scholarly journals Eshelby-Kröner Viscoelastic Self-Consistent Model Multi-Scale Behavior of Polymer Composites under Creep Loading

2013 ◽  
Vol 682 ◽  
pp. 105-112 ◽  
Author(s):  
A. Yousfi ◽  
Sylvain Fréour ◽  
Frédéric Jacquemin
Keyword(s):  
Mechanical Properties ◽  
Mechanical Response ◽  
Effective Properties ◽  
Time Dependent ◽  
Creep Process ◽  
Internal Stresses ◽  
Temperature Range ◽  
Consistent Model ◽  
Self Consistent ◽  
Different Temperatures

The mechanical response of the composite structure in T650-35/PMR-15 aged at different temperatures was studied numerically. The time-dependent internal stresses in the composite ply and its constituents were computed during the creep process. In order to predict the effective properties of PMR-15/T650-35 composite ply in the temperature range [250-350°, the time-dependent mechanical properties of PMR-15 matrix determined experimentally [, were considered. The mechanical properties of the fibers do not experience any change due to the aging process in such a temperature range [2, . In order to achieve the computations, the visco-elastic Eshelby Kröner self-consistent model was used.

scholarly journals Comparison of Different Micromechanical Models for Predicting the Effective Properties of Open Graded Mixes

2018 ◽  
Vol 2672 (28) ◽  
pp. 404-415 ◽  
Author(s):  
Hong Zhang ◽  
Kumar Anupam ◽  
Athanasios Scarpas ◽  
Cor Kasbergen
Keyword(s):  
Mechanical Properties ◽  
Young’S Modulus ◽  
Phase Angle ◽  
Young's Modulus ◽  
Asphalt Mixture ◽  
Dynamic Young’S Modulus ◽  
Consistent Model ◽  
Self Consistent ◽  
Dynamic Young's Modulus ◽  
Micromechanical Models

ZOAB (Zeer Open Asphalt Beton) is the most widely used asphalt mixture in the Netherlands. As a type of open asphalt mixture, it is known to suffer from raveling distress. In order to analyze the propensity of raveling, micromechanical models are considered effective. However, most of the research work about micromechanical models has focused on dense asphalt mixture and the application of these models on ZOAB mixes has not been paid adequate attention. Therefore, in this research study, the performance of various micromechanical models for predicting mechanical properties of ZOAB was evaluated. The predicted results were compared with the measured values from a dynamic uniaxial compression test. The analysis results showed that none of the applied micromechanical models could obtain acceptable predicted results of the dynamic Young’s modulus and phase angle of ZOAB. On one hand, the Dilute model, the Mori-Tanaka model, the generalized self-consistent model and the Lielens’ model provided lower values of dynamic Young’s modulus and higher values of phase angle, whereas, for the self-consistent model, the predicted results of dynamic Young’s modulus were higher, and the values of phase angle were lower. On the other hand, the shapes of the predicted master curves of both dynamic modulus and phase angle of ZOAB could not match well with the experimental results. The further research on the differential scheme method showed that at lower frequencies the predicted mechanical properties of ZOAB mixes by the applied micromechanical models could not be improved even by following this scheme.

scholarly journals Mechanical Behaviour of an Al2O3 Dispersion Strengthened γTiAl Alloy Produced by Centrifugal Casting

Metals ◽  
2020 ◽  
Vol 10 (11) ◽  
pp. 1457
Author(s):  
Daniela Pilone ◽  
Giovanni Pulci ◽  
Laura Paglia ◽  
Avishek Mondal ◽  
Francesco Marra ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Tial Alloy ◽  
Centrifugal Casting ◽  
Fracture Mechanisms ◽  
Potential Candidate ◽  
Dispersion Strengthening ◽  
Temperature Range ◽  
Structural Applications ◽  
Different Temperatures ◽  
Lower Temperature

γ-TiAl has been a hot topic of research for more than a few decades now, since it is a potential candidate for high temperature structural applications. In this paper, dispersion strengthening of γ based TiAl alloy, produced by means of centrifugal casting, has been performed to increase its mechanical properties beyond those of standard TiAl alloys. After a careful selection of the alloy composition based on the desired properties, several samples were produced by means of investment casting. This work focused on the effect of Al2O3 nano- and micro-dispersoids on the mechanical properties of the considered TiAl alloy. Microstructural investigations were carried out to study both the alloy microstructure and the Al2O3 dispersion homogeneity. Samples of the produced alloy were subjected to four-point bending tests at different temperatures for evaluating the effect of dispersed particles on mechanical properties. The results of this study were promising and showed that Al2O3 dispersion determined an increase of the mechanical properties at high temperatures. The Young’s modulus was 30% higher than that of the reference alloy in the lower temperature range. Over the temperature range 800–950 °C the dispersion strengthening affected the yield stress by increasing its value of about 20% even at 800 °C. A detailed evaluation of fracture surfaces was carried out to investigate fracture mechanisms.

