Flexural rigidity

Textile fibers must be flexible to be useful. The flexural rigidity or stiffness of a fiber is defined as the couple required to bend the fiber to unit curvature (3). The stiffness of an ideal cylindrical rod is proportional to the square of the linear density. Because the linear density is proportional to the square of the diameter, stiffness increases in proportion to the fourth power of the filament diameter. In addition, the shape of the filament cross-section must be considered also. For textile purposes and when flexibiUty is requisite, shear and torsional stresses are relatively minor factors compared to tensile stresses. Techniques for measuring flexural rigidity of fibers have been given in the Hterature (67—73). 

For a beam of width b, the formula for flexural rigidity (D) can be expressed as ... 

Considering another point of view, Swedish manufacturer DIAB quotes an example of a sandwich and a laminate of approximately the same flexural rigidity the laminate is 2.8 times heavier than the sandwich panel. 

Takasone T, Juodkazis S, Kawagishi Y, Yamaguchi A, Sakakibara SM, Nakayama H, Misawa H (2002) Flexural rigidity of a single microtubule. Jpn Appl J Phys 41(5A) 3015-3019... 

Drape. Drape is closely related to fabric hand. Whereas hand is based on tactile criteria, drape refers more to a fabric s appearance by its tendency to fall into graceful, three-dimensional folds. Fabric drape depends to a laige degree on the same properties that influence hand, ie, flexural rigidity, thickness, and compressibility. Although stiffness is normally measured in a single direction, drape implies bending in all directions. 

Feigner, H., Frank, R., Biernat, J., Mandelkow, E.-M., Mandelkow, E., Ludin, B., Matus, A., and Schliwa, M. (1997). Domains of neuronal microtubule-associated proteins and flexural rigidity of microtubules./ Cell Biol. 138, 1067-1075. 

Table VI. Mean Flexural Rigidity, Weight Gain and...

Flexural rigidity and moisture regain, mean of 10 specimens weight gain, mean of 2 specimens. 

The stiffness of a fabric can be objectively determined as the average of the flexural rigidities (in warp and weft direction). These depend on the shear modulus and the coefficient of friction both are influenced by swelling and, therefore by humidity. 

Fiber-reinforced polymer systems, 38 Fickian diffusion, 665 Fick s law, 663,684 Field flow fractionation, 20 Filled polymers, 38 First normal stress coefficient, 545 difference, 640 First-order transition, 27,152 Flame-retardant additives, 861 Flammability, 847 Flashing, 804 Flash line region, 807 Flexibility of a chain molecule, 246 Flexible polymer molecules, 706 Flexural deformation under constant load, 825 Flexural formulas, 826 Flexural rigidity, 877 Floor temperature, 751 Flory-Huggins... 

Figure 5. The flexural rigidity of degraded cotton print cloth (50-Mrad dose) after application of various acrylic resins (A1-A4) and grafted monomers (M1-M4) PE = polyethylene, AD = air dried. See text for identification of resins and monomers.

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