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Fatigue behavior of aluminum alloys under multiaxial loading was investigated with both cast aluminum A356-T6 and wrought alloy 6063-T6. The dominant multiaxial fatigue crack preferentially nucleates from flaws like porosity and oxide films located near the free surface of the material. In the absence of the flaws, the cracking/debonding of the second phase particles dominates the crack initiation and propagation. The number of cracked/debonded particles increases with the number of cycles, but the damage rate depends on loading paths. Among various loading paths studied, the circle loading path shows the shortest fatigue life due to the development of complex dislocation substructures and severe stress concentration near grain/cell boundaries and second phase particles.

The noise and vibration of electric vacuum pump (EVP) become a major problem for electric vehicles when the vehicle is stationary. This paper aims at the EVP’s abnormal noise of an electric vehicle when stationary. Driver’s right ear (DRE) noise was tested and spectrogram analysis was carried out to identify the noise sources. In order to attenuate this kind of abnormal noise, a new EVP rubber mount with a segmented structure was introduced, which optimized the transfer path of vibration. Then dynamic stiffness and fatigue life of the EVP mount with different rubber hardness were calculated through finite element analysis (FEA) approach. Bench tests of fatigue life and DRE noise were performed to validate the FEA results. Test data of the sample mount shows that sound pressure level of DRE was dramatically attenuated and thus passengers’ ride comfort was enhanced.

Due to the advantages of low weight, low emissions and good fuel economy, downsized turbocharged gasoline direct injection (GDI) engines are widely-applied nowadays. However, Low-Speed Pre-Ignition (LSPI) phenomenon observed in these engines restricts their improvement of performance. Some researchers have shown that auto-ignition of lubricant in the combustion chamber has a great effect on the LSPI frequency. To study the auto-ignition characteristics of lubricant, an innovative single droplet auto-ignition test system for lubricant and its mixture is designed and developed, with better accuracy and effectiveness. The experiments are carried out by hanging lubricant droplets on the thermocouple node under active thermo-atmosphere provided by a small “Dibble burner”. The auto-ignition process of lubricant droplets is recorded by a high-speed camera.

A compiled method of the programmed load spectrum, which can simplify and accelerate the fatigue bench test of a car body, is proposed and its effectiveness is checked by the fatigue simulation. By using the multi-body dynamics model with a satisfactory accuracy, the virtual iteration is applied to cascade body loads from the wheel hubs. Based on the rain-flow counting method and statistics theory, the distributions of the body loads are analyzed, and then the programmed load spectrum is compiled and simplified. Through comparative study, the simulation results of random and programmed load spectrum are found to agree well with each other in terms of the damage distribution and fatigue life, which demonstrates the effectiveness of the presented method.

The present work proposed to implement oxy-fuel combustion mode into a homogeneous charge compression ignition engine to reduce complexity in engine emissions after-treatment and lower carbon dioxide emission. The combination of oxy-fuel combustion mode with homogeneous charge compression ignition engine can be further optimized by the utilization of direct high temperature and pressure water injection to improve cycle performance. A retrofitted conventional diesel engine coupled with port fuel injection and direct water injection is utilized in this study. A self-designed oxygen and carbon dioxide mixture intake system with flexible oxygen fraction adjustment ability is implemented in the test bench to simulate the adoption of exhaust gas recirculation. Water injection system is directly installed in the combustion chamber with a modified high speed solenoid diesel injector.

The linear internal combustion engine-linear generator integrated system (LICELGIS) is an innovative structure as a range-extender for the hybrid vehicles, which contains two opposed free piston engines and one linear generator between them. The LICELGIS is a promising power package due to its high power density and multi-fuel flexibility. In the combustion process of linear engines, the top dead center (TDC) position is not stable in different cycles, which significantly affects system operations. Otherwise, pistons move away from the TDC with high-speed because of the tremendous explosive force, which incurs the short residence time of pistons around the TDC and rapid decrease of in-cylinder temperature, pressure and the combustion efficiency. In order to address this problem, a scientific simulation model which includes dynamic and thermodynamic models, is established and a combustion optimization control strategy is proposed.

Turbochargers improve performance in internal combustion engines. Due to low production costs, TC assemblies are supported on floating ring bearings. In current lubrication analysis of floating ring bearing, inner and outer oil film are usually supposed to be adiabatic. The heat generated by frictional power is carried out by the lubricant flow. In reality, under real operating conditions, there existed heat transfer between the inner and outer film. In this paper, the lubrication performance of floating ring bearing when considering heat transfer between inner film and outer film is studied. The lubrication model of the floating ring is established and the heat transferred through the ring between the inner and outer film is calculated. The calculation results show that heat flow between the inner and outer film under different outer film eccentricity ratio and rotate ratio has a large difference.

