Browse Topic: Bumpers, fasciae and grilles
MSIL (Maruti Suzuki India Limited), India’s leading automotive manufacturer, offers a diverse range of SUVs (Sports Utility Vehicles) in its portfolio. Traditionally, SUVs are associated with an assertive stance and a commanding road presence; however, this bold design language often compromises aerodynamic drag performance. Over the past decade, demand for this segment has surged, while CAFE (Corporate Average Fuel Economy) regulations have become increasingly stringent. To address this growing market need, MSIL conceptualized a new SUV - Victoris - targeted to deliver best-in-class aerodynamic efficiency in MSIL SUV portfolio. This paper details the aerodynamic development process using CFD (Computational Fluid Dynamics) and full-scale WTT (Wind Tunnel Testing). Initially, the aggressive styling of Victoris negatively impacted drag performance. Strategic exterior surface refinements and integration of aero components enabled recovery of aerodynamic efficiency. Key interventions included redesigned front and rear bumpers, roof-end treatment, quarter spoiler profiling, bumper corner vents, and aero-cut alloy wheels. Victoris successfully retained its bold styling while meeting ambitious aerodynamic targets. The optimized aerodynamic silhouette comprising hood-to-windshield transition, roof contouring, backdoor spoiler, and side body profiling - along with underbody elements such as covers, strakes, and air curtains improved drag performance by 14% compared to the initial design. Achieving this improvement required significant shape modifications and aero part additions without compromising SUV identity. This paper explains how these measures were implemented and the resulting airflow characteristics.
This research analyzes the significance of air extractor on car door closing effort, especially within the context of highly sealed cabins. The goal is to measure their effectiveness in lowering pressure-induced resistance, study how the cut-out cross section and location affect performance, and its contribution to vehicle premium feel. Current vehicle design trends prioritize airtight cabin sealing for improving aerodynamic efficiency, NVH performance. This causes a problem in door closing operation. Air trapped while closing door creates transient pressure pulses. This pressure surge creates immediate discomfort to user i.e., Popping in Ears and requires high door closing force, and long-term durability problems in hinges and seals. In properly sealed cabins, air pressure resistance can contribute to 25% to 40% of total door closing force. Air extractors, usually installed in the rear quarter panels or behind rear bumpers, serve as pressure relief valves, allowing for a smoother airflow out of the cabin during such incidents. This passive system lowers door-closing effort, improves occupant experience, and safeguard structural components. A combination of CFD simulations, and real-world validations was employed to assess various air extractor configurations. Extractor size, location, flap design, and sealing levels of the vehicle were varied. Cabin pressure behavior and door closing force were evaluated under controlled and dynamic conditions. Comparative studies were also conducted across vehicle segments, including electric vehicles with high sealing requirements. Through these factors, this paper gives a holistic view to improve overall user experience as well as help to align with industry standards. The results have been backed with case studies as well as with simulation analysis to properly optimize the extractor design for new vehicles.
The present work demonstrates a transient Fluid-Structure-Interaction (FSI) based numerical methodology for estimation of aerodynamic-induced flutter of the rear bumper of a Sports Utility Vehicle (SUV). Finite Volume Method (FVM) based High-fidelity transient full vehicle aerodynamic simulations were conducted for the estimation of the transient aerodynamic load. Subsequently, by mapping this transient aero load onto the surface of the rear bumper, Finite Element Method (FEM) based dynamic structural simulations were performed to predict its response. The results obtained through simulations were then compared against experimental wind tunnel test data of a prototype car with modified bumper for the specific test-case. The pressure and the time series data of rear bumper deflection were captured at multiple probe locations from wind tunnel experiments at 140 and 200 kmph. The distribution of pressure on the rear surfaces of the car was well captured by the aerodynamic simulation at both speeds. The deflection amplitude and patterns across multiple probe locations and across the two speeds were reproduced with reasonable accuracy by the methodology.
Automotive radar plays a crucial role in object detection and tracking. While a standalone radar possesses ideal characteristics, integrating it within a vehicle introduces challenges. The presence of vehicle body, bumper, chassis, and cables in proximity influences the electromagnetic waves emitted by the radar, thereby impacting its performance. To address these challenges, electromagnetic simulations can guide early-stage design modifications. However, operating at very high frequencies around 77GHz and dealing with the large electrical size of complex structures demand specialized simulation techniques to optimize radar integration scenarios. Thus, the primary challenge lies in achieving an optimal balance between accuracy and computational resources/simulation time. This paper outlines the process of radar vehicle integration from an electromagnetic perspective and demonstrates the derivation of optimal solutions through RF simulation.
