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In recent years, structural adhesives have rapidly become the preferred alternative to resistance spot welding in fabricating stronger, lighter aluminum connections. Connections inevitably undergo and must withstand complex quasi-static and/or dynamic loads during their service life. Therefore, understanding how loading conditions affect the mechanical behavior of adhesive joints is vital to their design and the advancement of structural safety. Quasi-static and dynamic tests are performed to analyze both the strength and failure modes of aluminum 6062 substrates bonded by an adhesive (Darbond EP-1506) for an array of loading directions. An Arcan test device, which enables application of mixed-mode loads ranging from pure peel (mode I) to pure shear (mode II) to the adhesive layer, is employed in quasi-static testing. A self-designed medium-speed test machine is utilized to perform dynamic testing.

To find out the main excitation sources of a bus floor's vibration, modal analysis and spectral analysis were respectively performed in the paper. First we tested the vibration modal of the bus's floor under the full-load condition, and the first ten natural frequencies and vibration modes were obtained for the source identification of the bus floor's vibration. Second the vibration characteristic of the bus floor was measured in an on-road experiment. The acceleration sensors were arranged on the bus's floor and the possible excitation sources of the bus, which includes engine mounting system, driveline system, exhaust system, and wheels. Then the on-road experiment was carefully conducted on a highway under the four kinds of test condition: in-situ acceleration, uniform velocity (90km/h, 100km/h, 110km/h, 120km/h), uniform acceleration with top gear, and stall sliding condition with neutral gear.

This study investigates the fundamental stiffness and damping properties of a self-damped pneumatic suspension system, based on both the experimental and analytical analyses. The pneumatic suspension system consists of a pneumatic cylinder and an accumulator that are connected by an orifice, where damping is realized by the gas flow resistance through the orifice. The nonlinear suspension system model is derived and also linearized for facilitating the properties characterization. An experimental setup is also developed for validating both the formulated nonlinear and linearized models. The comparisons between the measured data and simulation results demonstrate the validity of the models under the operating conditions considered. Two suspension property measures, namely equivalent stiffness coefficient and loss factor, are further formulated.

Starting control has become a troublesome issue in the developing field of the control system for heavy-duty trucks, due to the complexity of vehicle driving and the variability of driver's intention. The too fast clutch engagement may result in serious impact, influence on the comfort and fatigue life, and even the engine flameout, while the too slow clutch engagement may lead to long time of friction, the increased temperature, and accelerated wear of friction pair, as well as influence on the power performance and fatigue life[1]. Therefore, the key technique of starting control is clutch engagement control, for which the fuzzy PID based optimization of starting control for AMT clutch is proposed, with the pneumatic AMT clutch of heavy-duty trucks as the research object.

Low temperature combustion (LTC) is an advanced combustion mode, which can achieve low emissions of NOx and PM simultaneously, and keep relatively high thermal efficiency at the same time. However, one of the major challenges for LTC is the cold condition. In cold conditions, stable compression ignition is hard to realize, while thermal efficiency and emissions deteriorate, especially for gasoline or fuel with high octane number. This study presents using pressure sensor glow plugs (PSG) to realize Glow plug assisted compression ignition (GA-CI) at cold conditions. Further, a glow plug control unit (GPCU) is developed, a closed-loop power feedback control algorithm is introduced based on GPCU. In the experiment, engine coolant temperature is swept. Experimental results show that GA-CI has earlier combustion phases, larger combustion duration and higher in-cylinder pressure. And misfire is avoided, cycle-to-cycle variations are greatly reduced.

With the increasing regulatory stringency on emission reduction and efficiency improvement, the automotive industry has experienced a significant shift in the hardware platform. Among technology candidates, hybrid technology is still considered one of the most viable approaches to meet the regulation requirement (both emission and efficiency) at an affordable cost to both the customer and the manufacturer. New engine operating characteristics are expected in hybrid applications which would potentially result in different performance requirements for the engine oil. Therefore, it is crucial to understand those characteristics of a hybrid powertrain, from which the insights of fluid requirements can be derived. A hybrid vehicle test study was conducted to evaluate the engine operation of different kinds of hybrid platforms. The hybrid operation has been well characterized by thoroughly analyzing parameters on each engine.

