GATE (TF) Textile 2009 Question Paper Solution | GATE/2009/TF/16

Question 16 (Textile Engineering & Fibre Science)

With increasing twist, spun yarn strength

(A)Increase continuously
(B)Decrease continuously
(C)Decrease initially and then increases
(D)Increase initially and then decreases
[Show Answer]

Option D is correct

Frequently Asked Questions | FAQs

Why the fibre strength is reduced in yarn structure after twisting?

When yarn is twisted during the spinning process, the fiber strength can be reduced due to several factors:

Fiber Damage: During the twisting process, the fibers in the yarn are subjected to tension and friction. This can cause physical damage to the fibers, such as fiber breakage or weakening. The higher the twist applied, the greater the potential for fiber damage. The damaged fibers contribute to the overall strength reduction of the yarn.

Fiber Slippage: Twisting causes the fibers in the yarn to interlock and hold together. However, if the twist is not sufficient or if the fibers have low frictional resistance, they may slip or slide against each other within the yarn structure. This slippage can result in the redistribution of load and stress across the yarn, leading to reduced overall strength.

Stress Concentration: Twisting creates stress concentration points along the yarn structure. These points are typically located at the yarn twist nodes or areas of higher twist density. The stress concentration can weaken the fibers at those specific locations, making the yarn more susceptible to breakage under load.

Fiber Misalignment: The twisting process can also cause the fibers to become misaligned within the yarn structure. The fibers may not align perfectly parallel to each other due to various factors, including the twist level, fiber characteristics, and spinning conditions. Misaligned fibers can result in uneven load distribution, creating weaker spots within the yarn.

Lateral Compression: Twisting can cause lateral compression on the fibers, squeezing them together within the yarn structure. This compression can lead to fiber deformation or fiber-to-fiber contact, which may result in reduced fiber strength.

It’s important to note that the degree to which the fiber strength is reduced depends on various factors, including the fiber type, yarn twist level, spinning process, and fiber properties. Different fiber types have different inherent strengths and responses to twisting. Additionally, optimizing the spinning process and yarn construction parameters can help minimize the strength reduction while achieving the desired yarn characteristics.

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