Stress twisting

Torsions-faden, m. torsion filament or wire, -festigkeit, /, torsional strength, -kraft, /, torsional force, -spaonung, /, torsional stress, twisting stress, -wa(a)ge,/. torsion balance, winkeh m. angle of torsion. 

Gathering data on torsion is essential when reverse engineering a shaft. Torsion stress is a variation of shear stress that results from a force applied parallel to the surface. Torsion stress twists the part in response to a torque, as can be seen in an automobile driveshaft. Considering a cylindrical shaft subject to a torque, T, the maximum torsion stress, occurs on the shaft surface and is expressed by Equation 3.22, where r is the shaft radius and / is the polar moment of inertia of cross-sectional area ... 

Stress in a Cord. Twisting two or more filaments together to form a cord reduces the overall modulus and strength of the constmction. The degree of the reduction depends on the individual filaments (55). If the lay length is significantly higher than the filament diameter, the stress is... 

Cord materials such as nylon, polyester, and steel wire conventionally used in tires are twisted and therefore exhibit a nonlinear stress—strain relationship. The cord is twisted to provide reduced bending stiffness and achieve high fatigue performance for cord—mbber composite stmcture. The detrimental effect of cord twist is reduced tensile strength. Analytical studies on the deformation of twisted cords and steel wire cables are available (22,56—59). The tensile modulus E of the twisted cord having diameter D and pitchp is expressed as follows (60) ... 

K. Kabe, M. Koishi, and T. Akasaka, "Stress Analysis for Twisted Cord and mbbet of FRR," presented at 6th Japan—U.S. Conference on Composite Materials, Odando, Fla., June 1992. 

Figure 7 shows these results schematically for both twist and tilt crack deflections. Thus, for the stress intensity factor required to drive a crack at a tilt or twist angle, the appHed driving force must be increased over and above that required to propagate the crack under pure mode 1 loading conditions. Twist deflection out of plane is a more effective toughening mechanism than a simple tilt deflection out of plane. 

The rotor blades shall be of the tapered/twisted, free vortex, reaetion design (Figure 5-21). The blades shall be speeifieally designed for the dirty FCC flue gas applieation. Seller shall provide a Goodman Diagram for the highest stressed loeation... 

Component reliability will vary as a function of the power of a dimensional variable in a stress function. Powers of dimensional variables greater than unity magnify the effect. For example, the equation for the polar moment of area for a circular shaft varies as the fourth power of the diameter. Other similar cases liable to dimensional variation effects include the radius of gyration, cross-sectional area and moment of inertia properties. Such variations affect stability, deflection, strains and angular twists as well as stresses levels (Haugen, 1980). It can be seen that variations in tolerance may be of importance for critical components which need to be designed to a high reliability (Bury, 1974). 

Shear stress-strain data can be generated by twisting (applying torque) a material specimen at a specified rate while measuring the angle of twist between the ends of the specimen and the torque load exerted by the specimen on the testing machine. Maximum shear stress at the surface of the specimen can be computed from the measured torque that is the maximum shear strain from the measured angle of twist. 

The ratio of stress to strain in a given material. The strain may be a change in length, a twist or shear, or a change in volume. Modulus of elasticity in this scientific sense must not be confused with the term modulus which has a particular significance in rubber technology. 

The ratio of shear stress to shear strain. A property which determines the rate at which elastomers stiffen as the temperature is lowered. The force required to twist the test piece through 90° is measured at each temperature and the modulus calculated from a formula. 

Actually, in a twisted way of thinking, stress might be one of the most fruitful areas in which to apply innovative new thinking and paradigms in order not only to improve mechanistic understandings of disease but also to enhance the ability to implement new knowledge in society to improve overall public health. 

The usual starting point is to look at how the object is stressed mechanically in service and simulate it - drop a loaded sack, put force on a handle, pressurise a pipe, etc. The more complicated the service stresses are, the more complicated the simulation will become, for example, if a handle may be bent and twisted, this has to be tested together, whereas a sack could fall on its side or a corner and this could be tested sequentially. 

In the absence of chloroquine, the apparent torsion constants for supercoiled pBR322 DNAs with normal (allosteric transitions in secondary structure, so the secondary structures of supercoiled and linear DNAs might not be identical, despite their similar torsion constants. 

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