The lecture presents relationships between microstruktural parameters and
stress-strain and fracture behaviours of structural materials. It shows basic
method how to calculate stress-strain field in the nearness of stress
concentrations, especially ahead of sharp cracks under elastic and elastic-
plastic loading. The significance to connect these methods with local approach
is in the lecture emphasized. This enables to estimate reliability of materials
and rest of service life of structural parts which are from these materials
made. The lecture leads into evaluation methods of the influences of
statistical distributions in microstructural parameters on the scatter of
mechanical properties. This is a starting point for proposal of concepts in
structural design of material with called relationship between strength
behaviours and toughness.