The results all show how metallic materials have elastic and plastic properties which can be observed on the stress/strain curve. The results also indicate that denser metals like steel have greater strength than lighter materials like brass. The rupture energy is in pascals which is also J/m3. Percent elongation of aluminum: % elongation = final length – original length/original length X 100 = 53.72-50.04/50.04 total/original length =