Dynamic Behavior of Aviation Polymer Composites at Various Weight Fractions of Physical Modifier

The aim of this study was to determine the effect of a selected physical modifier with different granularity and mass percentage on the dynamics of aerospace polymer composites. The tests were carried out on samples made of certified aerospace materials used, among other purposes, for the manufacture of aircraft skin components. The hybrid composites were prepared from L285 resin, H286 hardener, GG 280T carbon fabric in twill 2/2 and alumina (Al2O3, designated as EA in this work). The manufactured composites contained alumina with grain sizes of F220, F240, F280, F320 and F360. The mass proportion of the modifier in the tested samples was 5% and 15%. The tested specimens, as cantilever beams fixed unilaterally, were subjected to kinematic excitation with defined parameters of amplitude and frequency excitation in the basic resonance zone of the structure. The results, obtained as dynamic responses, are presented in the form of amplitude–frequency characteristics. These relationships clearly indicate the variable nature of composite materials due to modifier density and grain size. The novelty of this study is the investigation of the influence of the alumina properties on system dynamics responses.

Influence of cerium content on the microstructure and thermal expansion properties of suction cast Al-Cu-Fe alloys

Low-expansion alloys are of great importance and can be used for the development of new aerospace materials. Herein, we report diverse rare earth quasicrystal alloys fabricated by the vacuum suction casting process. The effects of the addition of cerium (Ce) on the microstructure, thermal expansion properties and microhardness of the Al-Cu-Fe alloy were systematically investigated. This study discovered the tiny Al-Cu-Fe-Ce microstructure. A uniform distribution could be achieved after Ce addition amount is elevated. At the Ce addition amount of 1 at%, the lowest alloy thermal expansion coefficient was obtained. The alloy exhibited the maximum microhardness under these conditions. The microhardness of alloys containing 1 at% of Ce was approximately 2.4 times higher than the microhardness exhibited by alloys devoid of Ce additives. The coefficient of thermal expansion decreases by approximately 20%. The use of the suction casting process and the addition of an appropriate amount of Ce can potentially help design and develop Al-Cu-Fe-Ce alloys.

Microstructure and Oxidation Behavior of Anti-Oxidation Coatings on Mo-Based Alloys through HAPC Process: A Review

Mo and Mo-based alloys are important aerospace materials with excellent high temperature mechanical properties. However, their oxidation resistance is very poor at high temperature, and the formation of volatile MoO3 will lead to catastrophic oxidation failure of molybdenum alloy components. Extensive research on the poor oxidation problem has indicated that the halide activated pack cementation (HAPC) technology is an ideal method to solve the problem. In this work, the microstructure, oxide growth mechanism, oxidation characteristics, and oxidation mechanism of the HAPC coatings were summarized and analyzed. In addition, the merits and demerits of HPAC techniques are critically examined and the future scope of research in the domain is outlined.

К вопросу о режиме водных объектов Охотско-Колымского водораздела

The article discusses previously unexplored hydrological and hydrogeological manifestations of smallscale tectonics on a number of lakes and streams in the North-East of Russia. The research involves the results of the author's own observations, analysis of cartographic and aerospace materials of different years as well as published and interrogation data. Regime and evolution of the investigated objects display significant (to several years) variability within short time intervals, manifested in intense fluctuations of water levels in lakes, including their complete draining, absorption of rivers flow, and a number of other effects. The most unusual of them are: 1) counter-directed underground and surface water flows at one of the lakes' extremity; 2) an underground reservoir existence in low reaches of a stream. Most of the time, it drains the surface flow but occasionally it generates volleys of water many times exceeding the extreme floods on streams of comparable sizes. In high-water periods, it functions as a low-debit spring whose output oscillates daily under the influence of tidal force. Many of the studied objects are situated in localities of low-contrast relief without distinct features of tectonic activity. Undoubtedly, the presence of such features does not exclude the processes similar to the abovementioned, though in areas with intense and high-amplitude tectonic movements they are mostly obscure. Probably, in mountainous parts, including foothills, they are widespread. The results presented indicate the need for searching unconventional approaches to interpreting similar observations and using the maximum possible amount of available information. Practical importance of such studies is implied by the necessity to consider the possibility of local tectonic movements when designing industrial and civil objects. The leading inventory in this case should be the study of hydrological and hydrogeological peculiarities of regimes at the sites proposed and the retrospective analysis of cartographic and aerospace materials, examples of which are presented in this paper.

Compatibility Of Metallic & Non-Metallic Turbine Engine Materials With Aviation Fuels

As known alternative fuels shall undergo two crucial regulations in order to be certified: emission gas rate and the compatibility with engine parts. The objective of this research is to assess the compatibility of engine materials with JetA. The methodology here is in accordance with ASTM D4054; the proposed materials are soaked in proposed fuel. Subsequent to the soak period specimens are subject to specific test standards such as ASTM and visual inspection. Through assessment of compatibility the actual objective is to establish a systematic methodology for future alternative fuel research studies. In another meaning it is aimed to develop in-house capability to create optimum medium for future alternative fuel studies at Ryerson University's Facility for Research on Aerospace Materials and Engineered Structure. Results demonstrate that being wetted at elevated temperatures played a significant role on the physical properties of most non-metallic materials and there is almost no surface deformation observed on metallic materials.

Compatibility Of Metallic & Non-Metallic Turbine Engine Materials With Aviation Fuels

As known alternative fuels shall undergo two crucial regulations in order to be certified: emission gas rate and the compatibility with engine parts. The objective of this research is to assess the compatibility of engine materials with JetA. The methodology here is in accordance with ASTM D4054; the proposed materials are soaked in proposed fuel. Subsequent to the soak period specimens are subject to specific test standards such as ASTM and visual inspection. Through assessment of compatibility the actual objective is to establish a systematic methodology for future alternative fuel research studies. In another meaning it is aimed to develop in-house capability to create optimum medium for future alternative fuel studies at Ryerson University's Facility for Research on Aerospace Materials and Engineered Structure. Results demonstrate that being wetted at elevated temperatures played a significant role on the physical properties of most non-metallic materials and there is almost no surface deformation observed on metallic materials.