Experimental and Three-Dimensional Finite Element Study of Scratch Test of Polymers at Large Deformations

2004 ◽  
Vol 126 (2) ◽  
pp. 372-379 ◽  
Author(s):  
J. L. Bucaille ◽  
E. Felder ◽  
G. Hochstetter
Keyword(s):  
Strain Hardening ◽  
Penetration Depth ◽  
Large Deformations ◽  
Numerical Study ◽  
Scratch Test ◽  
Scratch Resistance ◽  
Plastic Strains ◽  
Thermosetting Polymer ◽  
Scratch Tests ◽  
Hardening Coefficient

An experimental and numerical study of the scratch test on polymers near their surface is presented. The elastoplastic response of three polymers is compared during scratch tests at large deformations: polycarbonate, a thermosetting polymer and a sol-gel hard coating composed of a hybrid matrix (thermosetting polymer-mineral) reinforced with oxide nanoparticles. The experiments were performed using a nanoindenter with a conical diamond tip having an included angle of 30 deg and a spherical radius of 600 nm. The observations obtained revealed that thermosetting polymers have a larger elastic recovery and a higher hardness than polycarbonate. The origin of this difference in scratch resistance was investigated with numerical modelling of the scratch test in three dimensions. Starting from results obtained by Bucaille (J. Mat. Sci., 37, pp. 3999–4011, 2002) using an inverse analysis of the indentation test, the mechanical behavior of polymers is modeled with Young’s modulus for the elastic part and with the G’sell-Jonas’ law with an exponential strain hardening for the viscoplastic part. The strain hardening coefficient is the main characteristic parameter differentiating the three studied polymers. Its value is equal to 0.5, 4.5, and 35, for polycarbonate, the thermosetting polymer and the reinforced thermosetting polymer, respectively. Firstly, simulations reveals that plastic strains are higher in scratch tests than in indentation tests, and that the magnitude of the plastic strains decreases as the strain hardening increases. For scratching on polycarbonate and for a penetration depth of 0.5 μm of the indenter mentioned above, the representative strain is equal to 124%. Secondly, in agreement with experimental results, numerical modeling shows that an increase in the strain hardening coefficient reduces the penetration depth of the indenter into the material and decreases the depth of the residual groove, which means an improvement in the scratch resistance.

scholarly journals Infrared spectroscopy, nano-mechanical properties, and scratch resistance of esthetic orthodontic coated archwires

2014 ◽  
Vol 85 (5) ◽  
pp. 777-783 ◽  
Author(s):  
Dayanne Lopes da Silva ◽  
Emanuel Santos ◽  
Sérgio de Souza Camargo ◽  
Antônio Carlos de Oliveira Ruellas
Keyword(s):  
Mechanical Properties ◽  
Infrared Spectroscopy ◽  
Elastic Modulus ◽  
Scratch Test ◽  
Scratch Resistance ◽  
Load Removal ◽  
Indentation Tests ◽  
Orthodontic Archwires ◽  
Scratch Tests ◽  
Coating Hardness

ABSTRACT Objective:  To evaluate the material composition, mechanical properties (hardness and elastic modulus), and scratch resistance of the coating of four commercialized esthetic orthodontic archwires. Materials and Methods:  The coating composition of esthetic archwires was assessed by Fourier-transform infrared spectroscopy (FTIR). Coating hardness and elastic modulus were analyzed with instrumented nano-indentation tests. Scratch resistance of coatings was evaluated by scratch test. Coating micromorphologic characteristics after scratch tests were observed in a scanning electron microscope. Statistical differences were investigated using analysis of variance and Tukey post hoc test. Results:  The FTIR results indicate that all analyzed coatings were markedly characterized by the benzene peak at about 1500 cm−1. The coating hardness and elastic modulus average values ranged from 0.17 to 0.23 GPa and from 5.0 to 7.6 GPa, respectively. Scratch test showed a high coating elasticity after load removal with elastic recoveries >60%, but different failure features could be observed along the scratches. Conclusion:  The coatings of esthetic archwires evaluated are probably a composite of polyester and polytetrafluoroethylene. Delamination, crack propagation, and debris generation could be observed along the coating scratches and could influence its durability in the oral environment.

scholarly journals Comparison of Ductile Damage Models During Scratch Tests - A Numerical Study

