martes, 22 de septiembre de 2015

What is mechanical engineering?

Although it was not formally recognized until the 19th century mechanical engineering origins can be traced back to the very first machines produced by the human species. Originally concerned mainly with agricultural and war machines the discipline of mechanical engineering is nowadays present in almost every aspects of our daily life (ASME International, 2000). From the power plant that generates the electricity we use, to the vehicles that we use every day (cars, bicycles, buses, trains, etc.), mechanical engineering is involved with most (if not all) machines and tools. 

In this entry I will briefly describe the mechanical engineering discipline and its evolution over time focusing on the main contributions of the discipline to our society and in particular the current and future contributions that the discipline has or could make to the human society. I argue that mechanical engineering was essential to the industrial revolution and that it has played and will play an essential role in addressing the current energy crisis.

Mechanical engineering is related to “…the properties of forces, materials, energy, fluids, and motion as well as the application of those elements to devise products that advance society and improve people lives.” (Wickert & Lewis, 2012). It is often considered as the engineering discipline that has the broadest scope, involving a diversity of subspecialisations such as thermodynamic machines, fluid dynamics, structural analysis, manufacture technology, material science, etc.Antique and even prehistorical machines, such as bow drills and early clocks, can be considered the first examples of mechanical engineering applications. These devices evolved largely through the practice of trial and error, and it wasn’t until the beginnings of modern science in the renaissance that a more systematic approach was applied to the development of machines and technology (Paz, Ceccarelli, José Luis, & Javier, 2008) (Davim, 2012). 


Although thermodynamics was not yet developed, the invention of the steam engine between the 17th and 18th century is considered a turning point in the development of mechanical engineering and a crucial factor for the industrial revolution (Paz, Ceccarelli, José Luis, & Javier, 2008). Steam engines allowed levels of production never seen before and animal and manpower was quickly replaced by steam power (Auyang, 2005). Although prior steam engines existed, in the 18th century James Watt modified an existing steam engine creating a machine that consumed 75% less coal than previous ones (Davim, 2012), indicating the concern for efficiency even in the early days of the mechanical engineering discipline .The development of the steam engine and of thermodynamics as a discipline in the 19th century gave rise to the development machines of all sorts, which led to the development of a new engineering discipline concerned with tools and machinery. 

Mechanical engineering gained formal recognition with the creation of the Institution of Mechanical Engineers in England in 1847 (John Fleetwood Baker, 2010).  Throughout the 20 and 21st century mechanical engineering diversified from the design of tools and machinery to various related subspecialisations such as fluid dynamics, structural analysis, material science, etc. giving rise to several mayor inventions and developments such as the automobile, airplanes, agricultural mechanization, air conditioning and refrigeration and computer aided engineering technology, among others (Wickert & Lewis, 2012). 

The rapid development and massification of new machines and the accelerated economic and demographic growth associated with them has led to a rapid increase in energy demand throughout the 20 and 21st century (U.S. Energy Information Administration, 2009) (Smil, 2010). This rapid increase in energy demand has led to several energy crises in the last century such as the oil crisis of 1973 or the current world energy crisis, which has drawn attention to the problem of rapidly consuming non-renewable energy resources such as oil. 

This has led to the development of more efficient ways to produce and consume energy. For example the fuel efficiency of the average automobile in the U.S. has steadily increased since the early 70s (U.S. Energy Information Administration, 2009), and the maximum efficiency of primary mover machines has increased by an order of magnitude in the last 200 years (Smil, 2010) (Ausubel & Marchetti, 1996 ). The rise of climate change awareness in the last decades has also heavily influenced the development of new, more efficient technologies (GEA Writing Team, 2012).As it is integrally related to the study of energy change, conversion and use, mechanical engineering has a major role in the development of new ways of generating energy and in improving the efficiency of existing power generating/consuming technologies. 

Machine efficiency ultimately depends on theoretical limits (thermodynamic efficiency) and on practical limitations due to friction and heat loss. Subspecialisations of mechanical engineering such as tribology, fluid mechanics and heat transfer are essential in the understanding of those limitations, which is why the improvement of machine energy efficiency is to a great extent a mechanical engineering problem. For example, thanks to the relatively new sub discipline of tribology improvements in tire rubber compounds have allowed for greater fuel efficiency in automobiles (The International Energy Agency, European Conference of Ministers of Transport, 2005).  In the future it can be expected that the efficiency of current technologies continues to improve and that new ways of generating energy continue to be developed, both factors should have a significant impact on the energy consumption of the human society in the future. 

Summarizing, a brief review of the history and development of mechanical engineering shows how mechanical engineering was essential to the development of modern society, particularly given its relevance to the industrial revolution. Economic and demographic growth in the last centuries has led to accelerated grow rates in energy demand, giving rise to the concern for machine efficiency and the efficiency in generation and consumption of energy. Since mechanical engineering studies energy change, it has had a leading role in the improvement of machine efficiency over the years. Energy demand growth should continue to put pressure on the need for more efficient technologies, making the development of more efficient technologies one of the more important contributions of mechanical engineering to the human society of the 21st century.

References

ASME International. (2000, October). What Is A Mechanical Engineer. Retrieved from http://www.tryengineering.org/pdf/whatisme.pdf

Ausubel, J. H., & Marchetti, C. (1996 ). Elektron: Electrical Systems in Retrospect and Prospect. Daedalus, The journal of the American Academy of Arts and Sciences, 139-169.

Auyang, S. Y. (2005). History of engineering. Retrieved from http://www.creatingtechnology.org/history.htm

Davim, J. P. (Ed.). (2012). Mechanical Engineering Education. John Wiley & Sons.
GEA Writing Team. (2012). Global Energy Assessment: Toward a Sustainable Future. (T. B. Johansson, Ed.) Cambridge University Press.

John Fleetwood Baker, B. B. (2010). Encyclopædia Britannica. Retrieved from http://www.britannica.com/EBchecked/topic/371845/mechanical-engineering/64671/History

Paz, E. B., Ceccarelli, M., José Luis, M. S., & Javier, E. (2008). The Evolution And Development Of Mechanical Engineering Through Large Cultural Areas. Grupo de Inv. en Ingeniería de Máquinas.

Smil, V. (2010). Energy Transitions: History, Requirements, Prospects. ABC-CLIO.

The International Energy Agency, European Conference of Ministers of Transport. (2005). Making cars more fuel efficient, Technology for Real Improvement on the Road. OECD/IEA.

U.S. Energy Information Administration. (2009). Anual Energy Review. Retrieved from http://www.eia.gov/totalenergy/data/annual/pdf/aer.pdf

Wickert, J., & Lewis, K. (2012). An Introduction to Mechanical Engineering. Cengage Learning.


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