Dynamic Mechanical Properties of Ceramics and Ceramic Composites at Elevated Temperatures

1997 ◽  
Vol 119 (1) ◽  
pp. 15-19 ◽  
Author(s):  
S. Yang ◽  
R. F. Gibson ◽  
G. M. Crosbie ◽  
R. L. Allor
Keyword(s):  
Mechanical Properties ◽  
Elastic Modulus ◽  
Room Temperature ◽  
Elevated Temperatures ◽  
Ceramic Composites ◽  
Dynamic Mechanical Properties ◽  
Internal Damping ◽  
Temperature Dependent ◽  
Dynamic Mechanical ◽  
Dynamic Mechanical Behavior

This paper presents the preliminary results of our research on dynamic mechanical properties of silicon nitride based ceramics and ceramic composites at elevated temperatures. The temperature-dependent dynamic elastic modulus and internal damping of the cantilever beam samples were measured from room temperature up to 1100°C. The dynamic mechanical behavior is found to be rather stable up to 700°C, but damping peaks are found to occur at around 900°C, accompanied by a corresponding relaxation in elastic modulus for the tested samples. By simulating the thermal cycling environment of engines, the resulting changes in the dynamic mechanical properties of the samples are observed. The possible mechanisms affecting the dynamic mechanical properties of these ceramics and ceramic composites, with special emphasis on high-temperature behavior, are discussed.

scholarly journals SHPB Testing and Analysis of Bedded Shale under Active Confining Pressure

2020 ◽  
Vol 2020 ◽  
pp. 1-8
Author(s):  
Guoliang Yang ◽  
Jingjiu Bi ◽  
Xuguang Li ◽  
Jie Liu ◽  
Yanjie Feng
Keyword(s):  
Mechanical Properties ◽  
Elastic Modulus ◽  
Strain Rate ◽  
Peak Stress ◽  
Confining Pressure ◽  
Dynamic Mechanical Properties ◽  
Dynamic Elastic Modulus ◽  
Peak Strain ◽  
Dynamic Mechanical ◽  
Bedding Angle

Shale gas is the most important new energy source in the field of energy, and its exploitation is very important. The research on the dynamic mechanical properties of shale is the premise of exploitation. To study the dynamic mechanical properties of shale from the Changning-Weiyuan area of Sichuan Province, China, under confining pressure, we used a split Hopkinson pressure bar (SHPB) test system with an active containment device to carry out dynamic compression tests on shale with different bedding angles. (1) With active confining pressure, the shale experiences a high strain rate, and its stress-strain curve exhibits obvious plastic deformation. (2) For the same impact pressure, the peak stress of shale describes a U-shaped curve with an increasing bedding angle; besides, the peak stress of shale with different bedding angles increases linearly with rising confining pressure. The strain rate shows a significant confining pressure enhancement effect. With active confining pressure, the peak strain gradually decreases as the bedding angle increases. (3) As a result of the influence of different bedding angles, the dynamic elastic modulus of shale has obvious anisotropic characteristics. Shale with different bedding angles exhibits different rates of increase in the dynamic elastic modulus with rising confining pressure, which may be related to differences in the development of planes of weakness in the shale. The results of this study improve our understanding of the behavior of bedded shale under stress.

PVA-Based Scaffolds for the Repair of Musculoskeletal Soft Tissue

2007 ◽  
Author(s):  
L. P. Serino ◽  
M. G. Cascone ◽  
L. Lazzeri ◽  
P. A. Torzilli ◽  
S. A. Maher
Keyword(s):  
Mechanical Properties ◽  
Phase Angle ◽  
Dynamic Modulus ◽  
Composite Scaffold ◽  
Dynamic Mechanical Properties ◽  
Cartilage Defects ◽  
Poly Vinyl Alcohol ◽  
Dynamic Mechanical ◽  
Dynamic Mechanical Behavior

