Design and stress calculations

The value of K represents the location of the neutral axis between the anchor bolts in tension and the concrete in compression. A preliminary value of K is estimated based on a ratio of the allowable stresses of the anchor bolts and concrete. From this preliminary value, anchor bolt sizes and numbers are determined and actual stresses computed. Using these actual stresses, the location of the neutral axis is found and thus an actual corresponding K value. A comparison of these K values tells the designer whether the location of the neutral axis he assumed for selection of anchor bolts was accurate. In successive trials, vary the anchor bolt sizes and quantity and width of base plate to obtain an optimum design. At each trial a new K is estimated and calculations repeated until the estimated K and actual K are approximately equal. This indicates both a balanced design and accurate calculations. 

A basic standard for piping engineering, for instance ASME Standard B31.3 for process piping is commonly employed. This addresses subjects such as the calculation methods to be employed for design and stress analysis, the treatment of thermal expansion, and the permissible stresses for various materials and temperatures. 

Example 3.17 Short carbon fibres with a diameter of 10 fim are to be used to reinforce nylon 66. If the design stress for the composite is 300 MN/m and the following data is available on the fibres and nylon, calculate the load transfer length for the fibres and also the critical fibre length. The volume fraction of the fibres is to be 0.3. 

Rib design An example of how ribbing will provide the necessary equivalent moment of inertia and section modulus will be given. A flat plastic bar of IV2 in. x 3/8 in. thick and 10 in. long, supported at both ends and loaded at the center, was calculated to provide a specified deflection and stress level under a given load. The favorable material thickness of this plastic is 0.150 in. Using... 

This information is supported by stress-strain behavior data collected in actual materials evaluations. With computers the finite element method (FEA) has greatly enhanced the capability of the structural analyst to calculate displacement, strain, and stress values in complicated plastic structures subjected to arbitrary loading conditions (Chapter 2). FEA techniques have made analyses much more precise, resulting in better and more optimum designs. 

Figures 4E, 5E, 6E and 7E depict the individual coil hoop stresses along the radial direction at the middle plane of each coil. Particularly for the high-field 11.75T magnet, the stress calculation indicates that the most inner coils are the ones that are most crucial in the design, because they are exposed to the greatest magnetic fields and sfresses. If is possible to use different superconductors (i.e. cheaper) to build the outer superconducting coils, since these are well within the superconductivity limit.

The design of thickwalled components for pulsating pressure is based on the stress calculation with analytical or numerical methods and the determination of the maximum equivalent stress in relation to the admissible stresses at uniaxial conditions. The latter have to be extracted from Woehler-tests with specimen. If the stresses yield too large at load conditions including a safety factor, the design must be optimized by avoiding the major stress concentrations at bore intersections. The avoidance of T-intersections is reducing stresses by factor 2-3 (Fig. Id). 

---