Display:

Results

Viewing 8521 to 8550 of 9353
1973-02-01
Technical Paper
730850
Charles D. Wood
Circumstances and results of tests of a three-chambered REDSOD built for attachment to a Caterpillar D9 tractor are discussed. The Caterpillar D9 tractor was chosen for its drawbar capability of 4000 lb/ft of width, bare weight of approximately 70,000 lb, and 10 ft width. Tests in straight trenching operations were performed at two sites: one in an area with a clay overburden, the other in sand. From the data presented, it is concluded that a REDSOD machine, with a 1200 ft3 min air compressor, handled by a skilled operator, can produce a 2 ft deep trench at approximately 2000 yd3/h. The noise level is not damaging to operator or adjacent structures or personnel. The use of higher air pressures increases production rates. The recoil produced by REDSOD has no appreciable effect on production rate or tractor reliability.
1973-02-01
Technical Paper
730824
J. Huot de Longchamp
A short survey of the literature about human tolerance to vibrations and about seat transmissibility is presented. A brief summary of European regulations concerning seat characteristics will include not only vibration absorption requirements but also recommended dimensions and necessary adjustments. Safety rules as issued in some countries, in particular for tractor seats, are also discussed. The practical problem of making a seat in accordance with all these factors at a reasonable cost with durability and easy adaptation to the unskilled user will be discussed as a compromise. Conventional systems and new trends are briefly indicated.
1973-02-01
Technical Paper
730823
Larry F. Stikeleather
Since vehicle seats interact dynamically with the human body, testing the response characteristics of such seats for proper application is important. Likewise, the methods and techniques used for such evaluations are equally important if meaningful results are to be obtained. This paper discusses two quantitative test procedures applicable primarily to judging the relative performance of several seats with regard to dynamic characteristics. In particular, the equipment and procedures necessary to plot seat transmissibility are discussed and specific example data are shown for two suspension seats and a static cushion seat. Also, equipment and procedures for assessing the relative dynamic response index (DRI) are discussed and example results for a suspension seat and a cushion seat are included.
1973-02-01
Technical Paper
730795
John Matthews
Methods of assessing the ride comfort afforded to tractor drivers by their vehicles and the ride improvement provided by seat suspension are reviewed in relation to information available on the human tolerance to whole-body vibration. Experience with different methods of measurement is reported and a proposal made for the establishment of an internationally agreed method of ride comfort rating based on standardized undulating surfaces over which vibration of the driver's seat is analyzed, using frequency weighting to represent the differing sensitivity of the body to different vibration frequencies.
1973-02-01
Technical Paper
730812
R. L. DeRuyter
The paper describes work of the SAE Small Engine Powered Equipment Subcommittee in the development of a new sound level measurement procedure for small engine powered equipment. Data were gathered in an effort to improve the test site used in the measurement of exterior sound level of small engine powered equipment such as mowers, riding mowers, garden tractors, snowblowers, etc. A procedure was developed with a shorter measurement distance and an artificial test surface. The new procedure provides accurate, repeatable sound level data.
1973-02-01
Technical Paper
730813
Arthur Lancaster
Commencing with a Canadian Federal Department of Transport contract to study the feasibility of snowmobile silencing, the commercial supply of exhaust systems, and the prototyping of representative machines, a considerable amount of data has been accumulated over the past two years in Winnipeg. From this data certain patterns have emerged which we feel provide a basis for developing a pragmatic approach to the problems of reducing the noise level of snowmobiles.
1973-02-01
Technical Paper
730811
James W. Mohr
The paper describes how the SAE Marine Sound Level Committee, and representatives of the boating industry, developed a procedure for the standardized measurement of maximum “pass-by” sound levels for pleasure motorboats up to 65 ft in length. Sound level data for typical boats are presented, as well as the reasons for the procedure and the justification for the tolerances used. The committee's activity resulted in SAE Recommended Practice J34, Exterior Sound Level Measurement Procedure for Pleasure Motorboats.
