Creation of an automatic utility to determine the values of coefficients of higher order terms of Williams power series by usage of over-deterministic method applied to results of finite element analysis is a main goal of this research. The developed procedure based on the support of Java programming language considerably simplifies analyses on optimization of selection of FE nodal results for improvement of accuracy of the near-crack-tip fields’ approximation using Williams series.
A quality of multi-parameter approximation of the stress and displacement fields around a crack tip in a non-brittle material test specimen is studied in the paper. The stress field approximation using Williams power series is intended to be utilized for estimation of the nonlinear zone extent which potentially plays a role within methods for determination of true values of fracture parameters of materials exhibiting nonlinear failure. Considering the fact that in the case of elastic-plastic and especially quasi-brittle materials the size of this zone is substantial in comparison to the specimen dimensions, it is necessary to take a large region around the crack tip into account for this task. An automatic utility created to determine the values of coefficients of the higher order terms of Williams power series by usage of over-deterministic method applied on results of finite element analysis of arbitrary mode I test geometry is one of the tested procedures. The second one provides a backward reconstruction of the crack-tip stress field analytically by means of truncated Williams expansion. The developed procedures are based on the support of Java programming language and considerably simplify analyses of the mechanical fields' description in a farther distance from the crack-tip. The presented research is focused on optimization of selection of FE nodal results for improvement of accuracy of the approximation.
Analysis on the aspects of the energy dissipation in the case of quasi-brittle fracture is presented. Dissipation both via cohesive forces at the crack faces and the one taking place within the volume of the fracture process zone is considered. Tools from the field of soft computing techniques are employed. The analysis is conducted on results from extensive experimental campaign.
Slewing operation involves a heavy loading and high cyclic movements. With no windows for error, operators and engineers need to operate while maintaining the performance of slewing. Sometimes, the strength of a components changes after repaired or modified. Thus, in order to predict the performance and safety of a gangway after repaired or modifies, this paper intended to predict the factor safety of a slewing post for gangway by using combination of experiment and FEA. This study was conducted on an actual slewing that has been repaired and slightly modified. The slewing was tested on load test for up to 14752 Kg and then the stress data was compared to the FEA analysis. For further analysis, FEA was conducted at 34 tons load and the stress was projected using the factor coefficient obtained in the comparison. The findings shows that the slewing is safe to be operated at 34 tones and below as the overall factor of safety is 1.2.
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