Demystifying Numerical Models

Step-by Step Modeling of Engineering Systems

John Mo, Sherman Cheung, Raj Das

• Publisher: Butterworth-Heinemann
• Year: 2018
• Print ISBN: 9780081009758
• eBook ISBN: 9780081017562
• Topic: Technology & Engineering
• Subtopic: Mechanical Engineering
• Index: Technology & Engineering

Demystifying Numerical Models: Step-by Step Modeling of Engineering Systems is the perfect guide on the analytic concepts of engineering components and systems. In simplified terms, the book focuses on engineering characteristics and behaviors using numerical methods. Readers will learn how the computational aspects of engineering analysis can be applied to develop various engineering systems to a level that is fit for implementation. - Provides numerical examples and graphical representations of complex mathematical models - Includes downloadable spreadsheets of the numerical tools discussed that allow the reader to gain a hands-on understanding of how they work - Explains the engineering foundations behind the increasingly widespread and complex numerical models

Chapter 1

Introduction to Engineering Systems

Abstract

This chapter introduces the concept of systems modeling. System design needs to tackle five critical challenges, i.e., integrity, stability, compatibility, safety, and sustainability. The nature of these five challenges is explored in this chapter. Numerical analysis of systems offers a viable means of analyzing complex engineering systems when complexity of the combined system model from components makes it difficult to be analyzed analytically.

Keywords

Systems modelling; grand challenges; integrity; stability; sustainability; safety; compatibility; numerical analysis; engineering of systems

1.1 Systems Engineering Principles

A system is a unified set of components with different functionality working together toward a common goal. Not surprisingly, bringing many components together and aligning the varying functions toward the goal is already a challenge. Engineers have to overcome many challenges in the design and analysis of engineering systems. The following sections discuss critical grand challenges that an engineering system should be analyzed against.

1.1.1 Integrity

Engineers have the responsibility to create, design, manufacture, manage, and dispose of systems that operate safely, reliably, and with minimal negative impact to the society. Human lives can depend upon the quality of engineering project outcomes, and significant economic and environmental consequences can result from underperforming engineering facets. The concept of integrity in systems is to maintain total knowledge of the principles, characteristics, constraints, and processes that exist around the engineering system, so that any foreseeable problems can be prevented and any damages can be minimized, even in extreme circumstances. Numerical analysis helps to analyze integrity of engineering systems irrespective of whether they are linear, nonlinear, discretional, random, or any difficult to express characteristics.

1.1.2 Stability

The concept of stability originates from mechanics and structures. When mechanical structures are stable, all forces in the structures are in equilibrium such that loads are distributed to the structural members that can bear the load for a long time. Similarly, in other engineering branches such as electrical systems, a stable electrical circuit is one that has equilibrium of voltages and currents being distributed appropriately. An extension of this concept to systems is the maintenance of equilibrium condition, so that the system can operate and perform at the right level for a long period. Numerical methods can search through a broad range of variables in different scenarios to ascertain stability of the system during operations and extreme circumstances.

1.1.3 Compatibility

A compatible system is one that can exist and operate in a harmonious, agreeable, or congenial manner with other systems. Compatibility can occur in many ways. For example, for medical systems, a cochlear implant should be able to exist in the patient’s body in a chemically and biochemically stable state, and stays harmoniously with other parts of the body. Modeling analysis can highlight incompatible interfaces between components and is the first step in resolving this problem.

1.1.4 Safety

Fatality and many types of injuries people operating engineering systems are irreversible. It is important to make sure that systems will operate such that personnel using or staying nearby the system are not exposed to any danger. Large-scale engineering systems operating in an extreme environment is no doubt much more dangerous. Any minor error can escalate to disaster easily if not carefully managed. When designing such a system, many safety measures must be installed, and processes are defined and rehearsed to ensure that these safety measures are followed. Each of these measures should be analyzed to ensure even the extreme situation will not induce significant safety issues.

1.1.5 Sustainability

Large complex engineering systems require huge investments from the stakeholders. It is clear that such a system is not supposed to serve its purpose for a short time only. This kind of systems are expected to be in-service for 30 years, and often longer. If 30 years is the average number of years for a generation, it is common that such complex systems are still in operation after a couple of generations of working personnel. During this time, many changes can take place. For example, technology may change so that the system on board becomes incompatible with ground systems, or some components are worn out after many cycles of operations (the so-called ageing effect). These changes can happen much sooner than the expected service life. Sustainability must be designed into the system, so that appropriate maintenance and upgrade services can be done in timely fashion. Sustainability design can be analyzed based on operating parameters and system model that is usually not readily represented by analytical models. The use of numerical analysis is an obvious choice to project system performance over this long period.

1.2 Nature of Engineering Systems

Developers of complex engineering products such as an aircraft or a ship are facing new challenges in meeting business goals and competition globally. They need to remain competitive by developing innovative products and processes which are specific to individual customer’s requirements, completely packaged, and made available globally to make best use of resources within defined constraints. New operational requirements demand not only a functional system, but also a reliable and precise product.

The complexity of these engineering products also means the need for full understanding and predictability of the system. However, many systems are working on the principles of nonlinear, and sometimes discontinuous or piecewise models. Analysis of these systems by solving equations becomes very difficult because more and more independent variables are incorporated into the system.

Professional engineers and operation managers working in the new engineering environment tend to use modern computational tools to analyze these systems. Typical process is to adopt whatever available components that produce the required performance outcomes. However, the overall performance of systems would not be predictable. Numerical methods are techniques that analysis the system with numbers. To examine the core knowledge base, we will use a number of examples to illustrate the key knowledge elements.

Chapter 2

Basic Numerical Techniques

Abstract

The basic concept of solving engineering system numerically is to express the system with a set of related numbers that will change as the independent variable of the system changes. There are many types of relationships. This book aims to explore numerical solutions of some key engineering systems. It is not possible ...

Table of contents

• Cover image
• Title page
• Table of Contents
• Copyright
• Preface
• Chapter 1. Introduction to Engineering Systems
• Chapter 2. Basic Numerical Techniques
• Chapter 3. Wind Power and Aerodynamics Systems
• Chapter 4. Steady-State Heat Conduction Systems
• Chapter 5. Two-Dimensional and Transient Heat Conduction
• Chapter 6. Electrical Power Systems
• Chapter 7. Industrial Systems
• Chapter 8. Systems Engineering
• Chapter 9. Beam Deflection
• Chapter 10. Mechanical Vibration
• Chapter 11. Thin Plate Deflection
• Index