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Technical Paper

A Statistical Method to Substructure Crash Simulation Model

2021-12-03
2021-01-5107
This work presents a statistical method to use a portion of a full finite element vehicle model on a crash analysis event. The substructure model is linked to the full model by recording the interface boundary history. The lateral moving deformable barrier (MDB) test by the Insurance Institute for Highway Safety (IIHS) is used to demonstrate this substructure method: Substructure portion is identified by energy absorption distribution, and noise elements are filtered out by density-based spatial clustering of applications with noise (DBSCAN), a nonsupervised machine learning method. Crashworthiness simulation is performed in LS-DYNA software, and results between substructure vehicle model, full vehicle model, and physical vehicle test results are compared. It shows the result from the substructure model is more effective without accuracy compromise.
Research Report

Unsettled Aspects of the Digital Thread in Additive Manufacturing

2021-11-15
EPR2021026
Additive manufacturing (AM), also known as “3D printing,” now provides the ability to have an almost fully digital chain from part design through manufacture and service. This “digital thread” can bring great benefits in improving designs, processes, materials, operations, and the ability to predict failure in a way that maximizes safety and minimizes cost and downtime. Unsettled Aspects of the Digital Thread in Additive Manufacturing discusses what the interplay between AM and a digital thread in the mobility industry would look like, the potential benefits and costs, the hurdles that need to be overcome for the combination to be useful, and how an organization can answer these questions to scope and benefit from the combination. Click here to access the full SAE EDGETM Research Report portfolio.
Research Report

Unsettled Issues in Commercial Vehicle Platooning

2021-11-15
EPR2021027
While platooning has the potential to reduce energy consumption of commercial vehicles while improving safety, both advantages are currently difficult to quantify due to insufficient data and the wide range of variables affecting models. Platooning will significantly reduce the use of energy when compared to trucks driven alone, or at a safe distance for a driver without any automated assistance. However, drivers typically drive closer to each other than recommended to achieve drafting efficiencies, which may shift the benefit of automated platooning to safety gains. More data will be needed to conclusively demonstrate these gains. Unsettled Issues in Commercial Vehicle Platooning discusses the technologies needed to enable close platooning, including brake system condition monitoring, vehicle-to-vehicle communication, and concrete infrastructure assessment. The report also looks at driver acceptance of platooning technology from a safety and job security perspective.
Technical Paper

Measurement Methods for Radar Cross Section of Passenger Vehicles

2021-11-09
2021-01-5103
Automotive millimeter-wave radar is used extensively in vehicle active safety. The Radar Cross Section (RCS) is one of the main parameters used by the automotive radar system to detect and identify surrounding vehicles. The RCS describes the electromagnetic scattering properties of objects. This paper describes a method and equipment to measure the RCS. An automobile-grade radar is used to measure the RCS of typical vehicles. A representative distance between the radar and the vehicle was chosen based on the analysis of the RCS of passenger vehicles in different distances in the near field. A cost-effective rotating platform was developed to rotate the passenger vehicles for RCS measurement in different azimuth angles. The RCS generated by the rotating platform was analyzed and mitigated. The measurement system can record the synchronized azimuth angle and RCS measurement.
Technical Paper

Seat Belts: A Review of Technological Milestones, Regulatory Advancements, and Anticipated Future Trajectories

2021-10-21
2021-01-5097
Decades after their introduction, seat belts remain the most important safety innovation in automotive history. Seat belt usage remains the single most effective way to minimize the risk of injury or death in severe crash events. Despite having matured, seat belts continue to evolve and improve and are expected to play an equally critical role in future passenger vehicles as increasing automation leads to changes in occupant compartment design and occupant-to-vehicle interaction. In this paper, an overview of major technical milestones in the development of seat belts is presented, ranging from the earliest lap belts to today’s systems that seamlessly synthesize and integrate information from a variety of sensors to prepare the restraints for an imminent crash. A brief overview of contemporary regulatory events is also provided, illustrating how regulatory actions have followed and occasionally driven the development and proliferation of various aspects of occupant restraints.
Technical Paper

