The influence of unqualified fracture strength
明明是我去年花了几千块钱买的名牌衣服，为什么今年穿在身上突然就破了呢？It's obvious that I spent thousands of yuan on famous brand clothes last year. Why did I suddenly wear them out this year?
In fact, besides blaming the world for its food allure, it is also crucial that the breaking strength and elongation of clothes you buy meet the criteria.
What is the breaking strength and elongation at break?
Fracture Strength: During the tensile test under specified conditions, the ratio of the maximum force recorded by the specimen to the linear density is shown at ordinate 1 as shown in the figure below.
Elongation at break: elongation at the top of the specimen under the action of maximum force, as shown in the abscissa 4 below.
The relationship between them?
Fracture strength and elongation at break are two important physical quantities to characterize the mechanical properties of textiles or fabrics. The small-scale yield of textiles at break belongs to the classical theory of linear elastic fracture mechanics.
Fibers in yarns are affected by various factors in the textile process, which makes yarns have invisible cracks. When yarns are woven into fabrics, they are pulled by certain external forces, and these cracks are enlarged macroscopically, which will lead to fabric rupture or tear.
Therefore, the breaking strength of textiles or fabrics is directly related to the density, thickness and spinning process of yarns, while the breaking elongation is essentially determined by the type of fibers. For the fibers with high Young's modulus, the breaking elongation is correspondingly high, followed by the morphology, orientation and crystallinity of the fibers. Definite influence.
breaking strength and Tear strength Any difference? Difference?
Perhaps many people will be wondering: what is the difference between breaking strength and tearing strength?Fracture strength is measured by the force needed to make the fabric crack. The force acts on the yarn with a certain width during the test. The tear strength is measured by the force needed to further tear the fabric crack under the pull of external force. Both of them are important mechanical indexes, which are related to each other and there are certain differences.
关于断裂强力测试的方法也是众多，比如条样法和抓样法，今天咱们重点讲下最常用的GB/T 3923.1-2013的测试操作。There are many methods for testing fracture strength, such as spline method and grab method. Today we will focus on the most commonly used test operation of GB/T 3923.1-2013.
GB/T 3923.1-2013Tensile properties of textile fabrics Part 1 testing of breaking strength and elongation at break(strip method)
This standard is mainly applicable to woven fabrics and fabrics produced by other technologies. It is not usually used for elastic fabrics, geotextiles, glass fiber fabrics, carbon fiber and polyolefin flat silk fabrics.
GB/T 3923.1-2013纺织品 织物拉伸性能第一部分 断裂强力和断裂伸长率的测试（条样法）
Experimenter: China Textile Joint Inspection (Quanzhou) Xu Youxin
If the specimen breaks within 5 mm from the nipple, it will be regarded as the nipple fracture. When the experiment of five samples is completed, if the value of nipple fracture is greater than the minimum "normal value", it can be retained. If the value is less than the minimum "normal value", it should be discarded, and five "normal values" should be obtained by additional tests. If all the test results are nipple fracture, it should be retained. It is pointed out in the report.
Fabric breaking strength and elongation at break influence factor
Strength of original yarn
The breaking strength of yarns is the direct determinant of the breaking strength of fabrics. The breaking strength and elongation at break of different kinds of yarns vary greatly. Secondly, the density and thickness of yarns also influence the breaking strength of thick and dense fabrics. The twist of yarns can effectively improve the strength by twisting yarns.
The number of yarns crossing in the fabric and the friction resistance between yarns vary with the fabric structure, which makes the strength of the fabric different.
平纹织物>斜纹织物>缎纹织物>绉组织Plain fabric > twill fabric > satin fabric > crepe tissue
The high breaking strength of plain weave fabric is due to the number of yarns interlaced in a certain length, the number of yarns under simultaneous force in the direction of drawing, and the uniformity of force is improved. Therefore, the breaking strength of twill and satin weave decreases in turn, and crepe weave has the lowest breaking strength because the yarn shrinkage in the drawing direction is different. When the yarn shrinks under the pulling force, the yarn is first stretched, while the yarn with large shrinkage is only slightly stretched, that is, the yarn of the fabric is different in the drawing process. When the force is uniform, the breaking strength is the smallest.
This is different from tearing strength, tearing strong twill, twill, satin. Because the size of triangular area formed by tearing of three kinds of tissues is different, which affects the number of yarns under stress during tearing of fabrics.)
As the density of warp and zonal decreases, the breaking strength decreases. This is because the smaller the density of the fabric, the less absolute number of yarns under load during stretching, and the smaller the breaking strength naturally. On the contrary, the greater the density of fabric, the greater the fracture strength to a certain extent.
改善织物或纺织品力学性能的方法Methods of improving mechanical properties of fabrics or textiles
The addition of suitable finishing agent or strong protective agent can effectively improve fracture strength.
blending with high Young modulus fibers, improving the breaking strength of fabrics by enhancing the original strength of yarns.
Increasing the warp and weft density of the fabric and increasing the number of forces in the fabric.