{"id":2460,"date":"2024-08-05T13:18:29","date_gmt":"2024-08-05T07:48:29","guid":{"rendered":"https:\/\/study.madeeasy.in\/?p=2460"},"modified":"2025-07-16T15:23:39","modified_gmt":"2025-07-16T09:53:39","slug":"stress","status":"publish","type":"post","link":"https:\/\/www.madeeasy.in\/study\/ce\/strength-of-material\/stress","title":{"rendered":"What is Stress in Strength of Materials?"},"content":{"rendered":"

The fundamental concept of stress can be understood by considering a prismatic bar that is loaded by axial force P at the ends as shown. \"Axial<\/p>\n

A prismatic bar is a straight structural member having constant cross-sectional area throughout its length. In the figure (a), axial force is acting away from the cross-section producing a uniform stretching of the bar, hence the bar is said to be in tension. Similarly in figure (c), axial force is acting towards the cross-section producing uniform compression of the bar, hence the bar is said to be in compression. To investigate the internal stresses produced
\nin the bar by axial forces, we make an imaginary cut at section mn as shown in figure (b) and (d). This section is taken perpendicular to the longitudinal axis of bar. Hence it is known as cross-section.<\/p>\n

Now isolating the part of the bar to the right of the cut and considering the right of the cut as a free body. The force P has a tendency to move free body in the direction of load, so to restrict the motion of bar an internal force is induced which is uniformly distributed over cross-sectional area. The intensity of force developed, that is, internal force per unit area is called the stress. \"Axial<\/p>\n

Stress differs from pressure because pressure is defined as the externally applied force on unit area while stress is internal resistive force on unit area. To have better understanding of difference between externally applied force and internal resistance. Consider a bar suspended from a fixed end and a weight W is gradually applied at its free end as shown in figure.<\/p>\n

Case-I: Weight, W is applied gradually<\/strong><\/h2>\n

Gradual loading means that value of load is zero at the starting time and gradually increases to value of W. Here, the bar gradually elongates with the increasing value of load. With increase in elongation, resistance forces say R will also increase gradually.<\/p>\n

\"External<\/p>\n

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