2015 ◽  
Author(s):  
A. Mostaani ◽  
M.P. Pereira ◽  
B.F. Rolfe
Keyword(s):  
Material Removal ◽  
Numerical Study ◽  
Damage Model ◽  
Scratch Test ◽  
Work Piece ◽  
Damage Initiation ◽  
Damage Models ◽  
Wear Mode ◽  
Scratch Tests ◽  
Wear Modes

The ‘wear mode diagram’ has been commonly used to classify the deformation regime of the soft work-piece during scratching, into three modes: ploughing, wedge formation and cutting. The scratch test is used to evaluate wear modes and material removal associated with wear. There are different damage models in the literature used for the description of material behaviour after damage initiation under different loading conditions. However, there has been little analysis to compare damage models during scratch test conditions. The first aim of this work is first to use a finite element modelling package (Abaqus/Explicit) to build a 3D model to capture deformation modes during scratching with indenters with different attack angles. Three different damage models are incorporated into the model and patterns of damage initiation and propagation are compared with experimental results from the literature. This work highlights the role of the damage model in accurately capturing wear modes and material removal during two body sliding interactions.

Viscoelastic Behavior of Polymer Films During Scratch Test: a Quantitative Analysis

1999 ◽  
Vol 594 ◽  
Author(s):  
Vincent D. Jardret ◽  
Warren C. Oliver
Keyword(s):  
Penetration Depth ◽  
Contact Pressure ◽  
Dynamic Properties ◽  
Abrasive Particle ◽  
Viscoelastic Behavior ◽  
Scratch Test ◽  
Dynamic Mechanical Properties ◽  
Scratch Resistance ◽  
Polymer Surfaces ◽  
Temperature History

AbstractDynamic properties of polymer surfaces affect their ability to withstand abrasive actions. Kinetic conditions, like velocity, penetration depth and shape of the abrasive particles, change the abrasion mechanisms and the morphology of the abraded surface. Using the scratch technique, along with profilometry measurement across the scratches, we have been able to completely characterize the residual scratch morphology. Pile-up deformation and visco-plastic relaxation are key phenomena that characterize the importance of ductility in the scratch resistance of polymer surfaces. Cross profilometry aids in studying the relaxation of the scratch morphology for different time and temperature history after the scratch is made. The effect of scratch velocity, penetration depth and indenter geometry on the contact pressure and friction coefficient estimated during a scratch test can also be analyzed. Following Eyring's law, a good correlation, was found between normal indentation and scratch testing in the evolution of the contact pressure with the applied strain rate. This work results in a better understanding of the stresses and the strains applied by an abrasive particle, and especially relates the dynamic mechanical properties of viscous materials, like stress exponent, to their scratch behavior. The method presented can provide for the measurement of dynamic properties of polymer surfaces or thin films under a very large range of strain rates.

A study on correlating microstructural features with abrasion resistance of a high strength low alloy steel

2014 ◽  
Vol 4 (2) ◽  
Author(s):  
Xiaojun Xu ◽  
Wei Xu ◽  
Sybrand Van der Zwaag
Keyword(s):  
Abrasion Resistance ◽  
Hsla Steel ◽  
High Hardness ◽  
High Strength ◽  
Scratch Test ◽  
Quantitative Information ◽  
Scratch Resistance ◽  
Dual Phase ◽  
Secondary Damage ◽  
Scratch Tests

Scratch tests were carried out in order to investigate correlations of the scratch resistance, representing the abrasion resistance to a certain extent, with various microstructural features as well as different resulting hardness of a high strength low alloy (HSLA) steel. The HSLA steel was subjected to selected heat treatment cycles in order to produce different microstructural combinations, thereby obtaining various abrasion resistance. Results of scratch tests suggested that a high hardness alone cannot guarantee a high scratch (abrasion) resistance, and the microstructural features play a vital role in determining the abrasion resistance. More specifically, it was shown that a dual phase (ferrite plus martensite) microstructure with a relatively low hardness possesses a better abrasion resistance than a full martensite with a higher hardness. Moreover, observations of scratch scars revealed different features of scar surface and debris: the dual phase microstructure results in a smooth scar surface and with plate debris, while a full martensite leads to a relatively coarse scar surface with sharp debris, which is very harmful to the abrasion resistance due to its secondary damage to the surface. Furthermore, results suggested the scratch test can well mimic the nature of abrasion wear and hence provide fast, reproducible, and quantitative information on abrasion resistance of different microstructures

scholarly journals Scratch Behaviour of Silicon Solid Solution Strengthened Ferritic Compacted Graphite Iron (CGI)

