Applied Mechanics and Materials Vols. 633-634

Abstract: In this paper, a new method is proposed to measure the early shrinkage of airport pavement concrete material. Also, the effect of fly ash with different grades and dosage on early shrinkage and late shrinkage deformation of commercial concrete were studied. The effect of fly ash with different grades and dosage on volume stability of commercial concrete was assessed by using the test method of shrinkage cracking, and the causes and mechanism of the effect were analyzed.

Abstract: The motion of strong earthquakes causes nonlinear deformation and damages to the structure. For structural systems of buildings, domestic and European (EC8) regulation apply algorithm of seismic design based on reference linear-elastic methods that are carried out in two phases. Phase I includes determination of dynamic characteristics of structure, which are then used in phase II for calculation of seismic effects. In this study, parametric analysis of influence of dynamic characteristics of structure was done on multiple numerical examples, according to domestic and EC8 regulations and comparison of results.

Abstract: Improving thermal shield in buildings and reducing energy consumption have become major problems to be solved for the recent decades. Natural ventilation accounts for nearly half of heat losses in existing buildings. A controlled heat recovery ventilation system makes it possible to reduce irrational heat losses and improve microclimatic comfort. A typical historic residential apartment building constructed before industrial times in Saint-Petersburg is subject of this article. Options of centralized controlled heat recovery ventilation systems for old historic apartment buildings in Saint-Petersburg are suggested in this article.

Abstract: The clay loams of semi-solid consistency was tested under static loads. The test results have proved that high values of soil density can change operating conditions of artificial foundations significantly, i.e. a so-called plate effect can be observed. Due to high hardness values highly compacted soil beds allow distributing foundation loads on the considerable part of the area and reducing its value on the edge of the weak layer.

Abstract: Usually the gearbox casing of twin screw pulping extruder was designed by experience and greater weight. In order to reduce the casing weight under the premise of ensuring its stiffness and strength, firstly the casting lower box and the weakest axle in the casing were analyzed with finite element method by ANSYS software. And then the optimum design was carried out to take the minimum volume as an objective function. Finally, the welding casing has been designed as considering the manufacturing cost. The results show that the weight of the casting lower box after optimization is 22.95% lower than that of the experience design, and the weight of the welding part is 19.09% lower than that. The work has certain significance for optimum design of gearbox casing.

Abstract: Firstly we analyzed the effect of the type of matrix asphalt, the dosage of SBS modifier and shear time on the properties of SBS modified asphalt with the analysis method of Multi-factor, then we analyzed the mechanism of interaction between SBS modifier and matrix asphalt based on the four-component test analysis. The results showed that different types of matrix asphalt had different modification effect. Among them, the matrix asphalt A and SBS modifier had the best compatibility. The high content of asphaltene helped to improve the temperature properties of asphalt, the asphalt with high content of aromatic was much easier to be modified. As the dosage of SBS modifier reached 4.2%, the interconnected network had been formed, the modification effect achieved the optimal result, but the modification effect would be reduced with an additional contribution of SBS modifier. With the prolonged shear time, SBS modifier could be dispersed in the matrix asphalt more uniformly, however, the shear time should not be too long, the optimum shear time is 40min.

Abstract: Based on the analysis of relevant characteristics of the traffic load, explores the impact of static and dynamic vehicle type, shaft type factors,and cars on the road, down to analyze the stress level in the soil loads -deformation relationship Through theoretical analysis, research, and future prospects, the measures proposed to solve the problem, come to study the mechanical properties of the program under the vehicle load soil and make the outlook for future work in this area terramechanics.

Abstract: For the problem of generating oval gear tooth profile and driving characteristic, desgin the tooth profile of oval gear by the conversion method of tooth profile, and get its three-dimensional modal by Pro/E. The transmission characteristics of a pair of ovate gear are researched; it would help to further study wire cutting of the oval gear based on the involute profile ,which got by the conversion of method of tooth profile, and the driving characteristic help to study other characteristics of oval gear as well as the application in the machinery.

Abstract: Based on the dislocation pile-up theory and the crystal plastic theory, a rate-dependent crystallographic plastic finite element method (FEM) was used to analyze the stress distribution in the contact zone of single crystal turbine blade rabbet. The FEM results show that the maximum stress and the maximum resolved shear stress location are in the upper edge of the first tooth contact area of the rabbet. The surface crack initiates in the edge and grows as the zigzag wave. The deflected angle of the plane defined by maximum resolved shear stress gradient direction and the upper edge of the first tooth contact area of the rabbet with respect to the Z axis is 35°. The fracture occurs along the {-1-11} plane. Fracture behavior of rabbet/groove modeling specimens made of nickel-based single crystal superalloys was studied by corresponding contact fatigue experiments. The initial place and developing direction of the fatigue crack observed from experiments are found to be in good agreement with the predicted results based FEM.

Abstract: Stress-strain model is an appliance for research of the strength and deformations. It can be used to solve technological problems in the production of materials. Rheological element is a part of stress-strain model. There are some disadvantages of existing rheological elements. They can’t be applied for research of the material strength and some experimental facts which are observed for many materials. The aim of the new element is to eliminate these disadvantages. The new rheological element includes the matrix and the puncheon. It differs from its analogues by configuration and characteristics of its parts. If the value of the friction coefficient between the matrix and the puncheon is not zero and greater than the tangent of the angle between the axis and the matrix on the section with the variable cross-section, the puncheon is jammed by frictional force under loading. When unloading and subsequent loading the puncheon retains a permanent deformation until the load exceeds the maximum value during the previous cycle. If the above-mentioned angle matrix is equal to zero, displacement of the puncheon does not require increasing of the load within this section. The plastic flow is observed. Deformation can be accompanied by strengthening on the section where the value of the friction coefficient is greater than the above-mentioned tangent. Fragmentation of the element is possible on this section. Thereby the new rheological element permits to relate different types of deformations of simulated solid. In other words, it allows researching the strength of material.