SAE J 1390-2017 Engine Cooling Fan Structural Analysis.pdf

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1、_ SAE Technical Standards Board Rules provide that: “This report is published by SAE to advance the state of technical and engineering sciences. The use of this report is entirely voluntary, and its applicability and suitability for any particular use, including any patent infringement arising there

2、from, is the sole responsibility of the user.” SAE reviews each technical report at least every five years at which time it may be revised, reaffirmed, stabilized, or cancelled. SAE invites your written comments and suggestions. Copyright 2017 SAE International All rights reserved. No part of this p

3、ublication may be reproduced, stored in a retrieval system or transmitted, in any form or by any means, electronic, mechanical, photocopying, recording, or otherwise, without the prior written permission of SAE. TO PLACE A DOCUMENT ORDER: Tel: 877-606-7323 (inside USA and Canada) Tel: +1 724-776-497

4、0 (outside USA) Fax: 724-776-0790 Email: CustomerServicesae.org SAE WEB ADDRESS: http:/www.sae.org SAE values your input. To provide feedback on this Technical Report, please visit http:/standards.sae.org/J1390_201706 SURFACE VEHICLE RECOMMENDED PRACTICE J1390 JUN2017 Issued 1982-04 Revised 2017-06

5、Superseding J1390 JAN2012 Engine Cooling Fan Structural Analysis RATIONALE This document has been reviewed for accuracy of contents and several statements added and/or revised for clarification of the procedures presented. A new section pertaining to Electric Cooling Fan Assemblies has also been add

6、ed. FOREWORD This SAE Recommended Practice is intended as a guide toward standard practice but may be subject to frequent change to keep pace with experience and technical advances, and this should be kept in mind when considering its use. 1. SCOPE Three levels of fan structural analysis are include

7、d in this practice: a. Initial Structural Integrity b. In-vehicle Testing c. Durability (Laboratory) Test Methods The Initial Structural Integrity section describes analytical and test methods used to predict potential resonance and, therefore, possible fatigue accumulation. The In-vehicle (or machi

8、ne) section enumerates the general procedure used to conduct a fan strain gage test. Various considerations that may affect the outcome of strain gage data have been described for the user of this procedure to adapt/discard depending on the particular application. The Durability Test Methods section

9、 describes the detailed test procedures for a laboratory environment that may be used depending on type of fan, equipment availability, and end objective. The second and third levels build upon information derived from the previous level. Engineering judgment is required as to the applicability of e

10、ach level to a different vehicle environment or a new fan design. This SAE Recommended Practice is applicable to any engine cooling fan application including medium and heavy-duty trucks, buses, construction equipment, industrial, and agricultural equipment. Some sections are more applicable to engi

11、ne-driven fans than to hydraulic-driven or electric-motor-driven fans, especially with respect to speed control. Fan failure modes, however, are generally the same regardless of driving modes. SAE INTERNATIONAL J1390 JUN2017 Page 2 of 18 The usage of non-metallic construction necessitates areas of e

12、valuation not required by metallic designs. Chief among these are temperature extremes, moisture content, impact resistance, chemical attack, material purity/homogeneity, and aging/weathering. Areas of evaluation affecting both metallic and non-metallic fans, but requiring somewhat different approac

13、hes with non-metallic parts, include natural frequency determination and durability testing. 1.1 Purpose The purpose of this document is to identify the general methodology for the structural analysis of engine cooling fans, and to provide expanded information on subset practices within the general

14、methodology, such that a user of this practice can adapt specific subsets related to a vehicle1 class. 2. REFERENCES 2.1 Applicable Documents The following publications form a part of this specification to the extent specified herein. Unless otherwise indicated, the latest issue of SAE publications

15、shall apply. 2.1.1 SAE Publications Available from SAE International, 400 Commonwealth Drive, Warrendale, PA 15096-0001, Tel: 877-606-7323 (inside USA and Canada) or +1 724-776-4970 (outside USA), www.sae.org. SAE J1099 Technical Report on Low Cycle Fatigue Properties Ferrous and Non-Ferrous Materia

16、ls SAE J1116 Categories of Off-Road Self-Propelled Work Machines SAE J1234 Specification Definitions - Off-Road Work Machines SAE J/ISO 6165 Earthmoving Machinery - Basic Types - Vocabulary 2.1.2 ASTM Publications Available from ASTM International, 100 Barr Harbor Drive, P.O. Box C700, West Conshoho

17、cken, PA 19428-2959, Tel: 610-832-9585, www.astm.org ASTM D618 Standard Practice for Conditioning Plastics for Testing 3. DEFINITIONS 3.1 NON-METALLIC FANS Non-metallic fans can be constructed from a variety of thermoplastic and thermosetting resins, with or without any of the following: reinforcing

