scholarly journals The Effect of Different Annealing Strategies on the Microstructure Development and Mechanical Response of Austempered Steels

Metals ◽  
2021 ◽  
Vol 11 (7) ◽  
pp. 1041
Author(s):  
Eliseo Hernandez-Duran ◽  
Luca Corallo ◽  
Tanya Ros-Yanez ◽  
Felipe Castro-Cerda ◽  
Roumen H. Petrov
Keyword(s):  
Mechanical Properties ◽  
Retained Austenite ◽  
Mechanical Response ◽  
Steel Grade ◽  
The Other ◽  
Microstructure Development ◽  
Microstructural Refinement ◽  
Heterogeneous Distribution ◽  
Parent Austenite ◽  
Conventional Annealing

This study focuses on the effect of non-conventional annealing strategies on the microstructure and related mechanical properties of austempered steels. Multistep thermo-cycling (TC) and ultrafast heating (UFH) annealing were carried out and compared with the outcome obtained from a conventionally annealed (CA) 0.3C-2Mn-1.5Si steel. After the annealing path, steel samples were fast cooled and isothermally treated at 400 °C employing the same parameters. It was found that TC and UFH strategies produce an equivalent level of microstructural refinement. Nevertheless, the obtained microstructure via TC has not led to an improvement in the mechanical properties in comparison with the CA steel. On the other hand, the steel grade produced via a combination of ultrafast heating annealing and austempering exhibits enhanced ductility without decreasing the strength level with respect to TC and CA, giving the best strength–ductility balance among the studied steels. The outstanding mechanical response exhibited by the UFH steel is related to the formation of heterogeneous distribution of ferrite, bainite and retained austenite in proportions 0.09–0.78–0.14. The microstructural formation after UFH is discussed in terms of chemical heterogeneities in the parent austenite.

Synergistic effects of fibre arrangements on the microstructure and properties of organic composite materials

2020 ◽  
Vol 54 (29) ◽  
pp. 4621-4634
Author(s):  
Fatma Makni ◽  
Anne-Lise Cristol ◽  
Mohamed Kchaou ◽  
Yannick Desplanques ◽  
Riadh Elleuch
Keyword(s):  
Mechanical Properties ◽  
Composite Materials ◽  
Mechanical Response ◽  
Synergistic Effects ◽  
The Other ◽  
Homogeneous Distribution ◽  
Carbonaceous Particle ◽  
Friction Materials ◽  
Fibre Bundles ◽  
Rock Wool

The arrangement of the constituents of organic-composite friction materials is a key factor of their microstructure and thermal and mechanical properties which can influence braking performance. Among these constituents, fibres can present complex morphologies and different arrangements depending on their type and the process of manufacturing. Besides, synergistic effects acting between these constituents and the resulting properties are still not well investigated. This work relates to rock- wool used for brake friction materials, and for which the process can lead to various arrangements. The focus is on synergies between these fibre arrangements and the other material constituents, in ways that reveals the link between the resulting microstructural characteristics and properties of organic composite materials. To achieve these objectives, two simplified formulations are elaborated with two distinct arrangements of rock wool fibres. The friction materials are investigated in terms of microstructure, thermo-physical and mechanical properties. It is found that fibre arrangements affect carbonaceous particle distribution, porosity, and fibre-matrix adhesion. On one side, homogeneous distribution and regular size of fibre bundles results in a better connectedness of conductive particles and thus enhances thermal conductivity. On the other side, a regular fibre bundles repartition lead to a more homogeneous distribution of strain localizations and a softer mechanical response.

scholarly journals A comparison between rotating squares and anti-tetrachiral systems: Influence of ligaments on the multi-axial mechanical response

2021 ◽  
pp. 095440622110431
Author(s):  
Luke Mizzi ◽  
Andrea Sorrentino ◽  
Andrea Spaggiari ◽  
Davide Castagnetti
Keyword(s):  
Mechanical Properties ◽  
Finite Element Analysis ◽  
Mechanical Response ◽  
The Other ◽  
Element Analysis ◽  
Strain Tolerance ◽  
Profound Influence ◽  
Mechanical Metamaterials ◽  
Auxetic Structures ◽  
High Level

