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The aerodynamic drag, fuel consumption and hence CO2 emissions, of a road vehicle depend strongly on its flow structures and the pressure drag generated. The rear end flow which is an area of complex three-dimensional flow structures, contributes to the wake development and the overall aerodynamic performance of the vehicle. This paper seeks to provide improved insight into this flow region to better inform future drag reduction strategies. Using experimental and numerical techniques, two vehicle shapes have been studied; a 30% scale model of a Volvo S60 representing a 2003MY vehicle and a full scale 2010MY S60. First the surface topology of the rear end (rear window and trunk deck) of both configurations is analysed, using paint to visualise the skin friction pattern. By means of critical points, the pattern is characterized and changes are identified studying the location and type of the occurring singularities. The flow field away from the surface is then analysed using PIV measurements and CFD for the scale model and CFD simulations for the full scale vehicle. The flow field is investigated regarding its singular points in cross-planes and the correlation between the patterns for the two geometries is analysed. Furthermore, it is discussed how the occurring structures can be described in more generalized terms to be able to compare different vehicle geometries regarding their flow field properties. The results show the extent to which detailed flow structures on similar but distinct vehicles are comparable; as well as providing insight into the complex 3D wake flow.

This paper presents the experimental work carried out on single-lap joints fastened together with bolts and nuts to investigate the contribution of mode shapes, and the effect that bolt sizes has in dissipating energy in built-up structures. Five different bolt sizes are chosen to assemble five single-bolted single-lap joints using aluminum plates. An analogous monolithic solid piece carved from the same aluminum material is used to determine the material damping and compare it against the damping from bolted joints. The dynamic response of all structures is captured under free-free boundary conditions, and the common modes are analyzed to understand the contribution and primary source of damping in the same range of the sampling frequency. This investigation has revealed that the source of damping in the joints is heavily linked to the mode shapes of the structure and structural damping (also referred to as material damping) contributes more during specific mode shapes compared to the joint damping itself. The findings allow a more accurate implementation of energy loss in automotive structures which contain bolted joints, allowing an implementation of both material and joint loss factor, respectively.

The aim of this paper is to develop a new concept of unconventional airship based on morphing a lenticular shape while preserving the volumetric dimension. Lenticular shape is known to have relatively poor aerodynamic characteristics. It is also well known to have poor static and dynamic stability after the certain critical speed. The new shape presented in this paper is obtained by extending one and reducing the other direction of the original lenticular shape. The volume is kept constant through the morphing process. To improve the airship performance, four steps of morphing, starting from the lenticular shape, were obtained and compared in terms of aerodynamic characteristics, including drag, lift and pitching moment, and stability characteristics for two different operational scenarios. The comparison of the stability was carried out based on necessary deflection angle of the part of tail surface. The comparison results indicated that new shape concept possesses much better aerodynamic and stability characteristics and could be used for detailed optimisation studies.

This paper summarizes the recent development of an adaptive aeroelastic wing shaping control technology called variable camber continuous trailing edge flap (VCCTEF). As wing flexibility increases, aeroelastic interactions with aerodynamic forces and moments become an increasingly important consideration in aircraft design and aerodynamic performance. Furthermore, aeroelastic interactions with flight dynamics can result in issues with vehicle stability and control. The initial VCCTEF concept was developed in 2010 by NASA under a NASA Innovation Fund study entitled "Elastically Shaped Future Air Vehicle Concept," which showed that highly flexible wing aerodynamic surfaces can be elastically shaped in-flight by active control of wing twist and bending deflection in order to optimize the spanwise lift distribution for drag reduction. A collaboration between NASA and Boeing Research & Technology was subsequently funded by NASA from 2012 to 2014 to further develop the VCCTEF concept. This paper summarizes some of the key research areas conducted by NASA during the collaboration with Boeing Research and Technology. These research areas include VCCTEF design concepts, aerodynamic analysis of VCCTEF camber shapes, aerodynamic optimization of lift distribution for drag minimization, wind tunnel test results for cruise and high-lift configurations, flutter analysis and suppression control of flexible wing aircraft, and multi-objective flight control for adaptive aeroelastic wing shaping control.