The objective of this study was to design a partly-degradable scaffold to repair cartilage defects. The scaffold, based on poly(vinyl alcohol), PVA, was intended to maintain long-term mechanical integrity and to facilitate cell proliferation via bioactive agent release from contained microparticles, made from either alginate, ALG or poly(lactic-co-glycolic acid), PLGA. The aim of this study was to characterize the morphological features and mechanical behaviour of composite scaffolds as a function of microparticle type and percent content. Our hypothesis was that the dynamic mechanical properties (Dynamic Modulus and Phase Angle) of the composite scaffold would not be affected by microparticle type, but that Dynamic Modulus would increase as a function of increased microparticle content. Scanning Electron Microscopy confirmed that the manufacturing process homogenously dispersed microspheres within the scaffolds. For pure PVA samples Dynamic Modulus ranged from 66±3 kPa at 0.01 Hz to 83±3 kPa at 50 Hz. As ALG microsphere content increased from 25% to 75%, Dynamic Modulus ranged from 92±5 kPa at 0.01 Hz to 153±19 kPa at 50 Hz. As the microsphere content increased from 25% to 75% PLGA, Dynamic Modulus ranged from 85±9 kPa at 0.01 Hz, to 157±16 kPa at 50 Hz. As expected, Dynamic Modulus increased with increasing test frequencies. For pure PVA specimens Phase Angle ranged from 4.3±0.8 degrees at 0.01 Hz to 12±1.2 degrees at 50 Hz. Phase Angle was not affected by microsphere content. In conclusion, the addition of microspheres affected the dynamic mechanical behavior, in particular Dynamic Modulus, of PVA scaffolds. However, the dynamic mechanical properties were not affected by the polymer from which the microspheres were manufactured. These findings suggest that microsphere type can be chosen to optimize the inclusion of bioactive factors, without detrimentally affecting the mechanical properties of the composite scaffold. It also suggests that % content of included microspheres can be used to modulate the mechanical properties of the scaffold at time zero.

Effect of Molecular Weight on Dynamic Mechanical Properties of SKD cis-1,4-Butadiene Rubber

1967 ◽  
Vol 40 (2) ◽  
pp. 517-521
Author(s):  
A. I. Marei ◽  
E. A. Sidorovich
Keyword(s):  
Mechanical Properties ◽  
Molecular Weight ◽  
Average Molecular Weight ◽  
Dynamic Mechanical Properties ◽  
Considerable Effect ◽  
Butadiene Rubber ◽  
Dynamic Mechanical ◽  
Temperature Range ◽  
Molecular Weights ◽  
Dynamic Mechanical Behavior

Abstract In the high-elastic temperature range the molecular weight has a considerable effect on the dynamic mechanical properties of linear (uncrosslinked) SKD cis-1, 4-butadiene rubber. In this temperature range an unequivocal correlation exists between the rebound resilience at a given temperature and the viscosity average molecular weight, and the determination of the resilience can therefore be recommended as a rapid method of finding the molecular weight of SKD. A similarity is found in the dynamic mechanical behavior of rubbers of different molecular weights in the high-elastic temperature range. In the low-temperature range an increase in the molecular weight of crystalline polymers of SKD is accompanied by an impairment of their elastic properties.

scholarly journals Dislocation Processes and Deformation Behavior in -Oriented FeX-Ni60–X-Al40 Single Crystals

2000 ◽  
Vol 646 ◽  
Author(s):  
P. S. Brenner ◽  
R. Srinivasan ◽  
R. D. Noebe ◽  
T. Lograsso ◽  
M. J. Mills
Keyword(s):  
Mechanical Properties ◽  
Elastic Modulus ◽  
Yield Strength ◽  
Strain Hardening ◽  
Single Crystals ◽  
Deformation Behavior ◽  
Room Temperature ◽  
Elevated Temperatures ◽  
Pseudobinary System ◽  
Dislocation Dissociation

ABSTRACTThe mechanical properties and dislocation microstructure of single crystals with a range of compositions within the Fex-Ni60–x-Al40 pseudobinary system have been investigated, with the purpose of bridging the behavior from FeAl to NiAl. Experiments are focused on the compression testing of <001> oriented single crystals with compositions where x = 10, 20, 30, 40, and 50 (in atomic percent). Observations of a<111> dislocation morphologies at room temperature and both a<111> and non-a<111> dislocation activity at elevated temperatures are reported and discussed. Measurements of the yield strength, elastic modulus and strain hardening rates are reported, and the variation of strength with composition is correlated with dislocation dissociation and overall dislocation morphology.

