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The objective of this investigation was to improve the thermal properties of plasma sprayed thermal barrier coatings (TBC) for internal combustion engines. There is a need for further reduction of thermal conductivity and volumetric heat capacity and the negative effects on heat loss and combustion phasing of surface roughness and permeable porosity, typical for plasma sprayed coatings, should be minimized. Four measures for improvement of TBC properties were evaluated: i) modification of the coating's microstructure by using a novel suspension plasma spraying method, ii) application of gadolinium-zirconate, a novel ceramic material with low thermal conductivity, iii) polishing of the coating to achieve low surface roughness, and iv) sealing of the porous coating surface with a polysilazane. Six coating variants with different combinations of the selected measures were applied on the piston crown and evaluated in a single cylinder light duty diesel engine.

Flow visualization techniques are widely used in aerodynamics to investigate the surface trace pattern. In this experimental investigation, the surface flow pattern over the rear end of a full-scale passenger car is studied using tufts. The movement of the tufts is recorded with a DSLR still camera, which continuously takes pictures. A novel and efficient tuft image processing algorithm has been developed to extract the tuft orientations in each image. This allows the extraction of the mean tuft angle and other such statistics. From the extracted tuft angles, streamline plots are created to identify points of interest, such as saddle points as well as separation and reattachment lines. Furthermore, the information about the tuft orientation in each time step allows studying steady and unsteady flow phenomena. Hence, the tuft image processing algorithm provides more detailed information about the surface flow than the traditional tuft method.

When it comes to the acoustic properties of electric cars, the powertrain noise differs dramatically compared to traditional vehicles with internal combustion engines. The low frequency firing orders, mechanical and combustion noise are exchanged with a more high frequency whining signature due to electromagnetic forces and gear meshing, lower in level but subject to annoyance. Previous studies have highlighted these differences and also investigated relevant perception criteria in terms of psycho-acoustic metrics. However, investigations of differences between different kinds of electric and hybrid electric cars are still rare. The purpose of this paper was to present the distribution of tonal components in today's hybrid/electric vehicles. More specifically, the number of prominent orders, their maximum levels and frequency separation were analyzed for the most critical driving conditions. The study is based upon measurements made on 13 electrified cars on the market.

The phenomenon of three-dimensional flow separation is and has been in the focus of many researchers. An improved understanding of the physics and the driving forces is desired to be able to improve numerical simulations and to minimize aerodynamic drag over bluff bodies. To investigate the sources of separation one wants to understand what happens at the surface when the flow starts to detach and the upwelling of the streamlines becomes strong. This observation of a flow leaving the surface could be captured by investigating the limiting streamlines and surface parameters as pressure, vorticity or the shear stress. In this paper, numerical methods are used to investigate the surface pressure and flow patterns on a sedan passenger vehicle. Observed limiting streamlines are compared to the pressure distribution and their correlation is shown. For this investigation the region behind the antenna and behind the wheel arch, are pointed out and studied in detail.

It is well known that wheels are responsible for a significant amount of the total aerodynamic drag of passenger vehicles. Tyres, and mostly rims, have been the subject of research in the automotive industry for the past years, but their effect and interaction with each other and with the car exterior is still not completely understood. This paper focuses on the use of CFD to study the effects of tyre geometry (tyre profile and tyre tread) on road vehicle aerodynamics. Whenever possible, results of the numerical computations are compared with experiments. More than sixty configurations were simulated. These simulations combined different tyre profiles, treads, rim designs and spoke orientation on two car types: a sedan and a sports wagon. Two tyre geometries were obtained directly from the tyre manufacturer, while a third geometry was obtained from our database and represents a generic tyre which covers different profiles of a given tyre size.

Volvo Car Corporation has developed a Reference Architecture for PAG1 Infotainment Systems. A Reference Architecture is an architecture scoping over more than a single system, i.e. an architecture aimed for a family of systems. The Infotainment Reference Architecture has since 2001 been successfully applied for the PAG family which so far covers the infotainment systems of Volvo XC90, Volvo S40/V50, Jaguar XK, Aston Martin DB9 and the brand new Volvo S80. In 1999, the system design departments started up with the clear objective to develop a system solution aiming for the PAG infotainment system family. The work was carried out according to the established development process at Volvo Cars. A year later a discouraging design review was performed. The number of involved functions, the level of function interaction and the distribution of functionalities between ECUs resulted in a non-manageable system solution.

