Damage Model ◽  
Stress Triaxiality ◽  
High Strength ◽  
Material Behavior ◽  
Shear Tests ◽  
Damage Process ◽  
Microscopic Damage ◽  
Evolution Of Microstructure

This work dealsa contribution to ductile damageof High-Strength Low-Alloy (HSLA) steel under low stress triaxiality. This work is based on micrographics observations and in-situ shear tests to examine the evolution of microstructure in this kind of loading and to identify the damage process associated. Numerical simulations by finites elements has been performed to simulate the material behavior of nucleation mechanism and the interaction between cavities during the coalescence phase, as well as the effect of the relative position of the inclusions in the shear plane.The model used as a reference in this work is the Gurson-Tvergaard- Needleman (GTN) model. It has been recently improved in order to take into account the effects of low triaxiality during shearing. A new modelisunderdevelopmentto takeintoaccounttheeffects oflowtriaxiality stresses (or loading) during shearing.

Molecular statics of polymer configurations

1988 ◽  
Vol 3 (6) ◽  
pp. 1414-1421
Author(s):  
David J. Quesnel ◽  
Lazhar Mazlout
Keyword(s):  
Initial Conditions ◽  
Bulk Material ◽  
Analytical Form ◽  
Elastic Stiffness ◽  
Material Behavior ◽  
Displacement Curve ◽  
Single Chain ◽  
Physically Based ◽  
Chain Force ◽  
Force Displacement

Molecular behaviors of single isolated chains of various lengths are simulated using four energy potentials: the twisting, bending, stretching, and Van der Waals potentials. The origin and analytical form of these potentials is discussed and easy-to-evaluate quantitative expressions are given. A physically based algorithm for energy minimization is developed and used to determine the static configurations of single chains in their lowest energy states. Not surprisingly, the majority of the energy minima found are local minima implying metastability, which is, of course, a central phenomena in noncrystalline material behavior. A progressive distortion approach is then used to suppress conformational variations that depend on initial conditions from developing, thus making possible study of the force displacement characteristics of single chains of various lengths. The single chain force-displacement curve found in this way has a form comparable with the gentle yield point observed in many bulk polymers but with an initial apparent elastic stiffness higher than that of bulk material. Some aspects of the fracture phenomena of single chains are also discussed.

scholarly journals Evaluation of bulk material behavior control method in technological units using DEM. Part 2

2020 ◽  
pp. 3-6
Author(s):  
A. V. Boikov ◽  
R. V. Savelev ◽  
V. A. Payor ◽  
A. V. Potapov
Keyword(s):  
Control Method ◽  
Recognition Accuracy ◽  
Bulk Material ◽  
Recognition Algorithm ◽  
Material Behavior ◽  
Operating Modes ◽  
Technological Unit ◽  
Neural Network Classifiers ◽  
Particles Trajectories ◽  
Future Work

The research is dedicated to the development of special devices (capsules) that can be used to control the mining ore behavior in the technological unit in order to increase processes efficiency. In the first part of the article, the choice of the discrete element method for generating various particle trajectories in the unit (drum pelletizer) was substantiated. This part describes the specific technologies that were used to recognize the pelletizing mode. In particular, conversation of paths to sensor readings is implemented using the Matlab Sensor Fusion and Tracking Toolbox. The obtained readings were processed using two neural network classifiers (DNN and LSTM). As a result, stable models for recognizing the pelletizing modes of the unit were obtained. LSTM recognition accuracy is greater than DNN. The developed approach can be used to recognize the operating modes of other technological units. In addition, data on particles trajectories can be used to improve DEM models of technological processes. Future work consists of the capsule physical implementation and testing the recognition algorithm on a real unit.

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