Flexural properties of textile fiber | Propagation of flexural properties

Flexural properties of textile fiber | Propagation of flexural properties

In this article , garment merchandising will provide you the information of Flexural properties of textile fiber | Propagation of flexural properties.

Flexural properties of textile fiber

The behaviours presented by textile materials (fiber, yarn and fabric), when it is exposed to bending, are called flexural properties.


a) Flexural rigidity:

Flexural rigidity is the confrontation of a textile fiber against bending. It may also be define as the couple essential to bend the fiber to unit curvature. The unit of flexural rigidity is N-mm2, N-m2 etc.


Mathematically, Flexural rigidity, Rf =  1 x ηЕT2

4∏      ρ

Where, η = Shape factor

Е = Specific shear modulus (in N/tex)

T = Linear density (in tex)

ρ = Density (in gram/cm3)


Specific flexural rigidity:

The specific flexural rigidity is the flexural rigidity of a textile fiber of unit linear density. Specific flexural rigidity is typically stated as N-mm2/tex, N-m2/tex etc.


Mathematically, Specific flexural rigidity = 1 x ηЕ (1)2  =  1 x ηЕ

4∏      ρ        4∏    ρ

b) Bending recovery:

The power of recovery from an instant curvature of textile fiber is called bending recovery. For example, nylon of 15 denier shows 100% recovery from a small curvature, whereas only 20% recovery is gained from a large curvature.


c) Bending modulus:

Bending modulus may be defined as the ratio between bending stress and bending strain. Here, bending strain is typically stated as degree or radian.


So, Bending modulus = Bending stress

Bending strain

Shape factor:

The Shape factor is a quantity or number that specifies the thickness or cross-section of a fiber. Shape factor is typically stated by η.


In case , η =1, then the fiber is round shaped.

and        η >1, then the fiber thickness is increased.

If          η <1, then the fiber thickness is reduced.


Shape factor of different fibers:


Propagation of flexural properties from fiber to fabric

Good handle, drape and suppleness are valued when measuring textiles. These properties are appearances of material behaviour under low stress. Yarn and fabric properties are prejudiced by the constitutive fiber properties. Knowing these interrelations would allow making fibers with properties known to supply required leads to yarns or fabrics. The most object of this thesis is to look at the interrelations of fibers’ and fabrics’ flexibility swaying properties.

A selection of cellulose-based fibers and fabrics were chosen for characterization. A completely unique fiber characterization platform was wont to measure individual fiber flexibility. Fabrics were characterized using Kawabata Evaluation System, applications of Cusack’s drape test and Shirley stiffness tester. A cloth extraction method

Using a funnel nozzle (modified ring method) was built and wont to evaluate fabric handle. Secondary objective was to also evaluate these assessment methods and their suitability for material evaluation.

The results showed the positive relation of fiber modulus and suppleness. Fiber properties also influence the material properties, although the influence is just to an extent. The mechanics of a cloth under stress depends on the material type and structure. These mechanics will be heavily influenced with macro level structural changes like texturing in non-woven fabrics.

Fiber characterization platform fulfilled expectations but needs more development. The extraction method results, stress-deviation-curves, weren’t used fully during this thesis and need more research. The utmost extraction force values calculated from the curves duly didn’t correlate well with the opposite measurements.

Rest of the material characterization methods gave comparable results and showed good interrelations (between 58-90 %). KES and also the difficulty tester are designed for specific fabrics, but were capable to live other fabric types in addition. Biggest issues with KES are the high price and result reproducibility. Corresponding properties will be measured with less costly, separate appliances.


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