Korozja pokrycia samolotu i względy bezpieczeństwa konstrukcyjnego

The aim of this article is to point out some peculiarities of airframe corrosion, the impact of external forces on aircraft skin elements and their impact on structural integrity. The corrosion process is generally associated with fatigue of aircraft structural elements due to the effect of many factors such as the type of loading, the properties of the materials, the corro-sive environment, etc. The article is not focused on corrosion processes, but on load factors that are specific to aircraft wing design elements and their influence on corrosion of critical struc-tural elements. Corrosion of the wing is perceived as a consequence of environmental impact on damaged surface protection of the skin and connecting parts (rivets, screws, and welded joints) caused by static and dynamic stress of the wing and also by the interaction of the indi-vidual structural elements as a whole. The dynamics of operation of individual structural ele-ments is further enhanced by the fatigue of the material. Early detection of corrosion processes has generally been and is crucial to overall safety of the aircraft. The proposals presented in the article are formulated in order to improve the system of work to ensure the safety of aircraft operation in terms of resistance to corrosion damage.

Morphing Winglet Design for Aerodynamic Performance Optimization of the CRJ-700 Aircraft. Part 1 – Structural Design

This study aims to design a morphing winglet structure for the CRJ-700 regional transport aircraft. The morphing technology is applied on winglets to demonstrate a significant increase of the aerodynamic performance of aircraft. From the aerodynamic data of the LARCASE Virtual Research Simulator VRESIM, the aerodynamic benefits in the cruising phase were obtained through a study on the ParaView software. The morphing winglet design was drawn using CATIA V5; this new concept included several structural components, as well as a simple and light mechanism allowing to orientate the winglet angles between 90° and -90° of inclination. The structural model was exported to HyperMesh structural analysis software. Maximum stresses were obtained, and the model demonstrated its resistance to maximum aerodynamic loads as well as load factors of -2G to 7G.

Dynamic Response and Reliability Analysis of Buried Steel Pipes Under Blast Load

Comprehensively considering the influence of multiple load factors involved in the stress of buried pipelines, the dynamic response model and failure function of buried pressurized pipelines under explosive loads are established, and the formula for calculating the stresses of buried pressurized pipelines is proposed. Design and carry out dynamic response model experiment of buried steel pipe under explosive load, and extract relevant model parameters according to experimental data. For the buried pressurized steel pipes under extreme experimental conditions, the reliability analysis was carried out by Monte Carlo method, and the limit proportional distance of pipeline failure under experimental conditions was obtained. To determine the degree of influence of various parameter changes on the reliability of buried steel pipes. The research results can provide a certain reference for the quantitative risk assessment and safe operation analysis of the adjacent buried pipelines in blasting construction.

A BUSINESS MODEL ENABLING A PASSENGER-DISTANCE-IMPROVED LONG-HAUL NETWORK TO DECREASE TRANSPORT INEFFICIENCIES

The air transport system faces pressing challenges arising from CO2-emission reduction targets, fragmented passenger needs, and a highly competitive market environment. Aiming for a reduction of CO2-emissions in the long-haul sector, a holistic solution is suggested incorporating both operational and technological innovations in three areas: (1) changes in the air transport network structure, (2) (liquid) hydrogen as energy carrier, and (3) new aircraft and cabin design. To these ends, this paper focuses on the implications resulting from a passenger-distance improved air transport network. Demand pooling is proposed to enable higher load factors, offer more point-to-point connections for passengers, and generate new revenue sources for airlines. Based on a discussion of traditional airline business models, a seat exchange platform named “ShAirline” is proposed, allowing multiple providers to rent out cabin space. The underlying business model is evaluated considering implications for aircraft and cabin design, new passenger services, additional revenue opportunities, passenger journey times, required aircraft, as well as implications for airports. Findings indicate that the proposed seat exchange platform in conjunction with a change in aircraft ownership structure assist in removing inefficiencies across the current long-haul network and help offset barriers connected to the use of novel eco-efficient technologies.

Analysis of distribution laws of transformer oil indicators in 110-330 kV transformers

Introduction. Ensuring the operational reliability of power transformers is an urgent task for the power industry in Ukraine and for most foreign countries. One of the ways to solve this problem is the correction of maximum permissible values of insulation parameters. However, such a correction is fundamentally impossible without an analysis of the laws of distribution of diagnostic indicators in the equipment with different states. The purpose of the research is to analyse the laws of distribution of the quality indicators of transformer oil with different states in 110 and 330 kV transformers. Novelty. It was found that both 330 kV autotransformers and 110 kV transformers have the displacements between the mathematical expectations of the distribution density of usable oil indicators. It caused by different service life of the analysed transformers and different values of load factors. This indicates the need to consider the influence of these factors when correcting the maximum permissible values of oil indicators. Also, the presence of displacement between the distribution densities of some indicators of usable oil in 110 kV transformers and 330 kV autotransformers has been revealed. It indicates a different intensity of oxidation reactions in transformers with different voltage class. In order to reduce the heterogeneity of initial data the procedure of statistical processing of in-service test results has been proposed as a method. This procedure combines the use of a priori information about the service life of equipment and values of load factors with the elements of statistical hypothesis testing. The results of the analysis of the distribution laws of transformer oil indicators with different states have shown that for both usable and unusable oil the values of oil indicators obey the Weibull distribution. Values of the shape and scale parameters for each of the obtained indices arrays have been obtained, as well as calculated and critical values of the goodness-of-fit criteria. Practical value. Obtained values of the distribution law parameters of the transformer oil indicators with different states, considering the service life and operating conditions allow to perform the correction of the maximum permissible values of the indicators using the statistical decision-making methods.

Simplified calculation of airblast variability and reliability-based design load factors for spherical air burst and hemispherical surface burst explosions

There can be significant uncertainty and variability with explosive blast loading. Standards and codes of practice are underpinned by reliability-based principles, and there is little reason not to apply these to explosive blast loading. This paper develops a simplified approach where regression equations may be used to predict the probabilistic model of airblast variability and associated reliability-based design load factors (or RBDFs) for all combinations of range, explosive mass and model errors. These models are applicable to (i) hemispherical surface bursts, and (ii) spherical free-air bursts. The benefit of this simplified approach is that the equations can be easily programed into a spreadsheet, computer code or other numerical methods. There is no need for any Monte-Carlo or other probabilistic calculations. Examples then illustrate how model error, range and explosive mass uncertainty and variability affect the variability of pressure and impulse, which in turn affect the damage assessment of residential construction.