Effect of a weft yarn spinning system on the shear characteristics of plain woven fabrics

Abstract

Spun yarns are almost entirely produced using ring, rotor and relatively new air vortex spinning systems. In this study, shear properties of fabrics woven with cotton, viscose, and polyester yarns spun using ring, rotor, and vortex spinning systems were investigated. Experimentally determined shear characteristic-related factors, such as initial shear rigidity, shear rigidity, shear hysteresis at a 0.5 degree shear angle, and shear hysteresis at a 5 degree shear angle along the principle directions, were statistically analyzed. In addition, differences between the shear behaviors of the woven fabric samples were identified using the digital image correlation (DIC) technique. While our analyses confirm the statistically significant difference between the shear behavior of samples woven with ring-spun yarns and samples woven with rotor and vortex yarns in the weft direction, no significant difference in shear behavior between the samples woven with rotor and vortex yarns was observed. It was found that the yarn spinning system has no significant effect on fabric shear characteristics in the warp direction. It also was concluded that the DIC technique can successfully be used to analyze the differences in shear characteristics of fabrics woven by various type of spun yarns.

Keywords

initial shear rigidity shear rigidity woven fabric parameters digital image correlation multiple comparison test analysis of variance

Introduction

The ability of textile fabrics to conform to various shapes is highly influenced by their architecture. As shown in Figure 1, during the transformation of fabric to apparel two major deformation mechanisms, namely simple shear and shear-slip, operate. The former is important in relation to woven fabrics, in which the unique double curvature phenomenon is crucial.^1–4

Figure 1.

Woven fabric deformation mechanisms.¹

Shear behavior is among the most important mechanical properties of fabrics. Fabric shear is detrimental during fabric usage, when the fabric is subjected to wide varieties of complex deformations. Fabric shear also affects handle, resistance to crease, and drape of the fabrics. In practice, shear properties can be evaluated by the Kawabata Evaluation System (KES) and Fabric Assurance by Simple Testing (FAST) instruments.^1,5,6 Various modes can be defined to determine the shear behavior of fabrics. The deformation modes can be associated with the rigidity of yarn intersection points relative to shear force. Yarn shear force is not adequate to overcome the frictional resistance at the intersections. Upon the start of the second mode, yarn slippage at the intersection points occurs. This is due to the increase in the shear force when the frictional resistances at the intersection points are overcome. Thus, subsequently elastic deformation and final yarn slippage occur and ultimately fabric jamming occurs.^7,8 A typical shear force–shear angle hysteresis curve is shown in Figure 2. The slope of such curve corresponds to fabric shear rigidity or fabric shear modulus. When the shear force is less than the limiting static friction resistance between the warp and weft yarns at the intersections, the highest fabric shear rigidity is denoted by line OA in Figure 2. This is known as fabric initial shear rigidity.^9–11 A further increase in shear force results in slippage of more yarns. This in turn leads to a swift decline in fabric shear rigidity, which is denoted by section OB. This is associated with the dynamic friction resistance, which is significantly less than the static friction resistance. Section BC denotes the dominance of dynamic frictional resistance over the static frictional resistance at the intersection points. This, in fact, shows the resultant linear relationship between shear force and fabric deformation. This linearity increase is due to the increase in yarn crimp at the intersections.¹⁰ Shear rigidity presented by the Kawabata Evaluation System for Fabrics (KES-F) is the slope of shear deformation curve between the 0.5 and 5 degree shear angles. This is the slope at section BC in Figure 2, which corresponds to the elastic shear modulus terminology proposed by Grsosberg et al.¹⁰ It is proposed that if this region is not linear then the mean slope over this distance should be considered.^12,13 The KES-F also presents parameters such as shear hysteresis at a 0.5 degree shear angle (2HG0.5) and shear hysteresis at a 5 degree shear angle (2HG5). The shear rigidity presented by the KES-F in many studies is considered to be the pivotal parameter of shear rigidity. However, it is clear that fabric initial shear rigidity is also of paramount importance in describing the shear characteristics of woven fabrics. In this study, in addition to shear parameters presented by the KES instrument, the initial shear rigidity of woven fabrics is also extracted based on the obtained shear force–shear angle curves by the KES-F.

Figure 2.

Typical shear behavior of woven fabric.

The spinning system influences the structure and properties of yarn. This effectively affects the physical and mechanical properties of the resultant fabric. The vortex spinning system is the latest technology in the field of spun yarn manufacture. This technology was pioneered by Murata Machinery Ltd in 1997. The system is capable of producing yarn at a rate of 400 m/min. Vortex spinning has undergone numerous modifications with the aim of vortex yarn quality improvement. There are many research works in which the properties of various type of spun yarns are investigated in relation to properties of the resultant woven fabrics.^14–27

