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Car accident investigations have shown that the head, the chest and the abdomen are the three most vulnerable body regions in side impacts, when serious-to-fatal (MAIS 3-6) injuries are considered. Injuries are much more common to occupants seated on the struck side than to those on the non-struck side. The development of new side impact protection systems has therefore been focused on struck side occupants. The first airbag system for side impact protection, jointly developed by Volvo and Autoliv, was introduced on the market in 1994. The SIPS bag is seat-mounted and protects mainly the chest and the abdomen, and also to some extent the head, since the head's lateral relative displacement is reduced by the side airbag, thereby keeping the head inside the car's outer profile. However, if an external object is exposed in the head area, for example in a truck-to-car side impact or in a single car collision into a pole or a tree, there is a need for an additional head protection device.

Approximately 25 % of a passenger vehicle’s aerodynamic drag comes directly or indirectly from its wheels, indicating that the rim geometry is highly relevant for increasing the vehicle’s overall energy efficiency. An extensive experimental study is presented where a parametric model of the rim design was developed, and statistical methods were employed to isolate the aerodynamic effects of certain geometric rim parameters. In addition to wind tunnel force measurements, this study employed the flowfield measurement techniques of wake surveys, wheelhouse pressure measurements, and base pressure measurements to investigate and explain the most important parameters’ effects on the flowfield. In addition, a numerical model of the vehicle with various rim geometries was developed and used to further elucidate the effects of certain geometric parameters on the flow field.

It has been shown that Inflatable Curtains have the potential to reduce head injuries in side impacts and the system has accordingly been introduced on a growing number of car models. There is also a potential benefit in rollover situations. This paper only consider performance in situations with belted occupants. To date, it has not been possible to implement an Inflatable Curtain in convertible vehicles because they lack a roof. The challenge of the Door Mounted Inflatable Curtain (DMIC) has been to overcome the lack of support and fixation possibilities offered by a roof. This paper includes a description of the DMIC and how it was integrated into the vehicle structure. The paper will also show how to create the space and support needed to utilize the internal stiffness and make it possible to fill the bag in time. The impact attenuation and ejection protection functions of the DMIC will be demonstrated.

This paper presents how hardware in the loop (HIL) simulations have been used for testing during the development of the adaptive cruise control (ACC) and collision warning with brake support (CWBS) functions implemented in the Volvo S80. Both the brake system controller and the controller where the ACC and CWBS functions were implemented were tested. The HIL simulator was used for automated batch simulations in which different controller software releases were analyzed from both system, fail-safe and functional performance perspectives. This paper presents the challenges and the benefits of using HIL simulations when developing distributed active safety functions. Some specific simulation results are analyzed and discussed. The conclusion shows that although it is difficult and time-consuming to develop a complete HIL simulation environment for active safety functions such as ACC and CWBS, the benefits justify the investment.

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.

In HYGE sled simulations of 35 mph barrier crashes with the Volvo 760 dummy kinematics and injury criteria have been different from what can be observed in barrier crashes One of the major differences between sled testing and barrier crashes is the car pitch in the barrier crashes. In order to improve the sled testing a method to simulate pitch on the sled was developed. Dummy kinematics and injury criteria from sled tests with pitch simulation have proved to be in good agreement with results from barrier crashes. The paper will give a more detailed description of vehicle pitch, the sled pitch arrangement and a comparison of dummy kinematics and injury criteria from barrier crashes and sled testing with and without pitch displacement.

Frontal Severe Partial Overlap Collisions (SPOC) also called small overlap crashes pose special challenges with respect to structural design as well as occupant protection. In the early 1990s, the SPOC test method was developed addressing 20-40% overlap against a fixed rigid barrier with initial velocities up to 65 km/h. The knowledge gained has been used in the design of Volvo vehicles since then. Important design principles include front side members orientated along the wheel envelopes together with a strong support structure utilizing a space frame principle with beams loaded mainly in tension and compression. This novel setup was first introduced in the 850-model in 1991 and has been refined and patented (2001) in later Volvo front structures. Among the design principles are multiple front side members on each side, helping energy absorption efficiency and robustness.

Several of the exterior noise sources existing around a vehicle can cause airborne noise issues at relatively low frequencies. SEA, traditionally used for airborne sound issues is not suitable for the frequency range of interest. Finite Element analysis has been used. Handling of the non-reflecting condition on the outer boundary of the exterior cavity is an issue. Recently, advances have been made in several commercially available codes, which made the analysis practical. Including the poro-elastic material model for foam-based carpets is also becoming practically possible. The purpose of the current study is to investigate the practical applications of those new developments against test data, and to estimate the feasibility of using these procedures in the vehicle development projects. Measurements were carried out in a new semi-anechoic chamber at Volvo Cars. These measurements involved 3 body objects - a Body-in-Blue (BIB) sedan, a Complete Vehicle (CV) sedan and a CV wagon.

With the growing concern about the potential dangers with rear facing child seats placed in the front seat of passenger airbag equipped cars, various systems are being considered for deactivation of the airbag. To increase the awareness of and confidence in these proposed systems, information displays were developed for the purpose of telling the status of the passenger airbag system and to warn when necessary. A study of the effectiveness, understanding and acceptance of a selection of such information displays was jointly undertaken by Volvo Car Corporation, SAAB Automobile AB and the Swedish National Road and Transport Research Institute. Respondents of various age and demographic composition, parents and grand parents of small children, were exposed to six different sets of information displays and were asked to interpret them and also rank which information displays that would most clearly convey the message.

