In mechanical engineering, torsion refers to the twisting of an object due to an applied torque (rotational force). This type of stress occurs when a force is applied in such a way that it tends to twist the object around its longitudinal axis. Torsion is common in various mechanical components such as shafts, springs, and other rotating parts. Understanding torsion is crucial in designing and analyzing structures to ensure they can withstand the applied torque without failure.
Motivation phase
What do you see?
Have you ever washed clothes by hand? When wringing out clothes, you twist one end of the garment in one direction while twisting the other end in the opposite direction. This allows for faster drying of the clothes. This wringing out of clothes is actually torsion.
Photo from https://www.istockphoto.com/search/2/image-film?phrase=twisted+clothes.
Motivation phase
Try it yourself
Take a small towel and wet it with water. Then try to wring it out by twisting one end of the towel in one direction while twisting the other end in the opposite direction. Try to twist as hard as you can to squeeze out as much water as possible. If you exert more force, the wringing is stronger, meaning there is more torsion.
Photo from https://www.news.com.au/lifestyle/home/interiors/youve-been-washing-your-towels-all-wrong-heres-how-to-keep-them-fluffy-according-to-an-expert/news-story/7b1836a13b3befb0d52eb48228b3dd01.
Information phase
Watch the video
In this video you will explore torsion, which is the twisting of an object caused by a moment. It is a type of deformation. A moment which tends to cause twisting is called torque.
Some of the things covered in this video include how circular bars deform under torsion, how we can calculate the angle of twist, and how we can calculate the stresses and strains that are generated in a circular bar as a result of torsion. You will also explore internal torque diagrams, and why torsional failure is different for brittle and for ductile and materials.
Information phase
Calculate real torsion stress in a shaft
In this presentation you will learn how to calculate torsion.
Consolidation phase
Calculate and conclude
Calculate real torsion stress in a shaft if F = 6 kN, Ï„tdop = 12 MPa and
a) D = 100 mm
b) D = 200 mm
Is the real torsional stress greater when the diameter is larger? Why?
