Load-carrying Properties Research Articles

Influence of interference of the wing and fuselage on aerodynamic characteristics

In this paper, a change in the aerodynamic characteristics of the aircraft layout with a wing and a fuselage depending on the position of the fuselage relative to the wing is studied. A simulation of the flow of calculation models with different positions and the angle of the wing with respect to the fuselage is performed. The aerodynamic characteristics have been obtained, the analysis of the change of bearing properties and the criteria of the efficiency of the layout has been made, the maximum peaks of aerodynamic perfection of K have been determined. For constructive considerations, the most acceptable variant of the layout with the angle of the 8 ° wing and the wing of Y KP equal to the wing chord b is determined. The lifting power of the calculation model for different values of φ KR and Ykr is practically unchanged. The value of the Суа α ≈ 0.083 derivative in comparison with the characteristics of the isolated wing remains unchanged, which confirms the absence of interference effects on the load-carrying properties of the layout. The value of the aerodynamic perfection of the calculation models depends greatly on the values of φ KR and Ykr. Decreasing Ykr for a given value of the Суа coefficient, it significantly reduces the value of aerodynamic perfection to the layout, which clearly demonstrates the effect of interference on the level of frontal resistance. It is proved that physically, the cause of the fall in the maximum value of K is not just the increase in the resistance of the interference, but the decrease of the lift force due to the presence of a significant discharging area on the lower surface of the wing caused by the dispersal of the flow around the surface of the fuselage and the corresponding decrease in the value of total pressure in the flow between the wing and the fuselage. It has also been proved that the existence of such correlations of the angle of the φKr installation and the excess Ykr of the wing, in which the interference is positive and the maximum value of the aerodynamic quality of the lay-outs, increases. The main results are presented in graphical form for all combinations.

An investigation on the tribological properties of Co(ReO4)2/MoS2 composite as potential lubricating additive at various temperatures

The Co(ReO4)2 powder was fabricated via the aqueous solution method, and mixed with MoS2 powder using ball milling technique. A certain concentration of Co(ReO4)2/MoS2 composite additive was dispersed into the poly alpha olefin base oil with the assistance of surface active agents. The load-carrying property and lubricating behavior of base oil containing a certain content of Co(ReO4)2/MoS2 composite additive at various temperatures were evaluated by four-ball test and ball-on-disc sliding friction test. The physical properties and friction-reducing mechanism of synthesized composite were ascertained by a series of characterization techniques including X-ray diffraction, scanning electron microscopy-energy dispersive spectroscopy, X-ray photoelectron spectroscopy, and differential thermal analysis/thermogravimetry. The four-ball test results suggested the Co(ReO4)2/MoS2 composite additive could effectively promote the load-carrying capacity of base oil, and decrease the friction coefficient as well as wear scar diameter. Ball-on-disc sliding friction test results showed that the base oil with Co(ReO4)2/MoS2 composite additive possessed lower friction coefficients than that of base oil in the whole temperature range, particularly at high temperatures. The protective layer consisted of composite additive and native oxides from superalloy substrate formed on the worn surface to prevent the direct contact between friction pair. The Co(ReO4)2/MoS2 composite played a dominant role in friction-reducing function in the protective layer at elevated temperatures, and the reason for this was that MoS2 possessed layered structure and superior adsorption capacity, and Co(ReO4)2 had experienced thermal softening with elevated temperatures and maintained shear-susceptible hexagonal structure.

The Effect of Concrete Shrinkage Crack on Load-carrying Properties of Floor Slab

Shrinkage crack is a common phenomenon in concrete. The driving forces of concrete shrinkage can be divided into two categories: temperature and humidity. For concrete floor, the main cause of shrinkage crack is plastic shrinkage and drying shrinkage. Shrinkage cracks appear on the concrete floor, which can easily cause the discomfort of perception and the suspicion of users' safety. Whether this type of floor slab is designed to meet the requirements of the design load, whether it can ensure the safe use and what kind of treatment measures should be taken is the key problem to be solved. In this paper, the load-carrying properties of the shrinkage crack floor slab are analyzed by field load test.

