Thermal Deformation and Strength of Materials for Heat-shielding Coatings of a Spacecraft on the Trajectory of Descent from Orbit| Chapter 8 | Techniques and Innovation in Engineering Research Vol. 2

 The basis for a fundamental understanding of the process of material interaction with a medium is the agreement between experimental research and the actual operating conditions of a specific model or structure. Thermal Shield Materials (TSMs) are designed based on certain requirements, such as the characteristics of heating and material destruction under the least amount of shield weight. The more useful space load it can give, the lighter it must be. Since the thermal shield serves as a missile's ballast weight, it is only natural to want to lower the weight of TSMs without sacrificing their capacity to reliably perform their thermal shield role. Utilizing calculations based on the physical characteristics of materials discovered during conditions replicating a spacecraft's re-entry into the atmosphere, the performance of thermal shield structures was examined. The dependence of the temperature T of a thermal shield side surface on the period of descent in dense air layers serves as the basis for physical modelling of the natural conditions of thermal shield use (temperature, heating/cooling rate, composition, and pressure of gas medium). A thermal barrier was made composed of a laminated fibreglass shell with a phenol-phormaldehyde matrix. Investigations were done on temperature-dependent mechanical and thermophysical characteristics. By using numerical analysis, elasticity theory, and thermal conductivity equations to solve a 3D problem, it is possible to characterise the thermally stressed state of a cylindrical shield that is being impacted by a high-temperature gas flow. According to the results, the maximum compression stresses in a fibreglass thermal shield shell are located close to the heated surface and are not higher than the material's strength limit at that temperature. A new, 30% lighter thermal protection system for the re-entry vehicle was proposed and put into practise as a result of the experimental and theoretical investigations that were conducted.

Author(s) Details:

Lyudmila I. Gracheva,
G. S. Pisarenko Institute for Problems of Strength, National Academy of Sciences of Ukraine, Kiev - 01014, Ukraine.

Please see the link here: https://stm.bookpi.org/TAIER-V2/article/view/8276

Metrological Support for the Measurement of Tribological Properties of Carbon-carbon Composite in Braking Devices | Chapter 7 | Advanced Aspects of Engineering Research Vol. 11

 The essay focuses on the precision with which tribological parameters of a frictional carbon-carbon composite may be quantified during braking. Carbon-carbon materials are one of the most promising materials for large-scale use in friction units of transportation braking devices. When the rotating shaft with a previously established flyweight was in the braking mode, the experiments were carried out on the IM-58 frictional testing machine. The frictional heat resistance tests were carried out with 2168 UMT. The study looks at how sample heating affects the friction and wear attributes of the material. The accuracy features of the measured tribological properties are described in this work. For the brake unit to operate reliably, the maximum acceptable temperature of frictional heating in terms of wear was defined.

Author (s) Details

V. V. Alisin
Mechanical Engineering Research Institute, Russian Academy of Sciences, 119334, 4 Bardina st, Moscow, Russia.

View Book : https://stm.bookpi.org/AAER-V11/article/view/1252