Özdemir and Tuğrul Oğulata¹⁴ investigated the effect of vortex and rotor cotton yarn structures and properties on color efficiency during the package dyeing process, where it was found that under a given dyeing condition the vortex-spun yarns have darker shades than rotor-spun yarns. Kuthalam and Senthikumar¹⁵ investigated the influence of spindle air pressure and the direction of rotation on the quality characteristics of polyester/cotton vortex yarn. Tyagi and Sharma¹⁶ studied the thermal comfort characteristics of polyester–cotton Murata vortex-spun (MVS) yarn fabrics. It has been reported that the absorbency of polyester–cotton MVS yarn fabrics is relatively insensitive to twisting jet pressure, nozzle distance, and delivery speed. In addition, an increase in yarn linear density and cotton content markedly increases fabric absorbency. Kostajnšek and Dimitrovski¹⁷ compared the pilling and tensile properties of fabrics woven using ring and vortex weft yarns. Rameshkumar et al.¹⁸ compared pilling and abrasion resistance and the bursting strength and drape of weft knitted fabrics knitted with ring, rotor, and vortex-spun yarns. Ortlek and Onal¹⁹ evaluated the effect of the yarn spinning system on the abrasion resistance and dimensional properties of weft knitted fabrics. Kim and Kim²⁰ in 2018 examined the mechanical properties of micro modal yarns spun on ring, compact, and air vortex spinning systems and the resultant weft knitted fabrics. It was claimed that fabrics knitted with air vortex yarn enjoy higher bending rigidity, lower compressibility, and slightly greater formability than fabrics knitted using ring and compact spun yarns. In addition, in this research using the FAST system, it was established that the shear rigidity of vortex-spun yarn knitted fabrics yield similar results to those obtained using ring and compact spun yarn. Kim and Kim²¹ also studied the hand and wear comfort of fabrics knitted with ring, Siro, and vortex-spun hemp/Tencel yarns and concluded that the fabric knitted with ring-spun yarns has lower shear rigidity than that of air vortex-spun yarns. Suzuki and Sukigara²² compared the tensile, compression, bending, and torsional properties of fabrics knitted with vortex, ring, and rotor viscose rayon spun yarns. Based on hand evaluation it was concluded that fabric knitted using vortex yarns is much smoother than rotor yarn knitted fabrics, but is less smooth than fabrics knitted using ring-spun yarns. In this research, weft knitted fabrics were tested along the course and wale directions using the KES-F. It was found that shear rigidity and shear hysteresis at 0.5 and 5 degree shear angles in the case of fabrics knitted using rotor-spun yarns are higher than those of ring and vortex-spun yarns. Fabric knitted using ring-spun yarns showed the lowest value of shear characteristics. Erdumlu et al.²³ compared vortex-spun yarn with ring and open-end rotor-spun yarns and the resultant weft knitted fabrics. Kim²⁴ studied the physical properties of ring, compact, and air vortex yarns spun using Poly trimethylene terephthalate (PTT)/wool/modal together with the wear comfort of the resultant knitted fabrics used in high emotional garments which are defined as clothing items that enjoy good formability, comfort, and soft hand during use. It was reported that the tactile hand of the fabric knitted with air vortex yarn was harsher than that of fabrics knitted with ring or compact yarns. This was attributed to the lower extensibility, compressibility, and higher bending and shear rigidities of the air vortex knitted fabrics in comparison with fabrics knitted using ring or compact yarns. Li et al.²⁵ compared the dimensional and mechanical properties of wool–polyester fabrics woven with vortex and ring-spun yarns. Erdumlu and Saricam²⁶ compared the vertical wicking, water absorption, and drying properties of fabrics knitted with vortex- and ring-spun combed cotton yarns. It was stated that the wicking and water absorption of vortex-spun yarns and the resultant fabric are lower than those of ring-spun yarns. Moreover, it was claimed that the yarn spinning system has no significant impact on the drying time of the fabrics.

The digital image correlation (DIC) technique is a noncontact optical method that can be used in the measurement of displacement using only two digital images. Thus, DIC is rendered as a robust, flexible, and “easy to apply” displacement measurement technique. The use of DIC is widespread in the evaluation of structural deformation, the mechanical behavior of engineering materials, and more recently in the evaluation of the shear and tensile properties of woven fabrics.^28–30

A review of the scientific literature shows that the use of knitted fabrics in most researches is more dominant in comparison with woven fabrics. In this paper the effect of the yarn spinning system and fiber type on the shear behavior of woven fabrics, an area that due to its complexities has rather been ignored in scientific researches, is studied. The deformation of fabrics woven using ring, rotor, and vortex-spun weft yarns under bias extension condition by the application of the DIC technique is also investigated.

Material and methods

Yarn and fabric production

Various 29.5 tex cotton, viscose, and polyester yarns were spun on ring, rotor, and vortex spinning systems. The fineness and staple length of the polyester and viscose fibers were 1.2 denier and 38 mm, respectively. Cotton fibers were of upper half mean length of 31.5 mm and fineness of 4.2 micronaire. The properties of cotton fiber were measured by an HVI9000 instrument. Cotton yarns were produced using combed slivers. Table 1 shows the main process parameters of the yarns used. The vortex, rotor, and ring yarns were produced on MVS861, Schlafhorst SE9, and Zinser 421 spinning systems, respectively.

Table 1.

Weft yarn process parameters

Spinning system	Ring	Ring	Ring	Rotor	Rotor	Rotor	Vortex	Vortex	Vortex
Fiber type	Cotton	Polyester	Viscose	Cotton	Polyester	Viscose	Cotton	Polyester	Viscose
Roving count (ktex)	0.51	0.51	0.51	–––	–––-	––-	––-	–––	––-
Sliver count (ktex)	––-	–––	–––	3.5	3.5	3.5	3.5	3.5	3.5
Delivery speed (m/min)	17.86	20.16	20.16	106.25	118.06	128.79	360	360	360
Twist (tpm)	700	620	620	800	720	660	–––	–––	––-
Rotor speed (rpm)	––	––-	––	85,000	85,000	85,000	–––-	–––-	–––-
Spindle speed (rpm)	12,500	12,500	12,500	––-	––-	––-	––––-	–––-	––––-
Nozzle air pressure (MPa)	––-	––-	––-	––-	––-	––-	0.57	0.59	0.59

A P7300 projectile weaving machine with nominal width of 390 cm at a speed of 300 ppm was used. In total, nine plain fabric samples with 19.68 tex warp polyester/viscose (65/35%) vortex-spun yarns [breaking strength: 490.88(8.77%) cN, breaking elongation: 12.96(8.98%), real count: 20.33 tex, bending rigidity: 1.725 mN.mm²] and the weft yarns, as listed Table 2, were woven. The warp and weft densities of the gray samples were 30 and 20 per cm, respectively. All samples then were de-sized, scoured, and dried.