A Multiscale Approach to the Smart Deployment of Micro-Sensors over Lightweight Structures.

A topology optimization approach has been recently proposed to maximize the sensitivity to damage of measurements, collected through a network of sensors to be deployed over thin plates for structural health monitoring purposes. Within such a frame, damage is meant as a change in the structural health characterized by a reduction of relevant stiffness and load-carrying properties. The sensitivity to a damage of unknown amplitude and location is computed by comparing the response to the external actions of the healthy structure and of a set of auxiliary damaged structures, each one featuring reduced mechanical properties in a small region only. The topology optimization scheme has been devised to properly account for the information coming from all of the sensors to be placed on the structure and for damage depending on its location. In this work, we extend the approach within a multiscale frame to account for three different length scales: a macroscopic one, linked to the dimensions of the whole structure to be monitored; a mesoscopic one, linked to the characteristic size of the damaged region; a microscopic one, linked to the size of inertial microelectromechanical systems (MEMS) to be used within a marginally-invasive health monitoring system. Results are provided for a square plate and for a section of fuselage with stiffeners, to show how the micro-sensors have to be deployed to maximize the capability to detect a damage, to assess the sensitivity of the results to the measurement noise and to also discuss the speedup in designing the network topology against a standard single-scale approach.

Experimental investigation on wear resistance of a new cutting fluid using a four ball tribometer – optimization of additive percent

The cutting fluid manufacturers aim to obtain the best products at the lowest possible price. To achieve such a compromise experimental work is needed, trying to get the lowest allowed content of additive in the base oil. The paper presents the results of standard tests carried out on four ball machine. This tribometer is used to analyze the load-carrying properties of cutting fluids. The results are compared with the standard requirements, related to the measured wear scar on the three lower balls of the four ball device. An optimum of sulphur additive content into the base oil was found around 10%. According to the actual standards and following the results of carried-out tests, for this specific case the lowest acceptable content of additive is around 4%.

Synthesis, Characterization, and Tribological Evaluation of TiO2-Reinforced Boron and Nitrogen co-Doped Reduced Graphene Oxide Based Hybrid Nanomaterials as Efficient Antiwear Lubricant Additives.

The microwave-synthesized reduced graphene oxide (MRG), boron-doped reduced graphene oxide (B-MRG), nitrogen-doped reduced graphene oxide (N-MRG), boron-nitrogen-co-doped reduced graphene oxide (B-N-MRG), and TiO2-reinforced B-N-MRG (TiO2-B-N-MRG) nanomaterials have been synthesized and characterized by various state-of-the-art techniques, like Raman spectroscopy, powder X-ray diffraction, scanning electron microscopy (SEM) with energy-dispersive X-ray spectroscopy, high-resolution transmission electron microscopy, and X-ray photoelectron spectroscopy. Furthermore, the tribological properties of prepared nanomaterials as antiwear additives in neutral paraffin oil have been evaluated using a four-ball machine at an optimized additive concentration (0.15% w/v). The tribological parameters, like mean wear scar diameter, coefficient of friction, and wear rates, revealed that these nanomaterials have potential to be developed as environmentally friendly sulfated-ash-, phosphorus-, and sulfur-free antiwear lubricant additives. The friction- and wear-reducing behavior of MRG increased upon successive doping of nitrogen, boron, and both nitrogen and boron. Among these additives, B-N-co-doped MRG shows superior tribological behavior in paraffin base oil. Besides this, the load-carrying properties of B-N-co-doped MRG have significantly improved after its reinforcement with TiO2 nanoparticles. A comparative study of the surface morphology of a lubricated track in the presence of various additives has been assessed by SEM and contact-mode atomic force microscopy. The X-ray photoelectron spectroscopy studies have proved that the excellent lubrication properties of TiO2-B-N-MRG are due to the in situ formation of a tribofilm composed of boron nitride, adsorbed graphene layers, and tribosintered TiO2 nanoparticles during the tribocontact. Being sulfur-, halogen-, and phosphorus-free, these graphene-based nanomaterials act as green antiwear additives, protecting interacting surfaces significantly from wear and tear.

