1、c o 0 vi a CI C m al E L 5 2 U E Testing of textiles Determination of the elastic behaviour of textile fabrics by a single application of tensile load between constant extension limits UDC 677.074/.076 : 001.4 : 620.1 72“752“ : 677.017.427 DEUTSCHE NORM DIN 53 835 Part 13 November 19 Prfung von Text
2、ilien; Prfung des zugelastischen Verhaltens; textile Flchengebilde, einmalige Zugbeanspruchung zwischen konstanten Dehngrenzen In keeping with current practice in standards published by the International Organization for Standardization (ISO), a comma has been used throughout as the decimal marker.
3、1 Scope and field of application The test specified in this standard serves to assess the elastic behaviour of stretch fabrics by a single application of uniaxial tensile load between constant extension limits. It enables the non-recoverable stretch to be determined and allows conclusions to be draw
4、n as to the probable deformation behaviour of the textile fabric under test. The method specified was devised to suit testing machines in which the application of the stretching load and the taking of measurements are performed manually. It is, however, also possible to use an electronic tensile tes
5、ting machine. 2 Concepts In addition to the concepts defined in DIN 53815, the concepts given below in subclauses 2.1 to 2.7 are also employed in this standard. 2.1 Total extension Total extension, Alga, as defined in this standard, is the difference between the length ZG given by the upper extensio
6、n limit, and the gauge length kv 1. D = IG - lFv 1) The gauge length is also referred to as the initial length. _c/ Predetermined extension level t Extension - Figure I. Force-extension diagram Note. The subscript D indicates “constant extension limit“. Continued on pages 2 to 6 Beuth Verlag GmbH, B
7、erlin 30, has exclusive sale rights for German Standards (DIN-Normen) DIN 53 835 Part 13 Engl. Price group 6 Sales No. O106 11.85 Page 2 DIN 53835 Part 13 2.2 Residual elongation Residual elongation, Al, as defined in this standard, is the difference between the initial gauge length I, and the lengt
8、h of the specimen, ID, measured under pretension after completion of one load-recovery cycle: Note. A complete load-recovery cycle shall be taken to comprise the following phases: a) extension of a specimen of gauge length lFV to the upper extension limit; b) a prescribed holding time, during which
9、the specimen is held at the specified extension; c) removal of the restraining force, followed by the prescribed recovery period; d) renewed extension of the specimen until the pretension level, F, is reached. Ah, D = ID - lFv 2.3 Total percent elongation Total percent elongation, eges, as defined i
10、n this stand- ard, is the ratio of the total extension AZgm,D to the gauge length IF, of the specimen (see also figure 1 ). IG - Fv Alga, D -_ cges, D - 1Fv 1 F* 2.4 Non-recoverable stretch Non-recoverable stretch, crest, as defined in this stand- ard, is the ratio of the residual elongation Alr-, t
11、o the gauge length of the specimen (see figure 1). ID - IFv Alresi, D - - - it shall be considered completed when the differ- ence in the distance measured between two points marked on the sample is less than 0,2 %. The time elaps- ing between successive measurements during the recovery process shal
12、l not be less than 12 hours. The distance to be measured shall be identified by bench marks drawn approximately 300 mm apart. Throughout the sampling and conditioning procedures, particular care shall be taken that the least possible stress is applied to the knitted fabric so as to avoid overstretch
13、- ing, especially so in the case of knitted fabrics which lack stability owing to their specific structure. 6.2 Selection of laboratory samples The laboratory samples shall be selected from the pieces in a lot so as to be representative of the properties of the textile fabric, If a laboratory sample
14、 can only be and conditioning DIN 53835 Part 13 Page 3 Mass per unit area of specimen over 1 upto g/m2 taken from the start or end of a fabric, the fulfilment of this customary requirement cannot always be ensured. The reliability of the generally used method of sampling from the start or end of a f
15、abric therefore has to be checked by statistical test methods (see also DIN 53803 Part 1 and Part 2). The laboratory samples shall be taken over the entire width of the fabric and have a length of about 1 m. Under no circumstances shall the laboratory samples be taken from the fabric at points where