A novel non-destroy repeatable-use impact theory based total cylinder sampling system has been established. This system is mainly composed of a knocking body and a sampling valve. The knocking body impacts the sampling valve with certain velocity resulting in huge force to open the sampling valve and most of the in-cylinder gas has been dumped to one sampling bag for after-treatment. The feasibility and sampling response characteristics of this impact theory based total cylinder sampling system were investigated by engine bench testing. Within 0 to 35°CA ATDC (Crank Angle After Top Dead Center) sample timing 50 percent to 80 percent of in-cylinder mass would be sampled, which was a little less compared with the traditional system. The half decay period of pressure drop was 10 to 20 degrees crank angle within 0 to 60°CA ATDC sample timing, which was about 2-3 times of the traditional system.

Low Speed Pre-Ignition (LSPI), also referred to as superknock or mega-knock is an undesirable turbocharged engine combustion phenomenon limiting fuel economy, drivability, emissions and durability performance. Numerous researchers have previously reported that the frequency of Superknock is sensitive to engine oil and fuel composition as well as engine conditions in controlled laboratory and engine-based studies. Recent studies by Toyota and Tsinghua University have demonstrated that controlled induction of particles into the combustion chamber can induce pre-ignition and superknock. Afton and Tsinghua recently developed a multi-physics approach which was able to realistically model all of the elementary processes known to be involved in deposit induced pre-ignition. The approach was able to successfully simulate deposit induced pre-ignition at conditions where the phenomenon has been experimentally observed.

In order to improve centrifugal compressor performance predictive capability, an improved recirculation loss model in two-zone modeling system is presented in this paper. The new loss model correlates Reynolds number of the impeller with the recirculation loss. Performance prediction by the improved model is carried out on two turbochargers with different sizes based on COMPAL mode of the code Concepts. The result shows that predictive performance by improved model is in high accordance with experimental measurement. On the other hand, compared with the larger size compressor, the small one has a performance which is more likely to be influenced by Reynolds number.

The incomplete combustion and misfire of diesel engine during starting result in unwanted white smoke. The histories of combustion and emission in different phases under different start conditions were studied in this paper. The optimization of the fuel injection control strategy under start conditions was performed. When the diesel engine is started under low temperature, the control strategy adapted to start the engine with a certain constant fuel mass injected per cycle, there may be misfire cycles in the initial period or in the transitional process, which is mainly caused by the mismatch between the fuel mass injected per cycle and the instantaneous engine speed. Therefore, an optimized control strategy was put forward, namely, the engine starts with high fuel mass injection in the first several cycles and then decreases step by step during the transitional period until it operates at idle condition. This strategy was validated to decrease significantly the misfire cycles.

Compressed Natural Gas (CNG), because of its low cost, high H/C ratio, and high octane number, has great potential in automotive industry, especially for heavy-duty commercial vehicles. However, relative slow flame speed of natural gas leads to long combustion duration and low thermal efficiency and tends to cause knock combustion at high load, which will aggravate engine thermal load and reliability. Enhancing turbulence intensity in combustion chamber is an effective way to accelerate flame propagation speed and improve combustion performance. In this study, the flow simulations of several piston bowls with different inner-convex forms were carried out using three-dimensional computational fluid dynamics (3D-CFD) software CONVERGE. The numerical results showed the piston bowls with inner-convex could disturb the charge swirl motion and enhance turbulence of different intensity. A hexagram geometry bowl was proved to have the best function in strengthening turbulence intensity.

An integrated simulation platform for turbocharged internal combustion engines has been developed. Multi-dimensional computational fluid dynamic (CFD) codes are integrated into the system to model the turbocharging circuit, gas circuit, in-cylinder circuit, coolant and oil circuits. As the turbocharger is a critical factor for the IC engine, a turbocharger through-flow model based on mass, momentum, and energy conservation equations has been developed and added in the integrated platform. Compared with the traditional MAP method, the through-flow model can solve the problems of transient matching and lack of numerous experimental maps during the pre-prototype engine design. Partial systems in the integrated platform, such as the in-cylinder flow and combustion circuit, can be modeled by 3-D CFD codes for the investigation of the detailed flow patterns.

The basic theory of statistical energy analysis (SEA) is introduced, a commercial heavy duty truck cab is divided into 35 subsystems applying SEA method, and a three dimensional SEA model of the commercial heavy duty truck cab is created. Three basic parameters including modal density, damping loss factor and coupling loss factor are calculated with analytical and experimental methods. The modal density of the regular wall plate of the cab is calculated with traditional formula. The damping loss factors of the regular and complicated plates are obtained using analytical method and steady energy stream method. Meanwhile, the coupling loss factors of structure-structure, structure-sound cavity, and cavity-cavity are also calculated. Four kinds of excitations are in the SEA model, including sound radiation excitation of engine, engine mount vibration excitation, road excitation and wind excitation.

