- Elasticity is the property of a material to return to its original shape and size after the removal of an external force.
- Stress is defined as the internal restoring force per unit area induced in a material when subjected to an external force.
- The formula for stress is: Stress = Force / Area, and its unit is Pascals (Pa).
- Strain is the measure of the deformation of a material, defined as the ratio of change in dimension to the original dimension.
- There are no units for strain as it is a dimensionless quantity.
- The relationship between stress and strain is determined by the material's elastic modulus.
- Hooke's Law states that within the elastic limit, the stress applied to a material is directly proportional to the strain produced.
- The mathematical expression for Hooke's Law is: Stress = Elastic Modulus × Strain.
- The elastic modulus is a constant that depends on the material's properties.
- There are three types of elastic moduli: Young's modulus, shear modulus, and bulk modulus.
- Young's modulus (Y) describes the elasticity of a material under tensile or compressive stress.
- The formula for Young's modulus is: Y = (Longitudinal Stress) / (Longitudinal Strain).
- Shear modulus (G) measures the material's response to shear stress, where the shape changes but volume remains constant.
- The formula for shear modulus is: G = (Shear Stress) / (Shear Strain).
- Bulk modulus (K) defines how incompressible a material is under uniform pressure.
- The formula for bulk modulus is: K = (Volume Stress) / (Volume Strain).
- For most materials, Young's modulus is significantly larger than the shear or bulk modulus.
- Stress can be classified into three types: tensile stress, compressive stress, and shear stress.
- Tensile stress is caused when a material is stretched, increasing its length.
- Compressive stress occurs when a material is compressed, reducing its length.
- Shear stress is caused by forces acting tangentially to the surface of a material.
- Elastic limit is the maximum stress a material can withstand without undergoing permanent deformation.
- If stress exceeds the elastic limit, the material enters the plastic region, where deformation is irreversible.
- The point where a material breaks under stress is called the breaking point.
- The region of stress-strain behavior before the elastic limit is the elastic region.
- The area under the stress-strain curve in the elastic region represents the elastic energy stored in the material.
- Materials with high elastic modulus are considered stiffer and more resistant to deformation.
- The Poisson's ratio is the ratio of lateral strain to longitudinal strain and is dimensionless.
- For most materials, Poisson's ratio lies between 0 and 0.5.
- Rubber has a low Young's modulus, making it highly elastic and deformable under stress.
- Steel has a high Young's modulus, making it strong and resistant to deformation.
- Elastic hysteresis occurs when the strain lags behind stress during cyclic loading and unloading.
- The spring constant (k) is a measure of stiffness and is related to Hooke's law by the formula: F = k × x, where F is force and x is deformation.
- In isotropic materials, the mechanical properties are identical in all directions.
- Anisotropic materials have varying mechanical properties depending on the direction of stress.
- Applications of Hooke's Law include designing springs, beams, and structures subjected to elastic deformation.
- The modulus of resilience measures the amount of energy a material can absorb without permanent deformation.
- The modulus of toughness represents the total energy a material can absorb before failure.
- The concept of elasticity is essential in engineering, material science, and structural analysis.
- In engineering, materials are chosen based on their elastic properties to ensure safety and efficiency.
- Stress-strain analysis helps predict the failure of materials under different loading conditions.
- The SI unit for stress is Pascals (Pa), while strain has no unit.
- Understanding elasticity is crucial for designing shock absorbers and suspension systems.
- The stress-strain curve provides valuable insights into a material's mechanical behavior.
- Materials like glass, ceramics, and some polymers are brittle and have low elastic limits.
- Ductile materials, like metals, can sustain significant deformation before breaking.
- Hooke's Law is valid only within the elastic limit of a material.
Questions
- What is stress in terms of elasticity?
- What is strain in a material?
- What is Hooke's law?
- The proportionality constant in Hooke's law is called?
- What is the SI unit of stress?
- What is the SI unit of strain?
- Which of the following represents tensile stress?
- Which of the following is NOT a type of stress?
- What is the elastic limit of a material?
- Beyond which point does Hooke’s law no longer apply?
- What is Young's modulus?
- What is the formula for stress?
- What is the formula for strain?
- Which modulus of elasticity is used for solids under tension or compression?
- The bulk modulus is defined as?
- What is the shear modulus?
- Which property measures a material's resistance to deformation?
- What type of stress acts parallel to the surface?
- What happens to a material under compressive stress?
- What is the work done per unit volume in stretching a wire within its elastic limit?
- What is Poisson’s ratio?
- Which material has the highest elastic modulus?
- Which type of stress is involved in the twisting of a shaft?
- What is the relationship between stress and strain in Hooke’s law?
- What does a high modulus of elasticity indicate about a material?
- What happens when a material exceeds its elastic limit?
- The slope of the stress-strain curve in the elastic region represents?
- What is the maximum stress a material can withstand without breaking?
- Which property is higher in rubber compared to steel?
- Which type of strain involves a change in volume without a change in shape?
- What is the unit of Young's modulus?
- In which type of stress does the shape of the material change but not its volume?
- What is the main characteristic of an elastic material?
- What happens to strain when stress is removed within the elastic limit?
- Hooke’s law is valid only in which region of the stress-strain curve?
- What is the energy stored in a stretched wire called?