The SAE Recommended Practice specifies a standardize method and test procedure to measure low pressure differential (< 1bar) brake component brake fluid flow performance. The standard can be utilized for flow measurements across hydraulic brake components such as master cylinders, apply system to chassis controls piping, or other sources of flow restriction in the low pressure side of the hydraulic brake system. It covers materials, manufacturing processes, and general properties required to meet the wide range of service encountered in automotive application. This specification covers only low pressure differential fluid flow and does not include measurement recommended practice for High Pressure differential (> 1 bar) flows.
This SAE Aerospace Information Report (AIR) applies to landing gear tires and airframe structure for all types and models of civil and military aircraft having tires as part of the landing gear.
Performance Analysis of the ABS Control on Parallel Hybrid Electric Vehicle Equipped with Regenerative Braking System
Abstract Anti-lock brake system (ABS) prevents the vehicle wheels from locking up and reduces the total stopping distance as far as possible. The current implementation is based on a traditional hydraulic disk brake and small wheel inertia. Seen the need for making vehicles cleaner in the future, it can be expected that an increasing the amount of vehicles will be equipped with electric motors able to regenerate energy during braking. The addition of this electric motor changes the properties of the brake actuation and has an influence on the wheel inertia. However, the objective of this paper is to study the change of the dynamics induced by the regenerative braking which assess the performance of traditional ABS systems on the parallel hybrid electric vehicles. The MATLAB software to establish the simulation model, which include the single wheel dynamic model, hydraulic brake system model, electric motor brake system model and traditional ABS controller were used.
This procedure describes a method for measuring the fraction of underlayer (also referred to as backing layer) existing at any given height above the a disc brake friction materials shoe plate. Measuring underlayer distribution is useful for computing useable lining thickness and for friction material quality management.
This SAE Standard covers motor vehicle brake fluids of the nonpetroleum type, based upon glycols, glycol ethers, and borates of glycolethers, and appropriate inhibitors, for use in the braking system of any motor vehicle such as a passenger car, truck, bus, or trailer. These fluids are not intended for use under arctic conditions. These fluids are designed for use in braking systems fitted with rubber cups and seals made from styrene-butadiene rubber (SBR), or a terpolymer of ethylene, propylene, and a diene (EPDM).
This SAE Standard covers motor vehicle brake fluids of the nonpetroleum type, based upon glycols, glycolethers and appropriate inhibitors, for use in the braking system of any motor vehicle such as a passenger car, truck, bus, or trailer. These fluids are not intended for use under arctic conditions. These fluids are designed for use in braking systems fitted with rubber cups and seals made from styrene-butadiene rubber (SBR), or a terpolymer of ethylene, propylene, and a diene (EPDM).
This SAE Aerospace Information Report (AIR) provides information on the parking brake system design for a variety of aircraft including part 23, 25, 27, and 29. The document includes a discussion of key technical issues with parking brakes. This document does NOT provide recommended practices for parking brake system design.
A New Semi-Empirical Method for Estimating Tire Combined Slip Forces and Moments during Handling Maneuvers
Modeling the tire forces and moments (F&M) generation, during combined slip maneuvers, which involves cornering and braking/driving at the same time, is essential for the predictive vehicle performance analysis. In this study, a new semi-empirical method is introduced to estimate the tire combined slip F&M characteristics based on flat belt testing machine measurement data. This model is intended to be used in the virtual tire design optimization process. Therefore, it should include high accuracy, ease of parameterization, and fast computational time. Regression is used to convert measured F&M into pure slip multi-dimensional interpolant functions modified by weighting functions. Accurate combined slip F&M predictions are created by modifying pure slip F&M with empirically determined shape functions. Transient effects are reproduced using standard relaxation length equations. The model calculates F&M at the center of the contact patch.
Off-highway machine mounting systems, especially the cab mounting system, significantly affect the operator comfort in the cab by providing enough damping for a good ride and isolating the structure-borne forces from traveling into the cab.
This document applies to direct acting vacuum power assist brake boosters only, exclusive of the master cylinder or other brake system prime mover devices for passenger cars and light trucks [4500 kg GVW (10 000 lb)]. It specifies the test procedure to determine minimum performance and durability characteristics.
This SAE Recommended Practice applies to all portions of the vehicle, but design efforts should focus on components and systems with the highest contribution to the overall average repair cost (see 3.7). The costs to be minimized include not only insurance premiums, but also out-of-pocket costs incurred by the owner. Damageability, repairability, serviceability and diagnostics are inter-related. Some repairability, serviceability and diagnostics operations may be required for collision or comprehensive loss-related causes only, some operations for non-collision-related causes only (warranty, scheduled maintenance, non-scheduled maintenance, etc.), and some for both causes. The scope of this document deals with only those operations that involve collision and comprehensive insurance loss repairs.
