Papers by Keyword: Dynamic Load

Abstract: The bond characteristics between reinforcement and self-compacting concrete under dynamic loads was analyzed experimentally. The tests were conducted by pulling-out with setting strain gauge in reinforcment. The bond stress distribution laws were analyzed with concrete strength change.

Abstract: Based on the significant destructive effect of heavy vehicle on uneven roads, two simplified models of pavement unevenness and vehicle dynamic load were established in accordance with D'A lembert principle, and Matlab software was used to analyze the changing law of dynamic load under the conditions of different road unevenness, vehicle speed and load. The results show that vehicles running on uneven road may produce more cumulative damages than static load, and DLC (dynamic load coefficient) changes in wide range, maximum up to 2.0 or more; the effect of speed and load on dynamic load is complex, and due to multi-factor interaction, DLC doesn’t consistently increase or decrease with speed and load increasing. Although the dynamic load level caused by high-speed heavy vehicle is not necessarily too high, its impact on the road can not be ignored.

Abstract: The dynamic model of planetary gear system was built up with the consideration of the running characteristics of variable speed and variable load of wind turbine transmission system. The expression of dynamic factor which described by external change load and deformation vibration was studied. Then, the response characteristics and dynamic load of planetary gear system of wind turbine have been studied with the consideration of changing external load and time-varying stiffness, mesh phase and nonlinear stiffness of bearing. The results show that: the frequency response of system reflects the low frequency component of external load. The influence of external incentives on sun gear and planet gear is very significant, and the distinguish between low frequency vibration and high frequency vibration is obvious. The flexibility of system has an obvious impact on dynamic load of bearing. The results lay a foundation for strength design and fatigue analysis of wind turbine gearbox.

Abstract: The failure damage of granite under axial load are caused by the propagation and coalescent of cracks at mesoscale, so it is of important theoretical value and practical significance to to understand the mechnical properties of rock by experimental research on meso damage of granite. The microfracturing process of the pre-crack marble sample on surrounding rock in immerged Long-big tunnel in Jinping Cascade II Hydropower Station under uniaxial compression is recorded by using the testing scheme. According to stereology theory, the propagation and coalescent of cracks at meso-scale are quantitatively investigated with digital technology. Therefore, the basic geometric information of rock microcracks such as area, angle, length, width, perimeter, is obtained from binary images after segmentation. The results show that the new meso-mechanical testing scheme on rock meso-damage could be used to quantitatively analyzed from the geometric information of rock microcracks.

Abstract: The arresting landing of carrier aircraft is especial dynamic problem. During this process,the gear would bear the very big dynamic load,which does the biggest harm to gear .In this paper,it analyzed the landing gear shock strut in carrier aircraft arresting landing,and aiming at the runout of shock strut and the flexibility of the landing gear by using the Lagrange equation.Then it concluded the chaging of landing gear shock strut with symmetrical and straight arresting,3m of off-center distance arresting and 2°of rolling angle arresting after simulating.The conclusion showed that the landing gear shock strut would be stable after a short time concussion;rolling and unsymmetrical affected the shock strutmore severe than off-center and symmetrical arresting,and the qualities of concussion also being more acute.

Abstract: Transmission influences on the performance and the security of tilt-rotor directly. A transmission-wing coupling dynamic model including time-varying mesh stiffness and static transmission error was proposed, then calculated the dynamic loads of the transmission-wing coupling system under two flight modes: aircraft and helicopter. Then, computed the life of transmission under different system reliability based on the dynamic loads. This paper presents a more accurate transmission life estimation method. The results present some useful informations for dynamic optimization of the transmission and provide a theoretical basis for the transmission design.

Abstract: The carry-loading capacity of the airtight structure is important for high-speed trains. The load of air tightness has been analyzed and universal mathematical model has been built. As a calculation model, the FE Model of the vehicle body for a type of high-speed train has been established and the modal, transient analysis has been done. Different influence of load parameters on the vehicle has been analyzed and compared to obtain the response characteristics of the structure. Finally, the strength of the train under different working conditions is verified, weakness is pointed out and suggestions based on the simulation test are given.

Abstract: Tapered Roller Bearing can take huge radial load or two way axial load. It is widely used in over loading, steel rolling, metallurgy, etc. In this paper, according to the structural properties of Tapered Roller Bearing, we established an mathematical model to optimize the design of Tapered Roller Bearing. Based on the comparison of the result from our design and the traditional design of the Four Column Tapered Roller Bearing 3811/750/HC, the dynamic load increases 22% and the working life expectancy increases 85% by using our design. This fully shows the economical meaning of the optimization design, and it provides a practical method for the optimization design in future.

Abstract: With the theory of M.W.Sayers, the pavement surface roughness was simulated by the sine curve. Through the Mat lab and VC + + program, the dynamic vehicle load caused by pavement surface roughness was analyzed and calculated. Given the dynamic road and environment factors and combined the test results of highway surface roughness, the deterioration law of pavement roughness were studied by amendment Shell permanent deformation theory. A new prediction method was put forward to predict the remaining life of asphalt concrete pavement, which was proved to be reasonable and reliable and can provide a valuable basis for the scientific decision-making of asphalt pavement management.

Abstract: The dynamic impact loading has the destructive effect to the surrounding rock mass. Rock specimen such as rock plate was found to become invalid under dynamic impact loading. This paper presents brittle damage evolution law for dynamic impact damage of brittle rock based on low velocity (10m/s~40m/s) impact test, when a source of impact loading is applied to a rock plate specimen, damage cracks are developed from the source to the boundaries. This paper is concerned with the description and explanation of this phenomenon. The test results show that the cracks propagation length and break area are not arbitrary, but are influenced by the angle of dynamic impact loading. According to the test results, the study found that the scope of impact resistance optimization angle is about 30°~45°, and the cuspidal point of impact velocity is about 30m/s~35m/s; The crack length and the break area increase with the increase of the impact loading; When the break area decreases abruptly, the crack length increases suddenly, which shows that there was an obvious incubation period of crack forming, at first some pits appearing on the verge of the rock plate and the propagation rate of crack length and break area decreasing with the impact velocity increasing.