Local loads

Procedure 7-4 Stresses in Cylindrical Shells from External Local Loads. 449 

Stresses caused by external local loads are a major concern to designers of pressure vessels. The techniques for analyzing local stresses and the methods of handling these loadings to keep these stresses within prescribed limits has been the focus of much research. Various theories and techniques have been proposed and investigated by experimental testing to verify the accuracy of the solutions. 

Other methods are also available for analyzing stresses due to local loads, and several have been included herein. It should be noted that the methods utilized in WRC Bulletin 107 have not been included here in their entirety. The technique has been simplified for ease of application. For more rigorous applications, the reader is referred to this excellent source. 

Since this book applies to thin-walled vessels only, the detail included in WRC Bulletin 107 is not warranted. No distinction has been made between the inside and outside surfaces of the vessel at local attachments. For vessels in the thick-wall category, these criteria would be inadequate. 

Other methods that are used for analyzing local loads are as follows. The designer should be familiar with these methods and when they should be applied. 

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Lukasiewicz S. (1979) Local loads in plates and shells. PWN-Polish, Warszawa. Noordhoff, Leyden. 

Clarify characteristics of the sources and calculation methods for calculation of local loads. 

Consider whether the local protection influences the emission of the process. In that case, return to Calculation of Local Loads. 

On the loaded side of a slab subjected to an intense reflected blast wave, a region of the slab will fail if the intensity of the compressive wave transmitted into the slab exceeds the dynamic compressive strength of the material. For an intense wave striking a thin concrete slab, the failure region can extend through the slab, and a sizeable area turned to rubble which can fall or be ejected from the slab. For a thicker slab or localized loaded area, spherical divergence of the stress wave can cause it to decay in amplitude within the slab so that only part of the loaded face side is crushed by direct compression. 

The load curve of Germany is then scaled by the peak demand in the north-western region to get the local load curve. In DENA (2005), the peak demand is indicated at... 

CNTs have extremely high stiffness and strength, and are regarded as perfect reinforcing fibers for developing a new class of nanocomposites. The use of atomistic or molecular dynamics (MD) simulations is inevitable for the analysis of such nanomaterials in order to study the local load transfers, interface properties, or failure modes at the nanoscale. Meanwhile, continuum models based on micromechan-ics have been shown in several recent studies to be useful in the global analysis for characterizing such nanomaterials at the micro- or macro-scale. 

Gulino, R., Schwartz, P. and Phoenix, L. (1991). Experiments on shear deformation, debonding and local load transfer in a model graphite/ glass/epoxy microcomposites. J. Mater. Sci. 26, 6655-6672. 

The paper presents a method for the rational design of reinforced concrete chimneys or cement silos, towers for warm liquids and cooling towers subject to the effects of thermal gradients. The loads acting on the structure are divided into general loads and local loads. The effects of these loads on the concrete, the vertical reinforcement, and the horizontal (annular) reinforcement are studied with the aid of tables to obtain the significant stresses. A numerical example is given. 8 refs, cited. 

The effect of highly localized loading on the surface of yttria-stabilized zirconia ceramic was investigated by polarized Raman microprobe spectroscopy. Figure 17.2a-d shows a micrograph of an indentation print, a map of... 

The use of a vertical venturi separator was successfully used to clean steel and synthetic fibres from rubber crumb produced from an automotive tyre recycling plant. The major advantage of the venturi separator was an inherent positive feedback loop that exists at the throat. If more material was introduced to the throat then a higher velocity was generated at the throat to help retain particles (dependant upon air mover characteristics). The more conventional cleaning units observed had a negative feedback inherent in their design, with an increased local load of product the air velocity would... 

Future 42 V electric subsystems will be greatly enhanced using DLCs. Their long life and high cycle life are ideal for the variable power load required of new electrical subsystems. Localized load leveling of pulse loads will reduce the need to run high-current wires for long distances in the vehicle. 

This conclusion was confirmed also by a different series of experiments elucidating the role of plastic deformations. The experiments were performed in the regime of practically uniform rather than local loading. To this end we employed the procedure developed to study the initiation and development of autowave processes under conditions of uniform compression (see Section VII). But whereas previously what were subjected to y radiation were massive samples under conditions of high static pressure (i.e., the stage of accumulation of active centers in the sample was preceded by plastic deformation during compression), in this work the experimental procedure was modified to fit the task formulated above. 

The acceptable limit with respect to local load stresses is... 

In this example, 217 + 112 is indeed less than 2 x 166.7, so the ears are acceptable as regards local load stresses. 

If we knew the mean pad surface shape then Equations 6.41 and 6.42 would provide the local load balanced solid contact polishing pressure. However, the pad mean surface shape is itself influenced by the local contact pressure. If we knew the pressure distribution, then the displacement field of the pad under the wafer at equilibrium could be found by solving the momentum equations [25] ... 

PD 6439 1969 A review of the methods of calculating stress due to local loads and local attachments of pressure vessels. 

At higher loading rates the load signal is not of sufficient quality to directly determine dK/dt values. Hence, to better compare the results of various specimen configurations the local loading rate defined as Kc/tf (secant method) was used as the relevant rate parameter. Moreover, the dynamic method also yields directly Kp/tf values. 

Fig. 10. Effect of local loading rate on fracture toughness of PC using various specimen configurations and data reduction schemes.

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