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?

其实除了怪这个世界美食诱惑太多,你购买衣服的断裂强力和断裂伸长率是否符合标准也至关重要。

断裂强力和断裂伸长率是什么呢?

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?

1

定义Definition

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.

断裂强力:在规定条件下进行的拉伸试验过程中,试样被拉断记录的最大力与线密度的比值,见下图所示纵坐标1处。

断裂伸长率:在最大力的作用下产生的试样伸长率,见下图所示横坐标4处。

它们之间的关系?

断裂强力和断裂伸长率的含义是表征纺织品或织物的力学性能的两个重要物理量,纺织品的断裂存在小范围的屈服属于经典的线弹性断裂力学理论。

纱线中的纤维在纺织过程当中受各方面因素的影响,使得纱线存在肉眼不可见的裂纹,当纱线织成织物后,受到一定外力的拉扯,这些裂纹宏观上被放大后则会导致织物的断裂或撕破。

因此纺织品或织物的断裂强度和纱线的致密程度、厚度以及纺丝的工艺有直接的关系,而断裂伸长率则本质上决定于纤维的种类,对于杨氏模量高的纤维其断裂伸长率相应高,其次纤维的形貌、取向程度以及结晶程度也会有一定的影响。

断裂强力和撕破强力有什么不同?不同之处?

或许有很多人就会有疑问:到底断裂强力与撕破强力有什么区别?断裂强力考核的是使织物产生裂口所需要的力,测试时力的作用在一定宽度的纱线上;而撕破强力考核的是在外力拉扯下使裂口进一步撕开所需要的力。这两者都是重要的力学指标,有一定的关系,又存在一定的区别。

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.

2

测试标准test standard

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)

此标准主要适用于机织物,也适用于其他技术生产的织物,通常不用于弹性织物、土工布、玻璃纤维织物以及碳纤维和聚烯烃扁丝织物。

3

测试参数Test parameters

Δ实验员:中纺联检(泉州)许友新

结果修约:

试样在距钳口5mm以内断裂,则作为钳口断裂,当5块试样实验完毕,若钳口断裂的值大于最小的“正常值”可以保留,如果小于最小的“正常值”应舍弃,另加试验以得到五个“正常值”,如果所有的试验结果都是钳口断裂,应在报告中指出。

Experimenter: China Textile Joint Inspection (Quanzhou) Xu Youxin

Result revision:

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.

4

织物断裂强度和断裂伸长率影响因素

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.

Fabric tissue

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.

原纱强力

纱线的断裂强力是织物断裂强力大小的直接决定因素,不同种类纱线表现出的断裂强力和断裂伸长率差异很大;其次纱线的密度和粗细也有影响,对于纱线粗且致密的织物其断裂强力大。纱线的捻度,通过对纱线进行加捻可以有效的提高强力。

织物组织

织物组织不同,则纱线在织物中的交错次数、纱线间的摩擦阻力,从而使织物的强力有所不同。

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.)

平纹织物断裂强力大是因为在一定长度内,纱线的交错次数多,使拉伸方向上同时受力的纱线根数多,且受力的均匀情况得到改善之故。因此斜纹组织与缎纹组织断裂强力依次减小,绉组织之所以断裂强力最小,是因为拉伸方向上的纱线织缩不同,当受拉力作用时,织缩小的纱线先被拉伸受力,织缩大的纱线则只受到轻微拉伸,即织物在拉伸过程中纱线不能同时均匀受力, 故其断裂强力最小。

(此点与撕破强力有所不同,撕破强力平纹

Fabric density

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.

织物密度

随着经、纬向密度的减少,断裂强力也随之减小。这是因为织物密度越小,拉伸时承受负荷的纱线绝对根数就越少,断裂强力自然越小。反之,织物密度越大,一定程度上断裂强力越大。

5

改善织物或纺织品力学性能的方法Methods of improving mechanical properties of fabrics or textiles

1

The addition of suitable finishing agent or strong protective agent can effectively improve fracture strength.

2

blending with high Young modulus fibers, improving the breaking strength of fabrics by enhancing the original strength of yarns.

3

Increasing the warp and weft density of the fabric and increasing the number of forces in the fabric.

①.加入合适后整理剂或强力保护剂能够有效的提高断裂强力。

②.与高杨氏模量纤维混纺,通过增强纱线原强力来提高织物的断裂强度。

③.提高织物的经纬密度,增加织物中纱线的受力根数。

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