MSIL (Maruti Suzuki India Limited), India’s leading carmaker, has various SUVs (Sports Utility Vehicle) in its model lineup. Traditionally, SUVs are considered to have a bold on-road presence and this bold design language often deteriorates aerodynamic drag performance. Over the years, the demand for this segment has significantly grown, whereas the CAFE (Corporate Average Fuel Economy) norms have become more stringent. To cater this growing market demand, MSIL planned for two new SUVs: (1) New BREZZA - A bolder design with similar targeted aerodynamic performance compared to its predecessor (BREZZA-2016) and (2) FRONX - A new cross-over SUV vehicle targeted best-in-class aerodynamic performance in this category at MSIL. This paper illustrates the aerodynamic development process for these two SUVs using CFD (Computational Fluid Dynamics) and full scale WTT (Wind Tunnel Test). During the initial stages, the bolder design of the New BREZZA (2022) deteriorated the aerodynamic drag of the vehicle. Styling exterior surface modifications and addition of new aero parts facilitated the recovery of aerodynamic drag performance. The front & rear bumper corners, roof end spoiler profile, rear quarter glass edging, slits on fender lining and air-dam on rear bumper helped in air flow attachment. In FRONX, the styling design language had been created by considering ambitious aerodynamic performance requirements. The aerodynamic silhouette consisting of hood-windshield transition, roof lining, optimized backdoor spoiler, side body profile etc. along with underbody aero-parts like underbody covers, strakes and central air-dam improved the aerodynamic efficiency in FRONX by 11% with respect to base model BREZZA-2016. To achieve this improvement in aerodynamic drag values, major technical counter measures in external shape and addition of aero parts while retaining the SUV styling image were done. This paper illustrates how these changes were realized in the aerodynamic development process and the corresponding air flow phenomenon.
Anyone who has ever tried to pack a family-sized amount of luggage into a sedan-sized trunk knows this is a hard problem. Robots struggle with dense packing tasks, too. For the robot, solving the packing problem involves satisfying many constraints, such as stacking luggage so suitcases don’t topple out of the trunk, heavy objects aren’t placed on top of lighter ones, and collisions between the robotic arm and the car’s bumper are avoided.
The automotive sector is evolving both globally and as well as in India. The Indian customer’s expectations from an automobile are also evolving at fast pace. This is resulting in a continuous shrinkage of the time available for vehicle development. To meet customers’ expectation of superior cabin thermal comfort it is important to predict cabin cooling performance at early stage. This can be achieved through thermal simulation. Existing studies of cabin thermal simulation explained the method of co-simulation. Wherein, Input for the cabin was used a grill air temperature which was obtained from the physical test. It showed good correlation for the cabin inside air temperature with actual test. However, cabin cooling performance does not only depend on cabin structure & layout but also, affected by AC system & its component level performance. AC systems and components were not considered in previous studies. As a result, replacing or modifying the AC system components does not allow us to estimate the cabin inside air temperature. Therefore, it is important to link AC system with existing co-simulation methods. This paper explains that, how the AC system is connected to existing co-simulation model and carryout the real-time cabin cooling simulation. Revised co-simulation approach will help in the development of an effective AC system and predict cabin inside air temperature while considering the impact of AC system components on cabin cooling.
Toyota's luxury arm concurrently introduced the all-new, three-row 2024 Lexus TX and the long-awaited redesign of the rugged Lexus GX, also a '24 model. Both were met with enthusiasm at a reveal in Austin, Texas, over what Lexus is calling the new “unified spindle,” an evolution of the spindle grille that has been divisive since it appeared on the 2012 GS sedan. In a nifty trick, engineers have figured out how to include ADAS sensors in the grille without having asymmetrical blocks interrupt the bars. Dealers and more mainstream customers will be most interested in the TX, as Lexus Group Vice President Dejuan Ross said buyers have been clamoring for a new three-row SUV. And there's good reason: 70% of all full-size SUVs sold in America have a third row. For midsize SUVs, the number jumped from 6% to 10% from 2016 to 2022, according to J.D. Power.
Nearly every company in the world performs some level of quality inspection on their products before delivering them to customers. If you’re in the downloadable software business, this might involve making sure the product is bug-free and easy to use. But in the realm of physical products, the appearance of the product is nearly as important as its functionality. Would you want to purchase a new car that has scratches on the bumper or hubcaps? What if there was a crack in the windshield? From large to small, the same is true of many other items including appliances, laptops, cellphones, watches, and earbuds.