Abstract Generally the brake system products are mounted on chassis with brackets which are subjected to dynamic loads due to road undulations. Exhaust brake is used to restrict the engine exhaust flow passage and thereby creates a back pressure in the engine for reducing the engine speed. This in turn reduces the vehicle speed. This is widely used in the vehicles operating in the hilly areas. This product is mounted on the exhaust passage and the air cylinder sub-assembly which actuates the exhaust brake is mounted on a bracket. Automotive industries perform durability tests on vehicles to reduce the failure on end-user environment. An assembly which has cleared the durability test got failed on addition of a spring into the assembly. The inclusion of spring is for enhancing the performance of the overall assembly.
Physical 1-D System Simulation Model for Monotube Shock Absorbers for Simulation with Excitation up to 70Hz
Abstract In an automotive suspension, the shock absorber plays a significant role to enable the vehicle performances, especially in ride, handling and Noise-Vibration-Harshness (NVH). Understanding its physical characteristics is of great importance, as it has a main influence on the overall vehicle performance. Within this research project simulation models for different passive monotube shock absorber systems have been created in a 1-D system simulation software. The simulation models are designed and parameterized physically. To validate the simulation models measurements on different hydropulse-shaker with specially designed control signals to investigate the response during high frequency excitation, have been done. A detailed discussion of the several models and results of a simulation to measurement comparison is given. After detailed investigation the shock absorber simulation models are now adaptable to the multi body simulation.
Comparison of Two Measurement Methods for Exterior Noise Radiation Characterization of a Loaded Rotating Tyre
Abstract In the context of the reduction of traffic-related noise the research reported in this paper provides tools that could be used to develop low noise tyres. Two measurement techniques have been analyzed for exterior noise radiation characterization of a loaded rotating slick tyre on a rough road surface. On one hand sound pressure measurements at low spatial resolution with strategically placed microphones on a half-hemisphere around the tyre/road contact point have been performed. This technique provides a robust solution to compute the (overall) sound power level. On the other hand sound intensity measurements at high spatial resolution by means of a scanning intensity probe have been performed. This technique allows a more detailed spatial visualization of the noise radiation and helps in getting more insight and better understanding of the acoustical phenomena.
Abstract Early studies on the tire vibration characteristics of road noise focused on radial modes of vibration because these modes are dominant in vertical spindle force. However, recent studies of Noise, Vibration and Harshness (NVH) prediction have suggested that tire modeling not only of radial modes, but also of lateral vibration, including lateral translational and lateral bending modes, affect interior noise. Thus, it is important to construct tire dynamic models with few degrees of freedom for whole-vehicle analysis of NVH performance. Existing tire dynamics model can't express tire lateral vibrations. This paper presents a new approach for tire vibration analysis below 200Hz, and a formula for tire natural frequencies. First, a tire dynamic model is developed based on the thin cylindrical shell theory. Kinetic and potential energies are derived. Mode shape function is also derived by the assumption of inextensility in the neutral of the tread ring.
Abstract Within the automotive industry, a typical way to account for tires in a roadnoise mission simulation is to use the “modal model” supplied by tire manufacturers. Even though this kind of models is certified by the suppliers and is very simple to use, it has the drawback to be disconnected from the physical description of the tire. This reflects in limiting the carmaker company to be able only to request certain modal characteristics to the supplier. The aim of this paper is to present an accurate, yet easy to use, methodology to develop an FE model of a tire, to be used in a full-vehicle simulation. The determined model must be connected to the tire physical properties. These properties are not measured directly, but determined by tuning a properly created geometric FE model to the measured point inertances of the inflated tire. This allows creating the model only by using an optimization algorithm to tune such properties.
Test Method, Simulation and Micro-process Dynamic Model for Noise Analysis of Auto Hydraulic Shock Absorber
Abstract In order to measure the noise of auto shock absorbers, a test bench used to detect piston-rod vibration responses of shock absorbers and measuring analyzer named SANTS-I were developed. The vibration response data was detected by bench tests, which shows that there are high-frequency violent peaks on the sine curve of piston-rod oscillating with relative low frequency. In order to explain the interior work dynamic mechanism of shock absorbers, a schematic Micro-process Dynamic Model with 10 steps particularly divided extension and compression stroke in more detail, and dynamic differential equations for each step were presented and discussed. Furthermore, numerical simulation for the inner impacts interaction between piston and damping fluid of hydraulic shock absorber was realized by ADINA software, by the establishment of a gas-liquid two-phase finite element model.
Abstract Recent trends in vehicle light-weighting and tire design requirements have created an increased awareness to tire flat-spotting. Tire flat-spotting occurs when tires remain in a loaded condition without rolling for an extended period of time. Tire flat-spotting can either be temporary or permanent depending on the length of storage and other environmental factors. Tire non-uniformity caused due to flat-spots often induces shake and shimmy (back and forth oscillation of steering wheel) vibration in vehicles due to increased tire-wheel force variation input into the chassis. This can result in increased warranty costs for OEMs (Original Equipment Manufacturers) as well as customer dissatisfaction exhibited in third party quality surveys like the annual J. D. Power IQS (Initial Quality Survey).
