Structural design

Air-Cooled Overhead Condensers Air-cooled overhead condensers (AOC) have been designed and installed above distiUation columns as integral parts of distiUation systems. The condensers generally have incliued tubes, with air flow over the finned sur ces induced by a fan. PrevaUing wind affec ts both structural design and performance. 

A further use of the Jenike method is its extension to the critical structural design of storage vessels. Because pressures can be calculated, it is possible to design for actual conditions rather than estimates. Also, flow-corrective devices may be designed by using his theoiy. 

Tower This may be tubular or lattice type to mount the mill s mechanism. The structural design is based on the cutout wind speed. 

Bloom, J. M. (ed.) 1983 Probabilistic Fracture Mechanics and Fatigue Methods Applications for Structural Design and Maintenance. American Society for Testing and Materials. 

Ellingwood, B. and Galambos, T. V. 1984 General Specihcations for Structural Design Loads. In Shinozuka, M. and Yao, J. (eds). Probabilistic Methods in Structural Engineering. NY ASCE. 

Kluger, P. 1964 Evaluation of the Effects of Manufacturing Processes on Structural Design Reliability. In Proceedings 10th National Symposium on Reliability and Quality Control, IEEE, Washington, 538-544. 

NASA Engineering Management Council (EMC) 1995 Preliminary NASA Standard, General Requirements for Structural Design and Test Factors of Safety. 1 August (http // amsd-www.larc.nasa.gov/amsd/refs/fac saf.html). 

Seismic zone basis must be specified for structural design. Soil data is important, especially for cases where extensive use of foundation piling is required with major cost impact. Availability of aggregate or natural pond stabilization materials near the site will not be considered for early cost estimates, but can be kept in mind for future planning if the project is given the green light. 

Current production aircraft include bonded structure designed up to 20 years ago as well as more recent designs on newer aircraft or derivatives. Materials, processes and design philosophy for metallic bonded structure have remained relatively stable over that period, while composite bonded structure has advanced significantly. Both will be reviewed and contrasted in the following sections. 

This specification covers the minimum requirements for the process, mechanical and structural design, materials, fabrication, shop inspection testing and supply for a flare system. The knock-out drum will be by N P Refinery. 

Structural design drawings for typical critical structures such as the lower elevation of the auxiliary building, reactor vessel, containment, reactor building and substructure, and concrete.. 

Fabrication of baghouses can be of modular design, factory-welded subassemblies, or structural design. The selection of the type of fabrication depends on size of unit, transportation requirements, site location, physical location of unit at plant (e.g., on roof), and materials of construction. 

In this book, attention will first be focused on macromechanics because it is the most readily appreciated of the two and the more important topic in structural design analysis. Subsequently, micromechanics will be investigated in order to gain an appreciation for how the constituents of composite materials can be proportioned and arranged to achieve certain specified strengths and stiffnesses. 

The key to a rational design process is establishing a set of mechanistic relationships that relate the configuration to its performance. Use of those mechanistic relationships is what distinguishes the structural designer from a dress designer. 

One of the key elements in laminated composite structures design is the ability to tailor a laminate to suit the job at hand. Tailoring consists of the following steps. We want to design the constituents of the laminate, and those constituents include the basic building blocks of the individual laminae and as well how they are oriented within the laminate. We design those constituents to just barely meet (with an appropriate factor of safety) the specific requirements for, say, strength and stiffness. 

In structural design, we start with a set of design requirements in order to define our objectives. The design requirements are merely a statement of what we want the structure to do. Tha verly simplistic definition will be expanded upon throughout the book, especially in Section 7.2.5 and in Section 7.6. With that objective in mind, we will now examine the steps we must take to attack the objective. 

Finally, failure analysis is the process of comparing actual performance with the desired performance. Thus, failure analysis is a nontrivial part of the structural design process. Facets of failure analysis including what failure means for a structure are addressed in Section 7.6 on Design Requirements and Design Failure Criteria. 

We have examined one view of structural design, and we will focus our attention later on in Section 7.4 how to reconfigure a composite structure as opposed to a metal structure. That reconfiguration process will be our principal interest. In this section, we simply address the basic structural design process irrespective of the materials used. 

The term design-analysis is used to emphasize the essential, but not dominant, role of analysis in the overall structural design process. Analysis plays no role whatsoever in dress design (with the possible exception of the now-classical analysis of a strapless evening gown). However, engineering design of a structure must involve analysis in the form of mechanistic relationships. Those mechanistic relationships must be used to quantitatively determine how to create the structural capabilities and then to match them to the structural requirements. The dis-... 

Recall from discussion of the structural design process in Section 7.2 that reconfiguration of the structure is an essential step. Reconfiguration occurs either to increase the capability or to decrease the weight because the structure has more than adequate capability. The term ca-pabi/ity s meant to include margin of safety relative to fracture, adequate resistance to buckling, sufficient difference of excitation frequency from resonant frequencies, etc. 

The purpose of this subsection is to familiarize the reader with some of the basic characteristics and problems of composite laminate joints. The specific design of a joint is much too complex for an introductory textbook such as this. The published state-of-the-art of laminate joint design is summarized in the Structural Design Guide for Advanced Composite Applications [7-5] and Military Handbook 17A, Plastics for Aerospace Vehicles, Part 1, Reinforced Plastics [7-6]. Further developments can be found in the technical literature and revisions of the two preceding references. 

Failure has many meanings or interpretations in the context of the structural design process. The main meaning is that failure is the inability of the structure to perform up to its design requirements. Those requirements can be expressed simplistically in terms of the following functional ways ... 

First, we must realize that many variables exist in any structural design. We can make a list of structural variables such as sizes, lengths of objects, materials, laminae orientations, and so on. those variables all have influence just as column length, moment of inertia, and Young s modulus influence column-buckling loads. The complete list of design variables will be called the vector Xj, and that vector will have N components. That list constitutes the definition of the structural configuration. 

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