normal stress, shear stress, bulk stress, normal strain, shear strain, bulk strain, ... The symbol for stress is often the Greek letter "sigma" Stress has the units of force over area i.e. N/m2 which is given the special name Pascal. ... 5.7. 0.4. polystyrene. 3.8. 1.0. 4.7. 0.4. polyethylene. 0.14. 0.05. 0.35. 0.4 ...