An ideal plastic material shows no deformation up to its yield point, after which it flows like a Newtonian fluid. Which of the following represents an ideal plastic?
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Answer: A. Sewage sludge
Explanation
An ideal plastic requires a minimum yield stress threshold to be exceeded before any deformation occurs. Once the yield point is surpassed, the material flows linearly just like a Newtonian fluid. Sewage sludge exhibits this exact Bingham plastic behavior, requiring initial pressure to start flowing. Bingham plastics behave like rigid solids until applied shear stress exceeds their specific yield point. Beyond the yield stress, the shear rate is directly proportional to the excess shear stress. Complex mixtures containing high concentrations of suspended solids often display ideal plastic properties.
Civil engineers must account for the yield stress of sewage sludge when sizing transport pipelines. Drilling muds used in oil exploration are engineered as plastic fluids to suspend rock cuttings effectively. Processing food products like toothpaste or tomato paste requires understanding non-Newtonian plastic behavior. Rubber latex exhibits viscoelastic properties rather than simple ideal plastic flow behavior. Blood is a pseudoplastic fluid that thins under shear without requiring a distinct yield stress. Sugar solutions typically behave as standard Newtonian fluids with constant viscosity characteristics.
- Subject
- Engineering
- Category
- Chemical Engineering
- Topic
- —
- Difficulty
- medium
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