Effect of Flexural Rigidity in Effect of Flexural Rigidity in TextileTextile

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Name : AZIZUL HAQUE JUELID: 112-23-2538Batch: 18th Batch (Session 2011-2015)Major: Fabric Manufacturing Email: azizulhaque230@gmail.comBlog: www.textilestudypoint.blogspot.comDepartment of Textile Engineering

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Daffodil International UniversityDepartment of Textile Engineering

102, Shukrabad, Mirpur Road, Dhanmondi, Dhaka-1207Bangladesh

Flexural Rigidity:

Flexural rigidity is the stiffness of a textile fiber. It can be defined as the couple needed to bend a fiber.

Mathematically,

Flexural rigidity = (1/4π) (ηET2/ρ)Where, 

η = shape factor, 

E = specific shear modulus, 

T =linear density (Tex), 

ρ = density (gm/cm3)

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Flexural Rigidity in TextileThe Flexural rigidity of fabric’s bending stiffness is important for both consumer and industrial applications of fabrics. While fabric stiffness may not be wanted too high for a good drape in apparel and garment fabrics, it may be an important requirement especially for industrial fabrics to be used widely in heavy duty applications such as geotextiles and forming fabrics. For example, a forming fabric that easily bends under load and its own weight between the drive rolls may cause poor sheet formation during process.

Effect of Flexural Rigidity in knitted fabricsFigure 1 show flexural rigidity for all the knitted fabric in course-wise and wale-wise directions. For PES/PBT knitted fabrics (fig.1), the increase in PBT increase the flexural rigidity of the knitted fabrics in both directions. However, the effect is more significant in the wale-wise direction due to the knitted fabric construction once the interloping of the knitted wales leads to higher flexural rigidity. At the same time, as PBT is a stiff fibre it affects the blend more in the wale-wise direction.

FIG.1 : Flexural rigidity of weft knitted fabric .

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It is related to handle & drape of fabrics.

The recovery from bending is a factor of creasing.

Bending plays an important role in the arrangement of fibre in yarn.

Bending strength is important in wear.

Importance

Flexural rigidity can be used to design sport clothing for professional football players. Drape and flexibility are important parameters to improve the comfort of the football players as they influence positively the clothing fitness to the body and freedom to move within the match.

Industrial Importance

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Flexural rigidity of different textile fibre

Different textile fibre has different flexural rigidity, they are not same. In the table some common fibre and its flexural rigidity given.

Fibres F.R of Textile fibre

Viscose rayon 0.19

Wool 0.20

Silk 0.19

Acetate 0.08

Nylon 0.14

Glass 0.89http://textilestudypoint.blogspot.com/

EXPERIMENTALThe flexural rigidity is related to the The flexural rigidity is related to the tensile modulus for a simple body, as in tensile modulus for a simple body, as in the case of a single fiber; however, this the case of a single fiber; however, this relationship is not so straightforward in relationship is not so straightforward in the case of a fabric. To measure the fabric the case of a fabric. To measure the fabric stiffness, the cantilever method is widely stiffness, the cantilever method is widely used in practice. The bending rigidity of a used in practice. The bending rigidity of a fabric is given byfabric is given byG=wcG=wc33

where where w w is the fabric weight per unit area is the fabric weight per unit area and and c c is the half of the fabric bending is the half of the fabric bending length. The fabric bending length is length. The fabric bending length is measured by using cantilever stiffness measured by using cantilever stiffness measurement equipment developed by measurement equipment developed by Shirley Institute. As shown in Figure 3.Shirley Institute. As shown in Figure 3.

Figure 3. Schematic representation ofFigure 3. Schematic representation ofstiffness tester.stiffness tester.

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Relation of flexural rigidity in textile

The relationship between the properties of fabrics and their flexural rigidity, warp diameter, filling diameter, number of warp yarns per unit length, number of filling yarns per unit length, total number of yarns per unit area, and modulus of fabric versus the measured flexural rigidity are plotted.

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Bending stiffness characteristics of fabrics arise from the structure of the fabric itself as well as from the structure of the constituent yarns. A stiff yarn like a wire makes a fabric stiff regardless of the weave. However, using flexible strands, one can produce fabrics with a wide range of stiffness, depending on the fabric structure. In this study, analytical relations have been found between fabric stiffness (or flexural rigidity) and various fabric structural parameters. Yarn (or fiber) diameter is the most important structural property of a fabric to affect its stiffness. As the fiber or yarn diameter is increased, the fabric stiffness increases.

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