Rotating unit systems are one of the most important and well-known classes of auxetic mechanical metamaterials. As their name implies, when loaded, these systems deform primarily via rotation of blocks of material, which may be connected together either directly through joints (or ‘joint-like’ connections made by overlapping vertices of the rotating units) as in the case of rotating rigid polygonal-unit systems or by ligaments/ribs as in the case of chiral honeycombs. In this work, we used Finite Element Analysis to investigate the effect which the presence/absence of ligaments has on the on-axis and off-axis mechanical properties of these systems by analysing two of the most well-known structures which characterise these two cases: the rotating square system and the anti-tetrachiral honeycomb. It was found that while the presence of ligaments has a negligible effect on the on-axis Poisson’s ratio of these systems, it has a profound influence on nearly all other mechanical properties as well as on the off-axis loading behaviour. Systems with ligaments were found to exhibit a high level of anisotropy and also a severely reduced level of stiffness in comparison to their non-ligamented counterparts. On the other hand, the rotating square system suffers from high localized stress-intensities and has a very low strain-tolerance threshold. In addition, an optimized ‘hybrid’ geometry which is specifically designed to capture the best features of both the anti-tetrachiral and rotating square system, was also analysed. This work shows the main differences between ligament-based and non-ligament-based auxetic structures and also highlights the importance of considering the off-axis mechanical response in addition to the on-axis properties when investigating such systems.

Role of some modifiers on the thermo-mechanical properties of Se90In10 chalcogenide glass (ChGs)

2021 ◽  
Author(s):  
A. Dahshan ◽  
H. Kumar ◽  
Neeraj Mehta
Keyword(s):  
Mechanical Properties ◽  
Mechanical Response ◽  
The Other ◽  
Mechanical Parameters ◽  
Micro Hardness ◽  
Optical Elements ◽  
Infrared Optics ◽  
Glassy Alloys ◽  
Direct Use

The studies on the micro-hardness of ChGs provide useful information regarding their straightforward involvement in the fabrication of sensors, fibers, and other optical elements for direct use in infrared optics. This work deals with the mechanical response of the glassy Se90In10 alloy under the influence of additives (Sn, Ag, Sb, and Ge). For this, we have determined the micro-hardness of all glassy alloys. Using the values of Vickers hardness (Hv), glass transition temperature (Tg), and present glasses, we have calculated the other significant thermo-mechanical parameters. The effect of Sn, Ag, Sb, and Ge additives on the micro-hardness of glassy Se90In10 alloy is also discussed.

Effect of Second Phase on Mechanical Properties of Bainite-Base Steels

2006 ◽  
Vol 15-17 ◽  
pp. 780-785 ◽  
Author(s):  
Hak Cheol Lee ◽  
Xiao Dan Wu ◽  
Young Min Kim ◽  
Nack J. Kim
Keyword(s):  
Mechanical Properties ◽  
Acicular Ferrite ◽  
Retained Austenite ◽  
Fine Particles ◽  
Volume Fraction ◽  
The Other ◽  
Second Phase ◽  
Effective Grain Size ◽  
Hot Rolling Conditions ◽  
Strength And Ductility

Effects of acicular ferrite and retained austenite on the mechanical properties of bainite-base steels were investigated. Various morphology and volume fraction of constituent phases have been obtained by control of hot rolling conditions and alloy compositions. It has been shown that the steels containing retained austenite have better combinations of strength and ductility than the ones with no retained austenite. However, there is no noticeable change in DBTT by the incorporation of retained austenite in the microstructure since retained austenite exists as fine particles. On the other hand, DBTT of the steels are largely affected by the presence of acicular ferrite in the microstructure. EBSD analyses of fractured Charpy specimens show that cracks are deflected within the morphological packet of acicular ferrite, indicating its role in reducing the effective grain size of the steels.

