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Technical Paper

Innovative Material Characterisation Methodology for Tyre Static and Dynamic Analyses

2020-09-30
2020-01-1519
Tyre structures are based on composite materials that constitute numerous layers, each providing specific properties to the tyre mechanic and dynamic behaviour. In principle, the understanding of the partial contributions of the individual layers requires knowledge of its mechanical properties. In case of non-availability of such critical information, it is difficult to perform tyre FE analyses. In the current work, a methodology is proposed to study the tyre static and dynamic behaviour to estimate its constituents properties based on the measured quasi-static responses of the tyre for certain specific loads. As a first step, a simplified tyre numerical model with standard rubber material properties is modeled that can substantively predict the necessary tyre static responses, i.e. radial, longitudinal and lateral stiffness. These responses are correlated with the physical tyre response that are measured using a kinematic and compliance (K&C) test rig in the laboratory.
Technical Paper

A Generic Testbody for Low-Frequency Aeroacoustic Buffeting

2020-09-30
2020-01-1515
Raising demands towards lightweight design paired with a loss of originally predominant engine noise pose significant challenges for NVH engineers in the automotive industry. From an aeroacoustic point of view, low frequency buffeting ranks among the most frequently encountered issues. The phenomenon typically arises due to structural transmission of aerodynamic wall pressure fluctuations and/or, as indicated in this work, through rear vent excitation. A possible workflow to simulate structure-excited buffeting contains a strongly coupled vibro-acoustic model for structure and interior cavity excited by a spatial pressure distribution obtained from a CFD simulation. In the case of rear vent buffeting no validated workflow has been published yet. While approaches have been made to simulate the problem for a real-car geometry such attempts suffer from tremendous computation costs, meshing effort and lack of flexibility.
Technical Paper

Analytical Prediction of Acoustic Emissions From Turbocharger Bearings

2020-09-30
2020-01-1504
Turbochargers are progressively used in modern automotive engines to enhance engine performance and reduce energy loss and adverse emissions. Use of turbochargers along with other modern technologies has enabled development of significantly downsized internal combustion engines. However, turbochargers are major sources of acoustic emissions in modern automobiles. Their acoustics has a distinctive signature, originating from fluid-structure interactions. The bearing systems of turbochargers also constitute an important noise source. In this case, the acoustic emissions can mainly be attributed to hydrodynamic pressure fluctuations of the lubricant film. The developed analytical model determines the lubricant pressure distribution in the floating journal bearings used mainly in the modern turbocharges. This allows for an estimation of acoustic emissions.
Technical Paper

Effects of On-Road Conditions on HVAC Noise

2020-09-30
2020-01-1555
Noise inside the passenger cabin is made up of multiple sources. A significant reduction of the major sound sources such as the engine, wind and tire noise helped to improve the comfort for passengers. As a consequence, the HVAC sound (heating, ventilation and air-conditioning) is unmasked as a primary noise source inside the passenger cabin and has to be taken into consideration when designing passenger cabin sound. While HVAC sound is often evaluated at stop, the most common situation of its use is while driving. In case of fresh air as mode of operation, the HVAC system is coupled to the environment through the air intake. Any change in the boundary conditions due to on-road driving events and gusts of wind affects the flow field in the HVAC system and in turn influences HVAC noise. This study investigates the effect of mass flow and pressure fluctuations on the HVAC noise. In a first step, major influences on the HVAC system are identified in an on-road test.
Technical Paper

Development of the Active Sound Generation Technology using Motor Driven Power Steering System

2020-09-30
2020-01-1536
As original engine sound is usually not enough to satisfy the driver’s desire for the sporty and fascinating sound, active noise control (ANC) and active sound design (ASD) have been great technologies in automobiles for a long time. However, these technologies which enhance the sound of vehicle using loud speakers or electromagnetic actuators etc. lead to the increase of cost and weight due to the use of external amplifier or external actuators. This paper presents a new technology of generating a target sound by the active control of a permanent magnet synchronous motor (PMSM) which is already mounted in vehicle. Firstly, an algorithm of this technology, called an active sound generation (ASG), is introduced with those signal conversion process, and then the high frequency noise issue and its countermeasure are presented.
White Paper

