scholarly journals Effect of Silane Treatment on Mechanical Properties of Polyurethane/Mesoscopic Fly Ash Composites

Polymers ◽  
2019 ◽  
Vol 11 (4) ◽  
pp. 741 ◽  
Author(s):  
Qin ◽  
Lu ◽  
He ◽  
Qi ◽  
Li ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Fracture Toughness ◽  
Fly Ash ◽  
Weight Percent ◽  
Bending Test ◽  
Fracture Toughness Test ◽  
Three Point Bending ◽  
Roof Fall ◽  
Bond Property ◽  
Polyether Polyol

In view of the accidents such as rock mass breakage, roof fall and coal slide in coal mines, polyurethane/mesoscopic fly ash (PU/MFA) reinforcement materials were produced from polymethylene polyphenylene isocyanate (PAPI), the polyether polyol, flame retardant, and MFA using stannous octanate as a catalyst. 3-Glycidoxypropyltrimethoxysilane (GPTMS) was grafted on MFA surface, aiming to improve the mechanical properties of PU/MFA composites. The analyses of infrared spectroscopy and compression resistance reveal that the GPTMS can be successfully attached to the surface of MFA, and the optimum modification dosage of GPTMS to MFA is 2.5 wt % (weight percent). On this basis, the effect of GPTMS on the mechanical properties of PU/MFA reinforcement materials during the curing process was systematically investigated through a compression test, a fracture toughness test, a three-point bending test, a bond property test, and a dynamic mechanics analysis. The results show that the compression property, fracture toughness, maximum flexural strength, and bond strength of PU/MFA composites increase by 21.6%, 10.1%, 8.8%, and 19.3%, respectively, compared with the values before the modification. Furthermore, the analyses of scanning electron microscope and dynamic mechanics suggest that the coupling agent GPTMS can successfully improve the mechanical properties of PU/MFA composites because it eliminates the stress concentration and exerts a positive effect on the crosslink density and hardness of PU/MFA composites.

Strength and Toughness of Graphite Materials for Solid Rocket Motor

2004 ◽  
Vol 449-452 ◽  
pp. 709-712
Author(s):  
Shoichi Nambu ◽  
Manabu Enoki
Keyword(s):  
Mechanical Properties ◽  
Fracture Toughness ◽  
Crack Propagation ◽  
Fracture Probability ◽  
Bending Test ◽  
Fracture Toughness Test ◽  
Solid Rocket Motor ◽  
Four Point Bending ◽  
Toughness Test ◽  
Solid Rocket

It was pointed out that one of the causes of recent failure to launch rocket was due to the fracture of nozzle throat insert made of graphite materials. The relationship between mechanical properties and microfracture process in graphite was not enough analyzed. To ensure the reliability of such aerospace equipment, we considered the necessity of assurance by non-destructive evaluation, evaluation of mechanical property for graphite material and design based on fracture probability. In this study, four-point bending test and fracture toughness test were used to evaluate mechanical properties. Mean strength, Weibull parameters, and R-curve for crack propagation were estimated. AE measurement during tests was performed in order to obtain location and stress of microfracture. AE results were analyzed by stochastic process theory. The result of AE demonstrates that microfracture process during bending test is divided into three stages. AE behavior in fracture toughness test was also closely related to crack propagation.

The Effects of MgO Addtion on the Mechanical Properties and the Phase Composition of Al2O3-TiC-TiN Ceramic Materials

2012 ◽  
Vol 457-458 ◽  
pp. 3-6
Author(s):  
Yu Huan Fei ◽  
Chuan Zhen Huang ◽  
Han Lian Liu ◽  
Bin Zou
Keyword(s):  
Mechanical Properties ◽  
Fracture Toughness ◽  
Phase Composition ◽  
Flexural Strength ◽  
Ceramic Materials ◽  
Bending Test ◽  
Vickers Indentation ◽  
Volume Percent ◽  
Sintered Ceramic ◽  
Three Point Bending

Al2O3-TiN-TiC ceramic materials with different MgO content were fabricated by hot-pressing technique. The MgO volume percent was varied from 0vol% to 5vol%. Three point bending test was applied to get the flexural strength and the Vickers indentation was applied to get the Vickers hardness and the fracture toughness. The phase composition of the ceramics was analyzed by XRD. The effects of the content of MgO on the mechanical properties and the phase composition of Al2O3-TiN-TiC were investigated. The results shows that the addition of MgO can change the phase composition of the sintered ceramic materials which displayed with diverse solid solutions and intermetallic compounds. The convertion of the mechanical properties can also be explained by the XRD results.

