Standard 25 mm
Pneumatic Vice Action Grip
Pneumatic vice action grips clamp the full specimen width at a constant, even pressure — which is what stops one side slipping or tearing before the other.
SpecificationsTesting standard
ASTM D5587
Standard Test Method for Tearing Strength of Fabrics by Trapezoid Procedure
Written and technically reviewed by Dak System Inc. engineeringLast reviewed
ASTM D5587 measures the force required to propagate a tear across a fabric by the trapezoid procedure. It provides two calculations from the same trace — the single-peak force and the average of the five highest peaks — and they are different numbers, so the one used has to be stated.
At a glance
- Test type
- Tear — a cut or nick is forced to grow
- Published by
- ASTM
- Edition
- D5587-15(2024)
- Runs on
- Series 7200 and Series 9000
What the test does
An isosceles trapezoid is marked on a rectangular specimen of conditioned fabric and a slit cut at the centre of its smallest base to start the tear. The non-parallel sides of the marked trapezoid are clamped in parallel jaws, and the jaws are separated at a constant rate on a recording constant-rate-of-extension machine. The tear propagates across the specimen and the force is captured throughout. Two calculations are then available from the same trace: the single-peak force, and the average of the five highest peak forces.
What it measures, and why it matters
The force needed to keep a tear running once it has started — the question that decides whether a small snag becomes a failure. Fabrics rarely tear from an unblemished surface; something catches, and what matters is whether the damage propagates. The reason the method offers two calculations is that the trace is a saw-tooth rather than a curve: the tear advances yarn by yarn, each resisting and then giving way, so there is no single obvious point to read. Both readings are defensible, they are not variants of the same figure, and on a coarse fabric they can differ by a wide margin.
One trace, two answers
The trace is a saw-tooth because the tear advances yarn by yarn. Which peaks you take from it is a decision the method leaves open, so it must be reported.
- Single-peak force
- The highest point on the traceThe more severe reading, and the more sensitive to a single strong yarn.
- Average of five highest peaks
- The mean of the five largestMore stable, and usually the one a specification means when it does not say.
- Applies to
- Woven, air bag, blanket, napped, knitted, layered and pile fabrics
- Geometry
- Isosceles trapezoid marked on a rectangular specimen
- Starting slit
- At the centre of the smallest base
- State which calculation was used
- Every timeDakThe two can differ by a wide margin on a coarse fabric, and a report that omits it cannot be compared with another.
The two calculations are not variants of the same figure. On a coarse or unevenly constructed fabric they can differ substantially, and mixing them within a data set produces scatter that looks like material variability.
Test speed
- Machine
- Recording constant-rate-of-extensionRecording is not optional — the calculation is made from the trace, not from a peak-hold reading.
- Reported
- Trapezoid tearing strength, by the stated calculation
- Directions
- Warp and weft, separately
- Discard specimens where the tear left the marked path
- Dak
Calculations
Single-peak force—
The maximum force on the trace
One reading from one event. It is sensitive to whichever yarn happened to be strongest.
Average of five highest peaks—
Mean of the five largest peak forces on the trace
A more stable statistic from the same trace, and the one most specifications intend. It cannot be derived from the single-peak value.
How the test runs
- 01Cut rectangular specimens in the warp and weft directions.
- 02Condition them in the standard textile atmosphere.
- 03Mark the isosceles trapezoid on each specimen.
- 04Cut the starting slit at the centre of the smallest base, in one clean pass.
- 05Clamp the non-parallel sides in parallel jaws.
- 06Set the clamping pressure to hold without cutting.
- 07Extend at the specified constant rate on a recording machine.
- 08Capture the full force trace as the tear propagates.
- 09Take either the single peak or the mean of the five highest peaks, as specified.
- 10Discard specimens where the tear deviated off the marked path.
- 11Report the calculation used with every value, and the directions separately.
The fixture this method needs
What the report has to contain
- Reference to ASTM D5587 and the edition
- Fabric identification, construction and mass per unit area
- Direction tested
- Conditioning atmosphere
- Rate of extension
- Which calculation was used — single peak or five-peak average
- Tearing strength for each specimen
- Mean and variability by direction
- Number of specimens discarded and why
- Which unit system was used
What the machine must be capable of
A constant rate of extension and, critically, a recording data system. This is not a machine on which a peak-hold reading will do: the five-peak average cannot be extracted from a stored maximum, so half the method becomes unavailable and the qualitative information in the trace — whether the tear ran steadily or jumped — is lost with it. Forces are modest, from a few newtons to a few hundred, so the load cell is chosen for the fabric rather than for the frame, and the jaws must clamp along the marked sloping sides.