Physical and Mechanical Properties of Tenun Pahang Fabrics using Alternative Yarns

2016 ◽  
Vol 13 (2) ◽  
pp. 67
Author(s):  
Engku Liyana Zafirah Engku Mohd Suhaimi ◽  
Jamil Salleh ◽  
Suzaini Abd Ghani ◽  
Mohamad Faizul Yahya ◽  
Mohd Rozi Ahmad
Keyword(s):  
Mechanical Properties ◽  
Physical And Mechanical Properties ◽  
The Other ◽  
Silk Fabrics ◽  
Recovery Angle ◽  
Made In

An investigation on the properties of Tenun Pahang fabric performances using alternative yarns was conducted. The studies were made in order to evaluate whether the Tenun Pahang fabric could be produced economically and at the same time maintain the fabric quality. Traditional Tenun Pahang fabric uses silk for both warp and weft. For this project, two alternative yarns were used which were bamboo and modal, which were a little lower in cost compared to silk. These yarns were woven with two variations, one with the yarns as weft only while maintaining the silk warp and the other with both warp and weft using the alternative yarns. Four (4) physical testings and three (3) mechanical testings conducted on the fabric samples. The fabric samples were evaluated including weight, thickness, thread density, crease recovery angle, stiffness and drapability. The results show that modal/silk and bamboo silk fabrics are comparable in terms of stiffness and drapability, hence they have the potential to replace 100% silk Tenun Pahang.

scholarly journals Influence of artificial aging: mechanical and physicochemical properties of dental composites under static and dynamic compression

2021 ◽  
Author(s):  
D. C. Gornig ◽  
R. Maletz ◽  
P. Ottl ◽  
M. Warkentin
Keyword(s):  
Mechanical Properties ◽  
Water Sorption ◽  
Artificial Aging ◽  
Filler Content ◽  
Dynamic Compression ◽  
The Other ◽  
Chemical Degradation ◽  
Dental Composites ◽  
Compression Tests ◽  
Acid Ph

Abstract Objective The aim of the study was to evaluate the influence of filler content, degradation media and time on the mechanical properties of different dental composites after in vitro aging. Materials and Methods Specimens (1 mm3) of three commercially available composites (GrandioSO®, Arabesk Top®, Arabesk Flow®) with respect to their filler content were stored in artificial aging media: artificial saliva, ethanol (60%), lactic acid (pH 5) and citric acid (pH 5). Parameters (Vickers microhardness, compressive strength, elastic modulus, water sorption and solubility) were determined in their initial state (control group, n = 3 for microhardness, n = 5 for the other parameters) and after 14, 30, 90 and 180 days (n = 3 for microhardness, n = 5 for the other parameters for each composite group, time point and media). Specimens were also characterized with dynamic-mechanical-thermal analysis (compression tests, F =  ± 7 N; f = 0.5 Hz, 1 Hz and 3.3 Hz; t = 0–170 °C). Results Incorporation of fillers with more than 80 w% leads to significantly better mechanical properties under static and dynamic compression tests and a better water sorption behavior, even after chemical degradation. The influence of degradation media and time is of subordinate importance for chemical degradation. Conclusion Although the investigated composites have a similar matrix, they showed different degradation behavior. Since dentine and enamel occur only in small layer thickness, a test specimen geometry with very small dimensions is recommended for direct comparison. Moreover, the use of compression tests to determine the mechanical parameters for the development of structure-compatible and functionally adapted composites makes sense as an additional standard. Clinical relevance Preferential use of highly filled composites for occlusal fillings is recommended.

scholarly journals Evolution of Meniscal Biomechanical Properties with Growth: An Experimental and Numerical Study

2021 ◽  
Vol 8 (5) ◽  
pp. 70
Author(s):  
Marco Ferroni ◽  
Beatrice Belgio ◽  
Giuseppe M. Peretti ◽  
Alessia Di Giancamillo ◽  
Federica Boschetti
Keyword(s):  
Mechanical Properties ◽  
Stress Relaxation ◽  
Developmental Stage ◽  
Mechanical Response ◽  
Numerical Study ◽  
Numerical Models ◽  
Mechanical Stimulus ◽  
Specific Response ◽  
Mechanical Parameters ◽  
Biochemical Analyses

