Dynamic Porosity of 3D Network SiC Ceramic as the Shock-Damping and Acoustic-Absorbing Material for Ultra-Precise Machine Laying

2015 ◽  
Vol 667 ◽  
pp. 267-273
Author(s):  
Dan Huang ◽  
Ying Wang ◽  
Wu Zhao
Keyword(s):  
Theoretical Foundation ◽  
Structure Design ◽  
Mesh Structure ◽  
Bulk Strain ◽  
Flexibility Matrix ◽  
Sic Ceramic ◽  
3D Network ◽  
Absorbing Material ◽  
Precise Machine ◽  
Porosity Model

The continuously improving of the performance of ultra-precise machine bed is claimed for, including not only the better tolerance stiffness, strength, shock and wear resistance, but also the further shock-damping and acoustic-absorbing performance. In this paper, the acoustic absorption for continuous network SiC ceramic as the laying of ultra-precise machine bed is investigated. By way of the constitutive relation of the network SiC ceramic, the flexibility matrix of such structural body is obtained. In line with the virtual loading application, the balance equation of the unit cell of the network structure is constructed, as well as the effective stress and effective Yang’s modulus. While the elastic flexibility matrix of the structure body can be re-construct with the results above, the bulk strain of the material under the infinitesimal strain would be derived from the modified matrix. The mechanism induced the deformation of network SiC structure is revealed by means of the combination of the dynamic porosity model with the bulk strain. The sensitivities of all kinds of effective factors to the dynamic porosity is analyzed and the order of parameters’ sensitivities to the dynamic porosity of 3D triangle structure is: pressure < temperature < initial porosity < network rod length < network rod radius. The results lay the theoretical foundation of the micro-mesh structure design of the network ceramics as the ultra-precise machine beding.

Preparation and Thermal-Physical Properties of Three Dimensional Bicontinuous SiC/Cu-Si Composite

2014 ◽  
Vol 804 ◽  
pp. 187-190 ◽  
Author(s):  
Kuo Zhang ◽  
Hong Yan Xia ◽  
Bo Wang ◽  
Zhong Qi Shi ◽  
Xiang Zhao Zhang ◽  
...  
Keyword(s):  
Physical Properties ◽  
Coefficient Of Thermal Expansion ◽  
Three Dimensional ◽  
Cu Alloy ◽  
Sic Ceramic ◽  
3D Network ◽  
Spontaneous Infiltration ◽  
Bicontinuous Structure ◽  
Porous Sic ◽  
Thermo Physical Properties

A three dimensional (3D) SiC/Cu-Si composite with bicontinuous structure was fabricated by spontaneous infiltration method, using porous recrystallized SiC ceramic with porosity of 37% as 3D network reinforcement and Cu alloy (Cu-18Si) as matrix. The phase composition, microstructure, and thermo-physical properties of the as-prepared 3D-SiC/Cu-Si composite were investigated. The experimental results showed that the Cu-18Si alloy could fully penetrate into the porous SiC ceramic at 1600 °C for 2 h spontaneously. SiC and Cu15Si4 phases were identified in the as-prepared composites. The interfacial bond between SiC and Cu-Si alloy was tightly and no severe interfacial reaction was observed. The thermal conductivity and coefficient of thermal expansion of the as-prepared 3D-SiC/Cu-Si composite were changed from 89.8 to 55 W·m-1·K-1 and 7.512 to 9.64×10-6 °C-1 with the temperature increased from room temperature to 500 °C, respectively.

Influencing Factors Analysis on Regulating Effect of the Pintle Controlled Thrust Regulating Mechanism

2010 ◽  
Vol 44-47 ◽  
pp. 1320-1324
Author(s):  
Lan Ting Zhang ◽  
Hai Qing Cheng ◽  
Li Ming Song ◽  
Jin Shun Yan
Keyword(s):  
Mathematical Model ◽  
Influencing Factors ◽  
Theoretical Foundation ◽  
Rocket Engine ◽  
Structure Design ◽  
Factors Analysis ◽  
Main Factors ◽  
Solid Rocket ◽  
And Control ◽  
The Mathematical Model

Based on the thrust regulating principle of pintle controlled solid-rocket engine, the mathematical model between pintle motion and thrust changing is established, and influence of main factors to thrust regulating effect is analyzed. These results can provide theoretical foundation for structure design and control of pintle controlled thrust regulating mechanism of solid-rocket engine.

scholarly journals Novel Three-Dimensional Graphene-Like Networks Loaded with Fe3O4 Nanoparticles for Efficient Microwave Absorption

Nanomaterials ◽  
2021 ◽  
Vol 11 (6) ◽  
pp. 1444
Author(s):  
Tao Shang ◽  
Qingshan Lu ◽  
Jianjun Zhao ◽  
Luomeng Chao ◽  
Yanli Qin ◽  
...  
Keyword(s):  
Microwave Absorption ◽  
Fe3o4 Nanoparticles ◽  
Large Scale ◽  
Three Dimensional ◽  
Ion Exchange Resin ◽  
Large Scale Preparation ◽  
3D Network ◽  
Hierarchical Porous ◽  
Absorbing Material ◽  
Scale Preparation