16、 there are visible flaws, faults or creases. Pretension F, cN 6.3 Preparing specimens from the laboratory sample The specimens, in the form of strips, shall be taken at least 100 mm from the edge, or selvedge of the fabric. The specimens shall be taken in accordance with the rules for sampling (see
17、DIN 53803 Parts 1 and 2) in both longitudinal and transverse directions, and be uniformly distributed across the area of the laboratory sample. Note. For carrying out dry and wet tests, the specimens for the wet test shall contain as far as possible identical fibres from the fibre systems of the spe
18、cimens for the dry test. 175 200 250 6.4 Dimensions of specimens and conditioning Specimens of knitted fabrics shall be marked out along the wale and course directions, preferably by using a 350 mm long, 100 mm wide template (for the gauge length = initial length 1, = 200mm) and cut with a cutting d
19、evice. Specimens of woven fabrics shall be cut to a length of 350 mm and a width of 60 mm along the fibres, and then ravelled to a width of 50 mm by taking yarns from each side of the specimen. After the specimens have been left to recover from strain (see subclause 6.1 1, and to reach equilibrium w
20、ith the test atmosphere (see clause 7) the initial length 1, shall be marked on them. 200 80 250 1 O0 300 120 7 Conditioning the specimens to standard atmosphere The specimens, except those to be used for wet testing, shall be laid out on a smooth backing prior to the test and allowed to reach equil
21、ibrium with the DIN 53802-2Of65 standard atmosphere. 400 8 Number of separate tests At least five separate tests shall be carried out longi- tudinally (.e. long dimension of the specimen parallel to the wale direction of the fabric) and transversely (.e. long dimension of the specimen parallel to th
22、e course direction of the fabric). If a particular confidence interval is speci- fied for the mean, and the mean of the five separate values obtained from the test does not meet this speci- fication, then the result of the test shall be used to calculate how many additional tests are required to rea
23、ch the confidence interval specified. That may involve making allowances for inhomogeneities in the test lot (see DIN 53803 Part 1 and Part 2). 200 9 Test conditions 9.1 Initial gauge length or effective specimen length between clamps The initial gauge length or the effective specimen length between
24、 clamps, IF, shall be 200 mm. 9.2 Pretension 9.2.1 Pretension for knitted fabrics The pretension Fv for knitted fabrics shall be equal to 0,4 times the upper limit of the relevant range of mass per unit area, mA (see table 1). The pretension shall be applied through the lower clamp in conjunction wi
25、th a tensioning weight. Table 1. Pretension for knitted fabrics Mass per unit area of specimen g/m2 over up to 200 200 300 300 400 PrqQension F, CN 200 300 400 I 100 I 40 I 400 500 600 700 800 1000 100 1 125 I 50 I 500 500 600 600 700 700 800 800 900 900 1 o00 150 I 175 1 70 I 300 I 400 I 160 I 9.2.
26、2 Pretension for woven fabrics The pretension F, for woven fabrics shall be equal to the value of the upper limit of the relevant range of mass per unit area, mA (see table 2). For each wet test, a value of half the pretension for the corresponding dry test shall be used. The pretension shall be app
27、lied through the lower clamp in conjunction with a tensioning weight. Table 2. Pretension for woven fabrics Page 4 DIN 53835 Part 13 9.3 Total percent elongation The specimen shall be stretched under load to a pre- determined extension limit. The upper extension limit can be selected as required by
28、the particular purpose of the test. It is recommended that one of the following values of total percent elongation be selected: 2 %, 5 %, 8%, 10%. 15%, 20%, 25%,30%, 40%. 50%. Permissible variations: f 0,5 % of the initial gauge length. 9.4 Holding time of the specimen at full extension The holding
29、time of the specimen at full extension shall preferably be 1 h. The holding time for each test shall be stated in the test report. 9.5 Recovery time The recovery time after removal of the load shall prefer- ably be 15 min. The recovery time for each test shall be stated in the test report. 9.6 Rate
30、of extension The specimen shall be stretched manually without inter- ruption at a rate of extension of about 20 mm/s, until the elongation corresponding to the predetermined total extension is reached. 10 Procedure 10.1 Drytest The test shall be carried out in a DIN 53802-20/65 standard atmosphere.
