Question

The strength utilization of yarn in a woven fabric is

• A. $>1$
• B. $<1$
• C. Either A or B
• D. $=1$

Hint:

Yarn crimp and interlacement reduce the effective load-bearing capacity of yarns in fabrics.

Answer 1

The Correct Option is B

Step 1: Definition of strength utilization.
Strength utilization is defined as the ratio of fabric strength to the sum of the strengths of individual yarns used in the fabric.
Step 2: Effect of fabric structure.
In woven fabrics, yarns are crimped and interlaced, which prevents all yarns from bearing load simultaneously and uniformly.
Step 3: Practical implication.
Due to yarn crimp, friction, and uneven load sharing, the effective strength of yarns in fabric is less than their individual strength.
Step 4: Conclusion.
Therefore, the strength utilization of yarn in a woven fabric is always less than 1.

Answer 2

Strength utilization compares how much of a yarn's own breaking strength actually shows up in the finished fabric. Since weaving bends, crimps and interlaces the yarn, it is worth checking each option against what interlacement does to the yarn's mechanical performance.

1. \(>1\): This would mean the fabric is stronger than the sum of the strengths of the straight yarns that went into it. Weaving cannot add strength beyond what the yarns already have; interlacement and crimp only ever introduce extra stress concentration and non-uniform load sharing, never a strength bonus, so this is not possible.
2. \(<1\): When yarn is woven, it is bent repeatedly at each interlacement point and carries some of the load at an angle rather than purely along its own axis. This bending stress and uneven load distribution between yarns means the fabric breaks at a load lower than the simple sum of individual yarn strengths.
3. Either A or B: This would require some circumstance where the fabric could exceed the combined yarn strength, which contradicts the physical effect of crimp and interlacement discussed above; there is no such circumstance in ordinary woven fabric.
4. \(=1\): This would require every yarn to carry its full straight-yarn strength simultaneously and uniformly under load, with no loss from bending or crimp. Real interlaced structures never achieve this ideal.

Because interlacement always cuts into the yarn's effective contribution rather than adding to it, the ratio must fall short of unity.

Therefore, the correct answer is \(<1\).