Papers by Keyword: Durability

Abstract: The durability airworthiness verification of turbine blade is one key issue in the process of certifying a type certificate for the aircraft engine. This paper summarizes the limiting factors for turbine blade durability and proposes a compliance method to evaluate the durability life of turbine blade. The typical standards of blade durability were selected and evolution history of the regulations was traced. The regulation contents and differences between CCAR-33 and CS-E were analyzed. A series of compliance methods in airworthiness verification process were discussed in detail. Furthermore, an experimental compliance methodology was proposed to estimate the durability life of turbine blade, considering the damage of creep and fatigue. The novel methodology was verified using the scanning electron microscope (SEM) analysis. These efforts are of great benefit to support the process of obtaining the final type certificate.

Abstract: The paper was removed due to copyright misconduct (missing consensus from all co-authors)

Abstract: The paper was removed due to copyright misconduct (missing consensus from all co-authors)

Abstract: This article presents the results of the effect of drawing speed on the strain rate and resistance to plastic deformation. The wire drawing on modern high speed wire drawing machines significantly increases the required amount of drawing dies. The influence of the technological parameters: speed drawing, half-angle of the die, wire diameter and a single strain on the rate of deformation of the metal. The influence of the technological parameters: speed drawing, half-angle of the die, wire diameter and a single strain on the rate of deformation of the metal. It is found that increasing the resistance to drawing dies and achieve passport velocities drawing, when selecting process parameters drawing guided by the principle of uniform strain over the cross section of the wire by matching the single strain with half-angle dies and friction coefficient on the formula given in the article.

Abstract: The strength of abrasive wheels is one of the key factors affecting the performance of abrasive machining. The paper discusses ways to improve the strength of abrasive wheels. The stress-state mathematical model presented herein is a generalization of the existing models. It is used herein to find for the first time that there are numerous optimal combinations of the elastic modulus and reinforcing material density, which result in the same minimum value of the objective function. It is found out that increasing the radius of the reinforcing component while also optimizing the mechanical properties of its material may increase the permissible breaking speed of the wheel several times. We herein present a regression equation and a nomogram for finding the optimal combination of control factors. Conventional methods for testing the mechanical properties of materials, which have been proven reliable for testing metals and alloys, are not as reliable for testing abrasive materials, as the test results they generate are not sufficiently stable or accurate. We therefore propose an alternative method that does not require any special equipment or special studies.

Abstract: A combined processing method for improving the performance features of machine parts (durability), that works under intense wear and high lubricated or boundary friction has been developed; a working installation based on a CNC lathe has been developed. The research on resulting surface hardness material of steels: С45Е; 1.1191 (1 option); SA-240 TP 310S (2 option); 34CrNiMo6, 36CrNiMo4, 40NiCrMo4KD (3 option) and hardening depth variation under different combined processing conditions has been carried out. Surface roughness parameters have been calculated. The suggested method can increase the operational life of a machine part due to improving features, such as surface hardening, creating a favorable surface topography.

Abstract: Based on the numerical solution of the differential equation that determines one-dimensional heat transfer under unstable conditions with constant coefficients, a method was developed to calculate the temperature distribution over the cross section of the enclosing structure. Based on the developed method, a method of determining the number of cycles of freezing and thawing of moisture in the cross sections of the outer wall of the building was calculated. This method was tested in the experiment on the exterior walls of operating buildings. The results showed good convergence of the real and calculated temperature values. The calculation of the number of cycles of freezing and thawing on the cross section of the outer wall of the building according to the developed methodology and the experiment showed the same results. The method of numerical assessment was developed to show the impact of global climate change on enclosed structures. The parameter of temperature load of enclosing structures was introduce. The method uses meteorological data of outdoor air temperature over the last 50 years and the results of calculation of temperature fluctuation of the enclosed structures. The use of this method allowed to calculate the number of cycles of freezing and thawing in cross sections of the outer wall at any given time period, and, therefore, more accurately predict the durability of enclosed structures. In addition, the developed technique allows quantitative comparison of different designs of external structures on the thermal load, taking into account global climate change.

Abstract: The results of experimental and theoretical studies of the process of destruction of concrete by the methods of fracture mechanics are considered. Results of studies of long-term strength, durability and deformability of concrete subjected to a preliminary short-term temperature action up to 300° C and 400° C under load and without load are presented. It is shown that after short-term heating up to 300о С the long-term strength of concrete decreases insignificantly. It is established that heating up to 400° C can be considered the boundary of the structural integrity of concrete. The conditions for using the results of these studies in determining the values of a function that characterizes the change in the long-term strength of a material in the mechanics of heterogeneous structures are formulated. The function of the material destruction measure is introduced to describe the nature of the structural changes in the material at a given constant continuous load, and its change for different levels of a continuous load is considered.

Abstract: The paper presents new results in the building materials area. One of the solutions of the thin-walled elements obtaining can be achieved due to new additive using. The main purpose of the paper was improvement concrete properties for thin-walled constructive elements. The experimental and standard methods have been used and new complex additive for concrete. The research shows that a comprehensive additive consisting of aqueous solution of polycarboxilate polymer, silica sol and potassium nitrite is effective and makes it possible to produce high-efficiency concrete with unique properties: higher compression strength, higher crack resistance, frost resistance, water resistance, abrasion resistance. The study shows that the concrete is chemical resistant. Modified concrete can be recommended for manufacturing critical concrete structures of special purpose, for example high-rise constriction.

Abstract: In recent years, the development of new procedures and solutions in the field of conservation has been very significant. The purpose of this article is to collect the main contributions of nanotechnology, in its multifunctional solutions applied in heritage, to offer a global vision of the state of the matter for both scientists and restaurateurs.Nanomaterials offer some advantages over traditional products, improved compatibility and efficiency and reducing the use of toxic organic solvents for humans and the environment. Solutions have been developed for both inorganic supports and organic supports for artistic, architectural and archaeological heritage. Especially relevant are the advances in consolidation processes, pH regulation and / or cleaning / elimination of alteration products on murals, frescoes or stone and in materials composed of cellulose and collagen.Also, nanotechnology is still a recent science and has yet to answer certain questions about its use protocols and reduce the possible risks to health.