The Behavior of Fuel Droplets on a Heated Substrate

2021-10-15
2021-01-5099
The processes of surface wetting and film evaporation play a major role in any application using liquid fuels. Since the behavior of entire multi-liquid films is influenced by many simultaneously occurring physical processes, exact modeling is not yet possible. In order to reduce the complexity and to determine the basic effects in the spreading and evaporation of multi-component films, this study was carried out by placing single 5 μl droplets on a heated metal surface. Various alkanes, ethanol, and mixtures, as well as real gasoline, were studied at surface temperatures between 69°C and 140°C. To describe the processes qualitatively and determine the time-dependent wetted surface area, the droplets were visualized using cameras. With the results, it was possible to determine the course of the wetted surface over time and to compare different liquids under varying surface temperatures.
Research Report

Unsettled Economic, Environmental, and Health Issues of Ammonia for Automotive Applications

2021-10-15
EPR2021022
Ammonia has been previously trialed as an automotive fuel; however, it was hardly competitive with fossil fuels in terms of cost, energy density, and practicality. However, due to climate change, those practical and cost-related parameters have finally become secondary deciding factors in fuel selection. Ammonia is safer than most fuels and it offers superior energy densities compared to compressed or liquefied hydrogen. It is believed that ammonia might be an ultimate clean fuel choice and an extension to the emerging hydrogen economy. Unsettled Economic, Environmental, and Health Issues of Ammonia for Automotive Applications examines the major unsettled issues of using ammonia as a clean automotive fuel alternative, including the lack of regulations and standards for automotive applications, technology readiness, safety perception, and presently limited supply.
Research Report

Unsettled Aspects of Insourcing and Outsourcing Additive Manufacturing

2021-10-15
EPR2021023
Additive manufacturing (AM), also known as “3D printing,” has transitioned from concepts and prototypes to part-for-part substitution—and now to the creation of part geometries that can only be made using AM. As a wide range of mobility OEMs begin to introduce AM parts into their products, the question between insourcing and outsourcing the manufacturing of AM parts has surfaced. Just like parts made using other technologies, AM parts can require significant post-processing operations. Therefore, as AM supply chains begin to develop, the sourcing of AM part building and their post-processing becomes an unsettled and important issue. Unsettled Aspects of Insourcing and Outsourcing Additive Manufacturing discusses the approaches and trade-offs of the different sourcing options for production hardware for multiple scenarios, including both metallic and polymer technologies and components. Click here to access the full SAE EDGETM Research Report portfolio.
Technical Paper

Decoding Genuine Ceramic Pad Formulations- Materials and Processing

2021-10-11
2021-01-1277
The need to develop genuine ceramic composites for PV applications arose to overcome the challenges associated with traditional semi-metallic pads. The main focus is to achieve better performance, low noise, better pad and rotor wear, and low dust compared to semi- metallic pads. In general, brake pads convert kinetic energy to thermal energy through friction, and operating temperature in semi-metallic brake pads is higher due to the presence of steel having high thermal conductivity. Over the last decade, the customer preference has moved over to ceramic pads due to light coloured pad surface, low rotor and pad wear and low dust compared to semi-metallic pads. The traditional steel has been replaced by Aramid, engineered ceramic fibre, potassium titanate (TISMO D), lapinus fibre (RB 250) to impart similar/better performance. The current work investigates the characterisation of genuine ceramic and semi-metallic composites.
Technical Paper

Effect of Material Anisotropy on Thermal-Mechanical Instabilities in Metal-Free Friction Materials

2021-10-11
2021-01-1289
An anisotropic ceramic matrix composite (CMC), which consists of a silicon carbide (SiC) based ceramic matrix reinforced with carbon (C) fibers, is considered as a metal-free friction material replacement in brake and clutch applications. The fibers are assumed to have a circular cross-section, arranged unidirectionally and packed in a rectangular array without the presence of voids. The rule of mixture showed the C-SiC composite to be transversely isotropic with the circumferential plane as the plane of isotropy. A set of parametric studies have been performed to computationally investigate the dominant parameters that affect thermal-mechanical instabilities. It is found that the chance of thermal buckling in the friction disc can be minimized by reducing the elastic moduli in the radial and circumferential directions, or by reducing the coefficient of thermal expansion in the same directions.
Technical Paper

