ASTM D4533 Test Fixture

Description

ASTM D4533 – Standard Test Method for Trapezoid Tearing Strength of Geotextiles

 

ASTM D4533 is an index test used to measure the force required to continue or propagate a tear in woven or nonwoven geotextiles by the trapezoid method.

While useful for quality control and acceptance testing, the trapezoid tear test does not provide all the information needed for all design applications and other test

methods should be used.

This test method is applicable to most geotextiles that include woven fabrics, nonwoven fabrics, layered fabrics, knit fabrics, and felts that are used for geotextile

applications.

---

ASTM D4533  / Significance and Use

The trapezoid tear method is a test that produces tension along a reasonably defined course such that the tear propagates across the width of the specimen.

The trapezoid tearing strength for woven fabrics is determined primarily by the properties of the yarns that are gripped in the clamps.

In nonwoven fabrics, because the individual fibers are more or less randomly oriented and capable of some reorientation in the direction of the applied load,

the maximum trapezoid tearing strength is reached when the resistance to further reorientation is greater than the force required to rupture one or more fibers

simultaneously.

The trapezoid tearing strength method is useful for estimating the relative tear resistance of different fabrics or different directions in the same fabric.

Some modification of clamping techniques may be necessary for a given fabric, depending upon its structure.

Special adaptation may be necessary with strong fabrics, or fabrics made from glass fibers, to prevent them from slipping in the clamps or being damaged as a

result of being gripped in the clamps.

---

ASTM D4533  / Apparatus

Tensile Testing Machine, of the constant-rate-of- extension (CRE) or constant-rate-of-traverse (CRT) type with autographic recorder conforming to the

requirements  of Specification ASTM D76/D76M.

Clamps, having all gripping surfaces parallel, flat, and capable of preventing slipping of the specimen during a test, and measuring 50.8 by no less than 76.2 mm

[2 by no less than 3 in.], with the longer dimension perpendicular to the direction of application of the load.

---

ASTM D4533  / Summary of Test Method

An outline of an isosceles trapezoid is marked on a rectangular specimen cut for the determination of tearing strength , and the nonparallel sides of the trapezoid

marked on the specimen are clamped in parallel jaws of a tensile testing machine.

The separation of the jaws is continu- ously increased so the tear propagates across the specimen.

At the same time, the force developed is recorded.

The tearing strength, which is the maximum value of the tearing force, is obtained from the autographic force-extension curve

*** Before conducting ASTM D4533 , it is important to read the entire specification. Standards can be obtained from appropriate standard authorities.

 

***PARSROS  offers several types of grips and fixtures which will enable you to perform a variety of tests

  that are accurate and repeatable.