1、DEUTSCHE NORM December 1996 DIN Determination of dynamic mechanical properties of plastics Flexural vibration - Resonance-curve method (IS0 6721 -3 : 1994 + Corr 1 : 1995) Endish version of DIN EN IS0 6721 -3 EN IS0 6721-3 This standard incorporates the English version of IS0 6721 -3. ICs 83.080.00
2、Descriptors: Plastics, testing, mechanical properties. Kunststoffe - Bestimmung dynamisch-mechanischer Eigenschaften - Teil 3: Biegeschwingung - Resonanzkurven-Verfahren (IS0 6721 -3 : 1994, einschlielich Technischer Korrektur 1 : 1995) This standard, together with December 1996 edition, supersedes
3、DIN 53440-1 to DIN 53440-3, January 1984 editions. DIN EN IS0 6721-1, European Standard EN IS0 6721 -3: 1996 has the status of a DIN Standard. A comma is used as the decimal marker. National foreword This standard has been published in accordance with a decision taken by CEN/TC249 to adopt, without
4、alteration, International Standard IS0 6721 -3 as a European Standard. The responsible German body involved in its preparation was the Normenausschu Kunststoffe (Plastics Standards Committee), Technical Committee Mechanische Eigenschaften und Probekrperherstellung. Amendments DIN 53440-1 to DIN 5344
5、0-3, January 1984 editions, have been superseded by the specifications of EN IS0 6721-1 and EN IS0 6721 -3. Previous editions DIN 53440-1: 1973-04, 1984-01; DIN 53440-2: 1973-04, 1984-01; DIN 53440-3: 1973-04, 1984-01. EN comprises 10 pages. No pari of this standard may be reproduced without the pri
6、or permission of Ref. No. DIN EN /SO 6727-3: 7996-72 DIN Deutsches Institut fr Normung e.V., Berlin. Eeuth Verlag GmbH, Berlin, has the exclusive right of sale for German Standards (DIN-Normen). Price group O8 Sales No. 11 O8 06.97 EUROPEAN STANDARD NORME EUROPENNE EUROPISCHE NORM EN IS0 6721-3 Febr
7、uary 1996 ICs 83.080.00 Descriptors: Plastics, testing, mechanical properties. English version Plastics Determination of dynamic mechanical properties Part 3: Flexural vibration - Resonance-curve method (IS0 6721 -3: 1994 + Corr 1 : 1995) Plastiques - Dtermination des proprits mcaniques dynamiques -
8、 Partie 3: Vibra- tion en flexion - Mthode en rsonance (IS0 6721 -3 : 1994 + Corr 1 : 1995) Kunststoffe - Bestimmung dynamisch- mechanischer Eigenschaften - Teil 3: Biegeschwingung - Resonanzkurven- Verfahren (IS0 6721-3: 1994, ein- schlielich Technischer Korrektur 1 : 19951 This European Standard w
9、as approved by CEN on 1996-01-15 and is identical to the IS0 Standard as referred to. CEN members are bound to comply with the CENKENELEC Internal Regulations which stipulate the conditions for giving this European Standard the status of a national standard without any alteration. Up-to-date lists a
10、nd bibliographical references concerning such national standards may be obtained on application to the Central Secretariat 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 responsib
11、ility of a CEN member into its own language and notified to the Central Secretariat has the same status as the official versions. CEN members are the national standards bodies of Austria, Belgium, Denmark, Finland, France, Germany, Greece, Iceland, Ireland, Italy, Luxembourg, Netherlands, Norway, Po
12、rtugal, Spain, Sweden, Switzerland, and the United Kingdom. CEN European Committee for Standardization Comit Europen de Normalisation Europisches Komitee fr Normung Central Secretariat: rue de Stassart 36, B-1050 Brussels O 1996. GEN - All rights of exploitation in any form and by any means reserved
13、 worldwide for CEN national members. Ref. No. EN IS0 6721-3:1996 E Page 2 EN IS0 6721 -3 : 1996 Foreword International Standard IS0 6721 -3 : 1994 Plastics - Determination of dynamic mechanical properties - Flexural vibration - Resonance-curve method, which was prepared by ISO/TC 61 Plastics of the
14、International Organization for Standardization, has been adopted by Technical Committee CEN/TC 249 Plastics as a European Standard. This European Standard shall be given the status of a national standard, either by publication of an identical text or by endorsement, and conflicting national standard
15、s withdrawn, by August 1996 at the latest. In accordance with the CENKENELEC Internal Regulations, the following countries are bound to implement this European Standard: Austria, Belgium, Denmark, Finland, France, Germany, Greece, Iceland, Ireland, Italy, Luxembourg, Netherlands, Norway, Portugal, S
16、pain, Sweden, Switzerland, and the United Kingdom. Endorsement notice The text of the International Standard IS0 6721-3:1994 was approved by CEN as a European Standard without any modifi- cation. 1 Scope This part of IS0 6721 specifies a bending-vibration method based upon resonance curves for deter
17、mining the flexural complex modulus E; of homogeneous plastics and the damping properties of laminated plastics intended for acoustic insulation, for example systems consisting of a metal sheet coated with a damping plastic layer, or sandwich systems consisting of two sheet-metal layers with an inte
18、rmediate plastic layer. For many purposes, it is useful to determine these properties as a function of temperature and frequency. 2 Normative reference The following standard contains provisions which, through reference in this text, constitute provisions of this part of IS0 6721. At the time of pub