IAASS-SSI-1700 Commercial Human-Rated System

2018-07-01
WP-0011
This document establishes the safety requirements applied by the IAASS Space Safety Institute (SSI) for the safety certification of Commercial Human Rated Systems (CHS). This standard covers any human-rated system commercially developed and operated to perform suborbital, orbital, or interplanetary missions, including transport vehicles such as capsules or winged bodies, orbital stations, unmanned cargo transport vehicles intended to dock with crewed stations, bases, descent and ascent vehicles, and integrated systems (e.g., capsule on launcher). NOTE: The mandatory (i.e., shall) requirements in this standard are based on selected best practices from past and present governmental space programs.
Technical Paper

Power Brakes for Passenger-Cars

1928-01-01
280017
THE use of a power medium in brake control points at once to the possibility of simplifying the brake system so that its characteristics, once established, can be expected to remain uniformly effective throughout extended periods without adjusting, with correspondingly long life of brake-linings. The author says also that, if the greater retarding effect possible with mechanically operated four-wheel brakes is to be fully realized, it is necessary to do one of three things: increase the pedal pressure, increase the brake leverage and consequently the pedal movement, or increase the “self-energizing” effect. The vacuum-type brake described is stated to be an amplifier which provides power to supplement muscular strength and assists the driver to apply the service brake, thereby reducing the required pedal stroke and pedal pressure without interfering with the regular service-brake hook-up.
Technical Paper

Data on Machinability and Wear of Cast Iron

1928-01-01
280022
THE hardness or chemical composition of an iron is, by itself, no indication of the wearing property and machinability of the iron. Irons containing a large amount of free ferrite have been found to wear rapidly, whereas others having considerable pearlite or sorbite in their structure show good wearing properties. The presence in cylinder-blocks of excess-carbide spots or of phosphides of high phosphorus-content is deleterious, because such spots wear in relief and the material ultimately breaks out, acting as an abrasive that scores the surfaces. Causes of wear in cylinder-blocks are discussed, and nickel, or nickel and chromium, intelligently added to the iron is suggested as a means of obtaining the correct microstructure for a combination of good wearing properties and machinability.
Technical Paper

Performance of a Supercharged Passenger-Car

1928-01-01
280041
A STUDY of the effect of supercharging on the performance of the engines of passenger-cars showed that the power increase varied from 35 per cent at 1000 r.p.m. to 59 per cent at 3000 r.p.m., with a maximum supercharging pressure of only 6.5 lb. per sq. in. In acceleration tests made at the General Motors Proving Ground of two cars of similar model, one equipped with a supercharged engine and the other with a high-compression engine, the supercharged car accelerated from 5 to 25 m.p.h. in 5 sec.; the unsupercharged car, in 10 sec. From 15 to 50 m.p.h. the supercharged car accelerated in 12.7 sec.; the unsupercharged car, in 21.0 sec. On an 11-per cent grade up which the cars were started at 10 m.p.h., the speed of the supercharged car was 40 m.p.h. at the top; that of the unsupercharged car was 18 m.p.h. These and other results of the tests are portrayed by curves.
Technical Paper

Automobile Bodies, from the Abstract Customer's Viewpoint

1928-01-01
280057
CONSTRUCTIVE criticism of automobile bodies as now built is given herein, based on experience gained in driving five-passenger sedan cars of many makes a total distance of nearly 10,000,000 miles in one year in tests at the General Motors Proving Ground. The fault finding, although humorously exaggerated, will be valuable if taken seriously, as it gives to all body designers and builders the benefit of testing experience that few companies are in a position to gain at first hand. The author treats his subject from the viewpoint of the abstract customer; that is, the automobile-purchasing public as a whole and as represened by the imaginary average man, who is assumed to have average stature and body structure and to drive all the different makes of car. Thus he is assumed to change from one to another make frequently, instead of becoming used to only one or two cars.
Technical Paper