Table 2.

Weft yarn specifications

Yarn code	Fiber	Spinning system	Real count (tex)	Breaking strength (cN)	Breaking elongation (%)	Yarn–yarn coefficient friction	Bending rigidity (mN.mm²)
Y-RI-C	Cotton	Ring	30.10	337.27(6.42)^a	5.58(8.30)^a	0.112 ± 0.02	1.537
Y-RI-P	Polyester	Ring	29.54	1038.35(5.24)^a	18.20(3.01)^a	0.125 ± 0.01	1.651
Y-RI-CV	Viscose	Ring	29.09	510.73(8.95)^a	17.15(4.50)^a	0.114 ± 0.01	1.365
Y-RO-C	Cotton	Rotor	28.94	189.34(4.13)^a	4.45(5.99)^a	0.153 ± 0.002	1.591
Y-RO-P	Polyester	Rotor	29.54	518.11(8.62)^a	15.17(7.84)^a	0.154 ± 0.02	2.250
Y-RO-CV	Viscose	Rotor	29.49	357.50(2.90)^a	12.58(3.44)^a	0.148 ± 0.02	1.818
Y-V-C	Cotton	Vortex	30.09	193.25(7.53)^a	4.66(3.51)^a	0.132 ± 0.02	2.232
Y-V-P	Polyester	Vortex	29.54	726.78(6.83)^a	14.50(8.21)^a	0.152 ± 0.03	3.915
Y-V-CV	Viscose	Vortex	30.91	404.63(8.72)^a	12.53(4.17)^a	0.136 ± 0.01	2.773

Denotes CV%.

RI: ring spinning; RO: rotor spinning; V: vortex spinning; C: cotton fiber; P: polyester fiber; CV: viscose fiber.

Measurement of yarn and fabric properties

The yarn and fabric tensile properties were measured according to ASTM-D2256 and ASTMD-5035, respectively, using a Zwick Tensile Tester in CRE mode. Table 2 shows the specifications of the weft yarns. The yarn–yarn friction coefficient was measured according to the method proposed by Nair et al.³¹ and Page and Wang,³² the schematic of which is shown in Figure 3. During the measurement of the yarn–yarn friction based on this method, a 6 cm * 6 cm sliding top surface was connected at one side to a 220 g weight and at the other side, as shown in Figure 3, to the upper jaw of the tensile tester. On the 6 cm width of the sliding surface, 16 equally spaced warp yarns were positioned parallel to each other. On the lower fixed surface, which effectively has replaced the lower jaw of the Zwick Tensile Tester, also 16 equally spaced weft yarns were positioned parallel to each other over 6 cm distance. Moreover, the weft yarns were vertical to the 16 equally spaced and parallel positioned warp yarns. The experiment was conducted at the optimized rate of 1 mm/s. The movement of the upper surface was limited to 60 mm. The bending rigidity of yarns was measured using a KES-F2A pure bending tester.

Figure 3.

Schematic representation of the yarn–yarn coefficient friction measuring apparatus.

The shear force–shear angle hysteresis of the samples was obtained along warp and weft directions using the KES-F1A instrument. The principle of the KES-F1A instrument, which is effectively based on the simple shear test method, is schematically illustrated in Figure 4. In this method, the sample is clamped between a fixed and a movable jaw. In order to delay the buckling of the samples during the test, as shown in Figure 4, normal forces (W) are applied on the sample. The initial shear rigidity, shear rigidity, shear hysteresis at a 0.5 degree shear angle, and shear hysteresis at a 5 degree shear angle along the principle directions were obtained. The specification and properties of the samples, with identical codes to those of Table 2, are shown in Tables 3 and 4. The fabric code of each sample was in accordance with the weft yarn code.

Figure 4.

KES-F1A shear test method.

Table 3.

