Lebid' N. Evaluation of quasibrittle and ductile materials crack resistance using deformation criteria

Constructive quasi-brittle and viscous materials and their welded joints.The theoretical - experimental methods of crack-strength estimation for quasi-brittle and viscous materials using deformation criteria are proposed.Mathematical modelling, solving of elastic-plastic mechanical problems for quasi-brittle failure by analytical and numerical methods, testing for crack-strength, measuring the critical value of crack opening in cylindrical and prismatical samples made from continuous materials and from deposits of welding by using control-measuring devices are considered.The deformation modell is developed. The criterion equations to determine the deformation and geometrical parameters for partsin prefailure region (particulary in regions of crushing and plastic deformations) are proposed.The methodology of measuring for critical value of crack opening, determining crack strength of viscous deposit weld, strength estimation for regions at welded joints, regimes of thermal strengthening and scaling fact or are also suggested.The instruments to realize the engineering estimation methods of constructive material strength are created.The engineering methods and recommendation to constructive materials and alloys are discussed.The results may be used in engineering calculations to construction elements, parts of machines and their welded joints in machine building.