There are three main test methods for bursting strength or bursting strength: bursting method, marble bursting method and steel ball method.
Foreign countries such as the United States, Japan, South Korea, Canada, Australia, etc. use the burst method to test.
my country's GB/T 7742.1-2005 "Breaking Properties of Textile Fabrics Part 1: Determination of Burst Strength and Burst Expansion Hydraulic Method" refers to the burst test method in the international standard ISO 13938-1:1999.
The test principle is: clamp the sample on the extensible diaphragm, apply liquid pressure under the diaphragm, and increase the liquid volume at a constant speed, so that the diaphragm and the sample expand until the sample ruptures, and the bursting strength is measured. This method can also test the burst expansion of the sample.
Before the revision of the national standard "cotton knitted underwear", the burst strength was tested by the marble burst method, that is, a 25 mm circular marble was used to test the knitted fabric.
There are two differences between the test methods listed in the GB/T 19976-2005 "Steel Ball Method for Determination of Bursting Strength of Textiles" formulated in 2005. It is 38 mm, and the second is to stipulate that the strength test instrument is the internationally accepted CRE (constant velocity elongation) strength tester.
【Burst Mechanism】
The plain weave will form slits parallel to the longitudinal direction of the fabric, and there will be more loop detachment along the transverse direction of the fabric;
However, the damage crack of the piqué is in the shape of a hole, and the damage is mainly manifested by the breakage of the yarn, and almost no coil detachment is formed.
Three approaches share similar failure mechanisms: weak ring theory
From the weak ring theory, it can be known that when the knitted fabric is subjected to bursting or bursting, it will first be damaged at a certain weakest place, and then a stress concentration will be generated at the damaged place. There will be a large number of loops scattered in the lateral direction, and the cracks will continue to expand in the longitudinal direction; the piqué fabric will have more yarn breaks, and the cracks will expand around.
【Test Results】
The results of the different test methods are compared as follows:
1) The diameter of the steel ball is larger than that of the marble, and the bursting strength obtained by the steel ball method is also greater than that of the marble bursting method
2) The three test methods have similar failure mechanisms, and the shape of the crack after the fabric is damaged is basically the same.
3) The results of the three test methods have a good linear relationship with each other, and there is a good correlation between the three.
Fabric burst and its mechanism
definition:
The phenomenon that the fabric bulges, expands and ruptures under the load of a vertical fabric plane is called burst.
The bursting strength of fabrics is an important mechanical index of fabrics.
test meaning
Tensile strength is not suitable for some fabrics (such as knitted fabrics and lace), but can be replaced by burst strength. When the fabric is damaged, it is often subjected to pressure in the warp, weft, and oblique directions at the same time, especially some knitted fabrics (such as weft knitted fabrics) have the characteristics of vertical extension and lateral contraction, and the vertical and lateral directions have a great influence on each other. If the tensile strength test is used, the warp, weft and diagonal directions must be tested separately, while the burst strength can be evaluated at one time for the fabric strength.
Burst Mechanism
Woven fabric: The deformation of the fabric in the non-warp and weft direction is caused by the mutual shearing of the two groups of warp and weft yarns, and its elongation deformation is larger than that in the warp and weft direction. The yarn at the weakest point breaks, followed by a relative tear in the warp or weft direction, so that the split is generally linear. If the warp and weft deformation capacity of the fabric is similar, the warp and weft yarns will break at the same time when bursting, and the cracks are often L or T-shaped, indicating that the warp and weft yarns play the greatest role at the same time, and the bursting strength is higher than that of a straight crack. Knitted fabrics: The loops are colluded to form a piece and together undergo elongation and deformation until the fabric is torn.
Non-woven fabrics: It is mainly the breaking of fibers and the loosening of the fiber web. The top rupture is a raised loose fiber package, and the burst is the tearing and cracking of the fiber web.
HT-229 Burst Strength Tester
1. Scope of application:
The HT-229 burst strength tester is used to measure the burst strength and burst expansion of knitted fabrics, woven fabrics, non-woven fabrics and other woven fabrics.
2. Applicable standards:
GB/T7742.1-2005 "Textiles - Bursting properties of fabrics - Part 1: Determination of bursting strength and bursting expansion by hydraulic method"
Fourth, the bursting mechanism
The plain weave will form slits parallel to the longitudinal direction of the fabric, and there will be more loop detachment along the transverse direction of the fabric;
However, the damage crack of the piqué is in the shape of a hole, and the damage is mainly manifested by the breakage of the yarn, and almost no coil detachment is formed.
Fifth, the three methods have similar failure mechanisms: weak ring theory
From the weak ring theory, it can be known that when the knitted fabric is subjected to bursting or bursting, it will first be damaged at a certain weakest place, and then a stress concentration will be generated at the damaged place. There will be a large number of loops scattered in the lateral direction, and the cracks will continue to expand in the longitudinal direction; the piqué fabric will have more yarn breaks, and the cracks will expand around.
Six, the meaning of the test
Tensile strength is not suitable for some fabrics (such as knitted fabrics and lace), but can be replaced by burst strength. When the fabric is damaged, it is often subjected to pressure in the warp, weft, and oblique directions at the same time, especially some knitted fabrics (such as weft knitted fabrics) have the characteristics of vertical extension and lateral contraction, and the vertical and lateral directions have a great influence on each other. If the tensile strength test is used, the warp, weft and diagonal directions must be tested separately, while the burst strength can be evaluated at one time for the fabric strength.
Report
1. It is indicated that the sample is carried out according to the method of D3786 hydraulic burst strength tester. Describe the raw material or product sampled and the method of sampling.
2. Report the burst strength of each sample and their average value in Kpa (or psi).
3. Report the model of the tester used.
Mullen fabric bursting strength tester is used to measure the bursting strength or seam bursting strength of woven fabrics, knitted fabrics and non-woven fabrics, and it is also applied to the bursting force required for paper and leather to burst. It is a testing machine for the resistance (bursting strength) of products, paper, etc., when they are damaged by various external forces. This article focuses on the experimental operation method of the Mullen fabric burst strength tester.
1. Selection of samples
Eight samples with different compositions and structure were randomly selected, and the bursting strength of each sample was tested 10 times, and the average value of the results was used for analysis and comparison.
2. Instruments
QS-LS bursting strength tester, M229AUTOBURST bursting strength tester.
3. Test plan
Different equipment and different test methods are selected, and the bursting strength results of the samples are also different. The burst time specified in GB/T7742.1-2005 can be (20±5) s; the test area is 50cm2, and other test areas such as 100cm2, 10cm2, 7.3cm2 can also be used [3]; FZ/T01030-1993 stipulates The oil pressure speed is (85±10)mL/min
In this paper, the three factors of test area, test conditions and equipment are selected to carry out single factor test respectively, and the average value of each sample result is used for analysis and comparison. Among them, the test area is selected as 7.3cm2 and 50cm2; the test conditions are selected as the constant oil pressure rate of 95mL/min and the constant burst time of 20s; the instruments and equipment are selected as the QS-LS bursting strength tester and the M229AUTOBURST bursting strength tester.
ps: (WLJCDM809)
9-27
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