1、BS EN 3987:2009ICS 49.025.01, 49.025.05NO COPYING WITHOUT BSI PERMISSION EXCEPT AS PERMITTED BY COPYRIGHT LAWBRITISH STANDARDAerospace series Test methods formetallic materials Constant amplitudeforce-controlled highcycle fatigue testingThis British Standardwas published underthe authority of theSta
2、ndards Policy andStrategy Committee on 30November 2009 BSI 2009ISBN 978 0 580 62413 1Amendments/corrigenda issued since publicationDate CommentsBS EN 3987:2009National forewordThis British Standard is the UK implementation of EN 3987:2009.The UK participation in its preparation was entrusted to Tech
3、nicalCommittee ACE/61/-/6, Mechanical testing of metallic materials.A list of organizations represented on this committee can be obtained onrequest to its secretary.This publication does not purport to include all the necessary provisionsof a contract. Users are responsible for its correct applicati
4、on.Compliance with a British Standard cannot confer immunityfrom legal obligations.BS EN 3987:2009EUROPEAN STANDARD NORME EUROPENNE EUROPISCHE NORM EN 3987 October 2009 ICS 49.025.01; 49.025.05 English Version Aerospace series - Test methods for metallic materials - Constant amplitude force-controll
5、ed high cycle fatigue testing Srie arospatiale - Mthodes dessais applicables aux matriaux mtalliques - Essais de fatigue mgacyclique en contrainte impose Luft- und Raumfahrt - Prfverfahren fr metallische Werkstoffe - Schwerlastwechselermdung (HCF) im kraftgesteuerten Versuch This European Standard w
6、as approved by CEN on 11 July 2008. CEN members are bound to comply with the CEN/CENELEC Internal Regulations which stipulate the conditions for giving this European Standard the status of a national standard without any alteration. Up-to-date lists and bibliographical references concerning such nat
7、ional standards may be obtained on application to the CEN Management Centre or to any CEN member. This European Standard exists in three official versions (English, French, German). A version in any other language made by translation under the responsibility of a CEN member into its own language and
8、 notified to the CEN Management Centre has the same status as the official versions. CEN members are the national standards bodies of Austria, Belgium, Bulgaria, Cyprus, Czech Republic, Denmark, Estonia, Finland, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembour
9、g, Malta, Netherlands, Norway, Poland, Portugal, Romania, Slovakia, Slovenia, Spain, Sweden, Switzerland and United Kingdom. EUROPEAN COMMITTEE FOR STANDARDIZATION COMIT EUROPEN DE NORMALISATION EUROPISCHES KOMITEE FR NORMUNG Management Centre: Avenue Marnix 17, B-1000 Brussels 2009 CEN All rights o
10、f exploitation in any form and by any means reserved worldwide for CEN national Members. Ref. No. EN 3987:2009: EBS EN 3987:2009EN 3987:2009 (E) 2 Contents Page Foreword 31 Scope 42 Normative references 43 Principle 44 Terms and definitions .45 Symbols and abbreviations 56 Test equipment 67 Test pie
11、ce 108 Test method . 149 Post-test checks . 1510 Test report . 16Annex A (informative) Use of thermocouples . 17Annex B (informative) Test piece preparation . 18Annex C (informative) Guidelines on test piece handling and degreasing 20Annex D (informative) Guidelines on producing an S-N curve 21Bibli
12、ography . 22BS EN 3987:2009EN 3987:2009 (E) 3 Foreword This document (EN 3987:2009) has been prepared by the Aerospace and Defence Industries Association of Europe - Standardization (ASD-STAN). After enquiries and votes carried out in accordance with the rules of this Association, this Standard has
13、received the approval of the National Associations and the Official Services of the member countries of ASD, prior to its presentation to CEN. This European Standard shall be given the status of a national standard, either by publication of an identical text or by endorsement, at the latest by April
14、 2010, and conflicting national standards shall be withdrawn at the latest by April 2010. Attention is drawn to the possibility that some of the elements of this document may be the subject of patent rights. CEN and/or CENELEC shall not be held responsible for identifying any or all such patent righ
15、ts. According to the CEN/CENELEC Internal Regulations, the national standards organizations of the following countries are bound to implement this European Standard: Austria, Belgium, Bulgaria, Cyprus, Czech Republic, Denmark, Estonia, Finland, France, Germany, Greece, Hungary, Iceland, Ireland, Ita
16、ly, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway, Poland, Portugal, Romania, Slovakia, Slovenia, Spain, Sweden, Switzerland and the United Kingdom. BS EN 3987:2009EN 3987:2009 (E) 4 1 Scope This document applies to constant amplitude force-controlled high cycle fatigue (HCF) testing of
17、metallic materials governed by EN Aerospace standards. It defines the mechanical properties that may need to be determined, the equipment, test pieces, methodology of test and presentation of results. It applies to uniaxially loaded tests carried out on plain or notched test pieces at ambient and el
