Bodies at rest have internal forces acting between its different parts and have force interaction with the other bodies in contact. Even with the internal and external forces acting bodies may remain at rest. In engineering mechanics the study of forces in the bodies at rest is called as statics.
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Statics, the branch of Engineering Mechanics dealing with the analysis of force interactions in bodies at equilibrium, mainly comprises of study of structures. In engineering mechanics an arrangement of rigid members connected in certain patterns is called as a structure. A bridge, a communication tower and frame of an automobile all are structures. Mechanisms and machines in static configuration, when the forces are balanced and there is no motion, are also analyzed for force interactions under Statics in Engineering Mechanics. Static mechanisms and machines are analogous to structures for force analysis.
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The collapsing door of an elevator is a commonly seen structure. This structure can be compressed or extended by moving the end members towards or away from each other. If more members are added to such structures or the connections between the members are rearranged such deformable structures can be converted to constrained static structures called as trusses in engineering mechanics terms. The truss formed by this collapsible door will be a two dimensional truss as all the members of this truss are in the same plane.
Bridges have members arranged and connected in three dimensional space. Thus a bridge forms a three dimensional truss. Eiffel Tower is a great example of a three dimensional truss. Trusses can sustain larger loads than beam or column of same mass. In fact load carrying capacity, strength and rigidity of a truss is much more than solid beam and column of same mass. This property of trusses enables construction of huge structures which are light and having greater strength and stability.
Material scientists and structural engineers are combining their core competencies to develop a new class of materials with trusses, at micro and even at nano level, as there building unit. Such materials will be very light weight with strength and rigidity comparable or even more than conventional materials. Trusses built with carbon nano tubes are examples of nano level structures. These materials can be enhanced with some interesting added features such as active response to act as sensor as well as actuators by themselves and are aptly proposed as Smart Materials.
Structures support load and their own weight, for particular load and orientation the members of a structure experience compressive and tensile forces. In statics different techniques are followed to calculate these forces, which are taken up in next article.
A bicycle moves down the street and carry us with a little effort on our part. Water falls from the height of dam and run large turbines. How these machines work? How the different bodies interact? Engineering Mechanics, the study of forces and motion of bodies in mechanisms, answers these questions