Stress is the internal restoring force per unit area developed in a material when subjected to an external force. It quantifies the material’s ability to resist deformation. Stress is measured in Pascals (Pa) and can be categorized into tensile compressive or shear stress based on the applied force’s nature.
Chapter 8 Mechanical Properties of Solids explains how solids respond to external forces. It introduces stress strain elasticity and plasticity with relationships between them. Key topics include Young’s modulus bulk modulus shear modulus and Poisson’s ratio. Understanding these properties is essential for analyzing material behavior in engineering and structural applications.
Definition of Stress:
Stress is defined as the force exerted per unit area within materials. It results from external forces applied to an object, resulting in deformation. Mathematically, stress is represented as
σ = F / A
where σ is the stress F is the applied force and A is the cross-sectional area over which the force is applied.
Units:
The SI unit of stress is Pascal (Pa), which is equivalent to Newton per square meter (N/m²).
Dimensions:
The dimensions of stress are represented as [M L⁻² T⁻²], where M is mass, L is length, and T is time.
Different Types of Stress:
1. Tensile Stress: This takes place when any material undergoes stretching or pull forces. The force per unit area along the direction of an applied force defines it.
2. Compressive Stress: It arises when compressive forces compress or squeeze the material. Force per unit area in a direction opposite to an applied force is defined by compressive stress.
3. Shear Stress: It happens when a material is subjected to forces that cause one layer of the material to slide over another. It is the force applied parallel to the surface divided by the area of the surface.
4. Volumetric Stress: This stress is due to changes in volume because of uniform pressure applied in all directions. It is significant in fluid mechanics and materials science.
Understanding these different types of stress is important in analyzing material behavior under various loading conditions.
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