Analysis and Research of the High-Cycle Fatigue Fracture Mode Based on Stress Ratio and Residual Stress of Ti-6Al-4V

The content of titanium is about 0.63% in the earth’s crust, and it ranks 10th among all elements. The content of titanium is next to the metal elements of aluminum, iron and magnesium, iron, and magnesium; titanium alloys have low density, high specific strength (the ratio of tensile strength to density), wide working range (−253°C–600°C), and excellent corrosion resistance melting point; the chemical activity of titanium alloy is very high, and it easily reacts with hydrogen, oxygen, and nitrogen, so it is difficult to be smelted and processed, and the processing cost is high. Titanium alloys also have poor thermal conductivity (only 1/5 of iron and 1/15 of aluminum), small deformation coefficient, large friction coefficient, and other characteristics. They are widely used in aircraft fuselage, gas turbine, petrochemical, automotive industry, medical, and other fields for important parts.

Properties of vehicle support suspensions

The processes of damping of vibrations of sprung masses with polyurethane foam support cushions in the frequency range of vibrations with an optimal transfer function are investigated. The amplitude-phase-frequency characteristics of the masses are determined during vibrations with the subsequent presentation of transient processes, according to which the damping time of the vibrations of the sprung masses is determined. The used support cushions made of polyurethane foam reduce the minimum damping time of vibrations of the sprung masses on 1520 %, they are more wear-resistant and have greater damping properties than rubber support cushions. Keywords: spectral density, exposure frequency, transmission coefficient, deformation coefficient, vibration damping time, polyurethane foam. [email protected]

Maximum Admissible Slip of Tractor Wheels without Disturbing the Soil Structure

One of the most important parameters that characterize the traction-coupling properties of a wheeled tractor is its slip. The more tractor’s gross traction exists, the higher its traction-coupling properties are. However, this gross traction should not exceed its maximum possible value, which, in turn out, is to be determined by the maximum permissible slip, . This article provides the equation to calculate this crucial parameter and establishes the dependencies between the tractor’s slip and soil structure coefficient. It was shown that the value of basically depends on such soil characteristics as the bulk deformation coefficient and the coefficient of rolling resistance. Calculations showed that, for the average value of the soil bulk deformation coefficient at , the average value of rolling resistance coefficient at 0.16, and the ratio value of the maximum permissible soil pressure to the tractor wheel rolling radius at , the maximum permitted amount slip of the tractor wheels should not exceed 15%. With more slip, the soil structure deteriorates significantly. In this case, its structure coefficient may be less than critical, equal to 0.4.

Study on Cutting Chip in Milling GH4169 with Indexable Disc Cutter

The study and control for chip have a significant impact on machining quality and productivity. In this paper, GH4169 was cut with an indexable disc milling cutter. The chips corresponding to each group of cutting parameters were collected, and the chip parameters (chip curl radius, chip thickness deformation coefficient, and chip width deformation coefficient) were measured. The qualitative relationship between the chip parameters and cutting parameters was studied. The quadratic polynomial models between chip parameters and cutting parameters were established and verified. The results showed that the chip parameters (chip curl radius, chip thickness deformation coefficient and chip width deformation coefficient) were negatively correlated with spindle speed; chip parameters were positively correlated with feed speed; chip parameters were positively correlated with cutting depth. The maximum deviation rate between measured values and predicted values for chip curl radius was 9.37%; the maximum deviation rate for cutting thickness deformation coefficient was 13.8%, and the maximum deviation rate of cutting width deformation coefficient was 7.86%. It can be seen that the established models are accurate. The models have guiding significance for chip control.

Model Test and Theoretical Analysis of New and Old Embankments Differential Settlement Considering Lateral Deformation

In the embankment widening project, the new embankment will produce large deformation due to the low degree of consolidation, which will affect the stability of the embankment. Obtaining the settlement law of embankment is the premise to ensure the stability of the embankment. In this paper, the deformation law of the new embankment is studied through the embankment model test, and the settlement calculation method of the new embankment is proposed. The model test results show that the new and old embankments have a large settlement difference during the loading process, and the maximum settlement of the new embankment is twice that of the old embankment. The lateral deformation of the new embankment is directly proportional to the vertical deformation, sliding occurs under the ultimate load, and the bearing capacity is lost. Based on the one-dimensional calculation method, the lateral deformation coefficient is introduced, and the two-dimensional embankment settlement formula is obtained. The new embankment is meshed, and the deformation of each node is calculated by the formula, and the difference between the settlement and the model test data is 6.2%, which proves the feasibility and accuracy of the calculation method.

