Determination of Bursting Strength in Fabrics

Fabric Bursting Strength Test

Md. Rubel Miah
Department of Textile engineering
World University of Bangladesh
Email: rubel099@gmail.com





Definitions: 
The distending force, which is applied at right angles to the plane of the fabric, under specified conditions, which will result in the rupture of a textile.

(In Other Word) Bursting strength test is an alternative method of measuring strength in which the material is stressed in all direction at the same time and is therefore more suitable for such material.

Example: Parachute fabrics, Filters, Sacks, Nets, paper, and also knitted fabrics.

Knitted fabric: A structure produced by interloping one or more ends of yarn or comparable material.

Woven fabric: A structure produced when at least two sets of strands are interlaced, usually at right angles to each other according to a predetermined pattern of interlacing, and such that at least one set is parallel to the axis along the lengthwise direction of the fabric.

Type of Bursting Strength Test:

  1. Diaphragm bursting test.
  2. Ball bursting test.
I. Diaphragm Method:
A is clamped over an expandable diaphragm. The diaphragm is expanded by fluid pressure to the point of specimen rupture. The difference between the total pressure required to rupture the specimen and the pressure required to inflate the diaphragm is reported as the bursting strength.

Apparatus and Materials:
Hydraulic Diaphragm Bursting Tester: A testing machine that meets the requirements of. In cases of dispute, a motor-driven tester shall be used unless the purchaser and the supplier agree otherwise.

Clamps: For firmly and uniformly securing the test specimen between two annular, plane, parallel, and preferably stainless steel surfaces, without slippage during the test. Use sufficient pressure to effect the practicable minimization of slippage.

Diaphragm: A 48 mm (1.875 in) diaphragm of Molded synthetic rubber, 1.80 6 0.05 mm (0.070 6 0.002 in.) in thickness with reinforced center, clamped between the lower clamping plate and the rest of the apparatus so that before the diaphragm is stretched by pressure underneath it the center of its upper surface is below the plane of the clamping surface. The pressure required to raise the free surface of the diaphragm plane shall be 30 6 5 kPa (4.3 6 0.8 psi).

Pressure Gage: A maximum-reading pressure gauge of the Bourdon type of appropriate capacity graduated in pounds and accurate throughout the entire range of its scale to within a value of 1 % of its maximum capacity. The capacity of the gage shall be such that the individual readings will be not less than 25 % nor more than 75 % of the total capacity of the gauge.

Hydraulic Pressure System: A mean of applying controlled increasing hydrostatic pressure to the underside of the diaphragm until the specimen bursts through a fluid displaced at the rate of 95 6 5 ml/min. The fluid is displaced by a piston in the pressure chamber of the apparatus.
Fig: Diaphragm Bursting Test
Sampling:
Lot Sample: As a lot sample for acceptance testing, take at random the number of rolls of fabric directed in an applicable material specification or other agreement between the purchaser and the supplier. Consider rolls of fabric to be the primary sampling units.

Laboratory Sample: As a laboratory sample for acceptance testing, take a full width swatch 1 m (1 yd) long from the end of each roll of fabric in the lot sample, after first discarding a minimum of 1 m (1 yd) of fabric from the very outside of the roll. From each roll or piece of circular knit fabric selected from the lot sample, cut a band at least 305 mm (1 ft) wide.

Test Specimens: Cut ten test specimens from each swatch in the laboratory sample with each specimen being.
  • 30mm Dia
  • 113mm Dia
Conditioning:
Bring the specimens from the prevailing atmosphere to moisture equilibrium for testing in the standard atmosphere for textile testing Measurement.

Procedure:
Make all tests on specimens conditioned in the standard atmosphere for testing textiles as directed.

Hand Driven Tester:
  1. Insert the conditioned specimen under the tripod, drawing the specimen taut across the plate, and clamp specimen in place by bringing the clamping lever as far to the right as possible. Rotate the hand wheel, clockwise at a uniform speed of 120 rpm until the specimen bursts. Stop turning the hand wheel at the instant of rupture of the specimen .
  2. Immediately after rupture and in rapid succession, release the clamping lever over the specimen.
  3. Immediately release the strain on the diaphragm by turning the wheel counterclockwise to its starting position and record the pressure required to inflate the diaphragm (tare pressure). Record the total pressure required to rupture the specimen.
Motor-Driven Tester:
  1. Insert the specimen under the tripod, drawing the specimen taut across the plate, and clamp specimen in place by bringing the clamping lever as far to the right as possible
  2. Inflate the diaphragm by moving the operating handle to the left.
  3. While the diaphragm is inflating, take hold of the latch that is located below, or to the right, of the operating
  4. At the instant of rupture of the specimen, swing the latch as far as it will go to bring the operating handle to an idling (neutral) position. Record the total pressure required to rupture the specimen.
  5. Immediately after rupture, and in rapid succession, release the clamping lever over the specimen.
Result: Mean bursting strength measured in Kn/m2

II. Ball Bursting Test:
  1. This test are done by coated fabric.
  2. Not for ordinary knitted fabrics .
  3. In the test a 25 mm diameter steel ball is passed through the stretched fabric can the force is required do so the recorded.
  4. This test can not be carried using an attachment on a standard tensile tester.
  5. The result from this test is not directly comparable with the result of diaphragm bursting test.
  6. This test measure force only not the force per unit area.
Fig: Ball bursting test
Significance and Use: This method for the determination of diaphragm bursting strength of knitted, nonwoven and woven fabrics is being used by the textile industry for the evaluation of a wide variety of end uses.

Calculation:
Calculate the bursting pressure of each specimen by subtracting the tare pressure required to inflate the diaphragm from the total pressure required to rupture the specimen. Report the pressure reading of each individual specimen and the average for each laboratory sampling unit and the lot. Report the type of bursting tester used.

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