A novel three-dimensional graphene-like networks material (3D-GLN) exhibiting the hierarchical porous structure was fabricated with a large-scale preparation method by employing an ion exchange resin as a carbon precursor. 3D-GLN was first studied as the effective microwave absorbing material. As indicated from the results of the electromagnetic parameter tests, and the minimum reflection loss (RL) of the 3D-GLN reached −34.75 dB at the frequency of 11.7 GHz. To enhance the absorption performance of the nonmagnetic 3D-GLN, the magnetic Fe3O4 nanoparticles were loaded on the surface of the 3D-GLN by using the hydrothermal method to develop the 3D-GLN/Fe3O4 hybrid. The hybrid exhibited the prominent absorbing properties. Under the matching thickness of 3.0 mm, the minimum RL value of hybrid reached −46.8 dB at 11.8 GHz. In addition, under the thickness range of 2.0–5.5 mm, the effective absorption bandwidth (RL < 10 dB) was 13.0 GHz, which covered part of the C-band and the entire X-band, as well as the entire Ku-band. The significant microwave absorption could be attributed to the special 3D network structure exhibited by the hybrid and the synergistic effect exerted by the graphene and the Fe3O4 nanoparticles. As revealed from the results, the 3D-GLN/Fe3O4 hybrid could be a novel microwave absorber with promising applications.

Microstructural Heterogenieties in a Commercial SiC Structural Ceramic:Hraem

1982 ◽  
Vol 40 ◽  
pp. 564-565
Author(s):  
W.M. Skiff ◽  
R.W. Carpenter
Keyword(s):  
Sic Ceramic ◽  
Second Phases ◽  
Structural Irregularities

SiC refractories made by various pressing and sintering methods may contain structural and chemical heterogenieties similar to tljiose reported for Si3N4 base refractories. Although some earlier work on SiC did not reveal second phases, other oxidation experiments showed the reaction to take place heterogeneously, leading to the supposition that such heterogenieties may be present. In this work we examine a typical commercial SiC ceramic to determine the existence of such structural irregularities.

КОНСТРУКТИВНО-ТЕХНОЛОГІЧНІ ОСОБЛИВОСТІ ХВОСТО-ВИХ БАЛОК СІТЧАСТОГО ТИПУ З ПОЛІМЕРНИХ КОМПО-ЗИЦІЙНИХ МАТЕРІАЛІВ ВЕРТОЛЬОТІВ ТРАНСПОРТНОЇ КАТЕГОРІЇ

2020 ◽  
pp. 15-30
Author(s):  
А. Г. Гребеников ◽  
И. В. Малков ◽  
В. А. Урбанович ◽  
Н. И. Москаленко ◽  
Д. С. Колодийчик
Keyword(s):  
Finite Element ◽  
Strain State ◽  
Layer Structure ◽  
Metal Structure ◽  
Element Model ◽  
Stress Strain ◽  
Element Analysis ◽  
Mesh Structure ◽  
Stress Strain State ◽  
Mesh Structures

The analysis of the design and technological features of the tail boom (ТB) of a helicopter made of polymer composite materials (PCM) is carried out.Three structural and technological concepts are distinguished - semi-monocoque (reinforced metal structure), monocoque (three-layer structure) and mesh-type structure. The high weight and economic efficiency of mesh structures is shown, which allows them to be used in aerospace engineering. The physicomechanical characteristics of the network structures are estimated and their uniqueness is shown. The use of mesh structures can reduce the weight of the product by a factor of two or more.The stress-strain state (SSS) of the proposed tail boom design is determined. The analysis of methods for calculating the characteristics of the total SSS of conical mesh shells is carried out. The design of the tail boom is presented, the design diagram of the tail boom of the transport category rotorcraft is developed. A finite element model was created using the Siemens NX 7.5 system. The calculation of the stress-strain state (SSS) of the HC of the helicopter was carried out on the basis of the developed structural scheme using the Advanced Simulation module of the Siemens NX 7.5 system. The main zones of probable fatigue failure of tail booms are determined. Finite Element Analysis (FEA) provides a theoretical basis for design decisions.Shown is the effect of the type of technological process selected for the production of the tail boom on the strength of the HB structure. The stability of the characteristics of the PCM tail boom largely depends on the extent to which its design is suitable for the use of mechanized and automated production processes.A method for the manufacture of a helicopter tail boom from PCM by the automated winding method is proposed. A variant of computer modeling of the tail boom of a mesh structure made of PCM is shown.The automated winding technology can be recommended for implementation in the design of the composite tail boom of the Mi-2 and Mi-8 helicopters.

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