Applied Mechanics and Materials Vol. 392

Abstract: This paper presents a characteristic of air-entrainment between a web and a guide roller with modified convex shape. Air film thickness is derived using the modified Reynolds equation, a roller shape equation, and a web deflection equation. A finite difference method and a Newton-Raphson scheme are employed to achieve numerical results, i.e. air film thickness and air pressure distribution profiles, a minimum air film thickness, and an air film thickness at the middle of roller length under varied convex roller shapes. The results show that both minimum and central air film thicknesses decrease when the roller is designed as convex shape, and a parameter of convex roller shape affects a minimum air film thickness position.

Abstract: A new effervescent atomized water mist fire extinguishing equipment was developed by combining the characters of water mist and effervescent atomization. A series of wood crib and gasoline pool fire suppression experiments were performed using the equipment. The fire extinguishment time, temperature and radiation heat flux of the flame were measured, and then the process of putting out different type fire was analyzed. A wood crib fire of 0.6A can be put out in 180 seconds using water mist produced by effervescent atomization equipment. Only 38 seconds was taken to suppress a gasoline fire.

Abstract: Finite element model of NC machine tools bed was set up in ANSYS, natural frequencies and modal shapes in low order were calculated by modal analysis of the bed. Then displacement-frequency curve and stress-frequency curve between 300 Hz and 700 Hz were acquired based on harmonic response analysis of the bed, and dynamic response of the bed which affected by harmonic load was clear; Transient dynamic analysis of the bed was finished by Full method, then displacement curve and acceleration curve about time domain were acquired, and influence of impact load during the process of starting NC machine tool which affect on the bed was understand, in results, some important references and basis were offered to optimal design of the beds dynamics.

Abstract: A method for path compensation of constrained chain transmission with heavy loads is presented in the paper. Polygon effects generated in chain transmission has been analyzed in the paper. Relevant position compensation programs and compensation trajectory have been given. As a result, polygon effects have been greatly reduced. This approach also provides a reference for other chain drive with constrained path.

Abstract: A numerical simulation has been carried out to study the flow field in the two-phase integration of sludge thickening and digestion reactor. The study is based on the solution of the complete NavierStokes equations and RNG k-ε turbulence models using a finite volume technique. The analysis results show that the two-phase integration of sludge thickening and digestion reactor exists some problems such as inlet sludge short flow in the connecting pipe, the lower utilization rate of higher part of outer chamber and uneven recycle in the inner reaction chamber. It is valuable to provide basis and improve design parameters, the two-phase integration of sludge thickening and digestion reactor will get a more ideal flow to improve sludge thickening and digestion effect.

Abstract: Crankshaft is an important component of an engine with intricate geometry which converts the linear displacement of piston into rotary motion. Since the crankshaft is predisposed to massive loads during combustion cycles, so different factors like endurance has to be kept in mind while designing crankshaft. Keeping in view the above scenario, the main motive of this paper is to do the fatigue analysis so that we can analyze various factors that are affecting the service life of crankshaft.

Abstract: In an archetypal engine the detonation frequency is usually analyzed using an overly simplistic model, incorporating only the rudimentary parameters (modeling the combustion chamber as a right circular cylinder). The research work is to develop a broader state space geometric model to discern the detonation frequency in a standard Otto engine based on engine conformation parameters. The intent of this project is to model the detonation event using a broader state-space i.e.to build on Draper’s Acoustic Wave Pressure formula and develop a sound underlying mathematical structure manifesting the models intricacies. The mathematical structure is predicated on standard wave equation, this mathematical generality makes it a potential candidate for future investigations into developing a superposition model using acoustic wave theory.

Abstract: The gear meshing is a very complicated process due to the nonlinear behaviors during the teeth contact. It is necessary to build a reliable model to simulate gear meshing process which can consider geometry and boundary conditions nonlinear behavior in gear tooth contact analysis. This paper propose a 3D finite element model to simulate the meshing process of a pair of spur gears, and then carry out the gear tooth contact analysis with the consideration of nonlinear behaviors. The results and relevant discussions will indicate and explain some significant phenomena of the gear tooth contact characteristics in gear meshing process.

Abstract: Multibody dynamics analysis is advantageous in that it uses real dimensions and design parameters. In this study, the stability analysis of a railway vehicle based on multibody dynamics analysis is presented. The equations for the contact points and contact forces between the wheel and the rail are derived using a wheelset model. The dynamics equations of the wheelset are combined with the dynamics equations of the other parts of the railway vehicle, which are obtained by general multibody dynamics analysis. The equations of motion of the railway vehicle are linearized by using the perturbation method. The eigenvalues of these linear dynamics equations are calculated and the critical speed is found.

Abstract: Under excitation of the engine and road surface, the vibration energy of the exhaust system which will result in the vibration of the body and produce the structure noise transfers to the body from the hanger. In view of these problems will cause noise, vibration and harshness (NVH) performance of the vehicle. A method called averaged driving DOF displacement (ADDOFD) is used to determine and optimize the exhaust hanger locations in this paper. Based on a sample vehicle, the Hyper Mesh and MSC. Nastrans oftware are adopted for meshing and calculation in the FEM modeling and vibration modal analysis of the exhaust system. Exhaust systems free-free mode and sum of its eigenvectors are offered using MSC. Nastran. Hanger locations are recommended at the position where the ADDOFD is relatively lower. Then static analysis and dynamic analysis of the exhaust system are done, and finally hanger locations of the exhaust system are selected. When the reasonable hanger positions have been decided, the vibration level of the body and the internal noise would have been decreased. This method can effectively select better NVH performance hanger locations in the earlier vehicle development process and can be extended to other types of vehicle, thus is instructive for saving both the time and the cost of operation.