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The need for a more complete understanding of the flow behavior in aerodynamic wind tunnels has increased as they have become vital tools not only for vehicle development, but also for vehicle certification. One important aspect of the behavior is the empty test section flow, which in a conventional tunnel should be as uniform as possible. In order to assess the uniformity and ensure consistent behavior over time, accurate measurements need to be performed regularly. Furthermore, the uncertainties and errors of the measurements need to be minimized in order to resolve small non-uniformities. In this work, the quantification of the measurement uncertainties from the full measurement chain of the new flow uniformity measurement rig for the Volvo Cars aerodynamic wind tunnel is presented. The simulation based method used to account for flow interference of the probe mount is also discussed.

Vehicle dynamics development relies on subjective assessments (SA), which is a resource-intensive procedure requiring both expert drivers and vehicles. Furthermore, development projects becoming shorter and more complex, and increasing demands on quality require higher efficiency. Most research in this area has focused on moving from physical to virtual testing. However, SA remains the central method. Less attention has been given to provide better tools for the SA process itself. One promising approach is to introduce computer-tablets to aid data collection, which has proven to be useful in medical studies. Simple software solutions can eliminate the need to transcribe data and generate more flexible and better maintainable questionnaires. Tablets’ technical features envision promising enhancements of SA, which also enable better correlations to objective metrics, a requirement to improve CAE evaluations.

Previous research on both small-scale and full-scale vehicles shows that base extensions are an effective method to increase the base pressure, enhancing pressure recovery and reducing the wake size. These extensions decrease drag at zero yaw, but show an even larger improvement at small yaw angles. In this paper, rear extensions are investigated on an SUV in the Volvo Cars Aerodynamic Wind Tunnel with focus on the wake flow and on the unsteady behavior of the surface pressures near the base perimeter. To increase the effect of the extensions on the wake flow, the investigated configurations have a closed upper- and lower grille (closed-cooling) and the underbody has been smoothed with additional panels. This paper aims to analyze differences in flow characteristics on the wake of an SUV at 0° and 2.5° yaw, caused by different sets of extensions attached to the base perimeter. Extensions with several lengths are investigated with and without a kick.

The automotive industry strives to develop high quality vehicles in a short period of time that satisfy the consumer needs and stand out in the competition. Full exploitation of simulation and Computer-Aided Engineering (CAE) tools can enable quick evaluation of different vehicle concepts and setups without the need of building physical prototypes. Addressing the aforementioned statements this paper presents a method for optimising the Electric Power-Assisted Steering (EPAS) ECU parameters employing solely CAE. The objective of the optimisation is to achieve a desired steering response. The developed process is tested on three specific steering metrics (friction feel, torque build-up and torque deadband) for two function parameters (basic steering torque and active return) of the EPAS. The optimisation method enabled all metrics to fall successfully within the target range.

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.

The durability peak load events Driving over a curb and Skid against a curb have been simulated in Adams for a Volvo S80. Simulated responses in the front wheel suspension have been validated by comparison with measurements. Due to the extreme nature of the peak load events, the component modeling is absolutely critical for the accuracy of the simulations. All components have to be described within their full range of excitation. Key components and behaviors to model have been identified as tire with wheel strike-through, contacts between curb and tire and between curb and rim, flexibility of structural components, bump stops, bushings, shock absorbers, and camber stiffness of the suspension. Highly non-linear component responses are captured in Adams. However, since Adams only allows linear material response for flexible bodies, the proposed methods to simulate impact loads are only valid up to small, plastic strains.

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.

One way of avoiding crashes or mitigating the consequences of a crash is to apply an autonomous braking system. Quantifying the benefit of such a system in terms of injury reduction is a challenge. At the same time it is a fundamental input into the vehicle development process. This paper describes a method to estimate the effectiveness of reducing speed prior to impact. A holistic view of quantifying the benefit is presented, based on existing real life crash data and basic dynamic theories. It involves a systematic and new way of examining accident data in order to extract information concerning pre-crash situations. One problem area when implementing collision mitigation systems is being able to achieve sufficient target discrimination. The results from the case study highlight frontal impact situations from real world accident data that have the greatest potential in terms of improving accident outcome.

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.

Model based development promises to facilitate the development of embedded control systems, including design, early verification and validation as well as implementation. Existing tools are beginning to support the development of distributed control systems. There are however still challenges when it comes to integration with mechanics and methodologies for such interdisciplinary systems.

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.

Structural topology optimization is a truly interesting and important area, which has developed very rapidly and matured considerably in many fields. However, the use of topology optimization for global structures, using detailed design, is still tremendously time-consuming. From this perspective, the author sees the development of methods and tools to include optimization on simplified models during the design process as the most interesting and important step towards implementing structure topology optimization in the vehicle industry. In the design process, structures are broken down into beams and joints, and are described using a PBM (Property Based Model). Beams are described using a rectangular cross-section with the possibility of being changed in size, shape and orientation. Joints are described as flexible elements using a set of sub-elements called 2-joints that makes it possible for the joint model to change topology and stiffness.

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.

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.

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.