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Unformatted text preview: Terms used with tensile testing • Applying a tensile force (i.e. pulling on it) Engineering Stress (σ) • σ = (applied force perpendicular to the cross-sectional area) h (initial cross-sectional area) • σ = F/A psi, Pa, N/m 2 • Common tensile Specimens – dog-bone specimens o A = (π/4)(d ) 2 where d is in the very center Engineering Strain (ε) • ε = change in length = Δℓ initial length ℓ • ℓ is the original length of specimen were all of the deformation will take place o Compression not as common • more difficult than tensile • not as informative for structural applications o Hooke’s Law E = σ/ε • E modulus of elasticity, young’s modulus Stress and strain are linearly proportional Typical values of the modulus for metals • 40-400 GPa stiffer materials have larger modulus (smaller ε, stretches less)...
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- Fall '07
- Recyclable materials, Plastic recycling