19、lication, the edition indicated was valid. All standards are subject to revision, and parties to agreements based on this part of IS0 6721 are encouraged to investigate the possibility of applying the most recent edition of the standard indicated below. Members of IEC and IS0 maintain registers of c
20、urrently valid International Standards. IS0 6721-1 :I 994, Plastics - Determination of dy- namic mechanical properties - Part 1: General prin- ciples. 3 Definitions See IS0 6721-1:1994, clause 3. NOTE 1 As stated in IS0 6721-1, frequencies derived from resonance cuwes based on deformation-rate ampli
21、- tude measurements can be exactly related to dynamic properties. For the recommended range of the loss factor of this part of the International Standard, .e. tan S i 0,1, resonance curves based upon deformation amplitudes can also be used. For highly damping materials, see IS0 6721-1 :1994. annex A
22、. 4 Principle A specimen is submitted to forced bending vibrations in the frequency range between about 10 Hz and 1 O00 Hz. The resonance curve (see IS0 6721-1:1994, subclause 3.1 1) is determined and, from the curve obtained, the flexural storage modulus E, (see IS0 6721 -1 :I 994, subclause 3.2) i
23、s calculated in the range above 0,5 MPa and the loss factor given by tan d = E”, (see IS0 6721-1 :1994, subclause 3.6) is calculated in the range between about lo-* and IO- (see note 1). The test frequency can be varied by making measurements at more than one vibrational order. The measurement range
24、 for the flexural loss modulus E”f (see IS0 6721-1:1994, sub- clause 3.3) is determined by that of the loss factor and by the value of the storage modulus. The mode of oscillation used is designated oscillation mode III (see IS0 6721-1:1994, table 2) and the type of modulus measured is designated E,
25、 (see IS0 6721-1 :1994, table 3). The test is performed on rectangular bars, either mounted vertically with the upper end clamped and the other end free (method A) or suspended horizon- tally by fine fibres at vibrational nodes (method B) (see figure 1). Method A is suitable for testing specimens Pa
26、ge 3 EN IS0 6721-311996 of most types of plastic, including relatively soft ma- terials, whereas method B is particularly suitable for testing rigid (.e. dimensionally stable) specimens, for example sheet metal covered by a plastic layer for damping purposes. 5 Test apparatus 5.1 General The apparat
27、us consists of devices for clamping (method A) or suspending (method 6) the specimen, electronic devices (frequency generator and recording device) for exciting the specimen to forced bending vibration and for measuring the frequency as well as the velocity ampiitude of the specimen (see note 1). Fo
28、r excitation and detection of the vibrations two electromagnetic transducers are situated near the ends of the specimen. The specimen, the clamping or supporting device and the electromagnetic trans- ducers are enclosed in a temperature-controlled chamber (see figure 1). 5.2 Clamps or suspension fib
29、res If the specimen is clamped at one end, the clamp shall be designed to hold the upper end of the speci- men securely and tightly see figure 1 a). It shall be constructed so that no additional damping of the sys- tem occurs. There are two causes of additional damping: - Friction between the test s
30、pecimen and the clamp: This can be detected by stimulating freely decaying oscillations of the relevant vibrational or- der. As explained in IS0 6721-1:1994, annex B, the type of decay is indicative of different types of deviation from linear viscoelastic behaviour. - Vibration of the clamp: The cla
31、mp shall be rigidly mounted on a heavy mass, which acts as a counterweight to the oscillating test specimen. This requires a heavy rigid stand within the temperaturecontrolled chamber (see figure 1). If the specimen is tested in the horizontal position, it shall be supported by two fine fibres at vi
32、brational nodes (see 9.3.2). 5.3 The the Exciter and detector frequency generator shall be capable of exciting specimen with the aid of the electromagnetic transducer to oscillations within the frequency range of 10 Hz to 1 O00 Hz with a constant force amplitude. The detector shall be capable of mea
33、suring the de- formation or deformation-rate amplitude (see note l) of the specimen and the frequency of the oscillation, thereby permitting the recording of the resonance curve (see IS0 6721-1:1994, subclause 3.11 and an- nex A). The amplitude of the exciter and the sensitivity of the detector shal
34、l not vary with frequency by more than 0,5 %within the range of a single-resonance peak, .e. for any 1 O % variation of the frequency. A tracking filter shall be used to minimize noise at the detector. Frequencies shall be measured with a res- olution of at least 0.1 % (see 11.2). Two small, thin st
35、eel plates shall be adhesively bonded at the ends of the specimen to permit the excitation and detection of the vibrations by means of suitable electromagnetic transducers (see 6.2). 5.4 Temperature-controlled enclosure See IC0 6721-1:1994, subclause 5.3. 5.5 Gas supply Supply of air or other suitab
36、le inert gas for purging purposes. 5.6 Temperature-measurement device See IS0 6721-1 :1994. subclause 5.5. 5.7 Devices for measuring test specimen dimensions and density See IS0 6721-1 :1994, subclause 5.6. The balance used for measuring the mass of the specimen shall be capable of weighing to 1 mg.