In the past decades, automotive structure design has sought to minimize its mass while maintaining or improving structural performance. As such, topology optimization (TO) has become an increasingly popular tool during the conceptual design stage. While the designs produced by TO methods provide significant performance-to-mass ratio improvements, they require considerable computational resources when solving large-scale problems. An alternative for large-scale problems is to decompose the design domain into multiple scales that are coupled with homogenization. The problem can then be solved with hierarchical multiscale topology optimization (MSTO). The resulting optimal, homogenized macroscales are de-homogenized to obtain a high-fidelity, physically-realizable design. Even so MSTO methods are still computationally expensive due to the combined costs of solving nested optimization problems and performing de-homogenization. To address these issues, this paper presents an efficient de-homogenization method that can be applied to any macroscale topology in order to obtain a high-fidelity multiscale structure. In contrast to prior de-homogenization methods, an alternative representation of the rectangular hole microstructure is proposed so that it is only dependent on the local density and stress distributions. Consequently, MSTO methods are not needed for the de-homogenization method to be applied. This makes the method applicable to any conceptual design, including those from simple single-scale TO codes. Additionally, the proposed de-homogenization method avoids the expensive mapping optimization problem associated with most projection de-homogenization methods by clustering sub-domains of the structure into discrete orientation angles. Pre-computed microstructures for each of the discrete angles are then assembled into each sub-domain. The proposed method is showcased for the design of a simple bumper and hood structure. The material distribution of each component is optimized in a two-dimensional TO problem for maximum stiffness.
This work is developed in the framework of an industrial R&D project, titled ARIA (Active Responsive Intelligent Aerodynamics), having the main goal to improve the efficiency of a vehicle by introducing active aerodynamics supported by innovative actuation systems. The work focuses on the development of a new aesthetic Active Grille Shutter (AGS), which, differently from the currently marketed vehicles, does not include the presence of a grille in front of it. In addition, an innovative actuation system, based on the adoption of Shape Memory Alloys (SMA) is being investigated for the new AGS, with the main goal to exploit the advantages arising in terms of increased efficiency coupled with a marked weigh reduction. The proposed analysis aims, at first, at evaluating the effects of different AGS configurations on the drag coefficient, Cx, of the vehicle and on the related benefits. To this purpose, simulations of the whole vehicle are carried out to estimate the Cx in different AGS configurations and a simple AGS opening/closing strategy is adopted for the estimation of CO2 reduction over a Worldwide harmonized Light vehicles Test Procedure (WLTP) cycle. Subsequently, for the design of the SMA-based actuation system, the estimation of the aerodynamic loads on the fins of the AGS and of the actuation forces is needed. Owing to the unavailability of experimental tests on the whole vehicle, an experimental/numerical study on the isolated component is carried out. A 1:1 model of the new aesthetic AGS is tested in a wind tunnel and data are used to validate a CFD model of the component. The aerodynamic loads on each fin of the AGS for different speeds are then computed and adopted in the numerical tool COMSOL Multiphysics for the design of the SMA based actuation system.
Recently, an aerodynamic theory for active grille shutters (AGS) of road vehicles has been developed that analytically describes the relationship among the flap position, cooling air mass flow, and drag. The experimentally validated theory is based on the assumption of a geometrically simple shutter which is arranged in a straight air duct and is flowed frontally, i.e., perpendicular to the flap plane. In the present work, this theory is extended and it is investigated how an inclined position affects the aerodynamic characteristic of an AGS. The theoretical results are then validated experimentally. Measurements on real vehicles with suitable AGS are used for this purpose. The results show good agreement between the theoretical predictions and experiment. The theoretical and experimental analyses allow conclusions to be drawn about how and under what conditions an inclined position affects the aerodynamic behavior of AGS.
The Range Rover Evoque is a compact luxury SUV, first introduced by Land Rover in 2012. Almost 800,000 units of the first-generation vehicle were sold. This paper explores some of the challenges entailed in developing the next generation of this successful product, maintaining key design cues while at the same time improving its aerodynamic efficiency. A development approach is outlined that made use of both numerical simulation and full-scale moving ground wind tunnel testing. A drag coefficient of 0.32 was obtained for the best derivative by paying particular attention to: the integration of active grille shutters; the front bumper and tyre package; brake cooling; underfloor design; wake control strategy; and detail optimization. This approach delivered the most aerodynamic Range Rover at the time of its introduction. The impact of these design changes on the aerodynamic flow field and consequently drag is highlighted. An interaction between front wheel deflectors and different tyres of the same nominal dimensions is explored over a range of small yaw angles, illustrating the need to develop vehicles using a range of boundary conditions. In addition, a relationship is shown between wake state defined in terms of the vertical pressure gradient and reduced aerodynamic drag. Finally, changes in regulations governing the assessment of emissions and fuel economy are driving a need for vehicle manufacturers to go beyond the traditional focus on the drag of the best vehicle derivative and manage the spread of values arising from customers’ choice of powertrain, wheel and tyre fitment along with exterior trim options. For this vehicle, we highlight that the average drag coefficient for sales in the European market over a year was 15% lower than the outgoing car, showing that improved aerodynamic efficiency has actually been delivered to customers.
