Fabric Tensile Strength, What are the Affecting Factors and How to Test it?

Tensile strength is undoubtedly a significant index in the textile fabric test. This article will go into great detail on several factors that have an impact on fabric tensile strength and identify methods to maximize fabric tensile strength, which can be used as a guide to further optimize product quality.

The top factors affecting the tensile strength of fabrics are as follows.

1 the breaking strength of  warp and weft  yarns

There are a few factors influencing the fabric tensile strength, such as the material of the finished yarn and the proportion of the blended yarn, the fineness of the fibers and the yarn (count or specialty), the homogeneity of the finished yarn, the moisture regain or moisture content, a single yarn or a strand, the number of twists (coefficient of twist) of the single yarn and the strand, and the storage life of the fiber or yarn. There are also other factors such as the elongation of elastic fibers, which can result in large differences between diverse fabrics.

2 weaving methods and weaving conditions (for instance, there exists the difference between knitted and woven fabrics), tissue structure (such as plain, twill, satin, jacquard, and so on), and the density of warp and weft yarns.

Different warp and weft strengths result in the strength of the top break. And we need to check out whether it has a fabric edge, a solid or raw edge and whether it makes no contact with blemishes and folds, and how far it is away from the original fabric edge (so the sample must be taken at least 150 mm from the edge) which make a huge difference on the test result. Additionally, stained and cloth after desizing, dyeing, and finishing cloth, especially cloth undergoing dipping and special finishing, vary considerably in the aspect of strength. The weaving process, dyeing, brushing, etc. all have an effect on the textile tensile force. Coarser yarns have better strength than finer yarns’, twill is better than plain,  not brushed is better than brushed, and the less corrosive the dyeing is the better.

3 the strength and fineness of the original yarn, the density of the warp and weft, and the finishing process

The tensile strength of non-iron fabrics may become smaller after non-iron finishing, affecting the fabric’s durability. The change of tensile strength of the fabric, the strength and elongation of the yarns, the interweave resistance, and the morphological structure all significantly affect the strength before and after the non-iron finishing. Yarns with strong strength and high elongation weave into fabrics that are subjected to external forces with a great number of yarn roots under common stress and are less likely to be pulled off.

Fabric tensile strength test

There are two frequently used testing methods, including the strip method and the grip method. And according to the strip method, fabrics can be divided into split strips and cut strips based on whether the edges can be removed.

1 Strip specimen test:

It alludes to a fabric tensile test about the overall strength of the specimen. In the test, the specimen needs to be ripped off into the one with a specified width (generally 5cm), and then the entire width of a specimen will be held by a gripper. For some non-woven fabrics, coated fabrics, and fabrics that are not easy to pull yarn at the edge of the specimen, only when they are cut to the ones with specified width, can the test be carried out.

2 Grip sample test:

It refers to a fabric tensile specimen held by a gripper in the central part of the specimen in the direction where the width of the fabric lie.

3  Principle of the two tests:

Both methods require the tester to stretch the specimen at a constant speed until it breaks off and then the data of breaking strength will be recorded.

4 The mechanism for fabric fracture:

After the fabric is stretched, the yarn first turns straight from flexion and then becomes thin. The fabric will not become thinner unless the area of yarn with the weakest strength suffers from fracture elongation. Only under such conditions, can the yarn break one by one, resulting in fabric fracture.

Due to the extrusion at the yarn interweaving points during the stretching process, the tangential sliding resistance at the interweaving points increases, decreasing the unevenness of the yarn strength and elongation. The more yarn interweaving points in the two systems, the shorter the floating length, which helps us to increase the fabric strength to a certain extent. And obviously, the warp and weft density and yarn strength also have a direct influence on the fabric tensile force.

Fabric Tensile Stretch Test

1 The principle of the test:

At first, the fabric needs to be stretched by a fixed elongation or a fixed force, which makes it suffer from a deformation. Then the tensile strength should be released after a certain period of time to make the fabric recover its original form. We can calculate the elastic recovery rate and plastic deformation rate by measuring fabric residual elongation to find out the fabric tensile elasticity.

Note: plastic deformation refers to the part of fabrics that are subject to a certain external strength and can not recover the original form despite the withdrawal of the force

L0: the initial length of the sample

L1: the length of the sample under the maximum load

L2: the remaining length of the sample which is stretched to the maximum elongation and recovers the initial form for a certain time

L1-L0: total elongation of the sample

L1-L2: entire recovery of the sample

L2-L0: elongation of the sample in reality

Maximum elongation: The ratio of the elongation length of the sample under maximum load to the initial length.

Maximum elongation rate is equal to(L1-L0) / L0 × 100%

Residual elongation rate (plastic deformation rate):

the ratio of the actual elongation to the original length of the sample after stretching to the maximum elongation and leaving it for some time.

Residual elongation rate is equal to (L2 – L0) / L0 × 100%

Response rate: the ratio of the total response to the total elongation of the sample

Response rate is equal to (L1-L2) / (L1-L0) × 100%