The menisci of the knee are complex fibro-cartilaginous tissues that play important roles in load bearing, shock absorption, joint lubrication, and stabilization. The objective of this study was to evaluate the interaction between the different meniscal tissue components (i.e., the solid matrix constituents and the fluid phase) and the mechanical response according to the developmental stage of the tissue. Menisci derived from partially and fully developed pigs were analyzed. We carried out biochemical analyses to quantify glycosaminoglycan (GAG) and DNA content according to the developmental stage. These values were related to tissue mechanical properties that were measured in vitro by performing compression and tension tests on meniscal specimens. Both compression and tension protocols consisted of multi-ramp stress–relaxation tests comprised of increasing strains followed by stress–relaxation to equilibrium. To better understand the mechanical response to different directions of mechanical stimulus and to relate it to the tissue structural composition and development, we performed numerical simulations that implemented different constitutive models (poro-elasticity, viscoelasticity, transversal isotropy, or combinations of the above) using the commercial software COMSOL Multiphysics. The numerical models also allowed us to determine several mechanical parameters that cannot be directly measured by experimental tests. The results of our investigation showed that the meniscus is a non-linear, anisotropic, non-homogeneous material: mechanical parameters increase with strain, depend on the direction of load, and vary among regions (anterior, central, and posterior). Preliminary numerical results showed the predominant role of the different tissue components depending on the mechanical stimulus. The outcomes of biochemical analyses related to mechanical properties confirmed the findings of the numerical models, suggesting a specific response of meniscal cells to the regional mechanical stimuli in the knee joint. During maturation, the increase in compressive moduli could be explained by cell differentiation from fibroblasts to metabolically active chondrocytes, as indicated by the found increase in GAG/DNA ratio. The changes of tensile mechanical response during development could be related to collagen II accumulation during growth. This study provides new information on the changes of tissue structural components during maturation and the relationship between tissue composition and mechanical response.

Ultrapurified Alginate Gel Containing Bone Marrow Aspirate Concentrate Enhances Cartilage and Bone Regeneration on Osteochondral Defects in a Rabbit Model

2021 ◽  
pp. 036354652110141
Author(s):  
Liang Xu ◽  
Atsushi Urita ◽  
Tomohiro Onodera ◽  
Ryosuke Hishimura ◽  
Takayuki Nonoyama ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Bone Marrow ◽  
Cell Transplantation ◽  
Cartilage Repair ◽  
Subchondral Bone ◽  
Bone Repair ◽  
Bone Marrow Aspirate ◽  
Defect Group ◽  
The Other ◽  
Osteochondral Defects

Background: Ultrapurified alginate (UPAL) gel implantation has been demonstrated as effective in cartilage repair for osteochondral defects; however, cell transplantation within UPAL gels would be required to treat larger defects. Hypothesis: The combination of UPAL gel and bone marrow aspirate concentrate (BMAC) would enhance cartilage repair and subchondral bone repair for large osteochondral defects. Study Design: Controlled laboratory study. Methods: A total of 104 osteochondral defects (1 defect per knee) of 52 rabbits were randomly divided into 4 groups (26 defects per group): defects without any treatment (Defect group), defects treated using UPAL gel alone (UPAL group), defects treated using UPAL gel containing allogenic bone marrow mesenchymal stromal cells (UPAL-MSC group), and defects treated using UPAL gel containing BMAC (UPAL-BMAC group). At 4 and 16 weeks postoperatively, macroscopic and histologic evaluations and measurements of repaired subchondral bone volumes of reparative tissues were performed. Collagen orientation and mechanical properties of the reparative tissue were assessed at 16 weeks. Results: The defects in the UPAL-BMAC group were repaired with hyaline-like cartilage with well-organized collagen structures. The histologic scores at 4 weeks were significantly higher in the UPAL-BMAC group (16.9 ± 2.0) than in the Defect group (4.7 ± 1.9; P < .05), the UPAL group (10.0 ± 3.3; P < .05), and the UPAL-MSC group (12.2 ± 2.9; P < .05). At 16 weeks, the score in the UPAL-BMAC group (24.4 ± 1.7) was significantly higher than those in the Defect group (9.0 ± 3.7; P < .05), the UPAL group (14.2 ± 3.9; P < .05), and the UPAL-MSC group (16.3 ± 3.6; P < .05). At 4 and 16 weeks, the macroscopic evaluations were significantly superior in the UPAL-BMAC group compared with the other groups, and the values of repaired subchondral bone volumes in the UPAL-BMAC group were significantly higher than those in the Defect and UPAL groups. The mechanical properties of the reparative tissues were significantly better in the UPAL-BMAC group than in the other groups. Conclusion: The implantation of UPAL gel containing BMAC-enhanced hyaline-like cartilage repair and subchondral bone repair of osteochondral defects in a rabbit knee model. Clinical Relevance: These data support the potential clinical application of 1-step treatment for large osteochondral defects using biomaterial implantation with cell transplantation.

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