Fabric specifications

Fabric code	Weight (gsm)	Crimp (%)		Warp direction			Weft direction
Fabric code	Weight (gsm)	Warp	Weft	Breaking strength (N)	Breaking elongation (%)	Elastic modulus (N/cm)	Breaking strength (N)	Breaking elongation (%)	Elastic modulus (N/cm)
F-RI-C	154.0	9.30	8.80	350.48(4.74)^a	24.58(7.74)^a	68.80(5.74)^a	231.07(5.35)^a	17.76(5.21)^a	40.08(6.54)^a
F-RI-P	160.1	9.81	3.77	324.63(5.07)^a	27.79(2.42)^a	140.40(5.48)^a	516.99(3.62)^a	29.53(1.47)^a	125.00(4.16)^a
F-RI-CV	159.9	8.59	8.70	363.39(3.27)^a	26.74(0.72)^a	144.00(5.80)^a	251.94(3.85)^a	26.61(2.58)^a	40.01(9.10)^a
F-RO-C	154.0	7.20	7.20	337.54(2.35)^a	24.19(1.22)^a	48.11(4.22)^a	154.54(3.96)^a	15.52(0.88)^a	37.50(4.63)^a
F-RO-P	156.3	9.80	4.69	303.04(3.08)^a	26.66(2.45)^a	144.09(7.72)^a	275.47(12.1)^a	21.89(4.04)^a	100.00(4.04)^a
F-RO-CV	156.5	7.75	7.00	335.01(0.68)^a	25.78(1.13)^a	91.33(8.27)^a	215.63(2.49)^a	23.78(6.42)^a	40.63(2.55)^a
F-V-C	152.6	8.10	6.70	365.61(3.01)^a	28.32(7.46)^a	72.10(6.51)^a	163.42(4.09)^a	15.30(6.13)^a	35.71(1.73)^a
F-V-P	154.5	8.27	4.50	383.26(3.15)^a	27.78(0.42)^a	154.00(8.57)^a	407.14(2.66)^a	25.84(1.56)^a	110.16(8.20)^a
F-V-CV	159.6	8.20	7.66	316.72(8.18)^a	25.14(3.24)^a	149.33(7.56)^a	190.94(9.37)^a	20.69(4.93)^a	33.33(4.64)^a

Denotes CV%.

RI: ring spinning; RO: rotor spinning; V: vortex spinning; C: cotton fiber; P: polyester fiber; CV: viscose fiber.

Table 4.

Fabrics shear properties

Fabric code	Warp direction				Weft direction
Fabric code	G (N/cm)	G-init^a (N/cm)	2HG0.5 (cN/cm)	2HG5 (cN/cm)	G (N/cm)	G-init^a (N/cm)	2HG0.5 (cN/cm)	2HG5 (cN/cm)
F-RI-C	2.59(4.53)^b	7.94(5.39)^b	4.84(8.61)^b	10.00(3.90)^b	1.59(6.17)^b	3.23(4.03)^b	2.19(9.15)^b	4.74(7.55)^b
F-RI-P	3.11(4.97)^b	9.35(3.28)^b	6.99(7.61)^b	13.10(6.30)^b	2.14(4.95)^b	5.11(7.46)^b	1.81(7.88)^b	7.37(7.62)^b
F-RI-V	2.48(6.44)^b	7.14(8.83)^b	6.11(9.89)^b	10.53(8.76)^b	1.53(3.91)^b	3.11(8.39)^b	1.96(6.67)^b	4.74(8.69)^b
F-RO-C	2.64(2.33)^b	7.67(6.56)^b	4.22(7.59)^b	10.11(1.16)^b	1.67(6.66)^b	3.86(9.65)^b	2.57(2.55)^b	5.42(2.57)^b
F-RO-P	3.38(3.90)^b	8.62(7.93)^b	7.21(7.49)^b	13.44(4.54)^b	2.30(2.68)^b	5.23(2.71)^b	2.46(4.59)^b	8.57(4.87)^b
F-RO-V	2.83(4.30)^b	9.29(7.50)^b	7.02(9.69)^b	12.25(5.00)^b	1.81(4.19)^b	5.05(2.32)^b	2.30(7.02)^b	6.47(8.51)^b
F-V-C	2.78(4.28)^b	7.27(7.76)^b	5.39(8.12)^b	11.91(7.02)^b	1.80(4.13)^b	4.57(8.92)^b	3.32(4.37)^b	6.43(7.09)^b
F-V-P	3.01(1.37)^b	8.88(6.51)^b	5.75(9.07)^b	13.44(2.40)^b	2.16(5.02)^b	6.70(9.58)^b	2.41(4.73)^b	7.64(3.70)^b
F-V-V	2.67(4.62)^b	7.56(3.44)^b	6.82(8.30)^b	11.11(7.92)^b	1.82(4.31)^b	3.50(7.34)^b	2.78(5.91)^b	6.31(9.22)^b

Initial shear rigidity.

Denotes CV%.

2HG0.5: 0.5 degree shear angle; 2HG5: 5 degree shear angle; RI: ring spinning; RO: rotor spinning; V: vortex spinning; C: cotton fiber; P: polyester fiber; CV: viscose fiber.

Statistical analysis

An analysis of variance and Tukey post hoc tests were used to study the effectiveness of each independent factor, that is, the spinning system, weft yarn fiber type, and the combined effect of weft yarn fiber type and the spinning system. The equality of variance of various samples was assessed using Levene's test in conjunction with the selected post hoc test. If the significance level value (p-value) is greater than the level of significance, then the variances are acceptable as equal.³³ Equal and unequal variances were respectively verified using Tukey's post hoc and Dunnett's T3 post hoc tests, and eventually the use of Tukey's post hoc test was confirmed.

The bias extension test using the digital image correlation technique

The bias extension test was carried out using 5 cm * 15 cm samples woven with weft polyester yarns spun on the three previously named spinning systems. Since statistical analysis vividly demonstrated the dominate effect of weft polyester yarn on the shear property of the fabrics in comparison to cotton or viscose weft yarns, then only the fabrics woven with polyester weft yarn were considered. The details of the DIC technique, which was used to investigate the strain field of the specimen throughout the test, is given by Ref. Dridi²⁸ et al. and Pierce²⁹ et al. Bias extension was performed using an Instron Tensile Tester (Model 4485, 500N load cell) at a speed of 10 mm/min. Since the focus of this paper is on the investigation of the in-plane shear behavior of woven fabrics, only two-dimensional DIC was used to analyze the deformation of the test samples using the GOM Aramis measuring software. In order to show a large gray scale, the test samples were sprayed with black pen ink.

