The maximum strength that a material can withstand before fracture and failure. It is therefore the maximum stress, which is the applied load divided by the cross-sectional area of a test piece of material. The SI unit is the pascal and is more commonly expressed as MPa. For materials that don’t deform under an applied load, this is the nominal stress at the point the material breaks. For materials that deform, this is the point that necking forms before breakage.