This paper presents an investigation of cold starts based on a cycle-by-cycle control strategy in an LPG EFI engine. Experiments were carried out in a four-stroke, water-cooled, single cylinder, 125cc SI engine with an EFI system. Effects of the first injection pulse width and the first combustion cycle on the characteristics of the cold-start were analyzed based on the histories of transient engine speeds and cylinder pressures. The study focuses on how to realize the controllable ignition cycle and the single-cycle and multi-cycle combustions were tested based on the single starting injection pulse width. Test results show that the first combustion cycle has an important effect on HC emission and combustion stability of following cycles at cold-start. The injection pulse width is the key factor determining the characteristics of an ignition cycle during the cold-start.

A three-dimensional numerical investigation into aerodynamic feature of the turbocharger turbine under pulsating flow conditions is conducted in this paper. Dual time stepping approach is applied to solve the unsteady Navier-Stokes equations, while the Jameson central scheme is brought in for spatial discretization, and Spalart-Allmaras turbulence model is employed in order to get good viscous resolution, accuracy and computing efficiency. The quasi-steady and unsteady performance of the turbine is given and compared. Five blade passage cross sections are chosen to analyze the structure of the secondary flow at 4 key instants. The developments of different vortex, especially the tip leakage vortex, passage vortex are discussed. The results have shown that the unsteady performance deviates substantially from quasi-steady performance, and the secondary flow structure varies tremendously under the pulsating flow conditions.

The calibration of the electronic throttle unit and the pedal unit was made. Based on it, an electronic control system of electronic throttle was designed and installed on a 4G18 engine. Engine experiment was made especially for its transient working condition. Engine performance at transient working condition was investigated. The test results indicate that the optimum way of opening the throttle valve is to open the throttle valve to the target location at once, when 4G18 engine transit from 2000r/min to 3000r/min without load. And its optimum calibration for the electronic throttle control unit is made based on the test results. The control system, the experiment, the test results and the calibration were introduced in this paper.

The ignition of lubricating oil droplet has been proved to be the main factor for pre-ignition and the following super-knock in turbocharged gasoline direct injection engine. In this paper, the ignition process of lubricating oil droplet in combustible ambient gaseous mixture was investigated in a rapid compression machine (RCM). The pre-ignition induction by oil droplet of the ambient gaseous mixture was analyzed under different initial droplet volume and effective temperature conditions. The oil droplet was suspended on a tungsten fiber in the combustion chamber and the ignition process was recorded by a high-speed camera through the quartz window mounted at the end of the combustion chamber. The pressure traces were also obtained by a sensor in order to get the ignition delay and analyze the combustion process in detail.

Based on a 125cm3 single cylinder SI engine, the designated idle speed was controlled by adjusting of cycle ignition advance angle. By analyzing the effects of different idle speed and throttle open position on three way catalyst (TWC) light-off time and conversion efficiency of HC and CO emissions, combined with the corresponding total HC and CO emissions level, the optimum idle speed and throttle open position at engine's warm-up phase were found by the matching optimum. The present method for engine control strategy is helpful to optimize the warm-up phase emission levels in SI engine with LPG fuel.

Neutral-idle strategy has been applied for years to improve the fuel consumption of automatic transmission cars. The updated demand is the use of expanded slipping control strategy for further improvement of the transmission efficiency and response speed. However, one major drawback of the continuous slipping clutches is the high tendency to produce shudder or low frequency variation. In this research, a special neutral-idle shudder phenomenon is presented. This special shudder is not only related to slipping clutches but also related to the vibration and structure of the powertrain system. Simulations and experiments are conducted to give an insight view of this phenomenon. The analysis reveals that this special shudder is caused by both torsional vibration of the driveline and rigid-body vibration of the powertrain system. A positive feedback loop between those two kinds of vibrations leads to this special neutral-idle shudder.

Early injection timing is an effective measure of pre-mixture formation for diesel low-temperature combustion. Three algebraic subgrid models (Smagorinsky model, dynamic Smagorinsky model and WALE model) and one-equation kinetic energy turbulent model using modified TAB breakup model (MTAB model) have been implemented into KIVA3V code to make a detailed large eddy simulation of the atomization and evaporation processes of early injection timing in a constant volume chamber and a Ford high-speed direct-injection diesel engine. The results show that the predictive vapor mass fraction and liquid penetration using LES is in good agreement with the experiment results. In combustion chamber, the sub-grid turbulent kinetic energy and viscosity using LES are less than with the RANS models, and following the increasing time, the sub-grid turbulent kinetic energy and viscosity also increase and are concentrated on the spray area.