In the bias extension test, the middle zone of the sample is subjected to pure shear, and thus this region was selected for carrying out the evaluation. The incremental amount of strain was calculated and visualized by contour maps on each image.

Results and discussion

Fabric shear characteristics in the weft direction

Fabric initial shear rigidity (G-init)

Table 5 shows statistical significance at the 95% confidence level (sig. < 0.05) of the effect of the weft yarn fiber type, spinning system, and their combined effect on fabric initial shear rigidity in the weft direction. The results indicate the dominant effect of the weft yarn fiber type over that of the spinning system. This finding is in line with the trend observed in the surface plot shown in Figure 5(a). Tables 6 and 7 show the multiple comparison test results. Table 6 confirms that the use of the ring spinning system leads to a reduction in the initial shear rigidity of the fabrics in comparison with fabric woven using the rotor or vortex-spun yarns. While this finding is statistically significant at the 95% confidence level, the difference between the initial shear rigidity of fabrics woven with vortex and rotor-spun weft yarns was not found to be statistically significant at the 95% confidence level. Table 7 shows that the increase in the initial shear rigidity of fabric due to use of polyester weft yarns is statistically significant at the 95% confidence level. Moreover, no statistically significant effect, as confirmed in Figure 5(a), exists in the initial shear rigidity of fabrics woven with either cotton or viscose spun yarns.

Figure 5.

Surface plot of shear characteristics in the weft direction versus fiber type and weft yarn spinning system: (a) initial shear rigidity [G-init] (N/cm); (b) shear rigidity [G-KES] (N/cm); (c) shear hysteresis at a 0.5 degree shear angle [2HG0.5] (cN/cm); (d) shear hysteresis at a 5 degree shear angle [2HG5] (cN/cm).

Figure 6.

Schematic representation of (a) ring, (b) rotor, and (c) vortex-spun yarns.³⁴ RS: Ring spun; OERS: Open end rotor spun; MVS: Murata vortex spun.

Table 5.

Analysis of variance of shear properties in the weft direction at the 95% confidence level

	G-init (N/cm)		G (N/cm)		2HG0.5 (cN/cm)		2HG5 (cN/cm)
	F-value	Sig.	F-value	Sig.	F-value	Sig.	F-value	Sig.
Model	8.945	0.000	15.108	0.000	3.202	0.019	17.062	0.000
Spinning	6.721	0.007	6.239	0.009	8.600	0.002	14.240	0.000
Fiber	20.918	0.000	50.947	0.000	2.808	0.087	48.002	0.000
Spinning * Fiber	4.071	0.016	1.624	0.212	0.701	0.602	3.002	0.046

2HG0.5: 0.5 degree shear angle; 2HG5: 5 degree shear angle.

Table 6.

Multiple comparison test results (effect of spinning system in the weft direction)

Spinning system (I)	Spinning system (J)	G-init (N/cm)		G (N/cm)		2HG0.5 (cN/cm)		2HG5 (cN/cm)
Spinning system (I)	Spinning system (J)	Mean difference (I – J)	Sig.	Mean difference (I – J)	Sig.	Mean difference (I – J)	Sig.	Mean difference (I – J)	Sig.
Ring	Rotor	−0.8989^a	.030	−0.1707^a	.019	−0.4584	.093	−1.1314^a	.001
Ring	Vortex	−1.1056^a	.008	−0.1750^a	.016	−0.8526^a	.002	−1.1782^a	.000
Rotor	Vortex	−0.2067	.798	−0.0044	.997	−0.3942	.163	−0.0468	.981

Denotes the mean difference is statistically significant at the 0.05 level.

2HG0.5: 0.5 degree shear angle; 2HG5: 5 degree shear angle.

Table 7.

Multiple comparison test results (effect of fiber type in the weft direction)

(I) Fiber type	(J) Fiber type	G-init (N/cm)		G (N/cm)		2HG0.5 (cN/cm)		2HG5 (cN/cm)
(I) Fiber type	(J) Fiber type	Mean difference (I – J)	Sig.	Mean difference (I – J)	Sig.	Mean difference (I – J)	Sig.	Mean difference (I – J)	Sig.
Cotton	Polyester	−1.7967^a	0.000	−0.5089^a	0.000	0.4693	0.085	−2.2616^a	0.000
Cotton	Viscose	−0.0011	1.000	−0.0311	0.847	0.3495	0.233	−0.3158	0.433
Polyester	Viscose	1.7956^a	0.000	0.4777^a	0.000	−0.1198	0.831	1.9458^a	0.000

Denotes the mean difference is statistically significant at the 0.05 level.

2HG0.5: 0.5 degree shear angle; 2HG5: 5 degree shear angle.