18、 fibers, fillers, stabilizers, modifiers, and pigments. Non-metallic fan materials in common use include but are not limited to polypropylene, nylon, polyester, and vinyl ester. 3.2 WELD-LINE or KNIT-LINE The area of a molded non-metallic part formed by the union of two or more streams of thermoplas

19、tic flowing together during an injection molding process. 3.3 STRESS WHITENING An effect noted in non-metallic materials under stress loading occurring as a result of molecular orientation, visible as a white area due to the change in the refraction index of the material. 1 The term “vehicle“ as use

20、d in this practice is defined as an all-inclusive term. SAE INTERNATIONAL J1390 JUN2017 Page 3 of 18 4. INITIAL STRUCTURAL INTEGRITY 4.1 Scope It is necessary to identify and attempt to evaluate the characteristics of an application which can have an effect on fan durability. Failures almost always

21、occur in fatigue, so careful attention should be paid to avoid resonance or forced vibration of the fan. This section considers vibrational inputs, fan natural frequencies, and operating speed as part of the initial structural integrity analysis. A fan application fact sheet (Figure 1) is recommende

22、d as a form to communicate between user and fan supplier. 4.1.1 A resonant condition may occur when the natural frequencies of the fan as determined from 4.3 is coincident with either of the vibrational input frequencies or their harmonics, as calculated in 4.2, or with the effects of airflow obstru

23、ctions near the fan. 4.1.2 It is desirable to separate these frequencies, including the upper and lower harmonics, whenever possible. In addition, torsional vibrations, auxiliary equipment, driveline vibrations, etc., may cause vibratory inputs to the fan which cannot be predicted in equation form.

24、4.1.3 Vibratory inputs to the fan caused by the fan tips rubbing against a shroud should be avoided. Such rubbing is generally accompanied by much noise but can also be easily identified by visual inspection of the fan and shroud. Engine movement and vehicle frame flexure are two conditions that can

25、 cause rubbing. SAE INTERNATIONAL J1390 JUN2017 Page 4 of 18 P A R T O N E - F A N US E R I N F O R M A T I O NC u st o m er : L o c a ti o n :C o n ta c t P er so n :P h o n e N u m b er : E - m a i l A d d r ess:P e r f o r m a n c e R e q u i r e d A i r D en si ty :V o l u m etr i c F l o w R a

26、te: S ta ti c R esi st a n c e P r essu r e:S p ee d : R P M M a x F a n P o w er :L i m i t a t i o n sM a x F a n D i a m eter : M a x O v er - S p ee d : R P MM a x P r o j ec ted Wi d th : M a x F a n P o w er :O t h e r :A p p l i c a t i o n ( V e h i c l e ) D e s c r i p t i o nM o d el N u

27、m b er : E n g i n e:R a ted P o w er : a t E n g i n e S p ee d : R P MF a n D r i v e T y p e:F a n /E n g i n e S p ee d R a ti o : F a n M o u n ti n g L o c a ti o n :F a n R o ta ti o n : B el t T en si o n :P i l o t a n d B o l t C i r c l e: M a x i m u m R u n - O u t:S y s t e mS h r o u

28、d ( fast idle or sub-idle. 5.2.2.1.5 Vibration Data Review any available vibration test data for magnitudes and frequency. Crankshaft torsional data is important. SAE INTERNATIONAL J1390 JUN2017 Page 8 of 18 5.2.2.2 Accessories Power steering pump, water pump, air brake compressor, air conditioning

29、compressor, alternator, emissions air pump, vacuum brake pump, and hydraulic brake booster pump. 5.2.2.3 Driveline Optional sizes, lengths, and types (one-piece or two-piece). Any driveline variant that affects first mode bending frequency can impact fan structural response. Therefore, something lik

30、e a transmission mounted parking brake that is unique to a particular axle ratio or vehicle weight rating may produce an input to the fan structure that differs from other vehicle variants. 5.2.3 Fan Drive The drive ratio and clutch, if used, control fan rotational speed. Additionally, the drive act

31、s as the path to transmit mechanical vibration to the fan. 5.2.3.1 Type Gear or belt, fixed or clutch (on-off, modulated engagement or viscous), hydraulic motor, electric motor (variable or incremental speed changes). 5.2.3.2 Ratio Fan speed to engine speed ratio. 5.2.3.3 Position Fan mounting posit

32、ion on end of crankshaft, on water pump shaft, or remote mounted fan spindle. 5.2.3.4 Fan Mounting Fan mounting surface or spacer configuration. 5.2.3.5 Lumped-Mass Effect The lumped-mass effect of a fan and clutch assembly can produce water pump or fan accessory drive bearing vibration inputs due t

