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
IS 1969 (Part 1)
Textiles — Tensile Properties of Fabrics — Determination of Maximum Force and Elongation at Maximum Force — Part 1: Strip Method
Written and technically reviewed by Dak System Inc. engineeringLast reviewed
IS 1969 (Part 1) is the Indian Standard strip method for the tensile properties of fabrics, giving maximum force and elongation at maximum force. It is identical with ISO 13934-1:1999, which the ISO parent has since replaced with its 2013 second edition.
At a glance
- Test type
- Tensile — the specimen is pulled apart
- Published by
- BIS
- Edition
- 1969
- Runs on
- Series 7200 and Series 9000
What the test does
A strip of conditioned fabric is cut oversize and ravelled down to the specified width so that its edges are whole yarns, then clamped across its full width in wide grips. It is extended at a rate set from the fabric's own extensibility — so that the time to peak load falls in a specified window whatever the material — until the force passes its maximum. Two values are recorded: the maximum force, and the elongation at the point that maximum was reached. Warp and weft are tested and reported separately.
What it measures, and why it matters
The load a fabric carries before it stops carrying more, and how far it has stretched by then. The distinction from elongation at break is real and often missed: a woven fabric commonly reaches its peak load with a proportion of yarns still intact, then holds together as those fail one after another, so rupture occurs some distance later. Elongation at maximum force describes the point at which the fabric ceased to gain load, which is the useful quantity. The result is a force for a stated strip width rather than a stress, because fabric thickness is not a usable area.
Strip, not grab
The full width of the strip is clamped, so every yarn in the section carries load. That is what separates it from Part 2.
- Method
- Strip — the full specimen width is clamped
- Reported
- Maximum force and elongation at maximum forceAt maximum force, not at break. On many fabrics the two differ, because the fabric holds together after the peak.
- Part 2
- Covers the grab method separatelyPublished 2010 and identical with ISO 13934-2. The two parts are not interchangeable.
- Directions
- Warp and weft, separately
- Conditioning
- Standard textile atmosphere
- Ravel the strip to the specified width rather than cutting to it
- DakFraying the edges down to whole yarns gives a section made of complete yarns, which a cut edge does not.
Identical with ISO 13934-1:1999. The ISO method is now in its second edition, ISO 13934-1:2013, so the two designations no longer point at the same text.
Test speed
- Rate
- Set from the fabric's extensibilityMore extensible fabrics are pulled faster so that the time to break stays within the specified window.
- Reported
- Maximum force and the elongation at it
- Elongation
- Normally from grip separation
- Reject jaw breaks and specimens that slipped
- Dak
Calculations
Maximum forceFmax
The highest force recorded during the test
A force for the stated strip width, not a stress. Fabric thickness is not a usable area.
Elongation at maximum force—
(ΔL / L₀) × 100 at the point of maximum force
- ΔL
- extension when maximum force is reached
- L₀
- gauge length
At maximum force, not at rupture. Reporting elongation at break instead is a different quantity and a common substitution.
How the test runs
- 01Condition the fabric in the standard textile atmosphere.
- 02Cut strips oversize in the warp and weft directions.
- 03Ravel each strip down to the specified width so the edges are whole yarns.
- 04Fit wide pneumatic grips and set an even clamping pressure.
- 05Mount the strip square, free of pre-tension and without slack.
- 06Set the gauge length and the rate of extension from the fabric's extensibility.
- 07Load until the force passes its maximum.
- 08Record the maximum force and the elongation at that point.
- 09Reject specimens that broke at the jaws or slipped.
- 10Repeat for the required number of specimens in each direction.
- 11Report warp and weft separately, and state the edition applied.
The fixture this method needs
What the report has to contain
- Reference to IS 1969 (Part 1) and the edition
- Fabric identification, construction and mass per unit area
- Direction tested and specimen width
- Conditioning atmosphere
- Gauge length and rate of extension
- Maximum force for each specimen
- Elongation at maximum force, and how it was measured
- Mean and variability for each direction
- Number of specimens rejected and why
- Whether wet or conditioned specimens were used
What the machine must be capable of
Modest capacity — most apparel and furnishing fabrics break between a hundred newtons and two kilonewtons — with grips wide enough for the full strip and an even clamping pressure across the face. Even pressure is what stops one edge of the strip taking load before the other, which on a strip specimen shows up directly in both the force and the failure position. Elongation is normally taken from grip separation, which the method accommodates, and the rate must be settable from the fabric's extensibility rather than fixed.