Weft and warp yarns at the intersection points in the fabric can be assumed to be welded when considering the proposed equations by Grossberg and Park⁹ and Leaf and Sheta.¹¹ In other words, in the initial stage of woven fabric shear deformation, the magnitude of the applied shear force is inadequate to cause yarn slippage. Thus, under this assumption, the bending of yarns is the only probable deformation that can take place. This points to the bending rigidity of the weft yarn as the principle factor that affects fabric initial shear rigidity. Table 2 confirms that not only in comparison to rotor and vortex-spun yarns is the bending rigidity of ring-spun yarns is less, but also the bending rigidity of polyester spun yarns is generally higher than that of viscose or cotton spun yarns. The highest value of bending rigidity was 3.915 mN.mm², which was for the polyester vortex-spun yarns. According to the findings of Soe et al.,³⁴ the high bending rigidity of vortex yarns in comparison with ring and rotor-spun yarns could be due to the helical coil spring structure of ring and rotor-spun yarns, which exerts a lower bending moment to the structure. In vortex yarns, fibers in the core part are assumed to be straight and can be assumed to be a straight rod. It is obvious that the force required to bend a straight rod is always higher than the force needed to bend a coil spring of the same outer perimeter. Figure 6 denotes the schematic representation of these yarn spinning systems.

Fabric shear rigidity (G)

Table 5 shows statistical significance at the 95% confidence level (sig. < 0.05) for the effect of weft yarn fiber type and the weft yarn spinning system on fabric shear rigidity. This trend is in line with the results shown in Figure 5(b). Table 6 shows that while the shear rigidity of fabrics woven with ring-spun weft yarns is the lowest, no statistically significant difference at the 95% confidence level exists in the shear rigidities of fabrics woven with vortex or rotor-spun weft yarns. Table 7 points to the highest value of G in fabrics woven with polyester weft yarns in the weft direction and the statistically insignificant difference between woven fabrics using cotton or viscose spun weft yarns at the 95% confidence level.

The results seem to indicate that in this region of shear deformation, that is, BC in Figure 2, the extent of pressure between the yarns and yarn frictional resistance at intersection points are the two main effective parameters that affect fabric rigidity. As is shown in Table 2, ring-spun yarns generally have the least yarn–to-yarn friction. The lowest yarn–yarn friction of 0.112 was associated with cotton ring-spun yarn. The low value of the friction coefficient of ring-spun yarns in comparison with rotor and vortex-spun yarns could be due to the more uniform surface of ring-spun yarns. The belt fiber located in the outer surface of rotor-spun yarns and also the wrapper fiber located in the outer surface of vortex-spun yarns can increase both surface irregularity and roughness in comparison with ring-spun yarns.^18,27,34 Moreover, polyester spun yarns in general have the highest friction in comparison with cotton and viscose spun yarn despite their difference not being very clear. This is in line with the higher elastic modulus of fabrics woven with polyester weft yarns in comparison with fabrics woven with cotton and viscose spun yarns in the weft direction. The elastic moduli of the fabrics are shown in Table 3. The elastic moduli of woven fabric with polyester ring, rotor, and vortex-spun yarns were 125, 100, and 110.16 N/cm, respectively.

Fabric shear hysteresis at a 0.5 degree shear angle

Table 5 shows the effect of the weft yarn spinning system to be the only significant parameter on 2HG0.5 at the 95% confidence level (sig. < 0.05). The multiple comparison test results, as shown in Tables 6 and 7, reveal that the only statistically significant difference at the 95% confidence level is between ring and vortex spinning systems. This is in contrast to the weft yarn fiber type and rotor spinning system, which has no significant effect on shear hysteresis at a 0.5 degree shear angle in the weft direction. Figure 5(c) shows the instability caused in 2HG0.5 by the spinning system. Figure 2 shows that generally due to an increase in shear force, yarn slippage at the intersection points occurs and continues as far as point B. This intricate shear behavior, as shown in Figure 2, is generally due to the fact that a 0.5 degree shear angle occurs in the vicinity of point B as the result of differences in fabric tightness and pressure between yarns at the intersection points. Beyond point B fabric shear behavior is complex, due to variation in yarn slippage and structural differences of the fabrics. This explanation may be verified by Figure 5(c), which shows that no distinct or coherent difference can be observed for shear hysteresis at the 0.5 degree shear angle.

Fabric shear hysteresis at a 5 degree shear angle

According to Table 5, the effect of the weft yarn fiber type and the spinning system and their combined effect are statistically significant at the 95% confidence level (sig. < 0.05). Shear hysteresis of the fabric can be defined as the energy loss within the fabric shear cycle when deformation is allowed to return fully to the original state. Thus, there is an inverse relation between shear hysteresis and the recovery of fabric. The weft yarn fiber type is the dominant effective parameter that affects the shear hysteresis at a 5 degree shear angle. Table 6 shows that the reduction in 2HG5 due to the ring spinning system is statistically significant at the 95% confidence level in comparison with either rotor or vortex spinning systems. The difference between the rotor and vortex spinning system was not statistically significant at the 95% confidence level. As presented in Table 2, the higher frictional resistance of polyester rotor and vortex-spun yarns could be the reason behind this trend. Table 7 shows that the use of polyester fiber increases 2HG5 in comparison with either cotton or viscose fibers. The difference between the cotton and viscose fibers was not statistically significant at the 95% confidence level. This trend is confirmed by the surface plot of shear hysteresis at a 5 degree shear angle, as is shown in Figure 5(d). The higher values of shear hysteresis at the 5 degree shear angle can be attributed to the higher elastic modulus of polyester spun yarn woven fabric compared with cotton and viscose spun yarns woven fabrics, as shown in Table 3, which yields to fabrics with more tightness.

