Tear strength testing quantifies a material's resistance to the growth of an initiated cut or slit, and it is a critical quality-control parameter for textiles, rubber, plastic films, paper, and nonwoven products. This guide summarizes the principal international standards, including ISO 13937, ISO 34, ASTM D1424, ASTM D624, and their GB/T and JIS equivalents, together with specimen requirements, test methods, and typical applications. Use this reference to select the correct test protocol and to interpret results reported by accredited third-party laboratories.
Technical Overview
Tear strength (also called tearing strength or tear resistance) is defined as the force required to propagate an existing cut, slit, or nick through a material under controlled tensile loading. It is fundamentally different from tensile strength, which measures the force needed to break an intact specimen. Tear testing answers a specific engineering question: if a product is damaged or punctured during service, how easily will that damage grow into a catastrophic failure?
Two types of tear behavior are distinguished in most standards. Tear initiation refers to the force needed to start a tear from a deliberately introduced cut or notch, while tear propagation refers to the continuing force needed to extend an existing tear. Methods such as the Elmendorf pendulum test measure propagation, whereas notched methods such as ASTM D1004 combine initiation and propagation in a single value.
The most widely applied standard families for tear strength testing include:
- ISO 13937 Parts 1 to 3 and EN ISO 13937 for textile tear testing (pendulum, trouser, and wing methods)
- ASTM D1424 and ASTM D2261 for fabric tearing strength by the Elmendorf and single-rip (tongue) procedures
- ISO 34-1, ISO 34-2, ASTM D624, GB/T 529, and JIS K 6252 for tear strength of vulcanized and thermoplastic rubber
- ISO 6383-1 and 6383-2, ASTM D1004, ASTM D1922, ASTM D1938, ASTM D2582, and GB/T 16578 for plastic films and thin sheeting
- ISO 1974 and ASTM D689 for internal tearing resistance of paper
- ASTM D5587, ASTM D5733, ASTM D5734, and ASTM D4533 for nonwovens and geotextiles
Depending on the method, results are reported in millinewtons (mN), newtons (N), pounds-force (lbf), or as tear strength normalized by thickness (N/mm or kN/m). Because tear behavior is highly directional, virtually all specifications require testing in both principal directions of the material, such as warp and weft for fabrics or machine direction (MD) and transverse direction (TD) for films and papers.
Testing Samples
Woven and Knitted Fabrics
Textile samples are tested according to ISO 13937-1, ISO 13937-2, ISO 13937-3, ASTM D1424, ASTM D2261, ASTM D5587, GB/T 3917, and JIS L 1096. Specimens are cut with edges parallel to the yarn directions, and separate sets are prepared in warp and weft. Careful sampling away from fabric edges, creases, and selvedges is essential, and the fabric must be conditioned to equilibrium in a standard atmosphere before testing.
Rubber and Elastomeric Materials
Vulcanized rubbers, thermoplastic elastomers, seals, gaskets, conveyor belting, and hose covers are tested using ISO 34-1, ISO 34-2, ASTM D624, GB/T 529, and JIS K 6252. Specimens are die-cut to trouser, angled, or crescent geometries, with a precise nick or slit introduced immediately before testing to control the tear path. Thickness is measured at the test location because tear strength is normalized by thickness.
Plastic Films and Thin Sheeting
Packaging films, liners, membranes, and laminates are tested using ISO 6383-1, ISO 6383-2, ASTM D1004, ASTM D1922, ASTM D1938, ASTM D2582, and GB/T 16578. Film specimens are die-cut cleanly without nicks or burrs at the edges, since flaws outside the intended cut location invalidate results. Machine-direction and transverse-direction specimens are always tested separately.
Paper and Paperboard
Printing papers, sack kraft, tissue, and board are tested under ISO 1974 and ASTM D689. Because paper tearing strength depends strongly on moisture content, specimens must be conditioned in the paper standard atmosphere before measurement.
Nonwovens, Geotextiles, and Coated Fabrics
Spunbond and meltblown nonwovens, filtration media, hygiene substrates, geotextiles, and coated industrial fabrics are tested under ASTM D5733, ASTM D5734, ASTM D4533, ISO 4674, and ASTM D751. These anisotropic materials frequently show large differences between MD and CD tear values, so directional testing is mandatory.