2018 ◽  
Vol 925 ◽  
pp. 318-325
Author(s):  
Rohollah Ghasemi ◽  
Anders E.W. Jarfors
Keyword(s):  
Solid Solution ◽  
Normal Load ◽  
Scratch Test ◽  
Scratch Resistance ◽  
Compacted Graphite Iron ◽  
Depth Of Penetration ◽  
Scratch Depth ◽  
Compacted Graphite ◽  
Diamond Indenter ◽  
Different Content

The present study focuses on scratch behaviour of a conventional pearlitic and a number of solid solution strengthened ferritic Compacted Graphite Iron (CGI) alloys. This was done by employing a single-pass microscratch test using a sphero-conical diamond indenter under different constant normal loads conditions. Matrix solution hardening was made by alloying with different content of Si alloy; (3.66, 4.09 and 4.59 wt%. Si) which are named as low-Si, medium-Si and high-Si ferritic CGI alloys, respectively. A good correlation between the tensile and scratch test results was observed explaining the influence of CGI’s matrix characteristics on scratch behaviour both for pearlitic and fully ferritic solution strengthened ones. Both the scratch depth and scratch width showed strong tendency to increase with increasing the normal load, however the pearlitic one showed more profound deformation compared to the solution strengthened CGI alloys. Among the investigated alloys, the maximum and minimum scratch resistance was observed for high-Si ferritic CGI and pearlitic alloys, respectively. It was confirmed by the scratched surfaces analysed using Scanning Electron Microscopy (SEM) as well. In addition, the indenter’s depth of penetration value (scratch depth) was found as a suitable measure to ascertain the scratch resistance of CGI alloys.Keywords: Silicon solution strengthening, CGI, Abrasion, Scratch testing, Scratch resistance

scholarly journals Relationship Between Rockwell C Hardness and Inelastic Material Constants

2002 ◽  
Vol 124 (2) ◽  
pp. 179-184 ◽  
Author(s):  
Akihiko Hirano ◽  
Masao Sakane ◽  
Naomi Hamada
Keyword(s):  
Finite Element ◽  
Friction Coefficient ◽  
Strain Hardening ◽  
Yield Stress ◽  
Plastic Material ◽  
Stress And Strain ◽  
Material Constants ◽  
Elastic Plastic ◽  
Elastic Plastic Material ◽  
Hardening Coefficient

This paper describes the relationship between Rockwell C hardness and elastic-plastic material constants by using finite element analyses. Finite element Rockwell C hardness analyses were carried out to study the effects of friction coefficient and elastic-plastic material constants on the hardness. The friction coefficient and Young’s modulus had no influence on the hardness but the inelastic materials constants, yield stress, and strain hardening coefficient and exponent, had a significant influence on the hardness. A new equation for predicting the hardness was proposed as a function of yield stress and strain hardening coefficient and exponent. The equation evaluated the hardness within a ±5% difference for all the finite element and experimental results. The critical thickness of specimen and critical distance from specimen edge in the hardness testing was also discussed in connection with JIS and ISO standards.

scholarly journals Effect of Preliminary Irradiation of 321 Steel Substrates with High-Intense Pulsed Ion Beams on Scratch Test Results of Subsequently Deposited AlN Coatings

Coatings ◽  
2021 ◽  
Vol 11 (10) ◽  
pp. 1169
Author(s):  
Vladislav Tarbokov ◽  
Sergey Pavlov ◽  
Egor Smolyanskiy ◽  
Vladimir Uglov ◽  
Mikhail Slobodyan ◽  
...  
Keyword(s):  
Ion Beam ◽  
Energy Levels ◽  
Scratch Test ◽  
Future Research ◽  
Surface Layers ◽  
Emission Signal ◽  
Future Research Directions ◽  
Modified Surface ◽  
Scratch Tests ◽  
Steel Substrates

The paper presents the effect of irradiation of 321 steel substrates with a high-intense pulsed ion beam (HIPIB) on changes in functional properties of the surface layers and tribological characteristics of AlN coatings subsequently deposited above by the reactive magnetron sputtering method. The morphology of the modified surface layers, their microhardness and free surface energy levels are presented for different HIPIB energy densities. HIPIB irradiation of the substrates caused variations in the results of scratch tests combined with the acoustic emission signal processing. Their analysis has enabled concluding that the crack initiation threshold could be at least doubled for the studied coating/substrate system due to preliminary HIPIB irradiation. Finally, the obtained data were discussed, and future research directions were proposed.

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