18、evated temperatures. It is not intended to cover the testing of more complex test pieces, full scale components or structures, although the methodology could well be adopted to provide for such tests. The purpose of this document is to ensure the compatibility and reproducibility of test results. It
19、 does not cover the evaluation or interpretation of results. 2 Normative references The following referenced documents are indispensable for the application of this document. For dated references, only the edition cited applies. For undated references, the latest edition of the referenced document (
20、including any amendments) applies. EN 10002-2:1991, Metallic materials Tensile testing Part 2: Verification of the force measuring system of the tensile testing machine. ASTM E 1012, Standard practice for Verification of test frame and specimen alignment under tensile and compressive axial force app
21、lication. 1)3 Principle The uniaxially loaded force-controlled high cycle fatigue test consists of maintaining a test piece at a uniform temperature and subjecting it to a constant force-amplitude waveform. The magnitude of the applied cyclic force affects the development of microscopic plastic stra
22、in within the test section, thus determining the fatigue life. A series of such tests allows the relationship between the applied force and the number of cycles to failure to be established. The fatigue lives generated are typically in the range 104- 108cycles to failure and the test regime is said
23、to be that of high cycle fatigue (HCF). 4 Terms and definitions For the purposes of this document, the following terms and definitions apply. 4.1 force-control used to describe tests in which the force acting on a known test section is controlled 4.2 test section defined as the region of the test pi
24、ece between the blending fillets into the gripping section, and may be a continuous radius or a parallel sided section 1) Published by: American Society for Testing and Materials (ASTM), 1916 Race Street- Philadelphia PA 19103 USA. BS EN 3987:2009EN 3987:2009 (E) 5 4.3 cycle defined as the smallest
25、section of the force-time function which is repeated periodically. This is shown for a sinusoidal waveform in Figure 1, together with appropriate nomenclature which further defines the force cycle 4.4 failure defined as complete separation of the test piece within the test section 5 Symbols and abbr
26、eviations See Table 1. Table 1 Definitions and symbols relating to force-controlled fatigue testing Symbol Units Term Definition F kN Force The force applied to the test section. Tensive forces are considered to be positive and compressive forces negative. Fmax.kN Maximum force The highest algebraic
27、 value of force applied. Fmin.kN Minimum force The lowest algebraic value of force applied. F kN Force range The algebraic difference between the maximum and minimum forces. (Fmax. Fmin.) Fa kN Force amplitude Half the algebraic difference between the maximum and minimum forces. (Fmax. Fmin.)/2 Fm k
28、N Mean force Half the algebraic sum of the maximum and minimum forces. (Fmax.+ Fmin.)/2 R Force Ratio The algebraic ratio of the minimum force to the maximum force. See Figure 2 for examples of different force ratios. (F min./F max.) MPa Stress The force applied divided by the nominal cross-sectiona
29、l area. The nominal cross-sectional area is that calculated from measurements taken at ambient temperature, and no account is taken for the change in section as a result of elevated temperatures. The above nomenclature for force also applies to stress, with F replaced by . N Number offorce cycles Th
30、e number of cycles applied. f Hz Frequency ofcycles The number of cycles applied per second. NfEndurance or fatigue life The number of cycles to failure. KtTheoretical stress concentration factor The ratio of the notch tip stress to net section stress, calculated in accordance with defined elastic t
31、heory, to the nominal section stress. NOTE Different methods used in determining Ktmay lead to variations in reported values. NMPa Fatigue strength at N cycles The value of the stress amplitude at a stated stress ratio under which the test piece would have a life of at least N cycles with a stated p
32、robability. BS EN 3987:2009EN 3987:2009 (E) 6 6 Test equipment 6.1 Test machine 6.1.1 General The tests shall be carried out on a tension-compression machine designed for a smooth start-up with no backlash when passing through zero. In order to minimise the risk of buckling of the test piece, the ma
33、chine should have great lateral rigidity and accurate alignment between the components used to grip the test piece ends. The machine loading system shall be a controlled system in which the loading of the test piece is servo-controlled. It may be hydraulic or electromechanical. During elevated tempe
