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Numerical analysis of fracture behavior of functionally graded materials using 3D-XFEM

Benhamena Ali, Fatima Benaoum, Foudil Khelil, Baltach Abdelghani, Chaouch Mohamed Ikhlef

Advances in Materials Science

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2023

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Vol. 23, nr 3(77)

33--46

EN

This paper presents the numerical evaluation of mixed stress intensity factors (SIFs) and non-singular terms of William's series (T-stress) of functionally graded materials (FGMs) using three-dimensional extended finite element method (3D-XFEM). Four-point bending specimen with crack perpendicular to material gradation have been used in this investigation in order to study the effect of some parameters (crack position, crack size, specimen thickness) on the failure of FGMs materials. The fracture parameters (KI KII, phase angle ψ and T-stress) obtained by the present simulation are compared with available experimental and numerical results. An excellent correlation was found of the 3D-XFEM simulations with those available in the literature. From the numerical results, a fitting procedure is performed in order to propose an analytical formulation and subsequently are validated against the 3D-XFEM results.

2

Research on hybrid modeling and predictive energy management for power split hybrid electric vehicle

Wang Shaohua, Zhang Sheng, Shi Dehua, Sun Xiaoqiang, Yang Tao

Bulletin of the Polish Academy of Sciences. Technical Sciences

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2021

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Vol. 69, nr 3

art. no. e137064

EN

Due to the coexistence of continuity and discreteness, energy management of a multi-mode power split hybrid electric vehicle (HEV) can be considered a typical hybrid system. Therefore, the hybrid system theory is applied to investigate the optimum energy distribution strategy of a power split multi-mode HEV. In order to obtain a unified description of the continuous/discrete dynamics, including both the steady power distribution process and mode switching behaviors, mixed logical dynamical (MLD) modeling is adopted to build the control-oriented model. Moreover, linear piecewise affine (PWA) technology is applied to deal with nonlinear characteristics in MLD modeling. The MLD model is finally obtained through a high level modeling language, i.e. HYSDEL. Based on the MLD model, hybrid model predictive control (HMPC) strategy is proposed, where a mixed integer quadratic programming (MIQP) problem is constructed for optimum power distribution. Simulation studies under different driving cycles demonstrate that the proposed control strategy can have a superior control effect as compared with the rule-based control strategy.

3

Statistical methods for constructing gestational age-related charts for fetal size and pregnancy dating using longitudinal data

Hynek M., Kalina J., Zvárová J., Long J. D.

Biocybernetics and Biomedical Engineering

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2018

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Vol. 38, no. 4

992--1003

EN

The assessment of fetal size and the accurate estimation of gestational age are of crucial importance for proper pregnancy management. The information is almost exclusively based on ultrasound measurements of fetal biometric parameters and the means for evaluating these measurements are age-related reference charts (centile charts) allowing interpretation of obtained fetal measurement in comparison with the expected average measurement in the reference population. The construction of such reference charts requires an appropriate statistical methodology. The most frequent method for the construction of fetal reference charts from cross-sectional data is the parametric approach with fractional polynomials regression functions for the mean and standard deviation of each fetal measurement. This article suggests how this method can be extended to longitudinal data using fractional polynomials in linear mixed effect regression. The presented approach includes maximum likelihood estimation for fitting first- and second-order fractional polynomial models, and multimodel inference using Akaike's information criterion and related tools as a suitable strategy for model selection. Finally, an example of the suggested approach is presented.

4

Elektroniczne łańcuchy dostaw

Strykowski E., Cellary W.

Logistyka

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2005

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Nr 6

48--48

PL

Artykuł jest pierwszym z serii sześciu poświeconych tematyce elektronicznych łańcuchów dostaw. W trzech następnych w sposób szczegółowy zostaną przedstawione trzy wymieniowe powyżej modele takich łańcuchów - model z hurtownią wirtualną i hurtownią rzeczywistą, model z hurtownią wirtualną i strategią dostaw bezpośrednich oraz model mieszany z hurtownią wirtualną, hurtownią rzeczywistą i strategią dostaw bezpośrednich. W artykule piątym zostanie zaprezentowana metoda wyboru modelu elektronicznego łańcucha, który w warunkach danego systemu logistycznego przyniesie producentowi największy możliwy zysk, natomiast w artykule szóstym - przykładowy scenariusz zastosowania tej metody.