A Molecular Dynamics Study of Tribological Properties of Silicon Carbide as a Metal-Free Friction Material

2021-10-11
2021-01-1284
Friction materials containing metal ingredients used in the automotive industry can cause unfavorable environmental impacts. Existing laws and regulations require heavy metals in brake pads to be phased out of production. Substitutions for metals in friction materials, however, may introduce operational safety issue and other unforeseen problems. In the current study, a molecular dynamics model based on LAMMPS has been developed to study the effect of material composition, density, and geometric configurations on the tribological, mechanical, and thermal properties of silicon carbide under various contact conditions at the atomic level. Simulations which incorporate interfacial contact between surface asperities were performed to predict the elastic modulus, thermal conductivity, wear rate, and coefficient of friction. The resulting predicted properties may help enhance the performance of engineered metal-free friction materials against thermal-mechanical failures.
Technical Paper

Potential and Challenges for Application-Specific Friction Characteristics of Race Brake Pads

2021-10-11
2021-01-1282
As a race driver hits the pedal to trigger the braking event, a dynamic load transfer takes place in the car. This is a similar kind of weight transfer experienced on the road while stopping any vehicle abruptly. Modern race cars such as FIA-regulated Grand Touring Car classes GT3 and LMGTE produce a significant aerodynamic downforce at a reasonably high efficiency level. In this type of high downforce race cars, load variations originated by aerodynamics are added onto the mass transfer. The combination of these effects provide a braking effect with this type of cars a highly transient character. At the same time, our customers are facing the challenge of strict technical regulations, usually forbidding brake control systems. In motorsport competition, car performance is of primary priority to help our customers win championships.
Technical Paper

Divergence of Thickness Losses and Weight Losses of Disc Pads for Passenger Cars: High-Copper NAOs and Copper-Free Low Mets

2021-10-11
2021-01-1290
The current investigation was undertaken to find out if lighter-weight passenger car disc pads would exhibit wear behaviors similar to pickup truck pads and commercial heavy truck drum linings in terms of the permanent volume expansion of the friction material contact surface region. 2 high-copper NonAsbestos Organic formulations and 3 copper-free LowMet formulations were tested according to the SAE J2522 test procedure. In all cases, the measured pad thickness loss was found to be less than the thickness loss calculated from the weight loss, indicating pad volume expansion in the pad surface region, in full agreement with the results from the pickup truck and heavy trucks. The heataffected swollen/expanded layer ranges from 0.27 to 0.61 mm in thickness depending on the formula and test conditions. Due to the expansion, pad durability projections made from test results based on high temperature city traffic tests can result in underestimating the actual durability.
Technical Paper

Sensor-controlled Friction Materials based on Liquid Friction Compounds, Chip-in-Pad Concept

2021-10-11
2021-01-1296
In this paper, the concept of integrating thin-film piezo transducers into friction pads by using a liquid friction material compound (LIQFRIC® HP), which is capable of completely embedding the sensor surface and allowing for the force transfer due to a direct contact between sensor and friction material, is explained. The low thickness of the sensor allows for an excellent ratio of sensor volume / friction volume in the pad. The piezo transducer, besides being able to detect positive and negative pressure changes, can also be used via its EMI capability to allow measurements of changes in the shape (and therefore thickness) of the pad during and after testing. Measuring the pressure distribution, the wear and possible defect situations of the pad potentially opens up new means of friction pad- and brake operations or developments.
Technical Paper

Measurement of Particle Dynamics on the Real Vehicle in Different Driving Scenarios with Swarm Sensors

2021-10-11
2021-01-1299
Due to the increase in public attention in the analysis of non-exhaust emission sources because of the growing electrification of vehicles, measurements have been performed in recent years to develop a consistent test standard. In particular, the consideration of tyre and brake abrasion took a predominant position due to the small particle sizes. With measurements under controlled and laboratory-like athmosphere, for example for brakes on dynamometers, attempts have been made to create a uniform test standard according to the Worldwide harmonized Light vehicles Test Procedure (WLTP). However, a transfer to the real driving environment is not yet feasible because of many external disturbance variables, such as the wheel housing or atmospheric variables. Typical reference measurement sensors in the vehicle are only suitable to a limited extent for mobile operation due to their size and the necessary measurement infrastructure.
Technical Paper