34、rature tests, the machine load cell should be suitably shielded and/or cooled such that it remains within its temperature operation range. 6.1.2 Test machine calibration The force measurement system shall be verified at intervals not exceeding one year. The method to be used is that of EN 10002-2 wi
35、th the following amendment related to the application of test forces, to cover calibration in tension and compression going through zero (clause 5.4.5 of EN 10002-2:1991). Three series of measurements shall be carried out. Each series shall comprise at least 20 force steps as follows: 5 increasing f
36、orce steps in tension at regular intervals from 20 % to 100 % of the full scale, 10 decreasing force steps at regular intervals from 100 % of the full scale in tension down to the full scale in compression, 5 increasing force steps at regular intervals from 100 % of the full scale in compression up
37、to zero. The relative errors of accuracy, repeatability, reversibility and zero shall be within the limits stated for class 1 of EN 10002-2:1991. During the calibration process, an initial calibration shall be performed prior to adjustment of the test machine, such that the effect of any errors outs
38、ide of the grade 1.0 requirement can be understood. NOTE Modern test machines should readily meet this requirement, however if initial errors are present then the calibration period would need to be reviewed accordingly. 6.2 Cycle counting The number of cycles applied to the test piece shall be reco
39、rded such that the resolution is better than 0,1 % of the indicated life. NOTE A calibrated timer is a desirable adjunct to the cycle counter. When used to indicate total elapsed time to failure, it provides an excellent check against the cycle counter frequency for a fixed waveform frequency. 6.3 W
40、aveform generation and control The force cycle waveform shall be constant and is to be applied at a fixed frequency throughout the duration of a test programme. The waveform generator in use shall have repeatability such that the variation in force levels between successive cycles is within the cali
41、bration tolerance of the test machine as stated in 6.1.2, for the duration of the test with the total variation in the force level within 1 % of the requested value. BS EN 3987:2009EN 3987:2009 (E) 7 Terms have been identified relative to a sinusoidal waveform in Figure 1. Other waveform shapes may
42、require further parameter definition although nomenclature should be retained where possible. NOTE The waveform frequency will generally be between 10 Hz and 200 Hz. Although higher or lower frequencies may be used, the effect of frequency and waveform shape on fatigue life can be significant. Figur
43、e 1 Fatigue force cycle Figure 2 Varying force ratio BS EN 3987:2009EN 3987:2009 (E) 8 6.4 Test fixtures 6.4.1 General An important consideration for test piece grips and fixtures is that they can be brought into good alignment consistently from test to test. Good alignment is achieved from very car
44、eful attention to design details, i.e. specifying the concentricity and parallelism of critical machined parts. In order to minimise bending strains the gripping system should be capable of alignment such that the major axis of the test piece coincides closely with the force axis throughout each str
45、ess cycle and in the case of tension-compression tests (R 0) the gripping system must also be free from backlash effects. The occurrence of misalignment either due to twist (rotation of the grips) or to a displacement on their axes of symmetry, must be controlled within known limits. NOTE A parallel
46、ism error of less than 0,2 mm/m, and an axial error of less than 0,03 mm for a test space of less than 300 mm, and of less than 0,1 mm for a test space of more than 300 mm, should allow the alignment requirements described in 6.4.2 to be achieved. A further benefit can be realised by minimising the
47、number of mechanical interfaces in the load train and the distance between the machine actuator and crosshead. 6.4.2 Alignment verification Alignment of the load train assembly shall be checked at intervals not exceeding one year or 100 tests, whichever occurs sooner. In addition, it must be checked
48、 following disassembly of the test fixtures, movement of the machine crosshead or following a compressive failure that has caused the two test piece halves to overlap. It is recommended that the alignment is checked by means of a strain-gauged test piece of geometry identical to that to be tested an
49、d that has been manufactured to the same tolerances. The maximum bending strain determined in accordance with Method 1 of ASTM E 1012 (Standard Practice for the Verification of Alignment Under Tensile Loading) must not exceed 5 % of the mean axial strain induced at the lowest maximum tensile force and the maximum compressive force to be encountered in the test programme. This criterion should be met at each of 4 positions as the test piece is rotated through 90. The use of 2 sets of strain ga
