Pset_MaterialSteel A set of extended mechanical properties related to steel (or other metallic and isotropic) materials. IfcMaterial/Steel IfcMaterial/Steel YieldStress A measure of the yield stress (or characteristic 0.2 percent proof stress) of the material. Yield Stress UltimateStress A measure of the ultimate stress of the material. Ultimate Stress UltimateStrain A measure of the (engineering) strain at the state of ultimate stress of the material. Ultimate Strain HardeningModule A measure of the hardening module of the material (slope of stress versus strain curve after yield range). Hardening Module ProportionalStress A measure of the proportional stress of the material. It describes the stress before the first plastic deformation occurs and is commonly measured at a deformation of 0.01%. Proportional Stress PlasticStrain A measure of the permanent displacement, as in slip or twinning, which remains after the stress has been removed. Currently applied to a strain of 0.2% proportional stress of the material. Plastic Strain Relaxations Measures of decrease in stress over long time intervals resulting from plastic flow. Different relaxation values for different initial stress levels for a material may be given. It describes the time dependent relative relaxation value for a given initial stress level at constant strain. Relating values are the "RelaxationValue". Related values are the "InitialStress" Relaxations