An investigation into the effect of substrate on the load-bearing capacity of thin hard coatings

TiN and diamond-like carbon (DLC) coatings were deposited on Ti substrates with and without processing by high-pressure torsion (HPT). The HPT processing refined the grain size of titanium from the coarse-grained (CG) size of ~8.6 µm to the ultra-fine grained (UFG) size of ~130 nm and increased the hardness from ~1.83 to ~3.05 GPa. Scratch test results revealed that all the thin hard coatings had a higher critical load when deposited on the harder UFG Ti substrate compared to those deposited on the softer CG Ti. A three-dimensional finite element model (3D FEM) revealed that the improved load-carrying property of the thin hard coatings on the harder titanium substrates was related to the higher stresses generated within the substrate and its deformation behaviour which reduced the strain at the coating/substrate interface. A model based on the hardness of a two-layered composite was used to explain this effect, and it is shown that the model is reasonably successful in predicting the critical load of a wide range of coating–substrate systems. The analytical model and the results of the 3D FEM modelling emphasize the contribution of the substrate to the load-bearing capacity of thin coatings.

Development of High Performance Aerogel Concrete

Current massive wall-building materials can be characterized by having either low thermal conductivities and thus low bulk densities and low compression strength or high compressions strength, high bulk densities and high thermal conductivities. In this paper, the first results of a research project are presented, in which a new aerogel-based construction material is developed that exhibits extra ordinary heat-insulating and load-carrying properties. By embedding silica aerogel granules in a high strength cement matrix “High Performance Aerogel Concrete” is developed, which combines the benefits of conventional concrete (compressive strength, unlimited moldability) with the properties of a heat insulating material. So far, various mixtures were examined in terms of their compressive strength and thermal conductivity. The first results are very promising with compressive strength between 3.0MPa and 23.6MPa and thermal conductivities between 0.16W/(mK) and 0.37W/(mK).

Impact of fracture toughness on surface properties of PVD coated cold work tool steel

Limited load-carrying capacity and impact loading resistance greatly restrict the use of hard coatings in forming applications, making substrate hardness and resistance crack initiation and propagation very important. Therefore, the aim of this research work was to investigate the effect of substrate fracture toughness and hardness on the load carrying capacity and impact wear resistance of coated tool steel, coated by monolayer (TiAlN), multilayer (AlTiN/TiN) and nano-composite ((Ti,Si)N) PVD coatings. By using different combinations and parameters of vacuum heat treatment and deep cryogenic treatment effect of the substrate fracture toughness and hardness on the load-carrying properties was determined under progressively loading dry sliding conditions, while ball-on-plate impact fatigue test was employed to investigate impact wear resistance. Results clearly show, that substrate hardness is the most important property influencing load-carrying capacity and impact wear resistance of the coated surface. However, with increased hardness and brittleness of the coating increase in fracture toughness although on the expense of the reduced hardness becomes beneficial.

The Analysis of Comparison of the 1000KV UHV Electrical Equipment and Circuit

The single UHV electrical equipment and numerical model for its circuit would be established by the Ansys software, after respectively analyze the Earthquake acceleration response spectrum of all the models, the stress distribution of equipments of all numerical model and its top displacement results would be get. By comparing the differences of every model’s result and focusing on the load-carrying properties of the structure, the experiments would get further optimizing space and confirm the circuit connection mode that is favorable for the Seismic resistance. After the comparison of single equipment and circuit results, it is suggested to establish a complete circuit numerical model while analyze and verify the converting station.