1973-02-01
Technical Paper
730814
A. J. Brammer
The sound pressure levels experienced by an individual exposed to noise can be obtained irrespective of the nature of the source or the presence of acoustic barriers by monitoring the sound field within the ear. The apparatus developed for this purpose consists of a miniature microphone located on the base of the concha connected to a lightweight instrument package strapped to the subject. The latter contains a modified cassette tape recorder, power supplies, and an oscillator used to record a calibration signal onto each tape and check the performance of the system. A pressure transformation is applied during analysis of the data to compensate for the frequency response of the components or to generate an equivalent sound field that would exist at the center of the head in the absence of the subject.
1973-02-01
Technical Paper
730815
M. B. Johnston
A theoretical analysis is presented that predicts significant reductions in exhaust pulse amplitudes and hence exhaust noise levels by varying the shape of the exhaust port in a spark-ignited 2-cycle engine. Verification and correlation with experimental results are also presented.
1973-02-01
Technical Paper
730773
K. F. Nowak
The environmental impact of snowmobile noise has received widespread publicity over the past few years. In order to define and solve any noise problem, a satisfactory and repeatable measurement practice must be evolved. In the case of SAE J192, the particular operating environment of snowmobiles proves a challenge to this task. Environmental conditions affect not only the propagation of sound at the test site, but also the performance of the vehicle itself. This results in a potential for significant variation in the sound pressure level of the sound source. Hence, the test procedure must be designed so as to minimize if not eliminate such sources of variations.
1973-02-01
Technical Paper
730793
J. C. Guignard
The recent work of the International Organization for Standardization (ISO), Technical Committee 108, Mechanical Vibration and Shock, Subcommittee 4 (ISO/TC 108/SC4, Mechanical Vibration and Shock Acceptable to Man) has established guidelines (Draft International Standard ISO/DIS 2631) for the evaluation of human response to whole-body vibration in the range of 1-80 Hz. These guidelines, which are subject to revision and to extension of the frequency range in the light of new and better data, provide a current consensus as to the limits of acceptable human exposure to whole-body vibration in vehicles, buildings, and workplaces, according to selected criteria: comfort, working efficiency, and protection from injury. The limits are expressed in terms of acceleration as a function of direction and frequency of vibration and daily duration of exposure.
1973-02-01
Technical Paper
730792
E. Gunnar Ahlstrom
A farm tractor protection cab made of thin steel sheet pressings is described. The cab is designed and produced using entirely automotive-type procedures. Curved glasses and a dampening suspension of the glasses are found to be an important means of achieving a low noise level in the cab. Using the pressing technique when producing a steel cab makes it possible to give the various cab details rigidity with a minimum of material. When welded together, these details form a very stiff cab body, which gives the necessary mechanical strength. The curved surfaces, the radii, and the round forms, which from a tooling point of view are natural for pressed steel parts, also have a vibration-dampening effect on the entire cab construction, thus making it easier to design a quiet tractor cab. Mounted on a farm tractor of conventional design, the cab meets the noise rating number ISO N85.
1973-02-01
Technical Paper
730748
D. J. Roesler, L. D. Gaddy
This paper describes and summarizes the tests of an electrically propelled tractor-trailer with power on all axles. The test rig showed superior performance over standard tractor-trailer vehicles of the same size and power on highways, beaches, and hills. It demonstrated that electric propulsion for heavy-duty applications can perform well in on-road and off-road applications. Further, it can be made cost effective by utilizing commercially available electrical equipment.
1973-02-01
Technical Paper
730377
R. J. Rulis
The noise goal of 95 PNdB for STOL aircraft imposes severe technology demands on propulsion systems. Effects of this goal on the design of the propulsion system are reviewed. Results from recent development programs associated with STOL noise reduction, such as high bypass fan tests, 25 PNdB acoustic suppression tests, sonic inlets, and powered lift system noise tests, are presented. Integrated propulsion system designs for the blown flap and augmentor wing powered lift systems capable of meeting the noise goal are shown and the performance, installation, and economic penalties assessed.