Self-Consistent Determination of Time-Dependent Behavior of Metals

1981 ◽  
Vol 48 (1) ◽  
pp. 41-46 ◽  
Author(s):  
G. J. Weng
Keyword(s):  
Driving Forces ◽  
Pure Shear ◽  
Time Dependent ◽  
Hardening Law ◽  
Dependent Behavior ◽  
Consistent Model ◽  
Self Consistent ◽  
The Matrix ◽  
Latent Hardening

Though Kro¨ner’s self-consistent model is not fully consistent in the elastic-plastic deformation of polycrystals, it is found to be perfectly consistent in the time-dependent deformation of such materials. Hill’s model, on the other hand, should be used with a modified constraint tensor containing the elastic moduli of the matrix in that case. Kro¨ner’s model is supplemented with a physically consistent constitutive equation for the slip system; these, together with Weng’s inverse method, form the basis of a self-consistent determination of time-dependent behavior of metals. The kinematic component of the latent hardening law and the residual stress introduced in more favorably oriented grains are the two major driving forces for recovery and the Bauschinger effect in creep. The proposed method was applied to predict the creep and recovery strains of a 2618-T61 Aluminum alloy under pure shear, step and nonradial loading. The predicted results are seen to be in generally good agreement with the test data.

Temperature Influence on Microindentation Data of a Viscoelastic Material

2013 ◽  
Vol 586 ◽  
pp. 206-209
Author(s):  
Jiří Minster ◽  
Vlastimil Králík ◽  
Jiří Němeček
Keyword(s):  
Mechanical Properties ◽  
Master Curve ◽  
Time Dependent ◽  
Berkovich Indenter ◽  
Temperature Influence ◽  
Short Term ◽  
Temperature Superposition ◽  
Different Temperatures ◽  
Creep Measurements ◽  
Time Temperature Superposition

This paper aims to apply time-temperature superposition to short-term microindentation data measured at different temperatures, and to compare the viscoelastic compliance master curve that is found with data derived earlier from standard macro creep measurements in pressure. Using a sharp standard Berkovich indenter a successful application of this geometry in characterizing time-dependent mechanical properties of viscoelastic materials is confirmed.

HETEROGENEITY OF TIME-DEPENDENT MECHANICAL PROPERTIES OF HUMAN CORTICAL BONE AT THE MICRO SCALE

2015 ◽  
Vol 18 (04) ◽  
pp. 1550017 ◽  
Author(s):  
Sebastián Jaramillo-Isaza ◽  
Pierre-Emmanuel Mazeran ◽  
Karim El-Kirat ◽  
Marie-Christine Ho Ba Tho
Keyword(s):  
Mechanical Properties ◽  
Cortical Bone ◽  
Mineral Content ◽  
Mechanical Response ◽  
Extreme Values ◽  
Numerical Models ◽  
Time Dependent ◽  
Femoral Diaphysis ◽  
Interstitial Tissue ◽  
Micro Scale

Background: Remodeling process affects the mineral content of osteons and imparts heterogeneity through secondary mineralization; the aim of the present study is to assess the elastic and plastic time-dependent mechanical properties of osteons reflecting different mineral content as well as interstitial tissue of human femoral cortical bone by nanoindentation. Methods: Four trapezoiform blocks approximately 3[Formula: see text]mm thick were cut from the distal end of different human femoral diaphysis. Osteons with different apparent mineral degrees were classified by means of gray levels imaging using Environmental Scanning Electron Microscopy (ESEM). Nanoindentation tests were performed in the longitudinal direction of the bone axis using a four-stage protocol (load-hold-unload-hold) and the experimental curves were fitted by a mechanical model allowing the determination of the time-dependent mechanical properties. Results: Apparent low mineral content impact negatively the mechanical response of bone material at the micro-scale. Mechanical response varies among osteons exhibiting different mineral degrees. The values of the apparent elastic modulus double when the strain rate is analyzed at the extreme values ([Formula: see text] and infinity) whatever the bone component. Conclusions: These results evidence the mechanical heterogeneity of bone microstructure due to remodeling process. The quantification of the time-dependent mechanical properties could be useful to improve numerical models of bone behavior and provide new insights to build up original biomimetic materials.