The objective of this paper is to investigate whether different appearance modes of the digital human models (DHM or manikins) affect the observers when judging a working posture. A case where the manikin is manually assembling a battery in the boot with help of a lifting device is used in the experiment. 16 different pictures were created and presented for the subjects. All pictures have the same background, but include a unique posture and manikin appearance combination. Four postures and four manikin appearances were used. The subjects were asked to rank the pictures after ergonomic assessment based on posture of the manikin. Subjects taking part in the study were either manufacturing engineering managers, simulation engineers or ergonomists. Results show that the different appearance modes affect the ergonomic judgment. A more realistic looking manikin is rated higher than the very same posture visualized with a less natural appearance.

When designing components, systems and fluid characteristics, thermal loads gathered over the life cycle of an automobile are of great interest. Ageing and deterioration based on the temperature/time distribution that a component or fluid is exposed to, affects the functionality and/or durability of electronics, polymers and lubricants. Optimal design in terms of quality and cost are two of the most governing parameters at Volvo Cars at present. To meet this need, designing terms of life cycles from a thermal perspective has been developed during recent years. This paper presents a methodology for designing components and choosing system solutions from life span thermal loads in Volvo Car's vehicles. The fundamental ideas behind the method, design criteria and examples of usage are discussed from a holistic point of view.

To elucidate the processes controlling the auto-ignition timing and overall combustion duration in homogeneous charge compression ignition (HCCI) engines, the distribution of the auto-ignition sites, in both space and time, was studied. The auto-ignition locations were investigated using optical diagnosis of HCCI combustion, based on laser induced fluorescence (LIF) measurements of formaldehyde in an optical engine with fully variable valve actuation. This engine was operated in two different modes of HCCI. In the first, auto-ignition temperatures were reached by heating the inlet air, while in the second, residual mass from the previous combustion cycle was trapped using a negative valve overlap. The fuel was introduced directly into the combustion chamber in both approaches. To complement these experiments, 3-D numerical modeling of the gas exchange and compression stroke events was done for both HCCI-generating approaches.

The following paper describes how to measure the global torsional stiffness of a complete car under field-like conditions. All that's needed are lifting devices, two stands of equal height, three glide planes or equivalent, three scales and two inclinometers, a spirit level, some pieces of aluminum and a glue gun. The results from four measured cars are presented and a comparison is made with values obtained with laboratory equipment and data from manufacturers. The method is a fast and economic means to find the most interesting cars that then can be selected for measurement by traditional methods, giving the stiffness as a function of the vehicles long axis, and thus minimizes the cost of benchmarking. Time for measuring one car with all equipment readily available and with personnel having some experience of the method is about two hours. Only the sway bars have to be disconnected. Absolutely no damage to the measured car means that rented cars can be used.

Experience from several car projects shows that S-N curves for spot welds generated under load control in the high cycle fatigue regime might be very conservative when used in the low cycle fatigue regime. Therefore, force and displacement controlled low cycle fatigue tests were carried out on peel and shear loaded specimens. Both constant (CA) and variable amplitude (VA) load signals were used. Finally, a method for predicting fatigue life of spot welds with increased accuracy in the low cycle fatigue regime is proposed. The method is simple, fast and accurate and can be used together with linear finite element analysis (FEA) and existing fatigue packages.

In the continuous struggle to improve car body properties, and at the same time reduce the weight of the structure, new materials and body concepts are being evaluated. In competition with more self-evident lightweight materials such as aluminium and plastic composites, new and different grades of high-strength steels with various surface coatings are being introduced. From experience it is known that to be able to weld and join these steel grades under high-volume conditions, it is necessary to perform comprehensive testing to establish those assembly parameters which give a superior and reliable weld quality. To meet the demands of cost-effective low volume production, we can notice a tendency to move away from traditional uni-body concepts and into the direction of space-frame structures. These can preferably be manufactured out of high-strength steels by using production methods like roll-forming, hydro-forming and hot-forming.

Today automotive system suppliers develop more-or-less independent systems, such as brake, power steering and suspension systems. In the future, car manufacturers like Volvo will build up vehicle control systems combining their own algorithms with algorithms provided by automotive system suppliers. Standardization of interfaces to actuators, sensors and functions is an important enabler for this vision and will have major consequences for functionality, prices and lead times, and thus affects both vehicle manufacturers and automotive suppliers. The investigation of the level of appropriate interfaces, as part of the European BRAKE project, is described here. Potential problems and consequences are discussed from both a technical and a business perspective. This paper provides a background on BRAKE and on the functional decomposition upon which the interface definitions are based. Finally, the interface definitions for brake system functionality are given.