What goes wrong in practice
Reporting a tearing strength without saying which calculation produced it, which makes it uncomparable and, worse, mixes silently into data sets that used the other one. Clamping square to the specimen rather than along the marked sides, which stops the tear propagating as the geometry intends. A ragged starting slit. Discarding deviated tears without recording how many. And substituting this method where a geosynthetic specification named D4533, where the reviewer is right to query it. A last one is testing a napped or pile fabric without recording which face was uppermost — the pile lies in a direction, and a tear travelling with it behaves differently from one travelling against it.
ASTM D5587 or ASTM D4533
| ASTM D5587 | ASTM D4533 | |
|---|---|---|
| Written for | Textile fabrics generally | Geotextiles |
| Geometry | Trapezoid | Trapezoid |
| Calculations | Single peak or five-peak average | Per the method's own rule |
| Cite | Where the specification names it | Where the specification names it |
The same geometry serving two industries. Geosynthetic acceptance documents name D4533 specifically, and substituting D5587 will be queried even though the principle is identical.
Questions we are asked about this test
What is ASTM D5587?
It is the ASTM trapezoid tear method for fabrics. An isosceles trapezoid is marked on a rectangular specimen, a slit is cut at the centre of its smallest base, and the non-parallel sides are clamped in parallel jaws so that separating them propagates the tear across the specimen. It applies to woven, air bag, blanket, napped, knitted, layered and pile fabrics.
Why does the method give two calculations?
Because the trace is a saw-tooth and there is no single obvious point on it. The tear advances yarn by yarn — each resists, gives way, and the load falls before building against the next — so the record is a series of peaks rather than one rise and fall. Taking the single highest peak and taking the mean of the five highest are both defensible readings of the same event, and the method offers both.
Which calculation should I use?
Whichever the specification names, and if it does not say, the five-peak average is usually what is meant because it is the more stable statistic. What matters more than the choice is stating it: on a coarse or unevenly constructed fabric the two can differ by a wide margin, and mixing them within one data set produces scatter that reads as material variability when it is really an inconsistent calculation.
Why does the machine have to be recording?
Because the calculation is made from the trace. A peak-hold reading gives only the single highest force and cannot supply the five highest peaks, so half the method becomes unavailable. It also hides whether the tear ran cleanly or jumped, which is the qualitative information a trapezoid trace carries and a single number does not.
Why are the sloping sides clamped rather than the ends?
Because that geometry is what makes the tear travel. Clamping the non-parallel sides puts the short base closest to the jaws and loads it first, so stress concentrates at the slit and the tear propagates progressively towards the wide end. Clamping the specimen squarely would simply stretch it, and the tear would either not start or would jump unpredictably across the width.
What if the tear wanders off the marked path?
The specimen is discarded and the number of discards recorded. A tear that turns into a grip or leaves the edge has not propagated across the width in the way the geometry intends, so its force is not comparable with specimens that tore correctly. A high discard rate is itself information — usually about clamping, or about a fabric with a strong directional bias.
Can a D5587 result be used where D4533 is specified?
Not safely. The two use the same trapezoid geometry, but D4533 is written for geotextiles and geosynthetic acceptance documents name it specifically, with their own specimen and calculation details. A substituted result will be queried, and the reviewer is right to query it — the principle being identical does not make the designations interchangeable.
Running ASTM D5587 on the Series 7200 and Series 9000
Dak verifies against whichever standard the method names, and where a class applies our frames sit a class tighter than it asks.
| The method asks for | Dak supplies | |
|---|---|---|
| Capacity | Low — fabric trapezoid tear forces commonly run from a few newtons to a few hundred | Load cells from 1 kg to 60 ton on the Series 7200, and 0.5 to 100 kN on the Series 9000 |
| Force accuracy | ASTM D76 requirements for textile testing machines | ISO 7500-1 Class 0.5, verified to ASTM E4, DIN 51221 and BS 1610 |
| Gripping | Parallel jaws clamping the non-parallel sides of a trapezoid marked on the specimen | Wedge, vice-action, pneumatic and hydraulic grips, built to the specimen |
| Environment | 23 ± 2 °C standard laboratory atmosphere | 3009 series chambers, −150 °C to +400 °C — temperature only |
This page describes the method as practised. The governing text is the current edition from the issuing body. Tell us what you are testing and we will answer with the machine, the fixture and a quotation.