Fabric shear properties in the warp direction

Fabric initial shear rigidity (G-init)

Table 8 shows that the weft yarn fiber type and the combined effect of the weft yarn fiber type and spinning system as single factors affect the fabric initial shear rigidity in the warp direction. Moreover, as shown in Table 8, the weft yarn spinning system has no effect on the fabric initial shear rigidity in the warp direction. Tables 9 and 10 show that while an increase in fabric initial shear rigidity in the warp direction is due to the use of polyester weft yarns, statistically significant at the 95% confidence level, the use of cotton or viscose weft yarns is not statistically significant. This is confirmed by the surface plot of Figure 7(a), in which G-init versus the yarn spinning system and weft yarn fiber type is shown. The behavior illustrated in Figure 7(a) can be substantiated firstly by the combined effect of yarn bending and yarn slippage that occurs during the initial stage of fabric shear at the intersection points due to the higher friction of polyester yarns. Secondly, as shown in Table 3, the use of high-friction polyester weft yarn tends to increase the crimp level of warp yarns due to the increase in contact length at the intersection points. This leads to reduction in the available warp yarn free length of bending during the initial stage of the shear fabric deformation cycle. The increase in fabric initial shear rigidity according to the proposed equations by Grossberg and Park⁹ and Leaf and Sheta¹¹ is inversely proportional to the yarn free length of bending. This is in line with the observed increase in the initial shear rigidity of fabrics woven with polyester weft yarns.

Figure 7.

Surface plot of shear characteristics in the warp direction versus fiber type and weft yarn spinning system: (a) initial shear rigidity [G-init] (N/cm); (b) shear rigidity [G-KES] (N/cm); (c) shear hysteresis at a 0.5 degree shear angle [2HG0.5] (cN/cm); (d) shear hysteresis at a 5 degree shear angle [2HG5] (cN/cm).

Table 8.

Analysis of variance in the warp direction

	G-init (N/cm)		G (N/cm)		2HG0.5 (cN/cm)		2HG5 (cN/cm)
	F-value	Sig.	F-value	Sig.	F-value	Sig.	F-value	Sig.
Model	3.615	0.011	17.037	0.000	4.906	0.002	7.568	0.000
Spinning	1.467	0.257	7.849	0.004	0.116	0.891	1.940	0.173
Fiber	6.856	0.006	52.326	0.000	14.508	0.000	16.128	0.000
Spinning * Fiber	3.069	0.043	3.987	0.017	2.500	0.079	6.102	0.003

2HG0.5: 0.5 degree shear angle; 2HG5: 5 degree shear angle.

Table 9.

Multiple comparison test (effect of spinning system in the warp direction)

(I) Spinning system	(J) Spinning system	G-init (N/cm)		G (N/cm)		2HG0.5 (cN/cm)		2HG5 (cN/cm)
(I) Spinning system	(J) Spinning system	Mean difference (I – J)	Sig.	Mean difference (I – J)	Sig.	Mean difference (I – J)	Sig.	Mean difference (I – J)	Sig.
Ring	Rotor	−0.3856	0.559	−0.2236^a	0.003	−0.2193	0.844	−0.8025^a	0.044
Ring	Vortex	0.2411	0.793	−0.928	0.256	−0.0098	1.000	−0.3953	0.420
Rotor	Vortex	0.06267	0.233	0.1308	0.081	0.2095	0.856	0.4072	0.399

Denotes the mean difference is statistically significant at the 0.05 level.

2HG0.5: 0.5 degree shear angle; 2HG5: 5 degree shear angle.

Table 10.

Multiple comparison test results (effect of fiber type in the warp direction)

(I) Fiber type	(J) Fiber type	G-init (N/cm)		G (N/cm)		2HG0.5 (cN/cm)		2HG5 (cN/cm)
(I) Fiber type	(J) Fiber type	Mean difference (I – J)	Sig.	Mean difference (I – J)	Sig.	Mean difference (I – J)	Sig.	Mean difference (I – J)	Sig.
Cotton	Polyester	−1.3244^a	0.006	−0.4983^a	0.000	−1.7832^a	0.001	−2.0395^a	0.000
Cotton	Viscose	−0.3700	0.585	0.0081	0.989	−1.7832^a	0.001	−0.6239	0.234
Polyester	Viscose	0.9544^a	0.047	0.5064^a	0.000	0.0000	1.000	1.4156^a	0.003

Denotes the mean difference is statistically significant at the 0.05 level.

2HG0.5: 0.5 degree shear angle; 2HG5: 5 degree shear angle.

Fabric shear rigidity (G)

Table 8 shows that the effect of the weft yarn fiber type and spinning system as a single factor and the weft yarn fiber type and spinning system as a combined factor on G are significant at the 95% confidence level. Figure 7(b) shows that the effect of the weft yarn fiber type on G is dominant in comparison to the weft yarn spinning system. Tables 9 and 10 not only point to the statistical significance of ring and rotor spinning systems on G, but also shows that the use of rotor-spun weft yarn tends to increase the value of G in the warp direction. However, in the Tukey honest significant difference (HSD) test, spinning system categorization includes the vortex spinning system in the two defined classifications, and thus the effect of the vortex spinning system cannot be defined. The high friction of polyester weft yarn, as illustrated in Table 2, tends to increase G in comparison with cotton or viscose spun yarns. This in turn leads to an increase in yarn–yarn pressure at the intersection points in comparison with viscose or cotton weft yarns. This phenomenon is further intensified by the higher elastic modulus of fabrics woven with polyester weft yarns (as shown in Table 3).