The Packard X 24-Cylinder 1500-Hp. Water-Cooled Aircraft Engine

1928-01-01
280064
AFTER outlining the history of development of the Packard X engine, the author states the legitimate position in aviation deserved by the water-cooled aviation-engine of this type and predicts large increases in the size, speed and carrying capacity of airplanes within the near future. Passing then to a discussion of the important features of the X-type engine, various illustrations of its parts are commented upon. The cylinders are built-up from steel forgings, with all welds arranged so as to be subjected to no excessive alternating stresses. The novel features of this cylinder design lie in the fact that the valve seats are entirely surrounded by water and that water space is provided above the combustion-chamber and below the top plate of the cylinder. The cylinder-head is extremely rigid, resisting deflection and assuring the maximum integrity of valve seats. The valve ports are machined integrally with the cylinder-head and are not welded thereto as in the Liberty engine.
Technical Paper

Automobile Induction-Systems and Air-Cleaners

1928-01-01
280051
AFTER indicating the trend of requirements in induction systems, the author discusses air-cleaners, carbureters and inlet manifolds. Particular attention is paid to improvements in centrifugal air-cleaners, that result in only slight pressure loss and in high cleaning efficiency. These improvements have been made by changing the body outline; by the addition of a diffuser, to make the resistance as small as possible; and by proportioning the vanes, as to angle and number, to increase the cleaning efficiency with only slight loss in pressure. Carbureters are considered briefly, only because of their interrelation with air-cleaners and manifolds. Inlet manifolding for four, six, and eight-cylinder-inline engines is studied, with variations in port arrangement. Recommendations are made as to the cross-sectional areas and form to secure best distribution of the mixture and adequate vaporization.
Technical Paper

Notes on Valve-Spring Design

1928-01-01
280052
A PAPER on Valve-Spring Surge,2 by Mr. Donkin and H. H. Clark, which was presented at the Semi-Annual Meeting of the Society in May, 1927, was presented during the last season by Mr. Donkin at Section meetings in Buffalo, Chicago and Milwaukee. At a meeting of the Cleveland Section he delivered a paper on Valve-Spring Design, part of which is printed herewith. The remainder was a duplication of the Semi-Annual Meeting paper. At each of these Section meetings the subjects of valve-spring surge and valve-spring design were discussed. Some of the discussion was upon part of the original paper in which were compared two valve-springs, the original design vibrating noisily and the improved design being satisfactory.
Technical Paper

Diesel Engines for Aircraft

1929-01-01
290057
ALTHOUGH the author and his associates have designed, built and tested a Diesel airplane-engine, a description of the mechanical details is omitted because the engine is still in the experimental stage. The general subject of Diesel engines for aircraft is therefore presented in its broader aspects. Typical indicator-diagrams of a gasoline engine and of a Deisel engine are compared as a means of ascertaining whether the pessimistic attitude that the Diesel engine cannot be made light enough for aircraft-propulsion purposes is justified. These considerations lead to the statement that, since a practicable Diesel aircraft-engine must run at speeds five or six times as fast as the stationary or marine-type of Diesel powerplants, whereas the ignition time-lag is substantially the same, it can be seen that the high-speed engine demands a different type of combustion than does the low-speed Diesel.
Technical Paper

High-Temperature Liquid-Cooling

1929-01-01
290058
BEGINNING with a statement of the requirements of a high-temperature cooling-liquid and a short history of what had been previously done in this field, the author gives a description of the liquid used in the investigation which was conducted by the Materiel Division at Wright Field. The investigation is divided into five parts which includes dynamometer test of Curtiss V-1570 and D-12 engines, endurance test and flight tests of D-12 engine and a dynamometer test of a high compression-ratio D-12 engine. The engines and cooling systems used, the results obtained and troubles experienced are given in detail, with curves, sketches and views of the airplanes. Extremely low fuel-consumption was obtained, and the results show that the ratio of installed weight to power of a liquid-cooled airplane-engine is considerably reduced by using this system of cooling.
Technical Paper

