Papers by Keyword: Life

Abstract: The rolling contact fatigue (RCF) tests of 13Cr-2Ni-2Mo and SUS440C stainless steels were carried out in water. Their groove surfaces and the flaking failures were observed. Some hair cracks, wear and high roughness area were found. While the flaking depth of SUS440C was shallower than that of 13Cr-2Ni-2Mo stainless steel, the RCF life of the latter was longer than the former one. The flaking depth did not influence the RCF life.

Abstract: The concept of service life of structures is included in international standards ISO (under the term Design Working Life), in the European document EN 1990 (Design Service Life) and in the upcoming document CEN for assessment of existing structures - Technical Specification TS (Remaining Working Life). The mentioned documents contain mainly material-independent provisions for the design and assessment of all types of structures and for any category of actions. The submitted paper includes the definition of service life (performance time) t_ser, which is extended for any concrete structure, considering the resistance of a structure R(t) and the effect of action S(t). Both the aggregate variables R(t) and S(t) are usually random variables significantly dependent on time t. Due to the random variability of the variables R(t) and S(t), the service life t_ser, needs to be related to the probability that the performance of the structure is weakened or completely eliminated. Basically, serviceability limit states (SLS) and ultimate limit states (ULS) should be considered. In the case of concrete structures another limit state corresponding to the beginning of a specific degradation process (corrosion of reinforcement), denoted t_init, may be important. In specific cases of buildings and bridges a functional (moral) service life may be taken into account. The paper includes also a practical example of assessing the remaining working life of a concrete structure.

Abstract: To develop modern CAE systems for durable and reliable structure components design, mathematical modeling of environmentally assisted metal cracking becomes very important. For structure components exploited in aggressive environment and under cyclic load, it is a problem of today. Besides, mathematical rule of damage accumulation of different causes (for instance, hydrogen media impact and cycling) is rarely used in CAE systems, but if such rule was used, crack propagation simulation considering several damage causes would be possible.Environmentally assisted metal cracking model (developed earlier by authors) is described in the paper. This model considers cyclic load and hydrogen embrittlement, the most important characteristics of which are hydrogen environmental concentration and load frequency respectively.The authors’ model successfully predicts effect, known from certain experimental data, that the greater is the frequency, the less hydrogen embrittlement affects fatigue cracks propagation and, vice-versa, that there are certain boundaries of cycling frequency for which embrittlement effect is comparably big.Such boundaries of frequency were numerically estimated by means of the presented model. Plots showing dependency of the component’s life on different defect and loading features are shown.

Abstract: The paper presents the investigations made on samples taken from the related rotor blade of an hospital cooling equipment.The failure analysis was made in order to find if the failure appear because the metallic material used or was functional problem.The objectives of our analysis and techniques used are described below:determining the chemical composition by optical emission spectrometry;determining the hardness of the material;metallographic analysis by optical microscopy;micro compositional and microstructural analysis by scanning electron microscopy (SEM) and by microanalysis, energy dispersive X-ray (EDAX). Research has highlighted the quality of piece elaboration and casting, which led to a long life of its use.

Abstract: The present paper proposes an analytical method for determining the course (path) of crack propagation. A fatigue crack arises at the tooth root of a cylindrical geared wheel due to loading connected with gear work conditions. The cracking model was built using the adequate NASGRO2/3 formula; moreover, for comparison purposes, Forman and Paris-Erdogan’s laws were utilized. The length of an increase (propagation) in the crack was directly calculated by means of the boundary element method.

Abstract: ordinary carbon steel hardness and life is difficult to achieve blanking dies and drawing dies requirements. In the surfacing alloy steel and alloy steel base can improve the surface hardness and durability of the mold. To reduce the use of electric arc welding carbide decomposition and burn in the shielding gas . Welding mold base structure to meet the requirements of the welding . Mold heat treatment after welding specifications and hardness to meet the processing requirements and use of strength requirements. Welding process design mold substrate heating requirements and the requirements of the solder layer thickness and the thickness between layers allocation.

Abstract: Nature works hard to destroy bearings, but their chances of survival can be improved by following a few simple guidelines. Extreme neglect in a bearing leads to overheating and possibly seizure or, at worst, an explosion. But even a failed bearing leaves clues as to what went wrong. After a little detective work, action can be taken to avoid a repeat performance.

Abstract: Stochastic simulation using authors’ empirically-specified deterministic model estimates technical risk, i.e. failure risk. Simulating a crack growth in hydrogenating and stress cycling high-strength steels requires a great computing performance. Cloud computing based on Microsoft Azure enables authors to provide a lot of required calculations to complete design tasks in appropriate time to ensure safety operation of the structure component under consideration. Obtained results illustrate benefits of using cloud computing for stochastic simulation of crack growth in high-strength steels in comparison with the same calculations executed on a workstation. The article emphasizes the prospects of cloud computing applications to technical risk management.

Abstract: This article, on the basis of several kinds of essential random truncated distribution functions in reliable analysis of existence and life, discusses the best efficiency unbiased estimation of the life distribution function parameter. It suppliijes reliable basis and efficient algorithm for solving the relative problem on reliable analysis of existence and on the best unbiased estimation in prediction of communication engineering and electrical load. The article is of extensive value in theory and in practice.

Abstract: Intellectual life has become a part of modern life. Watching television is now a major part of peoples’ leisure time. Previous literatures stated that television viewing would cause personal happiness and good feelings. How humans select their preferred TV channels and enjoy their leisure time is important for them in order to relax themselves. Previous literatures focused on their TV viewing records; however, it is not always pertinent for observing people's habits. A wrinkled brow is able to let the TV know the meaning behind changing channels. It should be based on face recognition and sensors. This research tries to improve the functions of the TV controller, making for an easier life and pursuit of more intelligent viewing. A new innovation finding was to propose, and also model it as mathematics formulas for future studies. Although it is still in mathematic form, perhaps, it would enter mass production someday. Future research also suggests studying multi person feelings, intelligent sensor and control.