Study on the test load for the structural test of the flight-load condition of the external fuel tank for fixed-wing aircraft

In this study, for the purpose of conducting the structural tests for the verification of structural soundness of the flight-load conditions of the external fuel tank for the fixed-wing aircraft, the flight load acting on the external fuel tank was converted to test load and the suitability of the converted loads was verified. The loads imposed on the external fuel tank were expressed as the combination of the inertial load (based on the acceleration in the translational direction) and the tangential direction inertial load (based on the angular acceleration of the moment). To calculate the test load, the transfer function table was generated by calculating the shear load and moment based on the unit load. For this purpose, a transfer function table was established by dividing the external fuel tank into a few sections and calculating the shear load and moment generated by the unit shear load and unit moment in each section. In addition, the test load for each section was calculated by computing the established transfer function table and flight-load conditions. However, in actual structural tests, it is often not possible to impose a load in the same position as the point at which the shear load and moment are calculated. For this reason, the actual test-load positions had to be determined and the calculated test loads were redistributed to those positions. Then, the final test load plan was established by applying a whiffle tree to increase the efficiency of the test while also making it easier to apply the actuators. Finally, the suitability of the established test load plan was confirmed by comparison with the flight-load conditions.

Effect of Nano-SiO2 on the Microstructure and Mechanical Properties of Concrete under High Temperature Conditions

The aim of the research was to determine how the admixture of nanosilica affects the structure and mechanical performance of cement concrete exposed to high temperatures (200, 400, 600, and 800 °C). The structural tests were carried out on the cement paste and concrete using the methods of thermogravimetric analysis, mercury porosimetry, and scanning electron microscopy. The results show that despite the growth of the cement matrix’s total porosity with an increasing amount of nanosilica, the resistance to high temperature improves. Such behavior is the result of not only the thermal characteristics of nanosilica itself but also of the porosity structure in the cement matrix and using the effective method of dispersing the nanostructures in concrete. The nanosilica densifies the structure of the concrete, limiting the number of the pores with diameters from 0.3 to 300 μm, which leads to limitation of the microcracks, particularly in the coarse aggregate-cement matrix contact zone. This phenomenon, in turn, diminishes the cracking of the specimens containing nanosilica at high temperatures and improves the mechanical strength.

Theoretical Estimate of Cooling Time of a Liquid Hydrogen Tank during Structural Tests

Russian enterprises continue developing rocket and space vehicles based on cryogenic propellants, i.e. liquid hydrogen, oxygen, and methane. Hence, the issues of fuel tanks’ thermal strength are increasingly important. During structural tests, the operating temperatures of the test object should be simulated, since the temperature condition affects the strength and rigidity of the structure. Consequently, during ground-based experimental tests, hydrogen tanks must be cooled down to 20 K, the boiling point of hydrogen. JSC TsNIIMash is developing a helium system capable of cooling large-sized structures to a temperature of 20 K. Helium can be used in a gaseous state to cool down the structure, since the boiling point of helium, 4 K, is lower than the boiling point of hydrogen. Until now, the tanks were cooled only by filling with liquid nitrogen, therefore the temperature state of the tanks during the tests was simulated only for this case. In order to determine the applicability of the method developed, the cooling time of large-sized containers was estimated by cooling a hydrogen tank, which by its dimensions is typical for an advanced medium-class second stage launcher, to 20 K by gaseous helium.

An investigation of the tensile characteristics of printed handsheets

Purpose The purpose of this paper is to investigate the influences of fibre lengths and a given range of paper grammages on the fundamental properties of unprinted and printed papers by using mineral oil-based offset printing inks and also evaluate these results in terms of printing and tensile characteristics. Design/methodology/approach A design research approach has been based on the production of various laboratory handmade papers and their printing process with mineral oil-based offset printing inks. The analysis of mechanical and structural tests results of the unprinted and the printed papers have been evaluated. Findings This study is confirmed that the mineral oil-based offset printing inks can be easily applied to the surface of papers having different grammages and pulp contents. An increase was observed in the tensile index values of the papers with the printing process, and these increases were more evident (about 80%) particularly in low grammage papers having high short fibre content. Originality/value The originality of this work is based on understanding and comparing the effects of grammage and the effect of pulp contents (having long and short fibre) on tensile characteristics of printed and unprinted handsheets.