The action of load on the component is crucial to evaluate the performance of durability. Another factor that affects fatigue life is the boundary conditions of the test specimen being tested by introducing unrealistic loads on the component of interest. The physical test is widely conducted in the laboratory. The fixture provides additional constraints on the test specimen as well as reaction forces to balance the test system [1]. The characteristics of the fixture involved in the test is important to analyze and assess the test results [2]. The impact of the reaction force of the fixture on the spindle-coupled axle road simulation test is presented in this article. A simplified 7-DoF (degrees of freedom) model is introduced to demonstrate the dynamic behavior of the vehicle. The influence on the internal load by the fixture has been analyzed. Followed by a more detailed MBS (multibodysystem) model to give a thorough understanding of the phenomenon.

Two control strategies, safety preferred control and master cylinder oscillation control, were designed for anti-lock braking on a novel integrated-electro-hydraulic braking system (I-EHB) which has only four solenoid valves in its innovative hydraulic control unit (HCU) instead of eight in a traditional one. The main idea of safety preferred control is to reduce the hydraulic pressure provided by the motor in the master cylinder whenever a wheel tends to be locking even if some of the other wheels may need more braking torque. In contrast, regarding master cylinder oscillation control, a sinusoidal signal is given to the motor making the hydraulic pressure in the master cylinder oscillate in certain frequency and amplitude. Hardware-in-the-loop simulations were conducted to verify the effectiveness of the two control strategies mentioned above and to evaluate them.

By changing the top-land radial clearance, this paper presents the effect of the piston crevice on the transient HC emissions of the first firing cycle at cold start on an LPG SI Engine. A fast-response flame ionization detector (FFID) was employed to measure transient HC emissions of the first firing cycle. At the same time, the transient cylinder pressure and instantaneous crankshaft speed of the engine were measured and recorded. The results show that increasing 50% crevice volume leads to 25% increase of HC emissions in the lean region and 18% increase of HC emissions in the rich region, however, the 50% increase of crevice volume contributes to 32% decease of HC emissions in the stable combustion region. For LPG SI engine, the HC emissions of the first firing cycle during cold start are relatively low in a wide range of the excess air ratio.

The effectiveness of after-treatment systems depends on the exhaust gas temperature, which is low during cold-start. As a result, Euro III, Euro IV and FTP75 require that the emissions tests include exhaust from the beginning of cold start. It is proved that 50%∼80% of HC and CO emissions are emitted during the cold start and the amount of unburned fuel from the crevices during starting is much higher than that under warmed engine conditions. The piston crevices is the most part of combustion chamber crevices, and results of mathematical simulations show that the piston crevice contribution to HC emissions is expected to increase during cold engine operation. Based on the transient HC test data and the double zone combustion model, this paper presents the study of the crevice HC Mechanism of the first firing cycle at cold start on an LPG SI Engine. A fast-response flame ionization detector (FFID) was employed to measure transient HC emissions of the first firing cycle.

“Soichiro Honda Cup, Honda Econo-Power Competition”, is an annual international energy-saving competition which is hosted by Honda Motor Co., Ltd. Till now it has been held 27 sessions. The aims of the EP project are: promoting the development of environmental protection, making full use of limit earth resources, challenging the fuel consumption limitation of vehicle. Tongji University's students' team has participated in the competition for seven consecutive times. In order to minimize the fuel consumption of the EP energy-saving vehicle, this paper focuses on the technical methods of improving the fuel economy of the engine. Firstly, the optimization of the carburetor. Secondly, for the purpose of improving combustion efficiency, researches on dual spark plug and compression ratio are done.

The frame of a low-speed electric vehicle was treated as the research object in the paper. The fatigue load of the frame was analyzed with multi-body dynamics method and the fatigue life of frame was analyzed with the nominal stress method. Firstly, the multi-body dynamics model of the vehicle was established and the multi-body dynamics simulation was carried out to simulate the condition where the vehicle used to travel. The fatigue load history of the frame was obtained from the simulation. Secondly, the amplitude-frequency characteristic of the fatigue load was analyzed. The frequency of the fatigue load mainly focused on 0~20HZ from the analysis. Thirdly, the modal of frame was analyzed. As the frequency of the fatigue load was less than the natural frequency of the frame, the quasi-static method was selected to calculate the stress history of the frame. Next, the fatigue life of the frame was analyzed based on S-N curve.

