ISO 3376:2011 download.Leather — Physical and mechanical tests — Determination of tensile strength and percentage extension.
ISO 3376 specifies a method for determining the tcnste strength, elongation at a specried load and elongation at break of leather. It is apçicab4e to all types of leather.
2 Normative references
The followrng referenced documents are indispensable for (tie application of ISO 3376. For dated references, only the edition oted applies. For undated references, the latest edition of the referenced document (lnckdng any amendmentsf apØles.
ISO 2418, Leather — ChemEcat. physical and mechanical and fastness tests — Samp&ng location
ISO 2419, Leather— Physical and mechanical tests — Sample preparation and ccrdtiooing
ISO 2589. Leather — Physical and mechanical tests — Determination of Thickness
ISO 75001 2004, Metathc rnatenats — Verification of static uniiaxiat testing machines — Part 1:
Ter,sjorivonmpreesron testing machines — Verification and calibration of the forve-measunng system
3 PrInciple
A test piece Is extended at a specified rate until the forces reach a predetermined value or until the test piece
breaks.
4 Apparatus
4.1 TensIle testing machIne with:
— a forte range appropriate to the specimen under lest:
— ameansofrecordlngthetorcetoanaocuracyofatleast2%asspecitiedbyClass2otlSO7500-1
— a uniform speed of separation of the jaws of 100 mmiThin ±20 mm/mm; a means of recording the force, ag. as an extension curve;
— jaws. min.mum length 45mm in the direction of the applied lead, designed to apply corlant clamping by mechancal or pneumatic means. The texture and design of the inside faces of the Jaws shall be such that. at the maximum load attained in the test, the specimen does not sup In either mv by an amount exceeding I of the original uaw separation.
6 Procedure
6.1 DeterminatIon of dimensIons
6.1.1 UsIng vernier calipers (4.5), measure the width of cecil test piece to the neatest 0,1 mm at three positions on the grain side and three on the flesh side. In each group of three measurements, make one at the mid•polnt E (as shown In Figure 1) and the other two at positions approxImately midway between the mld point E and the bnes AS and CD. Take the arithmetic mean of the six measurements as th width of the lest piece, w. For soft (llexibW) leather, the width shal be taken as the width of the press knife.
6.1.2 Measure the thickness of each lest piece ii accordance with ISO 2589. Make the measuremenls at three positions. namely the mid-poit F and at positions approximately midway between the mpoint F and the lines AS and CD. Take the arithmetic mean of the three measurements as the thickness of the lest piece.,.
6.2 DetermInation of tensile strength
62.1 Set the jaws of the tensile testing apparatus (4.1)50mm ± i mm aparl If using the standard test piece or 100 mm apart it using the large test piece. Clamp the test piece In the jaws so that the edges of the jaws he along the lines AS and CD. When the test piece is clamped, ensure its grar surface lies in one piano. The length axis shall be parallel to the traction direction.
6.2.2 Run the machine until the lest piece breaks and record the highest force exerted as the breaking force. F.
6.3 DeterminatIon of the percentage elongation caused by a specified load
6.3.1 Clamp the test piece between the faws of the apparatus, as described In 6.2.1. Measure the distance between the ‘aws at least to the nearest 0,5 nvn and record this distance, zc as the Initial length of the test piece lot the purpose of the test.
6.3.2 Start the test. Unless the apparatus automaticaly c’aws a forceextenslon csve with the necessary accuracy (see 4.2). lotlow the distance between the pair of jaws or the sensors as the force increases.
6.3.3 Note the distance. in millimetres, between the pair of jaws or sensors at the instant when the force first reaches the specified value. This distance represents the length of the test piece at this force, L1. Do not slop the apparatus if results from the procedures described in 6.2 or 6.4 are also required.
6.4 Determination of the percentage elongation at break
6.4.1 Carry out the steps gwen in 63.1.
6.4.2 Run the tensile test machine until the lest piece breaks.
6.4.3 Record the distance between the jaws or sensors at the instant when rupture of the test piece occurs.
This distance represents the length of the test piece at break, 1.2.
6.5 SlIppage
If there i slippage of the lest piece in either jaw when tested according to 6.2. 6.3 or 6.4, and the slippage is greater than I % of the initial jaw separation, reject the result and repeat the determination with a new lest piece cul using the large press knIfe (4.4).
8 Test report
The test report shall include the tollowing;
a) a reference to this International Standard, I.e. ISO 33762011;
b) the mean tensile strength, lo MPa (or newtons pet square mdllmelre). to the nearest 0.1 MPa, tot the test pieces with the longer edge cut parallel to the backbone;
c) the mean tensile strength. m MPa (or newtons per square mdllmetre). to the nearest 0.1 MPa. tot the test pieces With the longer edge cut perpendicular to the backbone;
d) the mean percentage elongation at break to the nearest 1 %. for the lest pieces with the longer edge cut parallel to the backbone:
e) the mean percentage elongation at break to the nearest 1 %. for the test pieces with the longer edge cut perpendicular to the backbone;
f) the mean percentage elongation at a specified bad to the nearest 1 %. for the test pieces with the longer edge cut parallel to the backbone: If required;
g) the mean percentage elongation at a specified load to the nearest 1 %. for the lest pieces with the longer edge cut perpendicular to the backbone. ii required:
h) the thickness of the sample, in milhmetres. in accordance with ISO 2589:
i) any deviations trom the method specified in ISO 3376:
j)ull details tot identification of the sample and any deviation from ISO 2418 wIth respect to sampling:
k) if requwecl by the customer or in specifications, it is permitted to report the results descr*ed in 81). 8 m arid 8 n) instead of 8 b) toS gf;
l) the average tense strength, in MPa (or newtons per square millenetre), to the nearest 0.1 MPa [I.e. the arithmetic mean of b) and c)J:
m) the average percentage elongation at break to the nearest I % [i.e. the arithmetic mean of d) and e)j;
n) the average percentage elongation at a specified load to the nearest 1 % [i.e. the arithmetic mean at f) and Q)I. if required;
o) the standard atmosphere used for conditioning arid testing. as given in ISO 2419.