scholarly journals Colour Fastness to Various Agents and Dynamic Mechanical Characteristics of Biocomposite Filaments and 3D Printed Samples

Polymers ◽  
2021 ◽  
Vol 13 (21) ◽  
pp. 3738
Author(s):  
Deja Muck ◽  
Helena Gabrijelčič Tomc ◽  
Urška Stanković Elesini ◽  
Maruša Ropret ◽  
Mirjam Leskovšek
Keyword(s):  
Mechanical Properties ◽  
User Satisfaction ◽  
Elevated Temperatures ◽  
Dynamic Mechanical Properties ◽  
Morphological Properties ◽  
Colour Fastness ◽  
Dynamic Mechanical ◽  
Hemp Fibres ◽  
Wood Fibres ◽  
3D Printed

The aim of the study was to analyse the colour fastness of 3D printed samples that could be used as decorative or household items. Such items are often fabricated with 3D printing. The colour of filaments affects not only the mechanical properties, but also the appearance and user satisfaction. Samples of biocomposite filaments (PLA and PLA with added wood and hemp fibres) were used. First, the morphological properties of the filaments and 3D printed samples were analysed and then, the colour fastness against different agents was tested (water, oil, detergent, light and elevated temperature). Finally, the dynamic mechanical properties of the filaments and 3D printed samples were determined. The differences in the morphology of the filaments and 3D printed samples were identified with SEM analysis. The most obvious differences were observed in the samples with wood fibres. All printed samples showed good resistance to water and detergents, but poorer resistance to oil. The sample printed with filaments with added wood fibres showed the lowest colour fastness against light and elevated temperatures. Compared to the filaments, the glass transition of the printed samples increased, while their stiffness decreased significantly. The lowest elasticity was observed in the samples with wood fibres. The filaments to which hemp fibres were added showed the reinforcement effect. Without the influence on their elasticity, the printed samples can be safely used between 60 and 65 °C.

scholarly journals Static and dynamic mechanical behavior of doum palm (Hyphaene thebaica) nut reinforced HDPE composites

2021 ◽  
Vol 40 (4) ◽  
pp. 639-647
Author(s):  
A.A. Alabi ◽  
A.I. Obi ◽  
D.M. Kulla ◽  
S.M. Tahir
Keyword(s):  
Mechanical Properties ◽  
Dynamic Mechanical Properties ◽  
Particle Sizes ◽  
Load Bearing Capacity ◽  
Palm Fruit ◽  
Environmental Friendliness ◽  
Dynamic Mechanical ◽  
Dynamic Mechanical Behavior ◽  
Static Mechanical ◽  
Static Mechanical Properties

The quest to discover more and to enhance the qualities of agro-residue for use as natural reinforcement of polymers continues to attract the attention of researchers because of the environmental friendliness. Hyphaene thebaica also known as doum palm is a fruit tree native to the Nile in Egypt and found in abundance in many parts of Africa. Doum palm fruit contains probably the hardest and toughest known nut. The doum palm nuts (DPN) are the most under-used hard-nut despite their abundance in nature. This study presents the potential doum palm nut particles (DPNp) as natural reinforcement for high density polyethylene (HDPE). Properties of DPN such as density, hardness and weight loss due to heating were determined. HDPE/DPNp composites were produced by reinforcing HDPE with 30, 35, 40 and 45% DPNp particles of two different sizes. The particle sizes 600 μm and 710 μm led to classifying the composites as X-composite and Y-composite respectively. The static and dynamic mechanical properties of the composites were determined and compared with the those of pure HDPE. Results showed that HDPE and DPNp can be formed into light and attractive components. Loading HPDE with DPNp significantly improve static mechanical properties of HDPE such as tensile strength, hardness, stiffness and resistance to impact failure by 50%, 200%, 800% and 1500% respectively. The HDPE/DPNp composites also had better dynamic mechanical properties. The ability of the composites to maintain load bearing capacity under dynamic conditions was superior to that of HDPE.

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