Thermomechanical training and structural tests for adaptive SMA bumps with two-way shape memory effect

In this paper, shape memory alloy (SMA) bumps with two-way shape memory effect (TWSME) are trained by simple but effective training approaches, which provides a new idea for the actuations of the shock control bump (SCB) on airfoil. Two different configurations of bump structures (2D and 3D SMA bumps) are designed and fabricated. The bumps are required to exhibit TWSME so that it can change its shape by heating and cooling between two stable states at austenitic phase and martensitic phase, respectively. To obtain the TWSME, the material is trained in the range of martensitic finish temperature and austenitic finish temperature whilst a displacement boundary condition is imposed. A set of fixtures, which can be assembled to the universal testing machine (UTM), are designed to achieve the clamped boundary condition during thermal cycles of the training process. After training, SMA bumps with the TWSME, that bulge at low-temperature and become flat at high, are obtained. Structural tests and deformation control are then carried out afterwards to show the deformation performance of the trained SMA bumps.

The Effect of Heat Treatment on the Structure of Zeolite A

Knowledge about the thermal properties of zeolites is extremely important due to their potential application in the chemical industry. In this work, the thermal stability and the dehydration process of zeolite A were investigated by in situ high temperature Fourier transform infrared spectroscopy. The progress of thermal decomposition that zeolite A underwent during the controlled temperature increase in the range of 25–600 °C was determined by the DRIFT spectroscopic method. Infrared spectra are presented and discussed for this compound on the basis of the crystal structure. Based on the courses of the obtained DRIFT spectra, it was found that, during heating, water was gradually removed from the structure of the material, followed by dehydration and formation of hydrogen bonds. It was established that the process of thermal degradation began as early as 550 °C. The analysis of the obtained results of structural tests can be repeated on other materials from the zeolite group and complements the research work on the thermal analysis of these materials.

A Novel Approach for Designing Boltless Connectors - Example on a New Drilling Riser Connector

A new method which uses elastic and elasto-plastic Finite Element analyses is developed to design a double breech-block type connector. All relevant criteria proposed by API16F are fulfilled. In addition, plastic and bearing criteria have been added to support the use of lugs for load transfer in the connector. The proposed methodology has been applied and validated through experimental tests at different scales and in particular on laboratory specimens and small-scaled connectors. Based on these last structural tests, a safety factor of almost 8 was obtained for the design method on small-scaled connectors. Prototype tests at scale 1:1 allowed the methodology to be fully validated and a new product to be qualified. Certification bodies validated the whole design process, the employed methodology and the new connector.

Friction Stir Welding of Wrought Aluminium Alloy EN AW- 6082

The article presents results of the friction stir welding of 6 mm thick plates made of wrought aluminium alloy EN AW-6082. Tests discussed in the article involved the identification of the effect of primary welding process parameters on the quality of welds. Test welds were subjected to visual tests, measurements of temperature (inside the weld), tensile strength tests as well as macro and microscopic metallographic tests and structural tests (performed using a scanning electron microscope). The application of the appropriate values of the primary welding process parameters (i.e. the tool rotation rate and the welding rate) enabled the obtainment of the high and repeatable quality of FSW joints made of aluminium alloy EN AW-6082. The test results presented in the article can offer technological solutions for potential

Carbon Coatings Deposited on Prosthodontic Ni-Cr Alloy

The study discusses the results of investigations conducted on carbon coatings applied on a prosthodontic alloy Ni-Cr. Carbon coatings with the thickness of about 1000 nm were deposited by means of the RF PACVD method with a titanium interlayer applied by magnetron spray dispersion. The coatings underwent microscopic examinations, as well as structural tests with the use of Raman spectrometry, investigations of mechanical properties, adhesion and corrosion tests; also, the bacterial adhesion to the sample surface was determined. It can be inferred from the performed studies that the obtained carbon coatings exhibit mechanical properties which allow them to be used for prosthodontic elements. The coatings’ adhesion to the metallic substrate made of Ni-Cr alloy equaled about 150 mN. The examined coatings clearly improve the corrosion resistance and reduce the number of bacteria adhering to the sample surfaces. Taking all this into account, it can be stated that carbon coatings can be potentially applied to protect metal prosthetic restorations.