Empowering the Brake Systems

2021-10-11
2021-01-1261
Some research shows that the transport system is one of the main responsible for the emission of pollutants in the atmosphere. The growing demand for automobiles contrasts directly with the scarcity of inputs, planet temperature increasing and air quality degradation in large cities. This counterpoint is explored and discussed a lot, demanding that studies would be conducted to find out sustainable solutions in the production to end-customers. Instead of use fossil resources, one of the options to reduce gas emissions is the use of vehicles powered by electricity. When converting part of the vehicle's kinetic energy into electrical one its reduces emissions in the production electricity - power plants - as well burning gases in transport. Technological advances allow us to use Electronic Stability Control to generate environmental and safety results in mobility for next years.
Technical Paper

Predictive Maintenance of Commercial Vehicle Brakes using Acoustic Monitoring

2021-10-11
2021-01-1280
This study evaluated the performance of a new approach for detecting problems with commercial vehicle brakes based on the analysis of sounds emitted during braking. Commercial vehicle brakes emit ultrasonic energy inaudible to humans as part of the friction process, and the spectral distribution of these sounds is highly dependent on the mechanical condition of the brakes. Data collected from a commercial vehicle fleet found that the acoustic signature changes as friction linings wear. This conforms with the acoustic theory that the resonant frequency of an object increases with its decrease in mass. The use of this information to inform maintenance operations is promising in that the scheduling of visual brake inspections could be based on acoustic wear patterns rather than arbitrary time intervals and the observation of anomalous signals that might indicate more immediate concerns.
Technical Paper

Application of Brake System Failed State Performance and Reliability Requirements to Brake System Architecting

2021-10-11
2021-01-1267
The modern braking system in the field today may be controlled by over a million lines of computer code and may feature several hundred moving parts. Although modern brake systems generally deliver performance, even with partial failures present in the system, that is well above regulatory minimums, they also have a level of complexity that extends well beyond what the authors of existing regulations had envisioned. Complexity in the braking system is poised for significant increases as advanced technologies such as self-driving vehicles are introduced, and as multiple systems are linked together to provide vehicle-level “features” to the driver such as deceleration (which can invoke service braking, regenerative braking, use of the parking brake, and engine braking). Rigorous safety-case analysis is critical to bring a new brake system concept to market but may be too tedious and rely on too many assumptions to be useful in the early architecting stages of new vehicle development.
Technical Paper

In-Depth Considerations for Electric Vehicle Braking Systems Operation with Steep Elevation Changes and Trailering

2021-10-11
2021-01-1263
As the automotive industry prepares to roll out an unprecedented range of fully electric propulsion vehicle models over the next few years - it really brings to a head for folks responsible for brakes what used to be the subject of hypothetical musings and are now pivotal questions for system design. How do we really go about designing brakes for electric vehicles, in particular, for the well-known limit condition of descending a steep grade? What is really an “optimal’ design for brakes considering the imperatives for the entire vehicle? What are the real “limit conditions” for usage that drive the fundamental design? Are there really electric charging stations planned for or even already existing in high elevations that can affect regenerative brake capacity on the way down? What should be communicated to drivers (if anything) about driving habits for electric vehicles in routes with significant elevation change?
Technical Paper

Research on High-efficiency Test Method of Vehicle AEB based on High-precision Detection of Radar Turntable Encoder

2021-10-11
2021-01-1273
With the increasingly complex traffic environment, the vehicle AEB system needs to go through a large number of testing processes, in order to drive more safely on the road. For speeding up the development process of AEB and solve the problems of long cycle, high cost and low efficiency in AEB testing, in this paper, a millimeter wave radar turntable is built, and a high-precision detection algorithm of turntable encoder is designed, at the same time, a test method of vehicle AEB based on the detection data of radar turntable encoder is designed. The verification results show that methods described in this paper can be used to develop the vehicle AEB test algorithm efficiently.
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