Abstract Experimental measurements of tire tread band vibration have provided direct evidence that higher order structural-acoustic modes exist in tires, not just the well-known fundamental acoustical mode. These modes display both circumferential and radial pressure variations within the tire's air cavity. The theory governing these modes has thus been investigated. A brief recapitulation of the previously-presented coupled structural-acoustical model based on a tensioned string approach will be given, and then an improved tire-acoustical model with a ring-like shape will be introduced. In the latter model, the effects of flexural and circumferential stiffness are considered. This improved model accounts for propagating in-plane vibration in addition to the essentially structure-borne flexural wave and the essentially airborne longitudinal wave accounted for in the previous model. The longitudinal structure-borne wave “cuts on” at the tire's circumferential ring frequency.
Abstract One of the elements of tire stiffness is sidewall stiffness. This stiffness, which influences tire vibration characteristics, is also an important design parameter for carrying the vehicle body. Tire is one of pressure vessels and inflation pressure is dominant in sidewall stiffness. Thus, tire sidewall stiffness is decided from the tension of inflation pressure and the structural dynamic, including the properties of the rubber material. To reveal the dynamic characteristics of tire sidewall stiffness, this study describes differences in stiffness due to inflation pressure. It can be expected that variation of inflation pressure is monitored from the axle vibration response during vehicle traveling in the future. That is because the relationship of the vibration characteristics and the inflation pressure of tire are derived by sidewall stiffness. First, we derive a formula for sidewall stiffness based on the structural dynamics of Akasaka's theory.
Abstract Hydraulic bushings with amplitude sensitive and spectrally varying properties are commonly used in automotive suspension. However, scientific investigation of their dynamic properties has been mostly limited to linear system based theory, which cannot capture the significant amplitude dependence exhibited by the devices. This paper extends prior literature by introducing a nonlinear fluid compliance term for reduced-order bushing models. Quasi-linear models developed from step sine tests on an elastomeric test machine can predict amplitude dependence trends, but offer limited insight into the physics of the system. A bench experiment focusing on the compliance parameter isolated from other system properties yields additional understanding and a more precise characterization.
This SAE Recommended Practice establishes a method of testing the structural integrity of the brake system of all new trucks, buses, and combination vehicles designed for roadway use and falling in the following classifications: a. Trucks and Bus Over 4500 kg (10 000 lb) GVWR b. Combination of vehicleTowing vehicle over 4500 kg 10 000 lb) GVWR The test consists of two parts: a Structural EnduranceTest followed by a Structural Ultimate Strength Test.
Automotive Engineering is serving as media partner for the 2015 Altair Enlighten Award. In collaboration with the Center for Automotive Research (CAR), the annual award recognizes achievements in lightweighting across the automotive industry and will be presented during the CAR Management Briefing Seminars (MBS), August 3-5 in Traverse City, MI.
Bosch upgrades ABS module for stability control that doesn't intrude.
Executive Viewpoints Off-highway industry executives from companies such as BorgWarner, Perkins, Cummins, and Danfoss reflect upon challenges inside, and outside, the industry, and what technologies, innovations, and strategies will need to be implemented to thrive into the long-term future. 16th Annual Product Guide Top products from throughout the industry covering technologies such as Powertrain & Energy, Hydraulics, Electronics, and Testing & Simulation.
This exclusive report produced by ABOUT Automotive concentrates on three of the most important areas within the automotive chassis sector: • Braking components, modules and systems • Suspension and damping systems • Steering systems It addresses the critical issues facing the automotive chassis sector, and is broken down into eight major sections: • Key market drivers • Braking components, modules and systems • Suspension and damping systems • Steering systems • Chassis sector supplier profiles • OEM system technology trends • OEM modular sourcing trends • Technology roadmap This includes mainstream, mass-market technology, as well as innovative and advanced technology where appropriate in each product area. The report also analyses the approach of each supplier to the market, including its role within the emergence of innovative technologies. Likewise, the research provides an analysis of the technology and sourcing trends apparent among the major global carmakers.
Efforts to replace tropical rubber trees with a wild desert shrub that grows in Southwestern U.S. and Mexico are just beginning to bear fruit.
This SAE Recommended Practice identifies and defines terms specifically related to brake systems.
A custom tractor-trailer technology demonstrator built by Alcoa is outfitted with various current and “soon-to-be-available” aluminum solutions that altogether can reduce the weight of a tractor-trailer by up to 2500 lb (1135 kg) compared to traditional steel components.
Abstract The present paper addresses an investigation about the definition of a parameter for quantifying the creep-groan propensity in brake pads. Creep-groan is a self-excited vibration caused by stick-slip phenomenon [1, 2, 3]. For the definition of the creep-groan propensity parameter, extensive experimental work was performed on a laboratory-scale tribometer. The experiments are divided in two main parts: (i) study of correlation between accelerometer signal with physical and operating parameters. (ii) validation of the chosen parameter, which was based on stick-slip tests performed with three different materials, one low-metallic (low-met) and two non-asbestos organic (NAO 1 and 2). From the first study, it was found that both the slip power and mean torque multiplied by torque variation showed a slightly higher correlation with the acceleration signal.