31、In the case of knitted fabrics, the specimen shall be folded lengthwise to half its width so that the longitudinal edges meet along the centre line of the specimen (specimen tube). Re-opening of the edges of the specimen tube can be avoided by affixing adhesive tape at either end of the specimen to
32、keep the folds in place. First, one end of the specimen (knitted fabric or woven fabric) shall be fixed in the lower clamp in such a manner that the edges of the clamp are in line with one of the bench marks (see subclause 6.4) and at right angles to the longitudinal axis of the specimen. With the s
33、pecimen mounted, the lower clamp shall still be sufficiently free in its movement for its full mass to be effective in the application of pretension. Next, the opposite end of the specimen shall be similarly inserted in the upper clamp, but so that it is just held fast. After the additional mass nec
34、essary to produce the required pretension has been suspended from the lower clamp, the specimen shall be aligned vertically, by adjusting the end placed in the upper clamp, and set to the initial gauge length (distance between edges of clamps) by adjusting to the other bench mark. The specimen shall
35、 then be fixed firmly in the upper clamp, as well. In the case of folded specimens of knitted fabric, a check shall be made that the longitudinal edges are still in contact over their entire length. After the specimen has been fixed in the clamps, it shall be stretched at the rate of extension speci
36、fied in sub- clause 9.6 up to the total percent elongation specified in subclause 9.3, and then held at this extension for the selected time. After expiry of the holding time in the extended position as specified in subclause 9.4, the load shall be removed and the movable clamp fixed in such a way t
37、hat the specimen is able to recover without being subjected to pretension, .e. under zero load, for the recovery time specified in subclause 9.5. Then, after the full pretension has been applied again, the length ID of the specimen shall be measured to the nearest 0,5 mm by measuring the distance be
38、tween the bench marks. 10.2 Wet test Tests on wetted specimens shall be carried out under the same conditions as for the dry test, except for the con- ditioning of the specimen in the standard atmosphere. The specimens shall be tested when completely soaked. Wetting of the specimens shall normally b
39、e carried out by immersing them for one hour in distilled water, to which 1 g/L of a standard commercial wetting agent has been added. For special tests, e.g. on swimwear, it is normal practice to use chlorinated water solutions or saline water, as appropriate to the application, for wetting the spe
40、cimens. 11 Evaluation The residual elongation is obtained from the meas- ured length ID and the gauge length lh. The coefficients defined in subclauses 2.4 to 2.6 shall be calculated and reported in % to one decimal place. The following shall be calculated from the individual values: arithmetic mean
41、; standard deviation; coefficient of variation; confidence interval of the mean. In the case of tests performed using a tensile testing machine, the tensile force required to achieve the upper extension limit shall be determined and reported as the “upper force level“, in cN, to the nearest whole nu
42、mber (see subclause 2.7). 12 Test report The test report shall refer to this standard and state the following particulars: description and technical data of the sample tested; pretension applied; initial gauge length; predetermined upper extension limit; holding time at the predetermined extension l
43、imit; recovery time after removal of load; non-recoverable stretch in the longitudinal and trans- verse direction; coefficients, as specified in subclauses 2.4 to 2.6, separately for the longitudinal and transverse direc- tion; testing machine; deviations from this standard; date of test. In cases w
44、here a tensile testing machine is used: i) rate of extension; m) coefficients as specified in subclause 2.7 (for longi- tudinal and transverse directions). DIN 53835 Part 13 Page 5 Spec i men No. 1 13 Example of application 13.1 Specimen material Knitted fabric (tubular fabric). Polyester/wool - 70
45、%/30 %. Yarn count: 25 tex. Fabric mass per unit area: 210g/rn2. Longitudinal direction Transverse direction mm rnrn % mm mm % 206,o 6.0 3.0 204,5 4.5 2,3 l30 Almst,30 conditioning of samples to standard atmosphere Testing of textiles; sampling; statistical principles of sampling by simple splitting
46、 Testing of textiles; sampling; practical procedure Testing of textiles; terminology relating to the simple tensile test Testing of textiles; simple tensile test on strip specimens of textile fabrics; woven fabric and tape Testing of textiles; simple tensile test on strip specimens of textile fabric
47、s; nonwoven fabrics Literature Wegener, W. Gebrauchswertprfungen an Flachdrahtgarnen und an den daraus gefertigten Kettgarnen und Geweben (Testing of service properties of flat wire yarns and warp yarns and fabrics prepared from them). Zeitschrift fr die gesamte Textilindustrie 64 (1 964). Latzke, P
48、. M., Schubert, O. Ein Beitrag zur lastizittsprUfung von Maschenwaren (On elasticity tests for knitted fabrics) Wirkerei- und Strickerei- Technik 25 ( 1975). Explanatory notes This standard has been prepared by NMP 521 Technical Committee Physikalisch-technologische Prfung von Textilien. To ensure t
49、hat the requirement regarding tensile testing apparatus serving to determine the elastic behaviour of textile fabrics is kept simple, the specifications in this standard have been designed for use with a manual testing machine. Tests for determining the elastic behaviour of textile fabrics can, in principle, also be carried out with an electronic tensile testing machine. In such cases, any tensile testing machine may be used, provided that it conforms to the general code of practice for material testing machines as specified in DIN 51 220, is equipped w
