Application of cohesive model in fracture mechanics by WARP3D

In the paper cohesive model implemented in WARP3D code and an example simulation of crack growth analysis ispresented. Cohesive model is an effective tool for a crack growth analysis and it was a main reason to invent it. For the "dassica" constitutive equation the crack growth simulation in the finite element method (FEM) is not possible without an additional crack growth criterion. In the commercial FEM codes cohesive model is not very popular unfortunately. Usually it can be applied as user implemented elements. However there is a code free of charge with high reliability acknowledged in the literature with cohesive elements in standard library. This program is WARP3D and it is dedicated to numerical simulations of three dimensional fracture mechanics problems. The Dugdale's model, void creation, the cellular model of material, the cohesion-decohesion curve, behaviour of cohesive element, comparison of curve shapes for brittle and ductile fracture, the profile of the cohesive element in WARP3D, specimen geometry, changes of crack shape under increasing load, opening stress distribution in the uncracked ligament are presented in the paper

Algorytm wyznaczania funkcji ... w rozwiązaniu HRR i jego trójwymiarowym uogólnieniu

In the paper the algorithm to determine ... functions that are necessary to obtain values of stresses, strains and displacements in the crack tip neighborhood according to the Hutchinson, Rice and Rosengren solutions is presented. The algorithm can also be used to determine ... functions for a 3D approximate solution of the stress field in front of the crack introduced by Guo Wanlin, where constraint due to the thickness effect is introduced through the Tz function.W artykule zaprezentowano algorytm pozwalający na określenie funkcji... niezbędnych do opisu pola naprężeń, odkształceń i przemieszczeń w materiałach nieliniowych według prawa Ramberga-Osgooda. Algorytm pozwala uzyskać również wartości funkcji ... dla próbek trójwymiarowych przy wykorzystaniu parametru Tz, który zależy od grubości próbki i może być wyznaczony numerycznie

Wpływ modelu wierzchołka pęknięcia na wyniki uzyskane metodą elementów skończonych

The paper contains recommendations of finite element models of the crack tip neighborhood to obtain results independent of the finite element mesh. The recommendations are valid for elastic-plastic problems and finite strains. As an example, analysis of single edge notched specimens under bending is presented.W pracy przeprowadzono analizę wpływu modelu MES na wartość naprężeń przed frontem pęknięcia w materiałach sprężysto-plastycznych, wyznaczaną w sposób numeryczny wartość całki J oraz rozwarcie wierzchołka pęknięcia (RWP). Obliczenia prowadzono dla płaskiego stanu odkształcenia przy założeniu dużych odkształceń

Verification of strength of the welded joints by using of the aramis video system

In the paper are presented the results of strength analysis for the two types of the welded joints made according to conventional and laser technologies of high-strength steel S960QC. The hardness distributions, tensile properties and fracture toughness were determined for the weld material and heat affect zone material for both types of the welded joints. Tests results shown on advantage the laser welded joints in comparison to the convention ones. Tensile properties and fracture toughness in all areas of the laser joints have a higher level than in the conventional one. The heat affect zone of the conventional welded joints is a weakness area, where the tensile properties are lower in comparison to the base material. Verification of the tensile tests, which carried out by using the Aramis video system, confirmed this assumption. The highest level of strains was observed in HAZ material and the destruction process occurred also in HAZ of the conventional welded joint