Leather
Leather and synthetic leather for footwear, upholstery, and garments are tested using ISO 3377-1 and ISO 3377-2, which specify single-edge and double-edge tear procedures performed on a constant-rate-of-extension tensile machine.
Testing Items
Accredited third-party laboratories typically offer the following tear-related test items, each mapped to a specific standard and reporting unit:
- Elmendorf (ballistic pendulum) tearing force, reported in mN, per ISO 13937-1, ASTM D1424, ASTM D1922, ISO 6383-2, ISO 1974, and GB/T 3917.1
- Trouser tear force, reported in N, per ISO 13937-2, ISO 6383-1, ASTM D1938, and GB/T 3917.2
- Wing tear force, reported in N, per ISO 13937-3 and GB/T 3917.3
- Tongue (single-rip) tearing strength on a CRE machine, reported in N or lbf, per ASTM D2261
- Trapezoid tearing strength, reported in N, per ASTM D5587, ASTM D5733, and ASTM D4533
- Graves tear resistance of plastic film, reported in N or lbf, per ASTM D1004
- Puncture-propagation tear resistance of film, per ASTM D2582
- Rubber tear strength, reported as force divided by thickness (N/mm or kN/m), per ASTM D624, ISO 34-1, GB/T 529, and JIS K 6252
- Directional tear comparison (warp versus weft, or MD versus TD) and tear anisotropy ratio
- Statistical reporting including mean value, median, maximum and minimum peaks, standard deviation, and coefficient of variation
Testing Methods
Falling Pendulum (Elmendorf) Method
The Elmendorf method is the most widely used propagation tear test. A rectangular specimen, typically 75 to 100 mm long by 63 to 75 mm wide depending on the standard, is clamped in two opposing jaws of a pendulum tear tester. A precise 20 mm slit is cut into the specimen between the clamps. When the pendulum is released, it tears the specimen along the slit, and the energy absorbed is converted into an average tearing force read from calibrated scales or digital load measurement. Augmenting weights extend the instrument capacity for stronger materials. A minimum of five valid specimens is tested in each principal direction, and results are reported in millinewtons. Applicable standards include ISO 13937-1, ASTM D1424, ASTM D1922, ISO 6383-2, ISO 1974, ASTM D689, ASTM D5734, GB/T 3917.1, and JIS P 8116.
Trouser (Single Rip) Method
In the trouser method, a specimen of 200 mm length and 50 mm width (ISO 13937-2) is slit for 100 mm along its centerline, forming two legs. Each leg is gripped in a jaw of a constant-rate-of-extension tensile tester, and the jaws separate at a specified speed, typically 100 to 250 mm/min depending on the standard. The force-extension curve exhibits a series of peaks as yarns or molecular alignments successively rupture, and the tear force is calculated from the peak values within the tearing region. This method is suitable for most fabrics and films and provides detailed information about tear propagation behavior. Applicable standards include ISO 13937-2, ISO 6383-1, ASTM D1938, ISO 34-1 Method A, and GB/T 3917.2.
Tongue (Single Rip) CRE Method
ASTM D2261 determines the tearing strength of fabrics by ripping a tongue-shaped specimen on a constant-rate-of-extension machine. A central cut divides one end of the specimen into two tongues, which are gripped separately and pulled apart at the rate specified in the method. The maximum or median tearing force is recorded for each specimen. This method is particularly useful for coated or layered fabrics where pendulum instruments may not provide sufficient capacity.
Wing Test Method
ISO 13937-3 specifies the wing test, a modification of the trouser procedure in which the cut ends of the specimen form a wing shape. This geometry reduces the influence of jaw pressure and yarn pull-out, improving reproducibility for fabrics in which individual yarns tend to withdraw rather than break during tearing.
Trapezoid Method
In the trapezoid method, a trapezoid outline is marked on a rectangular specimen and a small initial slit is cut at the short side. The nonparallel edges are clamped so that the stress concentrates at the slit, and the specimen is pulled on a tensile machine until complete rupture. The maximum force is reported as the trapezoid tearing strength. This method is the reference procedure for nonwovens and geotextiles under ASTM D5587, ASTM D5733, and ASTM D4533, because it produces a well-defined tear path even in materials with random fiber orientation.