37、 Page 4 EN IS0 6721 -3 : 1996 T From frequency o amplifier generator -Clamp -Detector Temperature-controlled enclosure -Specimen Exciter a) MethodA Tempera ture-controlled enclosure Vibrational nodes / oioe+ector -. To amplifier Exciter From frequency generator b) MethodB Figure 1 - Schematic diagra
38、ms of test apparatus for methods A and B Page 5 EN IS0 6721 -3: 1996 6 Test specimens See IS0 6721-1 :1994, clause 6. 6.1 Shape and dimensions Specimens shall be rectangular bars or strips thick enough to give sufficient bending stiffness, which is critical for the resonance frequency. On the other
39、hand, the thickness shall be sufficiently small when compared to the wavelength of the bending vibration. The specimen thickness shall also be limited to avoid effects due to shear deformation and rotatory inertia if accurate values of E are required. length-to- thickness ratios of less than 50 shal
40、l be avoided if values of E are required to be accurate to within f 5 %, from measurements up to the sixth order of homogeneous, isotropic specimens. The thickness of the layers of a multilayer system will depend on the purpose for which the system was designed. When comparing various systems by the
41、 bending-vibration test, the preferred ratio of the mass of the plastic layer to the mass of the basic sheet material is 1:5. The width of the specimens shall be less than one- half of the wavelength used in order to avoid lateral resonance vibrations. A width of 10 mm should be suitable in most cas
42、es. The length of the specimens depends on the desired frequency. For specimens clamped at one end, the length shall be sufficiently large to avoid the clamp influencing the vibration significantly. Usually a free length of 180 mm will be suitable. If the specimen is not clamped, its length shall be
43、 150 mm. 6.2 Preparation See IS0 6721-1:1994, subclause 6.2. Small, thin, light steel plates shall be adhesively bonded to the specimens near their ends to allow excitation and detection of the vibrations by means of electromagnetic transducers. To avoid errors in E greater than 4 %, the ratio of th
44、e added mass to the specimen mass shall not exceed 1 %. To avoid the steel plates causing additional stiffness, they shall not extend along more than 2 % of the length of the specimen. The distance between the steel plates shall be large enough to avoid cross-talk between exciter and detector. Multi
45、layer specimens shall be fabricated with the thickness and by the production techniques to be used in the projected end-use. For example, for a plastic material on steel sheet, the plastic may be ap- plied to the metal by spraying, as a mastic or as an adhesively bonded sheet. 7 Number See IS0 6721-
46、1:1994, clause 7. 8 Conditioning See IS0 6721-1:1994, clause 8. 9 Procedure 9.1 Test atmosphere See IS0 6721 -1 : 1994, subclause 9.1. 9.2 Measurement of specimen cross-section and density See IS0 6721 -1 :I 994, subclause 9.2. Determine the density of the specimen (.e. the mass of the free length p
47、er unit volume) to f 0,5 %. 9.3 Mounting the test specimens and adjustment of the tranducers 9.3.1 Method A Clamp the specimen so that the clamping force is high enough to avoid additional damping from friction between the specimen and the clamp (see 5.2). Measure the free length L of the specimen t
48、o Mount the specimen by fine, preferably non-metallic, fibres at the calculated positions of the vibrational nodes. Page 6 EN IS0 6721 -3 : 1996 9.3.3 Adjustment of the transducers After clamping or supporting the specimen, adjust the detector and exciter transducers so that they are just far enough
49、 from the specimen to avoid any noticeable effect on the resonance frequency. With the usual test apparatus, the recommended distance is greater than 3 mm for i = 1. Gaps of 1 mm or less can be used with higher orders. 9.4 Varying the temperature See IS0 6721-1 :I 994, subclause 9.4. 9.5 Varying the frequency See IS0 6721-1:1994, subclause 9.5. 9.6 Recording the resonance curve Excite the specimen using the frequency generator and determine the amplitude (or the effective value) of the deformation or deformation rate. By varying the frequency, record t