In this paper, the advanced damage analysis of composite materials and structures made of continuous fibers embedded in a polymer matrix is addressed. The solution is based on the LMS Samtech Samcef finite element code, from Siemens PLM Software, which is now available in the Siemens NX CAE environment, with the specific focus of solving non-linear analysis problems for composites. Globally speaking, LMS Samtech Samcef is an implicit non-linear solver able to solve quasi-static and dynamic problems, with a comprehensive library of structural elements and kinematic joints. First, the sizing strategy based on the building block approach (pyramid of physical and virtual tests) is recalled. Applied for years in the aerospace industry, it is here extended to the automotive context. In this approach, the knowledge on the composite material and structure is built step by step from the coupon level up to the final full scale structure. In this paper, stages of the pyramid starting from the coupon level are considered, and the predictions obtained by numerical simulations are validated by test results. The non-linear analysis approach available in the LMS Samtech Samcef finite element code is then described. It is based on the continuum damage mechanics, and is used to study the progressive failure of composites in the plies and at their interface (delamination). The material models are described. The identification procedure for these damage models is also discussed: it is based on a very limited number of tests results at the coupon level. It is then shown how this information on the material behavior can be used at upper stages of the building block approach and so applied to larger scale structures and/or more complex load cases and different stacking sequences. The very good agreement obtained in this paper between simulation and test results on composite structures of increasing complexity tend to demonstrate that LMS Samtech Samcef can be used as a predictive numerical tool for the evaluation of the non-linear behavior of composites, including the progressive inter- and intra-laminar damage analysis.

Wheel Loaders are heavy equipment machines which are used in construction fields. The main structure of a wheel Loader has a front and a rear bogie, connected through articulating pin joints. The wheel loaders have two axles viz. front and rear axles carrying its Front and Rear bogies. The front axle carrying front frame is fixed and articulates clockwise and anticlockwise about rear frame. However, to reduce the spillage of material carried in bucket while travelling in uneven terrains, the rear axle is designed to oscillate along the roll direction of vehicle movement. The rear axle is connected to rear frame with bearing hub called axle oscillation hub having separate shaft arrangement with tapered roller bearings (TRB). When machine operates in uneven terrain, the oscillating rear axle hits the rear frame structure which induces an impact load on vehicle structure. Mass and speed of the vehicle play a critical role in loader stability and safety. Apart from these, the impact force caused due to the rear axle hitting the vehicle frame influences the durability of the structural components. This paper explains the study on predicting the relationship between machine operating mass, vehicle speed and axle hitting loads. The study also focuses on determining the steps for selecting both structural and stopper components based on prediction of impact loads induced on wheel loaders during rear axle oscillation.

Innovative setting bracket design to improve the tractor Fit and Finish between the Bonnet and Custer panel (Scuttle)The paper presents an integrated approach for arriving a process to assemble scuttle regarding bonnet to achieve Gap and flushness aesthetic requirement. Variation is inevitable due to fitting of bonnet on Tractor front semi-chassis, scuttle fitting on tractor middle clutch housing and assembling many parts with different tolerances, hence the deviation (stack-up) obtained after their assembly varies from approximately -10.175 to 9.775 mm. This is quite large and gives a huge impact in aesthetic point of view.To overcome this issue, we introduced one Innovative intermediate bracket as the setting gauge which is assembled with reference to bonnet and scuttle is mounted on this setting bracket hence zero flushness and uniform achieved between bonnet and scuttle.This mechanism also decreases assembly tag time (which plays a vital role in mass production) as well as helps in identifying process failures in assembly. This in turn reduces cost as well as reduces assembly operator pain area.Apart from these aspects tolerance between them vary from design to design but it is usually kept at around 6mm (to provide a smooth motion). In present work, a gauging technique is suggested for minimizing the variance in tolerance. Utilization of metrology system also results in decreasing investment cost and provide high accuracy.

Many modern vehicles have blunt rear end geometries for design aesthetics and practicality; however, such vehicles are potentially high drag. The application of tapering; typically applied to an entire edge of the base of the geometry is widely reported as a means of reducing drag, but in many cases, this is not practical on real vehicles. In this study side tapers are applied to only part of the side edge of a simplified automotive geometry, to show the effects of practical implementations of tapers.The paper reports on a parametric study undertaken in Loughborough University’s Large Wind Tunnel with the ¼ scale Windsor model equipped with wheels. The aerodynamic effect of implementing partial side edge tapers is assessed from a full height taper to a 25% taper in both an upper and lower body configuration. These were investigated using force and moment coefficients, pressure measurements and planar particle image velocimetry (PIV). These geometries showed that the drag reductions are maximised with a 50% span, generating a vertically symmetric wake and less taper drag contribution when compared to a full span taper.

In this paper a novel approach in developing a simplified model of a vehicle front-end is presented. Its surface is segmented to form an MBS model with hundreds of rigid bodies connected via translational joints to a base body. Local stiffness of each joint is calibrated using a headform or a legform impactor corresponding to the EuroNCAP mapping. Hence, the distribution of stiffness of the front-end is taken into account. The model of the front-end is embedded in a whole model of a small car in a simulation of a real accident. The VIRTHUMAN model is scaled in height, weight and age to represent precisely the pedestrian involved. Injury risk predicted by simulation is in correlation with data from real accident. Namely, injuries of head, chest and lower extremities are confirmed. Finally, mechanical response of developed vehicle model is compared to an FE model of the same vehicle in a pedestrian impact scenario. VIRTHUMAN model of a 13-year-old boy (150 cm, 40 kg) is chosen to represent the pedestrian and the lateral impact at 45 km/h is considered for various initial positions of pedestrian. While local deformation of the MBS bonnet leads to the HIC value corresponding to the EuroNCAP assessment, prediction obtained in the case of FE model may differ. This reflects the fact that deformation of the bonnet caused by an impact of the torso may influence the shape and the stiffness of the bonnet at the location of head strike