1973-02-01
Technical Paper
730376
Richard E. Hayden
Proposed powered-lift STOL and RTOL (reduced takeoff and landing) aircraft are expected to require noise reductions on the order of 20 dB to meet community noise goals, according to a number of model and full-scale studies. Propulsive-lift STOL introduces to the designer a new class of noise problems in that the noise sources are exposed and not amenable to conventional muffling. Thus, the noise must be reduced at the source, a task for which thorough understanding of source mechanisms is required. A review of source mechanisms associated with various propulsive lift concepts is presented and current state-of-the-art of prediction technology is assessed for each important source. Sources are rank ordered for the various classes of lift-augmenting concepts. Parametric dependence of source levels on design and operating parameters is discussed. Fundamental concepts for noise reduction are developed and current progress toward implementation of these noise reduction concepts is reviewed.
1973-02-01
Technical Paper
730349
L. T. Goodmanson, B. Williams
This paper discusses the design objectives of and a development cycle for a second-generation supersonic transport (SST). The environmental impact of technological advancement and the rapidly changing economic market produce a wide divergence of possible programs for the 1985 time period. Areas of technological advancement that can move in the direction of the second-generation design objectives will be included. Some of these advances require development of a methodology to be able to reduce the technical risk of application to a commercial SST and some require exploratory development.
1973-02-01
Technical Paper
730656
Lyle V. Rennick
A technique is described for diagnosing the vibration source in a vehicle as it is driven on the road. The basic problem is to determine whether the vibration is related to excessive engine or transmission vibration, driveshaft imbalance, driveline misalignment, U-joints, differential, or whell assembly imbalance; and, in the latter case, to isolate which faulty wheel. The technique developed is to integrate samples of the vibration signal taken synchronously with the various rotating parts. The feasibility of the technique was demonstrated on two heavy trucks and several passenger vehicles.
1973-02-01
Technical Paper
730649
E. Franchini, C. Rossi, P. Filippa
This paper describes the use of a road simulator by Fiat to determine the effects of vibration and loads imposed on various parts of a vehicle. The instrument has been effective in identifying vibration sources that induce fatigue or discomfort or which may cause inefficient operation or a breakdown. The laboratory tests include clear procedures for obtaining preliminary information or for tracing down existing conditions.
1973-02-01
Technical Paper
730500
K. G. Peterson, R. E. Rasmussen
Vehicle/tire system performance is mainly influenced by mechanical properties. This discussion is devoted to radial tires in general, although the data are mostly derived from tests of steel belted radials. Also covered are dimension, handling, ride, traction, noise, and power loss performance of the same tire. The authors conclude that no generic class of tire construction or particular design evaluated thus far is unquestionably superior for every performance parameter, although performance differences between generic classes of tires can be defined statistically.
1973-02-01
Technical Paper
730503
D. E. Malen, E. A. Vaughan
A digital signal analysis system to aid in compiling vibration test data is described. The objectives of the system are explained, mathematical properties are derived, and system operation is discussed with respect to hardware, characteristics, and sample output. This method for digital filtering of time series data has proved to be fast, effective, and an easily implemented method of analyzing structural properties. In addition to providing the design engineer with all of the traditional forms of output offered by analog systems, the computer-based nature of the digital filter system facilitates the use of large-scale dynamic simulations requiring mode identification and other analytical software.
1973-02-01
Technical Paper
730504
Robert J. George
The objective of this paper was to establish the degree of correlation between the results obtained from a 3/8 scale plastic model, an actual frame, and a mathematical computer model. Results showed that a satisfactory dynamic simulation can be obtained from a scaled plastic model of the structure and that a mathematical model composed of beam elements is accurate at the lower frequencies but begins to differ with the actual frame at higher frequencies.
1973-02-01
Technical Paper
730825
M. B. Pearce
Traditional mechanical methods of preventing fasteners from loosening are now being reevaluated. Consumerism has put a priority on safety and reliability which has triggered a move toward a greater use of locking fasteners. The American National Standards Institute Subcommittee B18:20 on the performance of locking fasteners is currently drafting performance specifications on chemical-locking and free-spinning fasteners. The SAE Subcommittee on Vibration Testing of Fasteners has also begun to screen fastener testing equipment. The author of this paper, actively involved with both groups, offers a preview of locking fastener identification, benefits, and problems; also, fastener performance employing the latest transverse shock and vibration equipment, which shows that lock washers do not really lock.