The multi-body dynamics simulation and physical iteration were carried out based on the 4-channel road simulation bench, the solution of fatigue test bench which was suitable for cab with frame and suspension was designed. Large load and displacement above the suspension can be loaded on the test bench, and the same weak position of cab exposed on the road test can be assessed well on the fatigue test bench. The effectiveness of the bench test solution was verified though comparative study. And it has important reference for the same type of cab assembly with suspension in the fatigue bench test. According to the durability specifications of cab assembly, a multi-body dynamics model with a satisfactory accuracy was built. And the fixture check and virtual iteration analysis were used to verify the effectiveness of the solution. According to the road load signal analysis and multi-body dynamics analysis results, the test bench with linear guide and spherical joint was built.

Biomechanics and biodynamics are increasingly focused on the automotive industry to provide comfortable driving environment, reduce driver fatigue, and improve passenger safety. Man-centered conception is a growing emphasis on the open design of automobile. During the long-term driving, occupational drivers are easily exposed to the neck pain, so it is important to reduce the muscle force load and its fatigue, which are not usually considered quantitatively during traditional ergonomics design, so standards related are not well developed to guide the vehicle design; On the other hand, the head-neck models are always built based on the statics theory, these are not sufficient to predict the instantaneous variation of the muscle force. In this paper, a head-neck model with multi DOFs is created based on multibody dynamics. Firstly, a driver-vehicle-road model considering driver multi-rigid body model, vehicle subsystems, and different ranks of pavement is built.

For an innovative opposed-piston diesel engine (OPE) with two-stroke operation mode, it attracted even more attentions than ever in some developed countries all around the world, attributed to the unique advantages of higher power density that conducive to downsize IC engine, as well as the potential of further reducing fuel consumption for outstanding thermal efficiency. To achieve fast practical application and ensure the feasibility in concept design stage, the performance characteristic of OPE crankshaft system was investigated, and thus a theoretical analytic model of crankshaft system in an OP2S (Opposed-piston two stroke) engine was established. The effects of all structural design variables on averaged output torque of OPE crankshaft were analyzed, respectively. It was found that the initial crank angle difference between inner crank web and outer crank web was considered as a most critical contributor to boost the averaged torque output than other design variables.

Turbocharging industry mainly employ steady method in the design and development process in present. However, the unsteady method is becoming more important for the exploration of the advanced turbocharging technique. This paper discusses the influences of A/R value on unsteady performances of a double-entry turbocharger turbine. In the study, numerical simulation has been done by ANSYS CFX software, The turbine have three kinds of A/R values that change in order, and the three schemes has the same unsteady flow boundary conditions. The simulation results show that the unsteady turbine performances have the characteristics loops representing filling and emptying effects. And the unsteady performances of the three schemes have some regular differences. The mean unsteady turbine efficiency decreases with increasing A/R value in the involved range, but the overall entropy of the turbine in a pulse period has no significant differences.

Sealing system is an important subsystem of modern high-performance engine. Sealing system reliability directly affects the engine operating conditions. Cylinder head gaskets(CHG) sealing system is of the most importance to the engine sealing system, which is not only responsible for sealing chamber, the cooling fluid and lubricating oil passage, for preventing gas leakage, water leakage and oil leakage, but also responsible for force transferring between cylinder head and cylinder body. Basing on nonlinear solution method, the sealing performance of multi-layer-steel cylinder head gaskets to a gasoline engine is studied with the finite element software ABAQUS. The deformations of the cylinder liners and engine block are also considered.

For an in-line diesel engine with four cylinder operating in four-stroke mode, the second-order reciprocating inertia forces generally cannot be well balanced with direct approach. The unbalanced second-order inertia forces are the main reason to cause vibration and noise in a diesel engine within low frequency range. The more superior tone quality for modern diesel engine has been expected even for bus application all the time, and there are tougher requirements for truck noise in developed countries, i.e. in Europe and USA. In present research a unique crankshaft system configuration was proposed, which including opposed piston, inner and outer connecting rod, and crankshaft but running in two-stroke mode, to eliminate the second-order inertia force considerably rather than by adding an extra balance shaft mechanism.

The present work aims at optimizing diesel engine combustion efficiency with optimized water injection strategy. The engine had been modified based on a two-cylinder mechanical pump diesel engine into common rail diesel engine with capability of direct water injection. The direct water injection system was designed and manufactured independently. An air-fluid booster was utilized to establish the water injection pressure up to 40MPa. Customized diesel injector was selected to be used as water injector in this study. Water injection strategy was optimized in detail with injection timing around TDC which ranges from 12°CA BTDC to -5°CA BTDC under 10 bar IMEP. The engine efficiency can be improved under selected water injection strategy due to the increment of work fluid in the combustion chamber. Moreover, the nitric oxides emissions show decrement around 10%.