A Brief Review of the Modelling of the Time Dependent Mechanical Properties of Tissue Engineering Scaffolds

2010 ◽  
Vol 6 ◽  
pp. 19-33 ◽  
Author(s):  
N.K. Bawolin ◽  
W.J. Zhang ◽  
Xiong Biao Chen
Keyword(s):  
Mechanical Properties ◽  
Tissue Engineering ◽  
Treatment Process ◽  
Effective Properties ◽  
Critical Role ◽  
Time Dependent ◽  
Tissue Engineering Scaffolds ◽  
Wide Range ◽  
Scaffold Degradation

The functionality of tissue scaffolds in vivo plays a critical role in the treatment process. Due to the time dependent nature of the mechanical properties of the constituent phases of the scaffold, a wide range of mechanical property histories may be observed during the treatment process, possibly influencing outcomes. The critical nature of the mechanical properties in load bearing applications indicates a need for the simultaneous modelling of both scaffold degradation and tissue regeneration with time, and the resulting effective properties of the tissue engineering construct. To this end, a review of the literature is conducted to identify the various existing approaches to modelling scaffold degradation, tissue behavior, and the dependency of the two processes on one another.

scholarly journals Quantitative Nanomechanical Mapping of Polyolefin Elastomer at Nanoscale with Atomic Force Microscopy

2021 ◽  
Vol 16 (1) ◽  
Author(s):  
Shuting Zhang ◽  
Yihui Weng ◽  
Chunhua Ma
Keyword(s):  
Mechanical Properties ◽  
Elastic Modulus ◽  
Mechanical Response ◽  
Adhesion Force ◽  
Time Dependent ◽  
Surface Adhesion ◽  
Force Microscopy ◽  
Mechanics Model ◽  
Atomic Force ◽  
Force Volume

AbstractElastomeric nanostructures are normally expected to fulfill an explicit mechanical role and therefore their mechanical properties are pivotal to affect material performance. Their versatile applications demand a thorough understanding of the mechanical properties. In particular, the time dependent mechanical response of low-density polyolefin (LDPE) has not been fully elucidated. Here, utilizing state-of-the-art PeakForce quantitative nanomechanical mapping jointly with force volume and fast force volume, the elastic moduli of LDPE samples were assessed in a time-dependent fashion. Specifically, the acquisition frequency was discretely changed four orders of magnitude from 0.1 up to 2 k Hz. Force data were fitted with a linearized DMT contact mechanics model considering surface adhesion force. Increased Young’s modulus was discovered with increasing acquisition frequency. It was measured 11.7 ± 5.2 MPa at 0.1 Hz and increased to 89.6 ± 17.3 MPa at 2 kHz. Moreover, creep compliance experiment showed that instantaneous elastic modulus E1, delayed elastic modulus E2, viscosity η, retardation time τ were 22.3 ± 3.5 MPa, 43.3 ± 4.8 MPa, 38.7 ± 5.6 MPa s and 0.89 ± 0.22 s, respectively. The multiparametric, multifunctional local probing of mechanical measurement along with exceptional high spatial resolution imaging open new opportunities for quantitative nanomechanical mapping of soft polymers, and can potentially be extended to biological systems.

Effects of Pseudoelastic Cycling under Different Temperatures on Physical and Mechanical Properties of a NiTi Alloy

2016 ◽  
Vol 97 ◽  
pp. 134-140
Author(s):  
Mariana Carla Mendes Rodrigues ◽  
Guilherme Corrêa Soares ◽  
Vicente Tadeu Lopes Buono ◽  
Leandro de Arruda Santos
Keyword(s):  
Mechanical Properties ◽  
Test Temperature ◽  
Mechanical Response ◽  
Niti Alloy ◽  
Physical And Mechanical Properties ◽  
Dissipated Energy ◽  
Uniaxial Tensile ◽  
Mechanical Cycling ◽  
Uniaxial Tensile Testing ◽  
Different Temperatures

The effects of pseudoelastic cycling under different temperatures on physical and mechanical properties of a NiTi superelastic wire were investigated by uniaxial tensile testing. The samples were cyclically deformed up to 6% strain under several test temperatures above the austenite finish temperature (Af). In order to approach a cyclic saturation level, number of cycles was established as 20. The temperature at which mechanical cycling was performed played a strong role on residual strain, dissipated energy and also on the critical stress to induce martensite, being consistent with the Clausius-Clapeyron relationship. It was found that an increase in test temperature resulted in more significant changes in the alloy’s functional behavior, but cyclic stability tended to be reached within fewer cycles. X-ray diffraction results showed that no martensite was stabilized at any condition and that austenite diffraction peaks intensities increased with test temperature, which was attributed to stress relaxation. Tensile tests until rupture and three point bending tests revealed that the mechanical response of the specimens cycled at higher temperatures and as received were fairly similar, and that specimens cycled at lower temperatures exhibited a slightly higher flexibility.

