Questions and Answers
What is the term for the internal restoring force per unit area that acts in response to hydraulic pressure?
What does volume strain measure?
Which of the following statements about Hooke's Law is correct?
In a stress-strain curve, what does the slope represent at small deformations?
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What is the correct formula to describe the relationship between stress and strain according to Hooke's Law?
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What occurs in the region between points O and A on the stress-strain curve?
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What is indicated by the yield point on a stress-strain curve?
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What happens when a load is removed after reaching point C between B and D?
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What characterizes a material that has a close ultimate tensile strength and fracture point?
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How does rubber behave compared to metals in terms of stress-strain response?
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Study Notes
Hydraulic Stress and Volume Strain
- Hydraulic stress is the internal restoring force per unit area developed when a body is subjected to fluid pressure, counteracting the applied fluid forces.
- When removed from the fluid, the body restores its original shape and size.
- Volume strain is defined as the ratio of change in volume (∆V) to the original volume (V) and is dimensionless: (\Delta = \frac{\Delta V}{V}).
Hooke's Law
- Hooke's law states that for small deformations, stress is proportional to strain.
- Expressed as: stress ∝ strain or stress = k × strain, where k is the modulus of elasticity.
- Generally applicable to most materials but not valid for all.
Stress-Strain Curve
- A stress-strain curve plots the relationship between stress (force per unit area) and strain (fractional change in length) during tensile tests.
- Initially, stress and strain are linearly related (region O to A) where Hooke's law holds, indicating elastic behavior.
- Upon removing the load in the elastic region, the material regains original dimensions.
Yield Point and Permanent Deformation
- Beyond the yield point (B), the relationship between stress and strain becomes nonlinear, but the material can still return to its original dimensions after load removal.
- The yield point indicates the elastic limit and the yield strength (σy) of a material.
- Permanent deformation occurs when the load exceeds the yield strength, leading to plastic deformation, where original dimensions are not regained.
Ultimate Tensile Strength and Fracture
- The ultimate tensile strength (σu) is the maximum stress a material can withstand before failure, located at point D on the curve.
- Fracture occurs at point E; if ultimate strength and fracture points are close, the material is brittle; if far apart, it is ductile.
Material-Specific Behavior
- Stress-strain behaviors differ among materials.
- Rubber can be stretched significantly beyond its original length while returning to its shape, demonstrating its unique elastic properties.
- The stress-strain relationship for elastomeric tissues, such as those in the aorta, shows a large elastic region, indicating significant deformability without permanent change.
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Description
Explore the mechanical properties of solids with this quiz, focusing on concepts like hydraulic stress and internal restoring forces. Test your understanding of how solids respond to fluid pressure and the factors affecting their shape and size. Perfect for students studying material science or physics.