Variable-Pitch Propellers

1929-01-01
290060
WHILE much experimental work has been done on the controllable-pitch propeller, complexity of existing devices has prevented their being placed on the market. After reviewing briefly the difficulties encountered, due to propeller and engine characteristics, the author discusses the effect of camber ratio and of angle of attack on the speed at which burble occurs, following this with comments on the efficiency of propellers as static-thrust producers, the use of the method of momentum to compute thrust and the application of adjustable-pitch propellers to supercharged engines. The causes of the forces required to operate the control adjustments are given as (a) friction, (b) twisting moments produced by centrifugal force and (c) twisting moments produced by air pressure.
Technical Paper

Aircraft Propellers

1929-01-01
290059
NEARLY all the aircraft propellers used by both the Army and the Navy are of the detachable-blade type. The Navy has found it necessary to make its own designs and to furnish the propeller manufacturers with finished detail drawings. The author lists the sources from which data can be obtained and shows a chart from which can be found a diameter and setting of a pair of detachable blades that will give reasonably good performance for nearly any horsepower, revolutions per minute and airspeed commonly used with the direct-drive type of propeller. Discrepancies between model tests and wind-tunnel tests are cited, and the author then considers the subject theoretically. Substitute propellers are next considered, and also the strength of propellers.
Technical Paper

Specification-Writing for Petroleum Lubricants

1927-01-01
270061
ALL large users of petroleum lubricants are endeavoring to reduce to printed form their individual ideas of what the lubricants they want should contain and what their physical and mechanical properties should be. The lubricants manufacturer finds, however, that anarchy prevails among the requirements and that the technique of writing the specifications is distinctly amateurish. One method followed is to analyze a satisfactory lubricant and embody the results in the specifications, but the specifier does not know that the product is the best for his purpose and does not possess the facilities for accurate analysis and the ability to determine the pertinent from the irrelevant factors. Another method is to select from a number of analyses and specifications items that seem important and incorporate them in the writer's specification. The result calls for a non-existent hybrid that may be impossible to produce.
Technical Paper

Effect of a Centrifugal Supercharger on Fuel Vaporization

1929-01-01
290077
SUPPLEMENTING the results of an investigation at the Massachusetts Institute of Technology on supercharging a single-cylinder automobile engine which were presented at the 1928 Annual Meeting, this paper reports a study that was made to determine whether the mechanical action of a high-speed centrifugal supercharger improves engine performance by increasing the degree of atomization and vaporization of the fuel in the inlet manifold. While changes in the degree of fuel atomization and vaporization might be measured directly by sampling the gases as they pass to each cylinder, an indirect evaluation of these changes by measuring their effect on engine performance was considered more practicable. Tests were made on a six-cylinder automobile engine connected to an electric cradle-dynamometer.
Technical Paper

The Employment of Less Volatile Fuels for Motorcoach Engines

1929-01-01
290078
THE AMERICAN public demands that, in safety, comfort, appearance, speed, acceleration and deceleration, motorcoaches shall compare favorably with the present-day automobile, according to the author. These demands have resulted in a substantial increase in weight that has required the use of much larger engines, and this has brought about a tremendous increase in fuel consumption. Since fuel costs represent a large percentage of the total cost of operation, the possibility of decreasing these expenditures is receiving considerable attention. In addition, and apart from the increase in fuel usage resulting, taxation is causing grave concern. The author describes the fuel issue as it now exists in the United States. Data are submitted showing the tax situation, costs and refining operations, the potential saving assuming the employment of the less volatile fuels, their possible method of employment, advantages, disadvantages and the like.
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