Banca de DEFESA: Alvaro Martins Delgado Neto

Uma banca de DEFESA de DOUTORADO foi cadastrada pelo programa.
STUDENT : Alvaro Martins Delgado Neto
DATE: 22/11/2023
TIME: 09:00
LOCAL: TEAMS
TITLE:

NONLINEAR ALGORITHM BASED ON THE BOUNDARY ELEMENTS METHOD WITH DUAL RECIPROCITY APPLIED TO ELASTOPLASTIC FRACTURE PROBLEMS

KEY WORDS:

Elastoplastic Models, Crack Propagation, Dual Boundary Element Method, Dual Reciprocity Method, Elastoplastic Fracture

PAGES: 152
BIG AREA: Engenharias
AREA: Engenharia Civil
SUBÁREA: Estruturas
SPECIALTY: Mecânica das Estruturas
SUMMARY:

Due to the application of cyclic loads, the length of an existing crack in a structure increases over time, resulting in a higher stress concentration around the crack tip. Consequently, this leads to an increase in propagation rate and a decrease in the residual strength of the structure. After a certain period, the residual strength becomes so low that the structure can no longer withstand service loads. This study introduces a novel approach to assess two-dimensional elastoplastic models in a crack propagation scenario. The approach is based on the boundary element method and its dual formulations.
The adopted methodology consists of two steps: the first step involves simulating elastoplastic behavior, considering initial stress processes and enabling the treatment of various yield criteria without considering incompressibility of inelastic deformations. In this stage, the domain integral due to non-homogeneous terms in the plastic region is transformed into a boundary integral using the Dual Reciprocity Method (DRM), the first dual formulation. Local behavior "poliharmonics splines" functions are utilized for this purpose. Furthermore, the plastic calculation employs the J-Integral to compute the Stress Intensity Factors (SIFs).
The second step aims to incrementally simulate the crack propagation path using the in-house software BemCracker2D for crack modeling and analysis. This is based on Elastoplastic Fracture Mechanics (EPFM) and the Dual Boundary Element Method (DBEM), the second dual formulation. To validate the adopted methodology and accurately simulate the mechanical behavior of cracks in the plastic regime of the material, six models of 2D plates with straight and inclined edge cracks are employed. Three plasticity criteria (Tresca, von Mises, and Gao) for perfectly plastic materials are used. The numerical results are compared with classical models from the literature, demonstrating the efficacy of BemCracker2D in predicting the plastic zone using DRM at the crack tip. The same program exhibited excellent prediction of the propagation path and determination of mixed-mode plastic stress intensity factors in crack treatment.

COMMITTEE MEMBERS:
Presidente - 1439182 - GILBERTO GOMES
Interno - 1825564 - RAUL DARIO DURAND FARFAN
Externo ao Programa - 2212892 - MARCIO AUGUSTO ROMA BUZAR - UnBExterno à Instituição - DANIEL NELSON MACIEL - UFRN
Externo à Instituição - LUIZ CARLOS WROBEL - PUC - RJ