Engineering is the application of scientific, economic, social, and practical knowledge, in order to design, build, and maintain structures, machines, devices, systems, materials and processes. It may encompass using insights to conceive, model and scale an appropriate solution to a problem or objective. The discipline of engineering is extremely broad, and encompasses a range of more specialized fields of engineering, each with a more specific emphasis on particular areas of technology and types of application. Engineering branches:
To design a technological system, engineers must attend to both the whole and its minutest details, which require knowledge and expertise in diverse areas. Consequently engineering is divided into many branches. Here are the 10 major ones: 1. Electrical Engineering
2. Mechanical Engineering3. Civil Engineering4. Chemical Engineering5. Environmental Engineering6. Nuclear Engineering7. Textile Engineering8. Aerospace Engineering9. Petroleum Engineering10. Biological Engineering
Mechanical Engineering:Mechanical engineering is a discipline of engineering that applies the principles of physics and materials science for analysis, design, manufacturing, and maintenance of mechanical systems. It is the branch of engineering that involves the production and usage of heat and mechanical power for the design, production, and operation of machines and tools. It is one of the oldest and broadest engineering disciplines. Applications:
The principal lines of development of machinery have been an increase in the speed of operation to obtain high rates of production, improvement in accuracy to obtain quality and economy in the product, and minimization of operating costs. These three requirements have led to the evolution of complex control systems. Here are some important applications of mechanical engineering 1- Development of machines for the production of goods.
The high standard of living in the developed countries owes much to mechanical engineering. The mechanical engineer invents machines to produce goods and develops machine tools of increasing accuracy and complexity to build the machines.
2- Development of machines for the production of power.The steam engine provided the first practical means of generating power from heat to augment the old sources of power from muscle, wind, and water. One of the first challenges to the new profession of mechanical engineering was to increase thermal efficiencies and power; this was done principally by the development of the steam turbine and associated large steam boilers.
The 20th century has witnessed a continued rapid growth in the power output of turbines for driving electric generators, together with a steady increase in thermal efficiency and reduction in capital cost per kilowatt of large power stations. Finally, mechanical engineers acquired the resource of nuclear energy, whose application has demanded an exceptional standard of reliability and safety involving the solution of entirely new problems
3- Development of military weapons.The skills applied to war by the mechanical engineer are similar to those required in civilian applications, though the purpose is to enhance destructive power rather than to raise creative efficiency. The demands of war have channeled huge resources into technical fields, however, and led to developments that have profound benefits in peace. Jet aircraft and nuclear reactors are notable examples.
4- Environmental control.The earliest efforts of mechanical engineers were aimed at controlling the human environment by draining and irrigating land and by ventilating mines. Refrigeration and air conditioning are examples of the use of modern mechanical devices to control the environment.
5- In Aerospace Engineering.Aerospace Engineering deals with the design, construction, and study of the science behind the forces and physical properties of aircraft, rockets, flying craft, and spacecraft. An aircraft’s landing gear system may be considered primarily the field of mechanical engineering
Resolution of forceAny force can be resolved into the addition of two mutually perpendicular forces which are called components of force. The components of force are resolved along the x-axis and the y-axis of a given coordinate system. From Fig. 3-3, we see that x-component:
In fact, the resultant force of a system can be found by resolving all the forces into their x and y-components, and then adding up the components in each direction. The following animation illustrates the head-to-tail method of adding vectors, as well as the method of resolving components.
Moment:The tendency to produce rotation about some point is called the ‘moment of a force (M)
(d) (F) Mathematically_M=F(d)where F=applied forced=moment arm, the perpendicular distance from the line of action of the force to the moment center S.I unit of moment is (Nm)1- Moments are (+) if they cause a counterclockwise rotation 2- Moments are (-) if they cause a clockwise rotation