Stress strain behaviour
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Elastic Region
- follows hookes law
- stress is proportional to strain
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Yield point
- transition from elastic to plastic deform
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Plastic Region
- where permanent deformation begins (strain hardening may occur) also called ductile materials
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Ultimate tensile strength (UTS)
- peak stress before necking
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Fracture
- final meterial faliure after necking
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Polymers
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Elastic region
- often show non-linear elasticity especially in rubbery polymers
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Plastic region
- permanent strenching happens duet ot sliding molecular chains
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Fracture
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Two behavouirs
- rubbery or ductile materials strench before breaking
- brittle polymers break suddenly with little deformation
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Ceramics
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Elastic region
- linear behavior until brittle fracture (no plasitcity)
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Fracture
- occurs abruptly due to low toughness
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key feature
- high compressive strength but poor tensile strength duet ot flawsand crack propagation