Changes of Mechanical Properties of Lightweight Cement Mortar Mixed with Recycled Expanded Polystyrene and Subjected to High Temperatures

2014 ◽  
Vol 1051 ◽  
pp. 752-756 ◽  
Author(s):  
Rocío Sancho ◽  
Ángel Castillo ◽  
Ma Eugenia Maciá ◽  
Rosa Corral
Keyword(s):  
Mechanical Properties ◽  
High Temperatures ◽  
Mechanical Response ◽  
Cement Mortar ◽  
Construction Materials ◽  
Lightweight Aggregate ◽  
Expanded Polystyrene ◽  
Partial Replacement ◽  
Different Temperatures ◽  
Residual Product

The main aim of this paper is to evaluate the influence of the recycled expanded polystyrene as lightweight aggregate on the mechanical properties of lightweight cement mortar when subjected to high temperatures.Various tests have been carried out on different mixtures of mortar. The water/cement mix proportion has always been the same and only the nature of the aggregates has changed, with a partial replacement of the conventional aggregate by recycled ground EPS (EPS-G) with values ranging from 10% to 30%, achieving significant results in relation to exposure to high temperatures. In this research, the samples have been subjected to different temperatures of exposure, in order to analyze the influence of the lightweight recycled arid dosage in the mechanical properties of mortars.The results of this study show the ability of mechanical response at high temperatures with light mortars EPS-G. This study shows how this new mix can be used in different building types, optimizing construction materials and reducing mortars density while transforming a residual product into an active product.

scholarly journals Study on High-Temperature Mechanical Properties of Fe–Mn–C–Al TWIP/TRIP Steel

Metals ◽  
2021 ◽  
Vol 11 (5) ◽  
pp. 821
Author(s):  
Guangkai Yang ◽  
Changling Zhuang ◽  
Changrong Li ◽  
Fangjie Lan ◽  
Hanjie Yao
Keyword(s):  
Mechanical Properties ◽  
High Temperature ◽  
Low Temperature ◽  
Tensile Fracture ◽  
Temperature Range ◽  
High Temperature Mechanical Properties ◽  
Ductility Trough ◽  
Different Temperatures ◽  
Reduction Of Area ◽  
High Temperature Tensile

In this study, high-temperature tensile tests were carried out on a Gleeble-3500 thermal simulator under a strain rate of ε = 1 × 10−3 s−1 in the temperature range of 600–1310 °C. The hot deformation process of Fe–15.3Mn–0.58C–2.3Al TWIP/TRIP at different temperatures was studied. In the whole tested temperature range, the reduction of area ranged from 47.3 to 89.4% and reached the maximum value of 89.4% at 1275 °C. Assuming that 60% reduction of area is relative ductility trough, the high-temperature ductility trough was from 1275 °C to the melting point temperature, the medium-temperature ductility trough was 1000–1250 °C, and the low-temperature ductility trough was around 600 °C. The phase transformation process of the steel was analyzed by Thermo-Calc thermodynamics software. It was found that ferrite transformation occurred at 646 °C, and the austenite was softened by a small amount of ferrite, resulting in the reduction of thermoplastic and formation of the low-temperature ductility trough. However, the small difference in thermoplasticity in the low-temperature ductility trough was attributed to the small amount of ferrite and the low transformation temperature of ferrite. The tensile fracture at different temperatures was characterized by means of optical microscopy and scanning electron microscopy. It was found that there were Al2O3, AlN, MnO, and MnS(Se) impurities in the fracture. The abnormal points of thermoplasticity showed that the inclusions had a significant effect on the high-temperature mechanical properties. The results of EBSD local orientation difference analysis showed that the temperature range with good plasticity was around 1275 °C. Under large deformation extent, the phase difference in the internal position of the grain was larger than that in the grain boundary. The defect density in the grain was large, and the high dislocation density was the main deformation mechanism in the high-temperature tensile process.

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