Applied Mechanics and Materials Vols. 365-366

Abstract: Rail cant is one of the most important track geometry parameters, which can change the wheel-rail contact relationship and then influence the dynamic interaction. Static contact geometry parameters for 75kg/m rail in contact with LM wheel tread under different rail cants are analyzed on the basis of the wheel-rail spatial contact geometry algorithm. A train (multi-vehicle)-track coupling dynamic model is established with the help of the software Universal Mechanism (UM), and dynamic performances of train-track system in curves are compared under different rail cants. The results indicate that: (1) flange contact is less likely to occur under 1/20 rail cant, which will reduce uneven wear of wheel/rail tread. (2) In the single-point contact range, when the rail cant increases from 1/40 to 1/20, the corresponding rolling radius difference, contact angle parameter, equivalent conicity and equivalent contact angle parameter all increase, which means the self-centring capacity of wheelset is enhanced and the wheel-rail relationship is improved. (3) When the train passes curves, the increase of rail cant from 1/40 to 1/20 can reduce the wheel-rail dynamic interaction and wear. Besides, the wheel-rail contact area may become bigger, which is conductive to reducing contact stress and contact fatigue failures. The results can provide reference for the design of rail cant of heavy haul railway.

Abstract: Axial flow fans are widely used in our daily lives such as automotive cooling systems, electronic appliances and air conditioning. The factors that affect the aerodynamic performance of axial flow fans include blade number, fan diameter, hub ratio, blade angle, rotating speed, etc. This paper investigates effects of hub ratio and bladenumber on the aerodynamic performance of the axial flow fan of the radiator of a dump truck we previously designed for mining. With the computational fluid dynamics (CFD) method, the fans operation condition, such as entry static pressure, effective power and flow rate, are numerically simulated with various hub ratios and blade numbers. The results of the numerical simulations are quantitatively analyzed and curves of fans performance changing with hub ratio and blade number are given. An optimization design for the cooling fan is conducted. The results of numerical simulation give conclusion that an increase of 5.6% of the vacuum static pressure and an increase of 3% of flow rate can be obtained when the hub ratio is between 500-600mm, with the same or even less power consumption. The flow rate increment reaches its peak at 8%, while power consumption efficiency is almost linearly increased, when the blade number increases to be in the range of 8 to 10. That is to say when the blade number is between 8 to 10, the fan is apparently making better use of energy. Compared with experimental method, computational fluid dynamics (CFD) method can reduce design circle and lower cost. The CFD results provide guidance to improvement of design efficiency and energy utilization.

Abstract: A magneto-rheological fluid (MRF) elevator traction transmission is a device to transmit torque by the shear force of MR fluid. The development and principle of MRF transmission device are presented. Then the design method of the MRF transmission is investigated theoretically. The model of the torque transmitted by the MR fluid within the brake is derived to provide the theoretical foundation in the MRF elevator traction transmission design of the brake. Based on this model, after mathematical manipulation, the calculations of the structure and width of the MRF elevator traction transmission are yielded.

Abstract: Control methods of the anti-lock braking system have been researched. A BP based Fuzzy-PID controller is proposed to reduce the time and the distance during braking. Through the compare of PID controller and fuzzy-PID controller and the BP based Fuzzy-PID controller which were simulated on Matlab/Simulink, it shows that BP based Fuzzy-PID controller has shorter braking distance and less braking time. So ABS with BP based Fuzzy-PID controller will work better than traditional PID controller.

Abstract: This paper put forward a kind of vehicle anti-collision warning system and put the emphasis on the research of active control. It introduced the function and composition of the system and expounded its working principle. First the safety distance model was studied based on the vehicle kinetic theory. This model contained longitudinal and lateral safety distance model. And the longitudinal safety distance model can be further divided into Safety Critical distance, Lock-in Target distance, Danger Critical distance and Limited Critical distance. Then the dangerous targets were identified and classified based on safety distance model .Finally, according to different targets, the corresponding evasion control strategy and the control flow chart were established.

Abstract: A comparative study concerning the dynamics of chain drives mechanisms is presented in this article. The study compares the dynamic response using the spherical contact model proposed by Lankarani and Nikravesh with a new enhanced cylindrical model developed by the authors to describe the contact phenomenon in cylindrical clearance revolute joints. In the process, the influence of contact parameters and the numerical efficiency of using different contact modeling approaches are evaluated. It is demonstrated that cylindrical contact is stiffer than spherical contact. The spherical model represents a rough approximation to evaluate the contact between cylindrical bodies since contact forces are underestimated.

Abstract: Vibratory pile drivers are widely used in mechanical industry field. In this paper, the nonlinear dynamic model of vibration friction pile-soil system considering the soil friction force is proposed. By numerical simulation, the dynamics characteristics of vibration friction for pile-soil system were obtained. The results showed that with the increasing of excitation amplitude and frequency, the displacement of the pile and frame are both increased.

Abstract: A 1:10 tank-car 2D fluid simulation model based on the computational fluid dynamics is established, and exchange the data with tank-car vibration model while simulating. In the paper, the 2 dimension fluid-structure coupling tank-car which owns two DOF is simulated, and the affect of fluid sloshing to tank-car longitudinal vibration is analyzed through the coupled vibration experiment. In the simulation and experiment, fluid sloshing increased the tanker longitudinal vibration acceleration amplitude and slowed response time is obtained through analyzing the difference between the different volume of fluid and the relevant solid without sloshing, and the difference of longitudinal vibration between full tank and non-full tank is significant.

Abstract: This study analyzes experimentally the influence of the friction between the sheet metal and the die surfaces on the results of the Erichsen test in terms of load-displacement curve of the punch, the normalized thickness measured at the specimen apex and the distance measured between the thinnest area of the specimen and the lateral surface of the blankholder. Two types of aluminium alloys, AA 2017 Al-Cu alloy (Al-4.5%Cu-1.0%Mn-1.0%Mg) and AA 5083 Al-Mg alloy (Al-4.5%Mg-1.0%Mn-0.15%Cr), with thickness of 1.0 mm are selected as the experimental materials for Erichsen test.

Abstract: The implicit parametric method was briefly discussed in this paper. An implicit parametric 3D solid model and a finite element (FE) model of a body-in-white (BIW) were built up by this method. Low order natural vibration frequencies and modes, bending and torsional stiffness of the BIW were analyzed by FE calculation. A good agreement was acquired by comparing the prediction results with the test values. Results indicated that the implicit parametric model of the BIW established could be used for design and development of the BIW in concept design stage of the BIW.