Torsional resistance

The relative efficiency of the two stiffeners is compared principally on the basis of the torsional resistance. The reason for the lower efficiency rating of the sandwich-blade stiffener is its low torsional resistance (and the bending stiffness is not high) and for the high efficiency of the hat stiffener is its high torsional resistance because of the basic open-versus closed-section stiffener issue. Stiffener torsional resistance affects the buckling load of a stiffened panel or shell as shown by Card and Jones [7-3]. 

Since the measurements may be carried out over a period of several hours to several days, it is essential to design the balance and its supports so that the effect of any thermal change will be minimized. The important factors involved are (1) the relative length of the two halves of the balance beam, (2) the torsional resistance of the supporting wire, (3) the relative position of the beam to the supporting frame, and (4) torsional resistance of the end-supporting wires. 

The losipescu torsion measurement results are given in Table 1, with an example stress-displacement curve shown in Figure 2. These values are indicative of a relatively torsion-resistant material, particularly given the low density of the carbon composite. The stress-displacement curves indicate little delamination or other failures until ultimate failure. 

R, = torsional resistance factor Q = equivalent vertical force at each support due to dead weight and overturning moment, lb q = uniform vertical load on ring beam, Ib/in. q< = tangential shear, Ib/in. 

It has been found by tests as well as by mathematical analysis that the torsional resistance of a section, made up of a number of rectangular parts, is approximately equal to the sum of the resistances of the separate parts. It is on this basis that nearly all the formulas for noncircular sections have been developed. For example, the torsional resistance of an Tbeam is approximately equal to the sum of the torsional resistances of the web and the outstanding flanges. In an I-beam in torsion the maximum shearing stress will occur at the middle of the side of the web, except where the flanges are thicker than the web, and then the maximum stress will be at the midpoint of the width of the flange. Reentrant angles, as those in I-beams and charmels, are always a source of weakness in members subjected to torsion. 

The column web thickness-to-depth ratio, tcw/Tc influences the column flange rotation. The column web stiffness, when an idealization of the column cross section is made, as shown in Fig. 4, is proportional to the ratio, (tcw) /Tc. The greater the column web stiffness, the greater the torsional resistance provided to restrain column flange rotation, 6c, and beam lateral-torsional buckling. In the case of the W14 x 283... 

Expansion inserts are placed in predrilled or premolded holes and expanded against the walls by insertion of a screw. Torsional resistance and pull-out retention are obtained by embedding the knurls into the material. The inserts can be obtained with or without heads, depending on design requirements. 

Physical properties, such as tensile resistance, compression resistance, shock resistance, torsion resistance, the effect of permanent winding, bending resistance, etc., temperature property and the chemical properties of POF have been studied systematically. ... 

Fig. 8.15 A sketch of the cross section subjected to torsion. Note that Gdry and the overall torsional resistance are experimentally determined. The only unknown is G of the saturated region (Siriruk et al. 2009b)...

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