In areas such as Active Safety, new technologies, designs (e.g. AUTOSAR) and methods are introduced at a rapid pace. To address the new demands, and also requirements on Functional Safety imposed by ISO 26262, the support for engineering methods, including tools and data management, needs to evolve as well. Generic and file-based data management tools, like spreadsheet tools, are popular in the industry due to their flexibility and legacy in the industry but provide poor control and traceability, while rigid and special-purpose tools provide structure and control of data but with limited evolvability. As organizations become agile, the need for flexible data management increases. Since products become more complex and developed in larger and distributed teams, the need for more unified, controlled, and consistent data increases.

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.

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.

Increasing demand for simulation accuracy often leads to increased finite element model complexity, which in turn, results in higher computational costs. As a provision, component mode synthesis approaches are employed to approximate the system response by using dynamic substructuring and model reduction techniques in linear systems. However, the use of available model reduction techniques in nonlinear problems containing the contact type of nonlinearities remains an interesting topic. In this paper, the application of a component mode synthesis method in squeak and rattle nonlinear simulation has been investigated. Critical regions for squeak and rattle of the side door model of a passenger car were modelled by nonlinear contact definition in finite element simulation. Craig-Bampton model reduction method was employed to substructure the finite element model while keeping the nonlinear contacts in the model.

Car body structures and the joints between beam members have a great impact on global vehicle stiffness. With the method presented in this paper it is possible to experimentally assess the stiffness of joints by a robust and economic means. The stiffness of a beam can easily be found experimentally just by cutting it in two and using the cross-sections to calculate the polar moment of inertia. When it comes to a joint, there are no formulae or explicit expressions describing its behavior. Therefore, measurement of its mechanical behavior has to be made. The dynamic joint method presented here does not need levers or a costly, rigid set-up, but an economical free-free set-up and cast-on weights. Furthermore, the same method can be emulated by FEM when a digital model exists.

Many automotive electronic systems must be developed using a safety process. A preliminary hazard analysis is a first and an important step in such a process. This experimental study evaluates two methods for hazard identification using an electrical steering column lock system. Both methods are found to be applicable for hazard identification in an automotive context. It is also concluded that the induction with the failure modes method is less time consuming and easier to use than the method based on induction with generic low level hazards. Further, two proposals are presented to improve efficiency and consistency, reuse of generic hazards by component profiles and a domain specific catalogue of vehicle phases.

In a previous study, a passive sensor (HVAC) manikin coupled with a human thermal model was used to predict the thermal comfort of human test participants. The manikin was positioned among the test participants while they were collectively exposed to a mild transient heat up within a thermally asymmetric chamber. Ambient conditions were measured using the HVAC manikin’s distributed sensor system, which measures air velocity, air temperature, radiant heat flux, and relative humidity. These measurements were supplied as input to a human thermal model to predict thermophysiological response and subsequently thermal sensation and comfort. The model predictions were shown to accurately reproduce the group trends and the “time to comfort” at which a transition occurred from a state of thermal discomfort to comfort. In the current study, the effectiveness of using a coupled HVAC manikin-model system to evaluate a vehicle climate control system was investigated.

In 1993 new European legislation regarding side-markers for passenger cars became effective. Volvo requested the TNO-Human Factors Research Institute (HFRI) to investigate the possible safety benefit of this European side-markers configuration. A test panel at TNO- HFRI was used to determine the difference in response time and detection error of drivers, confronted with slides of vehicles with and without the mentioned new vehicle side-marker configuration in several visibility conditions, crossing illumination and different vehicle approach angles. The investigation showed a significant faster vehicle recognition with less detection errors in case the approaching car was equipped with the bright amber side-markers. This improved vehicle conspicuity can be a benefit in crash avoidance, especially when the driver approaches a crossing with complex light environment and reduced visibility.

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.

The development of a new combustion system for a light-duty diesel engine is presented. The soot-NOx trade-off is significantly improved with maintained or improved efficiency. This is accomplished only by altering the combustion chamber geometry, and thereby the in-cylinder flow. The bowl geometry is developed in CFD and validated in single cylinder tests. Tests and simulations align remarkably well. Under identical conditions in the engine the new combustion chamber decreases smoke by 11-27%, NOx by 2-11%, and maintains efficiency as compared to the baseline geometry. The injector nozzle is matched to the new bowl using design of experiments (DoE). By this method transfer functions are obtained that can be used to optimize the system using analytical tools. The emissions show a complex dependence on the nozzle geometry. The emission dependence on nozzle geometry varies greatly over the engine operating range.

Many accidents are road departures because of the drivers' lack of attention. This is in many cases due to distraction, drowsiness or intoxication. The Haptic Lane Departure Warning System described here is intended as an active safety system, thus aiming at decreasing the amount of unwanted lane departures. The challenge in the development of such kinds of functions lies in the determination of dangerous situations and the design of appropriate warning/intervention strategies. The system is intended to go unnoticed with the driver and intervenes only in instances where the driver mismanages steering control. Unlike systems which issue an audible sound, the type of warning is a tactile feedback via the steering wheel. This torque is designed in a way that it communicates to the driver the appropriate steering wheel angle required in order to come back in lane.