Evaluation of Mechanical Properties of Alumina Green Compact during Sintering at Relative Low Temperature

2005 ◽  
Vol 297-300 ◽  
pp. 945-950
Author(s):  
Shoichi Nambu ◽  
Manabu Enoki
Keyword(s):  
Fracture Toughness ◽  
Low Temperature ◽  
Complex Shape ◽  
Green Compact ◽  
Bending Test ◽  
Fracture Toughness Test ◽  
Three Point Bending ◽  
Temperature Fracture ◽  
The Relationship ◽  
Measured Strength

Recently, ceramics was used extensively as structural materials and ceramics components became larger and more complex. Fracture sometimes occurs during firing because of large and complex shape, and this fracture interrupts manufacturing process. The simulation of sintering has been studied to prevent this fracture. However, it was difficult to simulate fracture process because there was little data on strength of green compact. It is necessary to measure strength during sintering in order to perform a useful simulation. In this study, we measured strength of two kind of alumina green compact during sintering. Three point bending test at elevated temperature was performed and strength was estimated at each temperature. A model for strength at relative low temperature was also proposed using the temperature dependence of specific surface area. Furthermore, fracture toughness test was performed and the relationship between strength and fracture toughness was obtained. Strength at relative low temperature increased with temperature. Fracture toughness was proportional to strength at the temperature range where materials demonstrated brittle fracture manner. Strength of each alumina was analyzed using this model.

Influence of Confinement on Ceramic’s Mechanical Properties

2016 ◽  
Vol 848 ◽  
pp. 249-255
Author(s):  
Xiao Cong Hang ◽  
Yun Kai Li
Keyword(s):  
Mechanical Properties ◽  
Fracture Toughness ◽  
Boron Carbide ◽  
Fracture Process ◽  
Hot Spot ◽  
Efficiency Factor ◽  
Bending Test ◽  
Depth Of Penetration ◽  
Constraint Force ◽  
Three Point Bending

The wide use of ceramic material in engineering is restricted by its brittleness, so the strengthening and toughening of ceramics is always a hot spot of research in material area. And in general, the modification of ceramics is achieved by changing its internal microstructure. In this paper the influence of confinement on the mechanical properties of ceramics and the specific use of this method were investigated. Firstly, the influence of confinement on ceramic’s fracture process was analyzed in theory. Then the three-point bending test was conducted using two types of ceramics, viz. Zirconia and Alumina. The experimental results showed that the fracturing load of zirconia increased from 4.3298 to 5.4639KN as the confinement was increased from 0 to 150MPa, 26.19% increase was found in the confined specimen. The same trend was observed in alumina, whose fracturing load increased from 3.0446 to 5.0259KN as the confinement was increased from 0 to 150MPa, 65.07% increase was found. After that, a series of ballistic experiments were performed. The target in this experiment was boron carbide ceramic, and it was confined by 45 steel. The results showed that with the constraint force was bigger, the ballistic efficiency factor was better and the depth of penetration was smaller. In other words, the confinement can increase the defensible performance of the target. In summary, the ceramic’s fracture toughness, defensible performance and ballistic efficiency factor can be increased by adding confinement to it.

scholarly journals Effect of Nesfatin-1 on Rat Humerus Mechanical Properties under Quasi-Static and Impact Loading Conditions

Materials ◽  
2022 ◽  
Vol 15 (1) ◽  
pp. 333
Author(s):  
Anna Skic ◽  
Iwona Puzio ◽  
Grzegorz Tymicki ◽  
Paweł Kołodziej ◽  
Marta Pawłowska-Olszewska ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Fracture Toughness ◽  
Bone Structure ◽  
Critical Energy ◽  
Bending Test ◽  
Ovariectomized Rats ◽  
Loading Conditions ◽  
Sem Images ◽  
Three Point Bending ◽  
The Impact

