Properties of Engineering Materials

1. Properties of Engineering Materials

2. Overview • Purpose of lab is to familiarize you with basic properties of common engineering materials • Density, Young’s modulus, thermal conductivity, coefficient of expansion, modulus of torsion • Do simple experiments to find these properties • Also become familiar with the physical properties of some common optical materials used in the IR

3. Young’s modulus Use bars of material set on simple end supports Measure central deflection as a function of applied load Use physical dimensions of bars to calculate Young’s modulus

4. Density • Measure physical dimensions of bars • Calculate volume • Measure mass on an electronic scale • Density = mass/unit volume • Measure a drop of water, small piece of paper • Get a feel for how sensitive the scale is

5. Displacement Indicator Heat Gun Sample V Block Test Plate Thermal properties • Get a feel for the thermal properties of materials • Widely varying set of conductivities, expansions • Use heat gun and thermocouples

6. Optical materials Sapphire Al2O3, .14 – 6.5 um, very hard, low expanson, tough CaF2, .13 – 12 um, moderately soft, expansion like Al, good UV mat’l Silicon 1.2 – 15 um, reasonably hard, quite plastic and strong, brittle Germanium 1.8 – 23 um, similar to Silicon but not as tough, n = 4 ZnSe .5 – 22 um, reasonably easy to use but somewhat soft ZnS .5 – 14 um, similar to ZnSe but cheaper, maybe a little less durable

7. May do modulus of torsion • Measure oscillation of torsion pendulum