Fabric shear hysteresis at a 0.5 degree shear angle

Table 8 shows the statistical significance of the effect of weft yarn fiber type on shear hysteresis at a 0.5 degree shear angle. Table 10 shows that 2HG0.5 in the warp direction decreases with weft cotton yarn in comparison with polyester or viscose weft yarns. Figure 7(c) shows the effect of weft yarn spinning instability together with the reduction in 2HG0.5 due to the use of cotton weft yarns in comparison with the use of polyester or viscose weft yarns.

Fabric shear hysteresis at a 5 degree shear angle

Table 8 shows that the effect of the weft yarn fiber type and combined spinning system–fiber type is statistically significant at the 95% confidence level. In addition, Tables 9 and 10 not only point to the statistical significance of the difference between ring and rotor weft spun yarns, but also illustrate the reduction in shear hysteresis at a 5 degree shear angle by weft cotton yarns in comparison with viscose or polyester weft yarns. This phenomenon is more or less clear in Figure 7(d), in which the effects of the weft yarn fiber type and spinning system on shear hysteresis at a 5 degree shear angle are shown. The existence of a high correlation between the two parameters of shear rigidity and shear hysteresis, as reported by Lu and Hu,³⁵ points to the similarity of the mechanisms that affect these two parameters. Since fabric shear rigidity is mainly influenced by yarn–yarn friction, by similar virtue shear hysteresis must also be governed by yarn–yarn friction. The yarn–yarn friction effectively is present during the full fabric shear cycle. The results simultaneously point to an inverse in shear rigidity and shear hysteresis at a 5 degree shear angle in fabrics woven with rotor-spun weft yarns and cotton weft yarns, respectively. The above explanations are confirmed by the 0.883 correlation coefficient between G and 2HG5.

Digital image correlation results

Figure 8 shows the effect of the polyester weft yarn spinning system on the force–strain performance of woven fabrics in bias extension using the DIC technique. The results are based on the evaluation of the central zone of samples over which pure shear deformation occurs. Figure 9 shows the difference between fabrics woven with polyester weft yarns spun on various spinning systems. This is in line with the experimentally obtained results exhibited by fabrics woven with ring-spun weft yarn, which have the least initial shear rigidity and shear rigidity. The DIC technique results, which are compatible with the bias extension test results, are shown in Figure 8. Figure 9 shows the DIC contour strain of the samples at 5, 10, and 20 N. The DIC contour strain distinctly illustrates the difference between fabrics woven with weft polyester ring-spun yarns and those woven with weft rotor and vortex-spun yarns. The results are compatible with different yarn slippage modes when samples were subjected to bias extension. Moreover, in all images, clear signs of the three distinct shear regions that are commonly associated with the bias extension test can be observed.

Figure 8.

Force–strain in the bias extension (central shear zone) based on the digital image correlation (DIC) technique and experimental results.

Figure 9.

Effective strain (digital image correlation) image of F-RI-P, F-RO-P, and F-V-P samples at 5, 10, and 20 N force in the bias extension test.

Conclusion

The shear characteristics of fabrics woven with cotton, viscose, and polyester weft yarns spun on ring, rotor, and vortex spinning systems were evaluated. The effectiveness of the weft yarn fiber type and spinning system on the shear characteristics of woven fabrics in the weft and warp directions was examined. It was found that fabrics woven with ring-spun weft yarns had the lowest value of shear rigidity and also initial shear rigidity in comparison with fabrics woven using rotor or vortex-spun weft yarns in the weft direction. It was also stated that, in general, the effect of vortex or rotor spinning systems on fabric shear rigidity and initial shear rigidity is statistically is not significant. The lowest and highest values of initial shear rigidity in the weft direction were found to be 3.11m and 6.70 N/cm, respectively. These were found to be associated with samples woven with ring viscose weft yarn and vortex polyester weft yarn, respectively. The spinning system of the weft yarn was found to be the only parameter affecting shear hysteresis at a 0.5 degree shear angle at the 95% confidence level. Moreover, both parameters, that is, the fiber type and spinning system of the weft yarn, showed a significant effect on shear hysteresis at a 5 degree shear angle. The lowest and highest values of shear hysteresis at a 5 degree shear angle were found to be 4.74 and 8.57 cN/cm, respectively. These were associated with cotton and viscose ring-spun yarns and polyester rotor-spun yarns woven fabrics, respectively. However, while the effect of the weft yarn fiber type on the fabric shear characteristics in the warp direction was found to be statistically significant, the weft yarn spinning system was found to have no significant effect on fabric initial shear rigidity and shear hysteresis at 0.5 and 5 degree shear angles in the warp direction. It was concluded that the DIC technique DIC is a successful tool by which the difference in shear characteristics of fabrics woven with different weft spun yarns can established.

In addition, the lowest value of shear characteristics of knitted fabrics was found to follow the same trends as those associated with ring-spun woven fabrics. It is of paramount importance to realize that no fundamental study has been undertaken in the field of shear behavior of knitted fabrics.

Ultimately, it was found that considering the effect of shear characteristics on tailorability and formability during garment manufacturing, it is beneficial to use cotton or viscose ring-spun yarns. It is of vital importance to consider the interactions between the warp and weft yarn specifications during engineering design of the woven fabrics.

Footnotes

Declaration of conflicting interests

The authors declared no potential conflicts of interest with respect to the research, authorship, and/or publication of this article.

Funding

The authors received no financial support for the research, authorship, and/or publication of this article.

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