What goes wrong in practice
Treating this as interchangeable with ISO 13934-1 without checking editions — the Indian Standard is identical with the 1999 ISO text, and ISO has since issued a 2013 second edition, so the two designations no longer refer to the same method. Reporting elongation at break where elongation at maximum force was asked for. Cutting strips to width instead of ravelling them. Averaging warp and weft. And accepting jaw breaks, which on fabric usually mean the clamping pressure was cutting the yarns at the jaw line.
IS 1969 (Part 1) or ISO 13934-1
| IS 1969 (Part 1) | ISO 13934-1 | |
|---|---|---|
| Published by | BIS | ISO |
| Relationship | Identical with ISO 13934-1:1999 | The parent method |
| Current text | IS 1969 (Part 1) : 2009 | ISO 13934-1:2013, second edition |
| Same text today | No | — |
This is the clearest example on the site of an adopted standard drifting from its parent. Both designations are current, and they no longer refer to the same text.
Questions we are asked about this test
What is IS 1969 (Part 1)?
It is the Indian Standard strip method for the tensile properties of fabrics — the determination of maximum force and elongation at maximum force, with the full width of the strip clamped in the jaws. Part 2, published in 2010, covers the grab method. The current Part 1 is IS 1969 (Part 1) : 2009.
Is it the same as ISO 13934-1?
It was. IS 1969 (Part 1) : 2009 is identical with ISO 13934-1:1999. ISO has since published a second edition, ISO 13934-1:2013, so the two designations no longer point at the same text. Both remain current in their own systems, which means a report should name the designation and the edition rather than treating the two as one method under two numbers.
Why is it elongation at maximum force rather than at break?
Because they are different points on many fabrics. A woven fabric often reaches its peak load while a proportion of yarns are still intact, then holds together as those yarns fail one after another, so rupture happens some distance further on. Elongation at maximum force describes the point at which the fabric stopped carrying more load, which is what a designer needs. Substituting elongation at break reports a larger number for a different event.
Why ravel the strip instead of cutting it to width?
Because a cut edge leaves partial yarns that carry load until they slip out, contributing an amount that depends on how the cut fell. Ravelling an oversize strip down to the specified width leaves a section made of whole yarns, so the width genuinely corresponds to a countable number of load-bearing elements. It is the step that makes strip results repeatable between operators.
How is the strip method different from the grab method?
In what is clamped. The strip method holds the full width, so every yarn in the section is loaded directly. The grab method clamps only a central portion, and the fabric on either side shares some of the load through the weave, so the effective loaded width is larger than the clamped one. The grab test is quicker and more tolerant of specimen preparation; the strip test is the more analytically clean of the two. Neither converts into the other.
Why is the rate set from the fabric's extensibility?
So that the time to reach maximum force falls within a specified window regardless of how stretchy the fabric is. A highly extensible knit pulled at the rate suited to a rigid canvas would take far too long, and textiles are rate-sensitive enough that the difference shows in the result. Setting the rate from extensibility keeps every fabric on comparable terms.
Why are warp and weft never averaged?
Because they are built differently. Warp yarns are held under tension throughout weaving and are usually stronger and less extensible than weft, and the two can differ by a wide margin in the same cloth. An average describes neither, and a specification written against one would be met by fabric that is weak in the other direction.
Running IS 1969 (Part 1) 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 to moderate — most apparel and furnishing fabrics break between 100 N and 2 kN | Load cells from 1 kg to 60 ton on the Series 7200, and 0.5 to 100 kN on the Series 9000 |
| Force accuracy | Class 1 over the working range | ISO 7500-1 Class 0.5, verified to ASTM E4, DIN 51221 and BS 1610 |
| Gripping | Wide flat grips clamping the full strip width, with jaw faces suited to the fabric | 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.