In the early days of the automotive industry, durability and reliability were hit or miss affairs, with end-users often being the first to know about any durability problems - and in many cases forming an essential part of the development process. More recently, automotive companies have developed proving ground and laboratory test procedures that aim to simulate typical or severe customer usage. These test procedures have been used to develop the products through a series of prototypes and to prove the durability of the product prior to release in the marketplace. Now, commercial pressures and legal requirements have led to increasing reliance on CAE methods, with fatigue life prediction having a central role in the durability engineering process.

In May 1998 Volvo launched its most exclusive car model so far, the Volvo S80, which is aimed to compete with upper luxury segment products. The car is produced in the new production facility in the Torslanda plant in Sweden. Among the more highlighted features were a transversely mounted in-line six cylinder engine with a specially designed gearbox, electronic multiplex technology with 18 computers in the network, and safety features like stability and traction control (STC), front seats with integrated antiwhiplash system (WHIPS) and inflatable curtain (IC) for improved side impact protection. To fulfill the product's high demands on safety, quality and environmental care, the design, materials selection and assembly of the car body with high precision had to be very carefully engineered. As in previous product-/process development a holistic and concurrent engineering approach was necessary.

Flow simulations of an air distribution system have been carried out using the CFD code FLUENT/UNS [1]. The purpose of this study is to validate this complex flow problem versus experimental data. Two modes of the climate system are investigated; the Ventilation mode and the Floor/Defroster mode. The complete geometrical model contains all ducts, central unit, heat exchangers, defroster and nozzles of the air distribution system. A high level of geometrical detailing in the mesh, consisting of 2.1 - 3.3 million cells, is used. The study shows that CFD has a potential to give reliable results, even for complex systems, like air distribution systems, if used in a controlled manner.

A new in-vehicle communication concept for CAN networks has been developed, taking into account recent findings from real-time research. The concept is characterized by three impo features: (i) Ability to guarantee the real-time performance of the network already at the design stage, thus significantly reducing the need for testing; (ii) Built-in flexibility enabling the vehicle manufacturer to upgrade the network in the pre-production phase of a project as well as in the aftermarket; (iii) Low use of available resources, thus saving cost compared to other solutions. The concept is successfully used in all larger Volvo cars from model year 1999.

To give the customer an immediate impression of quality several of criteria must be fulfilled such as styling, paint finish and fitting of outer panels/closures. Therefore, higher demands on geometrical quality e.g. stability for both exterior and interior are needed. The structural part of the car body is the key element for success. Beside the visual impression, lack of noise and vibrations during driving can convince a potential buyer to become an actual customer. To achieve this, car manufacturers have to draw up an overall strategy in combination with proper working methods to be able to guarantee a stable geometrical output throughout the entire development process and during series production over the lifetime of the vehicle. On a simultaneous engineering basis, the OEM, the system/component- and the process suppliers (for the industrial system from press shop to final assembly) have to adopt a common measurement strategy.

A finite-element (FE) based method for numerically predicting fatigue life of MAG-welded thin-sheet structures has been established and tested. The method uses nodal forces and moments calculated along the weld line, together with an analytical expression for the structural stress at the weld toe. The calculated stress is used together with an experimentally determined Wöhler, or S-N, curve. A “stiff” welded joint with structural stress dominated by membrane forces is found to have a steeper S-N curve than a “flexible” joint with structural stress dominated by bending moment. All test results were seen to lie close to one of two different S-N curves. The proportion of bending stress over total structural stress could be used for choosing the appropriate S-N curve.

The aerodynamic properties of a full-scale car have been investigated in a wind-tunnel with upstream boundary layer suction, and in a water-basin where the car was rolling on the bottom. Measurements were carried out of the drag and lift forces, the static pressure distribution on the car body and the total head distribution between the car and the ground. By comparing data from the tunnel and the basin the ground simulation technique could be evaluated. The measured drag coefficients were found to be very similar in both facilities, while the absolute values of the lift coefficients were considerably higher in the tunnel. Lift differences due to configuration changes of the upperbody were essentially the same in the two facilities, while changes of the underbody caused smaller lift differences in the tunnel. In the project the water-basin technique was thoroughly investigated and proven.