1973-02-01
Technical Paper
730788
Horace F. Howell
This paper outlines the structure and interrelationships of the numerous European standards making organizations, with particular reference to agricultural machinery. Because many of the standards being developed by these organizations are becoming part of legislation in the various Common Market countries, their work is of great interest to the machinery manufacturers. Covered are the highway code-constructional requirements, safety constructional requirements, test codes, and engineering standards. The current status of requirements for lighting, tractor cabs (including structural tests, noise, and emissions), maximum speed limits, brakes, hitches, and safety in the various contries are discussed.
1973-02-01
Technical Paper
730939
Jon C. Calkins, Allan G. Piersol
Laboratory and captive flight experiments were performed using an instrumented Sparrow III missile to evaluate the relative merits of direct mechanical vibration and reverberant acoustic noise tests as techniques for simulating the Sparrow captive flight vibration environment. For the laboratory experiments, the mechanical vibration and acoustic noise excitations were applied in accordance with a common response-controlled test specification. The resulting missile vibration data were then standardized and compared with the vibration levels measured during captive flight to determine their similarity in terms of directional, spatial, and spectral distributions. The results indicate that the acoustic noise test simulated the captive flight vibration more accurately than did the mechanical vibration test. However, the accuracy of the simulation provided by the mechanical vibration excitation was not unacceptable for practical applications.
1973-02-01
Technical Paper
730938
Alan H. Burkhard
Traditional assembled store vibration testing techniques do not realistically simulate a store's captive flight environment. Extensive flight and laboratory testing has shown that an integrated acoustic and vibration shaker technique can realistically reproduce a store's captive flight vibration environment. This paper describes acoustic tests on six flight instrumented stores, giving details of physical setup, test procedure, and test results. Test procedures and analysis of test data are presented for those stores used to evaluate vibration shaker testing techniques.
1973-02-01
Technical Paper
730935
J. B. Bartley, M. J. Turner
The general characteristics of flutter problems affecting the structural design of both subsonic and supersonic transport aircraft are discussed in relation to configuration constraints resulting from mission performance and environmental impact requirements. Combined analytical and experimental approaches employed in the assessment and solution of these problems are outlined. Included are discussions of the extensive application of automated procedures in the use of high-speed digital computers for flutter analysis and the dependence on highly sophisticated wind tunnel flutter model construction techniques to provide reliable experimental data. Illustrations of the application of design techniques to supersonic and subsonic aircraft are presented.
1973-02-01
Technical Paper
730286
Robert L. Paullin
Business aircraft-a nongeneric term to certification authorities-are being given increased attention by national and international bodies concerned with noise reduction. This paper reviews the efforts of these groups from a regulatory standpoint. The status of domestic requirements in the United States and abroad is presented. Technical procedures of promulgated and proposed standards are discussed. Business aircraft are separated into turbojet-powered and propeller-driven categories, and each is presented in terms of recent certification experience. The relationship between domestic certification programs and those of the International Civil Aviation Organization, and between domestic and foreign programs are presented. Finally, a brief look is taken into the future for the efficacy of business aircraft noise certification programs.
1973-02-01
Technical Paper
730288
Frederick B. Metzger, Rose Worobel
Within the next few years tighter restrictions on general aviation aircraft noise are expected. It is anticipated that these noise restrictions, like those imposed on larger transport aircraft now certified under Federal Aircraft Regulations, will be revised downward over a period of time. While it is expected that initial restrictions can be met by the current propeller technology, the larger lower tip speed propellers necessary to meet succeedingly more stringent restrictions may prove difficult to accept. In this paper an alternative to the propeller as a propulsor for general aviation aircraft is discussed. This is the subsonic tip speed low-pressure ratio fan which can be mated to turboshaft, rotary combustion, or reciprocating engines to provide a low noise propulsor in a small package. Information is presented which shows tradeoffs among noise, weight, size, cost, and performance.
1973-02-01
Technical Paper
730289
J. C. Plucinsky
This paper describes the engine design details of the Pratt & Whitney JT15D-1 engine as related to noise generation. Design principles and factors contributing to the very low-noise levels on the Cessna Citation aircraft are illustrated. Noise testing experiences and data from static tests on the United Aircraft of Canada Ltd. (UACL) flight test aircraft and from both static and flight tests on the Citation aircraft are discussed. Lessons learned from these tests and some future probabilities are outlined.

Filter

Subtopics