EN 3987:2009

2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.Luft- und Raumfahrt - Prüfverfahren für metallische Werkstoffe - Schwerlastwechselermüdung (HCF) im kraftgesteuerten VersuchSérie aérospatiale - Méthodes d'essais applicables aux matériaux métalliques - Essais de fatigue mégacyclique en contrainte imposéeAerospace series - Test methods for metallic materials - Constant amplitude force-controlled high cycle fatigue testing49.025.01Materiali za letalsko in vesoljsko gradnjo na splošnoMaterials for aerospace construction in generalICS:Ta slovenski standard je istoveten z:EN 3987:2009SIST EN 3987:2009en,de01-december-2009SIST EN 3987:2009SLOVENSKI
STANDARD
EUROPEAN STANDARD NORME EUROPÉENNE EUROPÄISCHE NORM
EN 3987
October 2009 ICS 49.025.01; 49.025.05 English Version
Aerospace series - Test methods for metallic materials - Constant amplitude force-controlled high cycle fatigue testing
Série aérospatiale - Méthodes d'essais applicables aux matériaux métalliques - Essais de fatigue mégacyclique en contrainte imposée
Luft- und Raumfahrt - Prüfverfahren für metallische Werkstoffe - Schwerlastwechselermüdung (HCF) im kraftgesteuerten Versuch This European Standard was 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 national 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 notified to the CEN Management Centre has the same status as the official versions.
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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. 21Bibliography . 22 SIST EN 3987:2009

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 strain 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 - 108 cycles to failure and the test regime is said 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 piece 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. SIST EN 3987:2009

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.) σ MPa Stress The force applied divided by the nominal cross-sectional 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 σ. N
Number of force cycles The number of cycles applied. f Hz Frequency of cycles The number of cycles applied per second. Nf
Endurance or fatigue life The number of cycles to failure. Kt
Theoretical stress concentration factor The ratio of the notch tip stress to net section stress, calculated in accordance with defined elastic theory, to the nominal section stress. NOTE Different methods used in determining Kt may lead to variations in reported values. σN MPa 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 probability.
Figure 1 — Fatigue force cycle
Figure 2 — Varying force ratio
NOTE 1 For ambient temperature tests (10 °C to 35 °C) it is not necessary to measure the test piece temperature. NOTE 2 The effect of compounding errors could result in the real tolerance in temperature from the specified level to be 3 °C greater. NOTE 3 The temperature rise due to plastic deformation shall be minimised (see 8.3.1) and shall be compensated for within the Table 2 tolerances.
b) Test pieces with circular cross sections shall have a blending fillet radius of at least twice the test section diameter to minimise the theoretical stress concentration, Kt, of the test piece. The test section length should be greater or equal to two times the test section diameter Concentricity and parallelism must be less than or equal to 0,03 mm. c) Test pieces with rectangular cross sections may have a reduced test cross section along one dimension, generally the width. The test section length should be greater than twice the test section width. The edges of the test piece must be longitudinally polished to prevent premature crack initiation. Errors in flatness must be less than 0,03 mm. d) Test pieces used for compression should have a test section length less than or equal to twice the test section width or diameter, to avoid buckling. e) In view of the specialised nature of notched test pieces no r
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