The investigations on the response of bone tissue under different loading conditions are important from clinical and engineering points of view. In this paper, the influence of nesfatin-1 administration on rat humerus mechanical properties was analyzed. The classical three-point bending and impact tests were carried out for three rat bone groups: control (SHO), the humerus of animals under the conditions of established osteopenia (OVX), and bones of rats receiving nesfatin-1 after ovariectomy (NES). The experiments proved that the bone strength parameters measured under various mechanical loading conditions increased after the nesfatin-1 administration. The OVX bones were most susceptible to deformation and had the smallest fracture toughness. The SEM images of humerus fracture surface in this group showed that ovariectomized rats had a much looser bone structure compared to the SHO and NES females. Loosening of the bone structure was also confirmed by the densitometric and qualitative EDS analysis, showing a decrease in the OVX bones’ mineral content. The samples of the NES group were characterized by the largest values of maximum force obtained under both quasi-static and impact conditions. The energies absorbed during the impact and the critical energy for fracture (from the three-point bending test) were similar for the SHO and NES groups. Statistically significant differences were observed between the mean Fi max values of all analyzed sample groups. The obtained results suggest that the impact test was more sensitive than the classical quasi-static three-point bending one. Hence, Fi max could be used as a parameter to predict bone fracture toughness.

scholarly journals EPOXY/TITANATE MODIFIED NANOSILICA COMPOSITES: MORPHOLOGY, MECHANICAL PROPERTIES AND FRACTURE TOUGHNESS

2018 ◽  
Vol 56 (2A) ◽  
pp. 133-140
Author(s):  
Ho Ngoc Minh
Keyword(s):  
Mechanical Properties ◽  
Fracture Toughness ◽  
Impact Test ◽  
Charpy Impact ◽  
Charpy Impact Test ◽  
Bending Test ◽  
Tetrabutyl Titanate ◽  
Single Edge ◽  
Modified Silica ◽  
Three Point Bending

In this paper, the effect  of modified nanosilica as a reinforcement agent on the performance of epoxy resin using tetrabutyl titanate (TBuT) hardener were investigated. Morphology of the epoxy/modified silica composites was determined by Scanning Electron Microscopy (SEM) method. Impact strength and flexural strength of the composites were measured by Charpy impact test and three-point bending test mode methods, respectively. Fracture toughness and fracture energy were calculated according to pre-cracked, single edge notched method with specimens in three-point bending geometry and suitable equations. The mechanical properties and fracture toughness of composites were significantly enhanced with loading nanosilica content to 5 wt.%. 

Mechanical Properties of Zirconia Toughened Alumina Composites with TZP Partially Nanostructured Sintered by Liquid Fase

2008 ◽  
Vol 591-593 ◽  
pp. 436-440
Author(s):  
João Marcos K. Assis ◽  
Francisco Piorino Neto ◽  
Francisco Cristóvão Lourenço de Melo ◽  
Maria do Carmo de Andrade Nono
Keyword(s):  
Mechanical Properties ◽  
Fracture Toughness ◽  
Weibull Modulus ◽  
Bending Test ◽  
Sintering Aid ◽  
Zirconia Composites ◽  
Alumina Composites ◽  
Grain Size And Shape ◽  
Zirconia Toughened Alumina ◽  
Zirconia Powders

A comparative study between alumina added niobia ceramics and two alumina zirconia composites from nanostructured TZP (7% and 14% weight) was made. On this composites the zirconia were yttria stabilized and the alumina were submicron structured. As sintering aid a mixture of magnesia, niobia and talc were used on all samples. The sintering was performed at 1450 oC during 60 minutes. The characteristic grain size and shape of an alumina and zirconia powders, aggregates and agglomerates were characterized. The sintering ceramics were evaluated through hardness, fracture toughness and 4 point bending test. Weibull statistic was applied on the flexural results. Although the fracture toughness result from ZTA were lower, and seems to be affected by the liquid fase, the hardness and Weibull modulus were higher than alumina niobia. The grains size and the homogeneity of its distributions on the microstructure of this ceramics was correlated to these higher values. The results from these alumina zirconia composites showed a potential to apply as a ballistic armor material.

Influence of Honeycomb Core Compression on the Mechanical Properties of the Sandwich Structure

2013 ◽  
Vol 486 ◽  
pp. 283-288
Author(s):  
Ladislav Fojtl ◽  
Soňa Rusnáková ◽  
Milan Žaludek
Keyword(s):  
Mechanical Properties ◽  
Impact Test ◽  
Charpy Impact ◽  
Charpy Impact Test ◽  
Low Velocity Impact ◽  
Bending Test ◽  
Honeycomb Core ◽  
Low Velocity ◽  
Three Point Bending ◽  
Core Technology

This research paper deals with an investigation of the influence of honeycomb core compression on the mechanical properties of sandwich structures. These structures consist of prepreg facing layers and two different material types of honeycomb and are produced by modified compression molding called Crush-Core technology. Produced structures are mechanically tested in three-point bending test and subjected to low-velocity impact and Charpy impact test.