In this article, a methodology is presented to assess the influence of time-averaged deformations on a production car of the 2018 A-class due to wind load. Exemplary, the deformations of the front and rear bumper are investigated. The aerodynamic development of vehicles at Mercedes-Benz is divided into several phases. When comparing force coefficients, differences can be observed between these distinct hardware stages as well as when comparing steady-state simulations to wind tunnel measurements. In early phases when prototype vehicles are not yet available, so-called aero foam models are used. These are well-defined full-sized vehicle models as the outer skin is milled from Polyurethane. Important aerodynamic characteristics such as an engine compartment with a cooling module, deflecting axles with rotatable wheels, and underbody covers are represented. As attachment parts such as the front and the rear bumper are also milled from Polyurethane, they cannot deform under wind load. Geometric deviations and deformations of the bumpers are a vital difference between the early prototype and a series production vehicle. Thereby, some of the drag differences between those two vehicle stages can be explained. Measurements of the deformations were conducted in the wind tunnel facility in Sindelfingen. The greatest deformations happen in the low-pressure regions at the sides of the front and rear bumpers and at the lower and the upper part of the front bumper. A quadratic behavior of the deformations over the velocity is indicated. When adding the deformations to a scanned geometry state, steady-state simulations indicate an increase in drag, but only little influence on the integral lift value. Transient Delayed Detached Eddy Simulation (DDES) confirms this trend.
In the present work, it is investigated how a flush arrangement to the outer skin affects the aerodynamic characteristic curve of active grille shutters (AGS). For this purpose, a recently developed theory, which analytically describes the aerodynamic behavior of AGS arranged in a straight flow channel, is extended accordingly, and the influence of an arrangement of AGS flush with the outer skin is first theoretically analyzed. The theoretical results are then validated experimentally. For this purpose, measurements of real vehicles with suitable AGS are used. The results show a good agreement of the theoretical predictions with the experiment. The theoretical and experimental analyses allow conclusions to be drawn as to how and under what conditions an arrangement flush with the outer skin affects the aerodynamic behavior of AGS.
Recently, the Flexible Pedestrian Legform Impactor (or Flex-PLI) - an advancement over the existing EEVC legform - was included in the Global Technical Regulation for Pedestrian Safety viz. GTR-9. The legform tool undergoes impact testing with vehicle at 40kmph in order to evaluate the frontal structure of vehicle for Pedestrian Safety. Being more biofidelic design over the old EEVC legform, Flex-PLI is more flexible and sensitive towards different vehicle designs, shapes and inner bumper structure. This flexibility and sensitiveness of its design also calls for examining the Manufactured FlexPLI for its efficacy under impact testing in terms of its Durability, Repeatability and Reproducibility. This study aims at validating the performance of the test device by building a platform for computing the variations in test results. In this study, three key aspects are identified to measure the performance of this device - Durability, Repeatability, and Reproducibility. Through extensive testing, the device’s flexible yet structurally integral design is revealed - demonstrating its Durability. Multiple tests are executed with the same device and under similar test conditions to determine Repeatability. Additionally, for Reproducibility, similar tests are executed with two different Flex-PLI’s. Analysis of these tests is done and percent coefficients of variation has been established. Furthermore, these performance traits are mapped across different vehicle segments, and their variation with the number of tests executed is identified. To summarize, this study validates the suitability of FlexPLI, to consistently deliver accurate results, by quantifying the performance traits of the device.
Aesthetics contribute significantly to the customer’s buying decision of an automobile. This is traditionally achieved through painting. Sustainability and cost challenges have led automakers to look at substituting painting through molded-in color polymers in decorative bezels like pillar appliques. These appliques and bezels have a unique mix of material requirements that include color tone, gloss, stiffness, scratch resistance and weathering. Polycarbonates are an interesting class of polymers that has the potential to meet these challenging requirements. This paper reports the work done in evaluating a polycarbonate compound in piano black shade to meet the functional and aesthetic requirements. The results prove that the material can substitute painting thereby resulting in significant cost savings. This is a ready to mold material used in injection molding process. This modified polycarbonate material has been explored for thin wall appliques and bezels with thickness of 2.7 mm. These trims have critical functional requirements such as newness retention, load versus deflection criteria, gap and flush aspects under sun load. Structural durability of the design was validated by virtual engineering. Part design and material combinations with better tooling design iterations were analyzed by using mold flow analysis. Complete product performance was validated for predefined key test metrics such as structural durability, thermal aging, cold impact, scratch resistance and weathering criteria. This part met required specifications. The combination of material, optimized part and tool design led to weight savings, good surface quality, dimensional stability under sun load, grill integration and considerable cost reduction.
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