Applicability of sonoelastography in leiomyoma and adenomyosis

Background. Uterine leiomyoma and endometriosis are common gynecological diseases of women in childbearing potential. This fact necessitates developing an optimal protocol for examination of patients in order to implement an individual approach to treatment. Diagnosis of mixed forms of pathological myometrium conditions causes some difficulties. Elastography technique makes it possible to assess the density of the myometrium, which may be essential for differentiating the diagnosis of leiomyoma and adenomyosis in mixed forms. Рurpose – to ascertain the potential of transvaginal ultrasound along with compression sonoelastography to determine the deformation coefficient in differential diagnosis of various pathological myometrium conditions. Materials and methods. The paper presents the analysis of elastographic findings of the uterus in 155 women obtained via compression sonoelastography performed by means of HITACHI AVIUS device. Patients were divided into 4 groups: control, women with uterine leiomyoma, uterine adenomyosis, with combined leiomyoma and adenomyosis. The transabdominal/ transvaginal ultrasound findings were confirmed by histopathological examination. The standard point scale was used to determine the deformation coefficient. Results. Elastographic characteristics were assessed in accordance with sonoelastography findings, i. e. deformation coefficients common in leiomyoma and adenomyosis. The maximum values of the deformation coefficient were obtained in leiomyoma (in an amount of 2 to 6.0 units). In case of diffuse or focal adenomyosis, the deformation coefficient was in an amount of 0.5 to 1.5 units indicating high myometrial elasticity vs the unchanged myometrium. For its part, in Group I (control), the deformation coefficient ranged from 1 to 1.7 units. High myometrial elasticity in adenomyosis vs the unchanged myometrium as well low elasticity or high density of the myometrium in leiomyoma were observed. Conclusions. The deformation coefficients in patients with leiomyoma and adenomyosis and unchanged myometrium were obtained via ultrasound with compression sonoelastography and they made it possible to determine the degree of elasticity of the myometrium and its changes in the relevant pathology. Elastography is capable of identifying clear distinctive features of leiomyoma and adenomyosis. The coincidence of the diagnosis of adenomyosis based on elastography and histology is significant, but not optimal. The unchanged myometrium has a certain elasticity, which can be equated to a numerical value, i. e. the deformation coefficient, and this param changes in case of leiomyoma or adenomyosis, which makes it possible to differentiate these pathological conditions of the myometrium.

Optimizing the Geometric Parameters of Cutting Edge for the Finishing Machining of 30CR Alloy Steel

In order to optimize the geometric parameters of cutting edge for the finishing machining of 30Cr alloy steel, a two-dimensional (2D) finite element (FE) model of orthogonal cutting was built with FE software AdvantEdge. The optimized methodology of the cutting edge geometric parameters was likewise proposed based on the simulated results. Thereafter, the geometric parameters of the cutting edge were optimized based on a comprehensive criterion that combines chip deformation coefficient and tool stress. The chip deformation coefficient indirectly determines the surface roughness, whereas tool stress determines tool wear, thereby affecting the dimensional precision of the components. The rake angle ranges from 12[Formula: see text] to 20[Formula: see text], while the cutting edge radius ranges from 12[Formula: see text][Formula: see text]m to 20[Formula: see text][Formula: see text]m in the optimization process. The optimal rake angle for the finishing machining 30Cr alloy steel is 16[Formula: see text], while the optimal cutting edge radius is 14[Formula: see text][Formula: see text]m with a given relief angle of 7[Formula: see text].

Estimation of Energy Requirement of Jatropha Curcas L. Seedcake Briquettes under Compression Loading

The energy requirement of Jatropha curcas L. seedcake of different dimensions (4.5, 5.6, 6.7, 8 and 10 mm) for briquette compaction was investigated under compression loading (100, 200, 300 and 400 kN) using the universal compression-testing machine. The parameters measured and/or calculated were the deformation, thickness, numerical energy and theoretical energy. The statistical analysis results show that compression forces had a significant effect (P-value < 0.05) on the amounts of deformation and thickness, while that of the dimensions of the sample did not. The increase in compression forces increased the numerical energy while that of samples dimensions caused a decrease. Using the tangent curve mathematical model; the force coefficient of mechanical behaviour (kN), the deformation coefficient of mechanical behaviour and the fitting curve function exponent were determined for describing the experimental dependency between the force and deformation curves as well as the numerical energies of densified jatropha seedcake briquettes.