Second Shell Course Thickness

The thickness ( 2) depends on the height of the bottom course h, inches), the radius-thickness of the bottom course (rti) and the thickness of the second course as calculated in the paragraph on the upper shell course (t2a inches). The equation is... 

The second method, the variable point method, is an extension of the one-foot method in that it calculates a more exact location of the maximum stress near the junction of the bottom or shell courses with differing thickness. In this case the bottom course is assumed to be hinged at its junction with the bottom plate. Hence the deflection due to internal pressure at the junction is equal to the deflection due to an applied shearing force as shown in Fig. 13.5. From Section 5.2.1,... 

However, the bending stresses from wind and seismic loads increase with X. Therefore, the shell thickness must be increased more frequently or in greater degrees in progressing down the column. For example, the second increase in shell thickness may require 1/8 in. increment and may be satisfactory for two or three more courses down. The calculations are continued in this manner until you reach the junction of the vessel with the supporting skirt. 

From this point in the preparation, one of two outcomes may be chosen either thickening of the HgS layer or an increase in the outermost CdS layer thickness. The first alternative is achieved by repeated addition of mercury ions and H2S to the former solution, the second by successive addition of Cd " and HjS. Both branches have been followed, giving rise to a family of new materials having a 4.7-nm CdS core, one to three layers of HgS as the well and one to five monolayers of CdS acting as the outermost shell. The course of the preparation has been followed by optical spectroscopy, polarography, mass spectrometry, and electron microscopy. 

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