Applied Mechanics and Materials Vols. 130-134

Abstract: This paper presents the finite element damage simulation of laminated plates induced by low-velocity transverse impact. The solid elements are used to model the laminae, and the solid-shell interface elements are employed to characterize the behavior of the interfacial layers of the laminated plates. The material properties of the adhesive layers are used in the solid-shell interfacial elements for the damage prediction. The simulated damage propagation agrees well with the experimental results. Therefore, the numerical results show that the solid-shell interface element is a good computational model for the interfacial layer modeling in the damage simulation.

Abstract: In the face of power shortages, an analytical investigation on the displacement of electrically driven heat pump by gas engine driven heat pump is undertaken. The energy conversion process comparison based on existing data between electrically driven vapor compression heat pump (EVCHP) and gas engine driven vapor compression heat pump (GVCHP) indicates that GVCHP can improve the energy efficiency and exergy efficiency with the application of waste engine heat recovery for heat supply and the majority of loss in GVCHP occurs in the engine.

Abstract: For the stick-slip phenomenon encountered in the pneumatic cylinder motion in practical application, the stick-slip mechanism was analyzed and an nonlinear mathematical model based on the improved LuGre model of pneumatic cylinder movement was established. The movement of the piston and the pressure of the rodless chamber in the pneumatic cylinder based on meter-in circuit were obtained through solving the differential equations by four-order variable-step Runge-Kutta method. The comparison between simulation and experimental results shows that the established mathematical model can describe the stick-slip motion of pneumatic cylinder with a relatively good accuracy.

Abstract: The compressed air engine is receiving increasingly worldwide attention because it takes advantage of renewable energy and has zero exhaust emissions. This paper presents a systematic study on valve timing and size of a prototype compressed air engine for optimizing its efficiency and performance. An in-house air engine system model has been developed using the FLOWMASTER platform. The simulated results show that the optimizing valve timings is probably the most critical requirement in the compressed air engine design process.

Abstract: The effects of ignition advance angle and excess air ratio on the combustion and emissions characteristics were investigated on a CNG engine at idle conditions. The throttle valve was fully closed. When the parameters were changed, the stepper motor was adjusted automatically to control the engine speed at 800r/min. When the θ_i is changed from 40 to 10^o BTDC, the maximum ITE and the maximum power are observed at λ=1.1. As λ increases, the maximum ITE is corresponding to a greater θ_i. The COV_imep will be increased if the θ_i is too advanced or too small. When λ is more than 1.3, the COV_imep increases obviously. When λ=1.1, NO_x emissions get the highest level.

Abstract: Internal combustion Rankine cycle engine uses oxygen instead of air as oxidant during the combustion process in gasoline engine. Recycled fluid is employed to control the reaction rate and recycles the exhaust heat inside the cylinder as well. CO₂ could be recaptured after separated from the exhaust gas (CO₂ and water vapor) during condensation, and an ultra-low emission working cycle is achieved. Considering the side effects of water injection process, EGR is employed to control the combustion process and thermal efficiency of the oxy-fuel combustion cycle is calculated and optimized in this paper. Results show that the application of EGR could slow down the combustion process effectively, and appropriate EGR rate matched with ignition timing would control the reaction rate and cylinder pressure, therefore enhance the engine performance.

Abstract: This paper presents the feasibility of semi-direct injection on a 50cm³, two-stroke motorcycle gasoline engine, which is applied FAI semi-direct injection fuel system. The structure and fuel injection system is improved based on the original carburetor engine and the FAI injector is easily installed. The results of laboratory and drive test show that, compared with the original carburetor fuel system, through optimization calibration of fuel injection timing and injection quantity can improve power performance and fuel economy.

Abstract: Aim to the exhaust manifold breaking phenomenon which appeared during pedestal experiment of a certain model engine, the main damage resource was detected through the studying and analyzing of exhaust manifold’s dynamic characteristic by means of FEM method. According to the results, one optimization design from both of materials and structure modified was provided. The engineering application and FEM analysis of modified structure show that the optimization design was efficient to deal with such problem.

Abstract: In this paper, a synchrodrive scheme for dual linear motors position servo system in gantry moving type milling machine is presented. The feedforward control, disturbance observer and electrical cross coupled control algorithm based on fuzzy PID are applied to the position servo system to counteract the influence of mechanical coupling rapidly, and then meet dynamic synchronized performance in machining. From the simulated, the results show that the proposed control method is effective and yield superior performance.

Abstract: The monitoring signal of oil analysis is usually not from a single friction pair but from the whole friction system, which leads to insufficient pertinence of oil analysis. On the basis of proportional relationship between metal constituents of single friction pair namely wear source, constrained linear separation model was put forward to separate spectral wear detection signal to obtain single wear source signal. The application of the model to engine spectral wear detection information shows its availability, and the pertinence of oil analysis has been improved.