Comparison of the Cross Sectional Area, the Loss in Volume and the Mechanical Properties of LAE442 and MgCa0.8 as Resorbable Magnesium Alloy Implants after 12 Months Implantation Duration

2010 ◽  
Vol 638-642 ◽  
pp. 675-680 ◽  
Author(s):  
Martina Thomann ◽  
Nina von der Höh ◽  
Dirk Bormann ◽  
Dina Rittershaus ◽  
C. Krause ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Cross Sections ◽  
Degradation Process ◽  
Cross Sectional Area ◽  
Bending Test ◽  
Sectional Area ◽  
Cross Sectional ◽  
Initial Strength ◽  
Three Point Bending ◽  
The Cross

Current research focuses on magnesium based alloys in the course of searching a resorbable osteosynthetic material which provides sufficient mechanical properties besides a good biocompatibility. Previous studies reported on a favorable biocompatibility of the alloys LAE442 and MgCa0.8. The present study compared the degradation process of cylindrical LAE442 and MgCa0.8 implants after 12 months implantation duration. Therefore, 10 extruded implants (2.5 x 25 mm, cross sectional area 4.9 mm²) of both alloys were implanted into the medullary cavity of both tibiae of rabbits for 12 months. After euthanization, the right bone-implant-compound was scanned in a µ-computed tomograph (µCT80, ScancoMedical) and nine uniformly distributed cross-sections of each implant were used to determine the residual implants´ cross sectional area (Software AxioVisionRelease 4.5, Zeiss). Left implants were taken out of the bone carefully. After weighing, a three-point bending test was carried out. LAE442 implants degraded obviously slower and more homogeneously than MgCa0.8. The mean residual cross sectional area of LAE442 implants was 4.7 ± 0.07 mm². MgCa0.8 showed an area of only 2.18 ± 1.03 mm². In contrast, the loss in volume of LAE442 pins was more obvious. They lost 64 % of their initial weight. The volume of MgCa0.8 reduced clearly to 54.4 % which corresponds to the cross sectional area results. Three point bending tests revealed that LAE442 showed a loss in strength of 71.2 % while MgCa0.8 lost 85.6 % of its initial strength. All results indicated that LAE442 implants degraded slowly, probably due to the formation of a very obvious degradation layer. Degradation of MgCa0.8 implants was far advanced.

Fracture behaviors of HVFA-SCC mixed with seawater and sea-sand under three-point bending

2022 ◽  
pp. 136943322110273
Author(s):  
Lingzhu Zhou ◽  
Yu Zheng ◽  
Linsheng Huo ◽  
Yuxiao Ye ◽  
Xiaolu Wang ◽  
...  
Keyword(s):  
Fracture Toughness ◽  
Fly Ash ◽  
Unstable Fracture ◽  
Replacement Ratio ◽  
Three Point Bending ◽  
Model Code ◽  
Softening Curve ◽  
Sea Sand ◽  
Fracture Behaviors ◽  
Tensile Softening

This paper aims to study the fracture behaviors of high-volume fly ash-self-compacting concrete (HVFA-SCC) mixed with seawater and sea-sand (SWSS) or freshwater and river sand (FWRS). Three-point bending test were performed on 24 notched beams fabricated with varying in replacement ratio of fly ash (0%, 30%, 50%, and 70%) and the type of water and sand (SWSS and FWRS). The initial and unstable fracture toughness of these test specimens are determined by the double- K fracture model. The effect of fly ash replacement ratio and type of water and sand on the fracture parameters is analyzed and discussed. In addition, the cohesive fracture toughness of all the test specimens is calculated by using Gauss–Chebyshev integral method and the weight function method based on the bilinear tensile softening curve given in CEP-FIP Model Code. A comparison of fracture toughness parameters of determined from the experimental approach and analytical approaches is presented in these SCC specimens. Results show that SCC mixed with SWSS replacing FWRS can improve the unstable fracture toughness and fracture energy, and decrease its brittleness behavior. The cohesive fracture toughness of SWSS-SCC specimens is underestimated by these analytical methods based on the tensile softening curve given in CEP-FIP Model Code.

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