41—making–up Properties of Wool Fabrics

A mathematical model is presented for the buckling of fabric under combined shear and tensile forces. This model takes account of the anisotropic characteristics of the fabric in terms of the flexural rigidities in the warp and weft directions, its corresponding Poisson's ratios, the shear modulus, and the width to height ratio of the rectangular specimen. Numerical solutions show that the critical shear force at which buckling starts and the number of buckles increase with increasing pre-tension. Furthermore, as the height or width of the rectangular specimen decreases, the critical shear force increases. For most fabrics where the flexural rigidity in the warp direction is higher than that in the weft direction, the results suggest that during tailoring, it is beneficial to orient the fabric so that the tension is in the warp direction to reduce the possibility of shear buckling in the garment. I In the process of tailoring a flat piece of fabric into a three-dimensional surface, shearing must occur. This ability of fabric to deform within its plane is important not only to tailorability [3,8,13], but also to the handle of fabric [5, 61. As the shear stress increases, however, a critical stage is reached where the fabric starts to deform out of its plane, i.e., it buckles. The shear force at which this occurs is termed the critical shear force. Behre [I] treated the fabric specimen under combined shear and tension as a cantilever beam and used the classical theory of elasticity to obtain the criterion where V, is the critical shear force, N is the tensile load, and w/h is the ratio of width to height of the specimen and is called the aspect ratio. Cusick [2] arrived at a similar equation by simply estimating the couple at which the tension at two diagonal corners reduces to zero. Treloar [ 12] considered the stress distribution in a sheet and showed that the tensile stress in a direction normal to the direction of shearing cannot eliminate compressive stresses in certain directions of the sheet; therefore, it cannot eliminate an inherent tendency to buckling. All these classical static analyses treated the fabric as an isotropic material and neglected an important parameter: the fabric flexural rigidity. ' In this paper, we discuss a more appropriate model for fabric buckling in which anisotropic characteristics of the fabric are accounted for. The results are then used to discuss the influence of the aspect ratio, the tensile stress, and the flexural rigidity on the critical shear stress.Theory . The energy method of Rayleigh-Ritz [ 10, 11 was used to investigate the buckling of a rectangular piece of fabric subjected to shear and tensile loads as shown _ in Figure 1. This method is based on the principle that during loading, the elastic strain energy DU stored in a structure is equal to the work done 0 Tby the applied loads, i. e., FIGURE 1. A rectangular specimen subjected to shear ( V) and tensile (N) forces per unit length; h and w are the height and width of the specimen.

Section: Resultsmentioning

confidence: 99%

mentioning

confidence: 99%

A Model for Fabric Buckling in Shear

1985

“…Extensive research conducted since the 1960s has indicated that the more important fabric properties in producing suits and tailored garments with good appearance and stability are fabric weight; bending, shear, and tensile properties; longitudinal compressibility; dimensional stability; and possibly surface frictional characteristics [9,10,11,12,14,18]. Various data charts [ 12] have been developed using different combinations of mechanical properties to define the region in which fabrics would be expected to have good tailoring performance and handle.…”

mentioning

confidence: 99%

Effects of Structure and Finishing on the Mechanical and Dimensional Properties of Wool Fabrics

Wemyss

Boos

1991

We have investigated the effects of the interaction between fabric cover factor and finishing on fabric properties with a systematically designed array of fabric structures and finishing treatments. Permanent setting induced in finishing had the greater effect on fabric mechanical and dimensional properties. For lightly finished fabrics with a low degree of set, the influence of cover factor was significant. For the entire range of plain weave and twill fabrics, the hygral expansion could be related to the weave crimp and the shear properties of the fabric. There was also a contribution from yarn curvilinear expansion.The tailoring performance of woven wool fabrics is affected by a wide range of fabric properties. Extensive research conducted since the 1960s has indicated that the more important fabric properties in producing suits and tailored garments with good appearance and stability are fabric weight; bending, shear, and tensile properties; longitudinal compressibility; dimensional stability; and possibly surface frictional characteristics [9,10,11,12,14,18]. Various data charts [ 12] have been developed using different combinations of mechanical properties to define the region in which fabrics would be expected to have good tailoring performance and handle. Naturally, the details of such charts are determined by the end-use requirements of the fabric (e.g., men's suiting or ladies' wear). Formability, derived from fabric bending and longitudinal compressional properties, or from bending and tensile properties, has been shown to predict tailoring performance to some extent [9, 10]. Other formability parameters incorporating bending, shear, and tensile properties have also been used [ 14]. Predictors of seam pucker and overall tailoring performance [ 15] (derived from a range of mechanical data) have also been developed with limited success.Although these approaches have ascertained the properties that ensure good tailorability, there remains the problem of predicting a fabric's mechanical properties and dimensional stability from the construction and the routine used to finish it. Moreover, a finisher would be greatly aided by a knowledge of how fabric properties might be changed if they fall outside the guidelines set by the tailor.In the 1960s, Karrholm and co-workers examined the effect of fabric structure and finishing on some of the mechanical properties of wool fabrics [5]. They concluded that (a) finish was more important than construction in determining some fabric properties, e.g., bending stiffness and shear stiffness, (b) the properties of highly sett (high cover factor) fabrics were more affected by finishing than those of lightly sett (low cover factor) fabrics, and (c) the effect of construction was more pronounced in lightly finished fabrics. More recently, Mori described techniques, both successful and unsuccessful, used by a Japanese finisher to meet the specifications for fabric properties requested by tailoring firms [ 11 ]. Mori also reported the effect of individual construction and fini...

“…Many researchers have investigated the relationships between these properties and the mechanical properties of fabric. Lindberg et al 5 and Waesterberg 6 investigated the relationship between the making-up properties of several wool fabrics and the mechanical properties of fabrics such as tensile strain, bending stiffness and shearing. Morooka and Niwa 7 , Shishoo 8 , and Kawabata and Niwa 9 investigated the factors that contribute to the making-up properties and a good appearance in finished garments by measuring the mechanical properties of fabrics, such as extension, bending, shearing, compression, and surface friction.…”

Section: Introductionmentioning

confidence: 99%

“…Relating to garment tailoring, the ability of fabric deformation is called the making-up property, tailorability or formability [5][6][7] . Many researchers have investigated the relationships between these properties and the mechanical properties of fabric.…”

Section: Introductionmentioning

confidence: 99%

Measurements and prediction of fabric surface fitting ability under low tension

Kim

Suzuki

Takatera

2017

This study investigated the surface fitting ability of woven fabric under low tension using a new measurement method. The limit angle of shear buckling, the maximum shear angle, is defined as the surface fitting ability. To estimate the maximum shear angle, we measured the base radius of a spherical crown of woven fabrics while covering the spherical surface without wrinkles. The relationship between the maximum shear angle and base radius was calculated numerically. We constructed a new testing equipment to determine the surface fitting ability of fabric with an aluminium hemisphere set on a laboratory jack and acrylic boards with holes of varying size at the centre. Nineteen kinds of woven fabric samples and three hemispheres of different radii were used to measure the surface fitting ability. The relationships among the maximum shear angle and mechanical and structural properties were investigated. Thickness, interlacing point density and shear stiffness showed high correlation with the surface fitting ability. Using these properties, a new prediction formula for surface fitting ability was proposed. The predictive values showed a good agreement with the measured values. Therefore, the proposed method and the prediction equation are useful for evaluating the surface fitting ability of woven fabrics. The effect of the sphere radius on the surface fitting ability was also clarified.