Pre-Test on the Behaviors of Vertical Prestressed Spacing to Composite Masonry Walls with Holes from the Aspect of Eccentrical Compression

Based on the eccentric compression performance testing of the out-of-planes of 4 pieces of different pre-stressed composite masonry walls with holes and constructional columns, the pre-stress’s influences on the horizontal and vertical transmission and distribution, emergence and development of cracks, deformation of the components and fracture morphology and mechanism of the section stress along composite wall with holes are revealed. The testing shows that the pre-stress not only improves comprehensively the load-carrying properties of composite wall, but its fracture mechanism and mechanical model are the same as that of the non-pre-stressed composite wall, so that the same design approach can be used. And it provides further experimental basis to supplement and improve the basic theory and computation methods of eccentric compression of composite wall’s out-of-plane in the current masonry structure specifications. Only crack resistance and bearing capacity are studied in this article.

Preparation and tribological properties of complex nanoparticle styrene/calcium borate with core-shell structure

Purpose – The purpose of this paper is to develop a potential nanoparticles lubricant additive for solving the problem of the insolubility and stable dispersity; the complex nanoparticles with core-shell structures are less studied in the field. Therefore, this paper determines novel complex nanoparticles and their tribological properties. Design/methodology/approach – According to the conventional preparation method, the complex nanoparticle styrene/calcium borate (PS/O-CaB) was synthesized. The microstructures of the as-obtained samples were characterized by X-ray diffraction infrared spectroscopy and thermogravimetric analysis. Tribological properties of PS/O-CaB used as lubricating oil additive were evaluated on four-ball tribometer. The worn surface of the steel ball was investigated by a three-dimensional non-contact surface profilometer and X-ray photoelectron spectroscopy (XPS). Findings – The results of the structure characteristic indicate two different crystalline forms, namely, Ca2B6O11 and Ca2B2O5, and the average size of calcium borate nanoparticles in PS/O-CaB is about 20-40 nm. Moreover, the good tribological properties are due to a wear resistance film containing both depositions and the tribochemical reaction products which comprise B2O3, FeB and Fe2O3. Originality/value – Novel complex nanoparticles with core-shell structure (PS/O-CaB) were successfully prepared. Moreover, the PS/O-CaB shows excellent tribological capacity such as load-carrying, friction-reducing and antiwear property.

Performance Analysis of One AP with 802.11g WLAN Network

This paper mainly presents Access Point s (APs) performance according to 802.11g standard. Our study illustrates the performance of one AP, including its coverage performance, load-carrying properties and fairness. Performance analyses are evaluated by simulation for a dense wireless network. Our contribution is that the simulation and test results can be the basis offered to network operators.

Knitted Wire Mesh Reinforced Powder Composite Materials Produced by Rolling*

The rolling of porous knitted wire mesh reinforced powder composite tapes is discussed. Data are reported on the effect of the architecture and structural and deformation features of knitted metal wire meshes on the processing parameters of reinforced composite tapes. It is established that using knitted wire as reinforcement for powder composites can help rolling difficult-to-form powder compositions. Despite their porosity, the resultant tapes have sufficient load-carrying capcaity and service properties required for some applications (electrode tapes, reinforced graphite seals).

Research of Reinforce Stress on the Pressure Structure of Submersible Vehicle

In order to improve the load-carrying properties of pressure structure, a new method to improve the external bearing limit is put forward and residual stress is used. Based on finite element analysis, finite element models of cylinder pressure structure of submersible vehicle are established to produce hoop residual stress in the process of outward expansion. According to a lot of data of simulation experiments, the result indicates that hoop residual stress is compressive on the outer surface of the pipe and the hoop stress keeps tensile on the inside surface. This kind of stress distribution is helpful to the cylinder structure and can improve its bearing capacity of external pressure. Moreover, the rules of the residual stress are got. The influences of physical dimension, yield strength of material and the expansion rate to the stress distribution are analyzed. The measures to produce the stress distribution are also presented.

