Murtolujuus

Murtolujuus is a material property describing the stress level at which a material fails due to fracture under an applied load. In Finnish technical literature, the term is commonly used to denote fracture strength, i.e., the maximum nominal stress a specimen can sustain before fracture under prescribed testing conditions. It is related to, but distinct from, fracture toughness, which measures resistance to crack propagation, and from yield strength, which marks the onset of plastic deformation.

Measurement and interpretation: Murtolujuus is typically determined from a fracture or tensile test to fracture, with the result expressed in units of stress such as megapascals (MPa). The measured value depends on test geometry, notch or flaw size, loading rate, temperature, and the material’s microstructure. For brittle materials, it closely corresponds to the strength at failure, while for ductile materials it is influenced by flaw populations and may exhibit significant scatter.

Application: The value is used in design and failure analyses to ensure operating stresses stay below the fracture strength, providing a conservative criterion for safety. It is one of several material strength properties; others include yield strength and fracture toughness (K_IC).