Replicated with permission by SAE, Copyright © 2016 SAE International. Further distribution of this material is not permitted without prior permission from SAE. George, J., Gross, D., Jahed, H., and Roostaei, A., "Fatigue Life Prediction of an Automotive Chassis System with Combined Hardening Material Model," SAE Technical Paper 2016-01-0378, 2016, doi:10.4271/2016-01-0378.

Despite the increasing knowledge of the thorax mechanics, the effects of inter-individual differences on the mechanical response are difficult to take into account. Several methods are available in the literature to refine the biofidelity corridors or to extrapolate them to other populations (eg: children, small females, large males). Because of the lack of concrete cases, the relevance of the assumptions is rarely investigated. In 2014, Baudrit et al. published data on thorax dynamic responses of small female and midsize male Post Mortem Human Subjects in side and forward oblique impact tests. The impactor mass was 23.4 kg for all the tests and the nominal impact speed was 4.3 m/s. The diameter of the rigid disk was 130 and 152 mm respectively for the small female specimens and for the midsize male specimens. The authors found that the maximum impact force was a function of the total body mass for each loading. They also reported that the ratio of dissipated energy on total deformation energy was almost constant and equal to 0.88. From these observations, a method was developed to aggregate data of the whole PMHS sample and to construct force time history and deflection time history corridors, for the 50th male and the 5th female, in pure lateral and in forward oblique tests. These corridors are provided in the paper and compared to the literature. Scaling factors derived from the corridors are also provided and used to evaluate the assumptions associated with the corridors provided in the literature.

In this paper the finite element model of an Unmanned Aerial Vehicle is updated by using experimental data coming from a standard ground vibration test in order to improve the numerical-experimental correlation. A sensitivity-based updating methodology that iteratively minimizes a residual vector, defined on the modal parameters (e.g. natural frequencies and mode shapes), is considered to identify the unknown values of the updating parameters. The structure under investigation is the Clarkson University Golden Eagle UAV. An initial numerical model of the structure is obtained by assembling the individual components previously updated which included wings, fuselage, horizontal tail, vertical tails and tail booms. As a result the identification procedure shifts its focus on the joints between UAV elements which could not be modeled accurately in earlier investigations.

The high number of hull losses is a main concern in the UAV field, mostly due to the high cost of on-board equipment. A crashworthiness design can be helpful to control the extent and position of crash impact damage, minimizing equipment losses. However, the wide use of composite materials has recently put the accent on the lack of data about the behavior of these structures under operative loads, such as the crash conditions. This paper presents the outcome of a set of tests carried out to achieve a controlled crush of UAV structures, and to maximize the Specific Energy Absorption. In this work, a small-scale experimental test able to characterize the energy absorption of a Carbon-fiber-reinforced polymer under compression was developed introducing self-supporting sinusoidal shape specimens, which avoid the need for complex anti-buckling devices. The specimens were produced with different auto-triggering configurations and fibers' continuity was interrupted in selected position and for different extent in order to investigate the Specific Energy Absorption of the weakened laminates. The auto-triggering configuration was able to control the position of the initial failure of the specimen without any decrease in safety performance. This new kind of very light crash absorber can be used in small UAV to reduce the crash loads in the avionic and payload bay. With reference to a small UAV designed and manufactured at University of Bologna, an optimization of the crash absorbers positions has been carried out in order to achieve the best results in terms of energy dissipation.

Current techniques used to evaluate and analyze lateral impact speeds of vehicle crashes with poles are based on measuring the deformation crush and using lateral crash stiffness data to estimate the impact speed. However, the stiffness data is based on broad object side impacts rather than pole impacts. The premise is that broad object side impact tests can be used for narrow object impacts; previous authors have identified the fallacy of this premise. Publicly available pole crash test data is evaluated. A range of simulated pole impact tests at various speeds are conducted on validated publicly available Finite Element Vehicle models of a 1991 Ford Taurus, a 1994 Chevrolet C2500 and a 1997 Geo Metro (Suzuki Swift), providing a relationship between impact speed and crush depth. This paper builds on a previous publication (Richardson S., Jiang T., Grzebieta R.H. and Rechnitzer G., Vehicle Lateral Side Impacts with Poles - A Review and Analysis, Proceedings 4th Int. Crashworthiness Conf. ICRASH2004, Bolton Institute U.K., San Francisco, July 2004) and contains additional pole tests and new data based on Finite Element Analyses.