Rigid Body

Rigid body is a basic concept in statics problems. When you study in university, the curriculum has been designed from the simplest coarse to the most advanced one. Simple coarse such as statics are based on some simplification which are not eligible in more complex coarse such as mechanics of material.

For example in statics we do not consider any deformation or any energy dissipation for the structural members. Quite on the contrary, the main objective of mechanics of material is about deformations. So in this article I explain one of basic concepts of static coarse which is called “Rigid Body”. It is theoretically referred to an object in which deformation is zero. However in reality all objects are deformable, but if they are stiff enough their deformation can be considered nearly zero. Since rigid bodies are nor deformable the distance between any two given points remains constant during loading.

Thanks to the concept of rigid body, we can use an interesting trick to simplify the static problems. Any complex rigid body can by replaced by a simple rigid line. By doing this no change happens in the results. for example in the figure if the objects are of the same weight with similar loading, the reaction forces are will be computed the same in all cases.

 

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