Performance And Interference Analysis of 802.11G Wireless Network

This paper mainly presents Access Point s’ (APs’) performance and co-channel, adjacent channel interference according to 802.11g standard. Firstly, our study illustrates the performance of one AP, including its coverage performance, load-carrying properties and fairness. Next we propose the details about co-channel, adjacent channel interference which should be paid attention to in deploying network services. Then, performance analyses are evaluated by simulation and real test for a dense wireless network. Our contribution is that the co-channel, adjacent channel interference analysis, the simulation and test results can be the basis offered to network operators

The Basic Performance Analysis of the Rail Vehicle Body

The design and manufacture of the vehicle structure determines of the safety and suitability during operation. For most designers, the bearing capacity of the vehicle body is not completely understood. The initial estimate of the vehicle is simply a uniform simply supported overhang beam structure. With the development of computer technology, people can use more complex and closer to the actual body computational model, but it generally requires a lot of work, and designers are often only able to see the final result. It is not clear that the factors affect Load-carrying properties of the body structure. Designers often can not look find a process of improving the design. This method to scan the body structure by a computer calculation and analysis, the geometry, mechanical properties of parameters of the body cross-section has been plotted map. You can quickly and accurately understand the overall performance of the body, analysis the performance difference of different body cross-section. Reasonableness and balance of the body can be measured and awarded. In general, it is very important for the designer of the vehicle.

Effects of Lubricant Viscosity-Temperature Relationship on the Capacity of Sliding Bearing

Depending on the experimental data of Water-based lubricant viscosity-temperature relationship, this paper adopts Fluent software to analyze how lubricant viscosity-temperature relationship affects load-carrying properties of hybrid sliding bearings. The results show that lubricants will rise obviously when hybrid sliding bearings are in high speed, which will greatly affect bearing capacity and stiffness of bearings. The maximum stiffness of hybrid sliding bearings appears when the eccentricity is from 0.4 to 0.5. This conclusion is dramatically different from bearing capacity number ignored lubricant viscosity-temperature relationship.

The effect of heat treatment on the mechanical, tribological and load-carrying properties of PACVD-coated tool steel

The limited load-carrying capacity of tool steels greatly restricts the use of hard coatings in forming applications. This can, however, be improved by increasing the substrate's hardness, but especially for hot forging, the fracture toughness and resistance to cracking are equally important. The present work was focused on the possibilities of combining a vacuum heat treatment, a deep-cryogenic treatment and plasma nitriding in order to improve the properties of PACVD-coated tool steel.The investigation included TiCN-coated P/M high-speed steel, with 12 different combinations of the vacuum heat treatment, the deep-cryogenic treatment and plasma nitriding, which were investigated as a way of simultaneously improving the mechanical, tribological and load-carrying properties of tool steel. The results show that for the most demanding forming operations the substrate toughness is far more important than the hardness, especially at elevated temperatures, with just a vacuum-heat-treated steel substrate giving the best support for the top coating.

Lubrication of PVD coatings with ethyl-dimethyl-2-methoxyethylammonium tris(pentafluoroethyl)trifluorophosphate

This paper analyses the ethyl-dimethyl-2-methoxyethylammonium tris(pentafluoroethyl)trifluorophosphate [(NEMM)MOE][FAP] ionic liquid as pure lubricant and as an additive (PAO 6 as base oil) within the lubrication of three PVD coatings (TiN, CrN and DLC). Tribological tests were performed using a ball-on-plate reciprocating machine. The results show a slight decrease in friction when the ionic liquid was used as additive in comparison with performance of neat PAO 6. [(NEMM)MOE][FAP] as pure lubricant showed the highest friction and wear reduction. The formation of tribofilms due to the ionic liquid–surface interactions improved the load-carrying properties of the coatings. These results were compared to the ones obtained with another previously studied ionic liquid which has the same anion.