Angle and Crescent Tear Methods for Rubber
ISO 34-1 defines trouser (Method A), angled (Method B), and crescent (Method C) test pieces, while ASTM D624 specifies equivalent die-cut trouser, angle, and crescent geometries. Specimens are pulled on a tensile machine at 500 mm/min until the tear propagates fully. Tear strength is calculated by dividing the maximum force by the specimen thickness and is reported in N/mm or kN/m. The nick depth and die sharpness are critical control points, because a dull die or incorrect nick dramatically changes the measured value.
Graves and Puncture-Propagation Methods for Films
ASTM D1004 measures the tear resistance of plastic film using a die-cut notched specimen pulled in tension until the notch propagates across the specimen. ASTM D2582 evaluates puncture-propagation tear resistance by driving a pendulum-mounted probe through a clamped film specimen, simulating damage caused by impact or abrasion during handling and transport.
Specimen Preparation and Conditioning
Conditioning requirements before tear testing follow the material-specific atmospheres:
- Textiles: 20 ± 2 °C and 65 ± 4 % relative humidity per ISO 139 and ASTM D1776, until moisture equilibrium is reached
- Plastics: 23 ± 2 °C and 50 ± 5 % relative humidity per ISO 291 and ASTM D618, with a minimum conditioning period of 40 hours for hygroscopic materials
- Rubber: 23 ± 2 °C per ISO 23529 and ASTM D1349, normally without humidity control
- Paper: 23 ± 1 °C and 50 ± 2 % relative humidity per ISO 187
Slits and nicks must be cut immediately before testing using a sharp blade or die without a template, and specimens with visible flaws outside the intended tear path must be discarded and replaced.
Applications
Tear strength data are used across industries for material qualification, incoming inspection, product design, and failure analysis. Typical applications include:
- Automotive interior trim, airbag fabrics, seat covers, and safety belt webbing, where tear integrity is safety-critical
- Protective clothing and personal protective equipment, including chemical protective suits and coveralls
- Medical device packaging and sterile barrier systems, where tear resistance must balance clean peeling with damage resistance
- Flexible packaging films for food, pharmaceuticals, and consumer goods, including easy-tear laminate design
- Geotextiles, roofing membranes, and construction fabrics subject to installation damage and point loads
- Tarps, tents, sails, banners, and awnings exposed to wind-driven tear growth from small punctures
- Footwear uppers, leather goods, and upholstery evaluated under ISO 3377 procedures
- Hygiene nonwovens, wipes, and filtration media where MD/CD tear balance controls converting performance
- Rubber seals, gaskets, hoses, and conveyor belts where cut growth resistance determines service life
- Paper sacks, wrapping papers, and board packaging where internal tearing resistance governs runnability and strength
FAQ
What is the difference between tear strength and tensile strength?
Tensile strength measures the force required to break an intact, unnotched specimen, while tear strength measures the force required to propagate a pre-existing cut. A material can have high tensile strength but low tear strength, which means a small cut can spread rapidly even though the undamaged material is strong.
Which tear testing standard should be selected?
Selection depends on the material type and the failure mode of interest. Fabrics are most commonly tested by the Elmendorf method (ISO 13937-1 or ASTM D1424) or the trouser method (ISO 13937-2), rubber by ISO 34-1 or ASTM D624, films by ASTM D1004 or ASTM D1922, paper by ISO 1974, and nonwovens and geotextiles by the trapezoid method. Always verify which standard your customer specification, regulatory requirement, or end-use application mandates.
Why are machine direction and cross direction tear results different?
Most materials are anisotropic: fibers, yarns, or polymer chains are preferentially aligned during manufacturing. In films, tear resistance is usually lower in the machine direction, while in woven fabrics it depends on yarn crimp and interlacing geometry. Reporting both directions is therefore a universal requirement in tear standards.
How many specimens are required for a valid test?
Most standards require a minimum of five valid specimens in each principal direction, with additional specimens if results show excessive scatter. Outliers caused by cutting defects or yarn pull-out are rejected according to the criteria defined in each method.
Are Elmendorf and trouser method results comparable?
No. The pendulum method measures an average propagation force in mN under dynamic impact loading, while the trouser method measures peak forces under quasi-static extension in N. The values differ both numerically and conceptually, so results must only be compared within the same standard and method.
What atmosphere is required before tear testing?
Specimens must be conditioned to equilibrium in the standard atmosphere specified for the material, such as 20 °C and 65 % relative humidity for textiles, 23 °C and 50 % relative humidity for plastics, and 23 °C for rubber. Testing must then be performed in the same atmosphere, since temperature and moisture content significantly influence tear behavior.
