Stiffness factor

Stiffness For an isotropic material with a modulus of elasticity E, the bending stiffness factor (El) of a rectangular beam b wide and h deep stiffness is ... 

Under transverse loading, bending moment deflection is proportional to the load and the cube of the span and inversely proportional to the stiffness factor, El. Shear deflection is proportional to the load and span and inversely proportional to shear stiffness factor N, whose value for symmetrical sandwiches is ... 

TABLE 9.1 Stiffness factor, ct, skeletal factor, s, and Kuhn length, A, for some vinyl polymers... 

Stiffness factor Kilogram-force centimeter squared kgf cm2 9.81 x 10 4 Nm2... 

Stiffness. Paper is nearly twice as stiff in the machine direction as it is in the cross direction. The degree of stiffness is related to the caliper (substance), so that the thinner the paper, the lower is the stiffness, to the extent that the stiffness factor is proportional to the cube of thickness. Arising from this is a basic recommendation that the thinner the paper the more advantageous it is to print in the machine direction because of its greater stiffness. 

FIGURE 5 The dependence of stiff factor A4> on solubility parameter component 8. ... 

An example of the foregoing is an RP beam [Figure 8.17 (c)] made up of five layers having three different moduli of elasticity, and three different strengths. The neutral axis, found by applying the neutral axis X equation, is 0.415 in fi-om the bottom of the cross-section. Distances from the neutral axis to the centers of the individual layers are computed, and the stiffness factor El calculated. This is found to be ... 

Interaction factors for two floating piles in a semi-infinite mass. Note (1) 1/ = Poisson s ratio of soil mass, (2) K = (Ep/EJR where Ep is the Young s modulus of pile E, is the Youngs s modulus of soil mass is the area of pile/(rcd /4) Ris the pile stiffness factor. (From Poulos, H.G. and Davis, E.H., Elastic Solutions for Soil and Rock Mechanics, John Wiley Sons, New York, 1974. Reprinted with permission of Harry Poulos.)... 

At the neutral axis the statistical moment Q is the weighted moment of the flange or of the roving about the neutral axis El, is the stiffness factor of flange plus roving and b is the total thickness of the mat at the neutral axis plus the effective thickness of the cellular filler. This effective thickness may be computed in accordance with the principles set forth on combined action. If, for example, the shear modulus of the cellular core is Vis the shear modulus of the mat-reinforced material, the effective width of the core is 0.8/15 or 0.053 in. The total effective width of the mat and the care at the neutral axis is therefore 0.05 + 0.05 + 0.053 = 0. 1 53 in. 

In a rectangular structural sandwich of the same dimensions as above whose facings and core have moduli of elasticity Eyand respectively, and a core thickness C, the bending stiffness factor El is... 

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