33、o mounting offsets or imbalance. 5.3 Instrumentation This section considers the preparation and instrumentation of the subject fan and the selected test vehicle. 5.3.1 Strain Gage Location It is important that strain gages are placed at all of the highly stressed locations on the subject fan. Severa

34、l methods exist for determining gage location. The best procedure is to employ multiple methods of gage location and to use a generous number of gages. This will reduce the risk that a highly stressed location has been overlooked. The fully strain gaged fan becomes in effect a “master fan.” It shoul

35、d be handled carefully during the in-vehicle test and should be safely stored after test completion. Retention of the “master fan” will allow for its use in future in-vehicle tests or to correlate bench durability tests. 5.3.1.1 Brittle Lacquer Strain gage locations are determined by crack patterns

36、developed in a brittle lacquer coating. The brittle coating can be patterned in the test vehicle and/or on a bench test stand. The bench procedure can use rotational and/or axial excitation. SAE INTERNATIONAL J1390 JUN2017 Page 9 of 18 5.3.1.2 Judgment Gage locations can be determined by past experi

37、ence with similar fan designs or by analytical analysis of the subject fan design. Contact fan supplier for gage location information. 5.3.1.3 Modal Analysis Gage locations are along the node lines of the principal modes that are expected to receive the largest amounts of vibrational energy. 5.3.1.4

38、 Finite Element Gage locations are determined from the computer analysis of a finite element model. 5.3.1.5 Photoelastic Gage locations are determined from the bi-refringent pattern in a photoelastic coating on the subject fan. 5.3.1.6 Failures Gage locations determined by the fatigue crack pattern

39、in a failed fan. 5.3.2 Strain gage life is an important consideration when materials exhibit strain levels much higher than those for which the gage is designed to measure. Typically, a gage provides an accurate indication of strain levels several times above its rated high cycle life, but only for

40、a limited number of cycles, and then typically with a zero shift and a gage factor shift. It is important to understand these characteristics of the gage in use. 5.3.3 Recorded Data Suitable instrumentation is required to record engine speed, fan speed except when fan is solidly driven on the cranks

41、haft, and strain gage output magnitude and frequency. For a viscous drive, sensor air temperature and clutch housing temperature may be recorded. For a plastic fan, (non-metallic) the adjacent air temperature, plastic material temperature and temperature of fan mount material in contact with fan are

42、 required. 5.3.3.1 Instruments for speed measuring shall have a demonstrated accuracy within 1.0% of the value being measured or within 10 rpm, whichever is greater. 5.3.3.2 Instruments for temperature measuring shall have a calibrated accuracy within 3 C and shall have scale divisions of 1 C or sma

43、ller. 5.3.4 Vehicle Measurements Specific measurements may be made on the selected test vehicle so that the following factors will be known. 5.3.4.1 Fan Drive Break-In New friction disks in fan drives may require a break-in period. 5.3.4.2 V-Belts Adjust belt tension on all accessory drives includin

44、g the fan drive to the specified maximum. New V-belts may require a break-in period. 5.3.4.3 Fan Mounting Record the axial runout of the fan drive mounting surface and the radial runout of the fan drive pilot. SAE INTERNATIONAL J1390 JUN2017 Page 10 of 18 5.3.4.4 Fan to Shroud Record radial tip clea

45、rances at top, bottom, and both sides. Record the axial position of fan in fan shroud. Record the fan to radiator clearance. 5.4 Vehicle Test The intent of the in-vehicle fan test is to record fan strains while vehicle operational duty cycle conditions and the fan operating environment are varied in

46、 a systematic way. This will determine the combination of factors that cause the highest fan strains. 5.4.1 Vibration Sources Determine the effect on fan strains for different vibration input conditions. 5.4.1.1 Engine Load Test with engine at full load, partial load, and no load conditions. 5.4.1.2

47、 Engine Speed Test condition of maximum speed (governed speed or rated speed and a specific over speed) and speed transients due to automatic or manual transmission shifting. Test engine start-up, shut-down, idle, and specific below idle speed conditions. Scan the engine operating speed range in a c

48、ontinuous sweep mode in each transmission gear position to identify fan resonances and maximum fan strain amplitudes. 5.4.1.3 Accessories Test the effect of the on-off duty cycle of various accessories. 5.4.1.4 Fan Clutch Determine the effect of the fan clutch operating modes: fully engaged, disenga

49、ged, mechanically locked, and/or on-off transients. Note also that the speed of clutch engagement can impart an inertial impulse loading to the fan blades. 5.4.1.5 Fan Drive Test with fan mounting components (water pump, spacer, fan drive) that produce the maximum allowable radial and axial runout. 5.4.1.6 V-Belts Test with both a “loose” belt tension condition and with an over-tightened belt tension condition. This is applicable to th