The aim of this study was to investigate the influence of different stitch factors on the mechanical behavior of the seam section of sportswear under periodic load. Multiscale finite element (FE) modeling was then utilized to predict the mechanical behavior of the samples under periodic tensile load. The unit cells of the fabric and the stitched section were modeled in the mesoscale. Elastic and viscoelastic properties of the yarns were assigned to the model. In order to obtain the mechanical properties of the sample, periodic boundary conditions were applied to the unit cell. Elastic and viscoelastic properties calculated from the mesoscale were then used for the macromodel. FE results had a good agreement with the experimental ones in predicting the mechanical behavior of the seam section under the periodic tensile load. By using Taguchi method, the optimum sample was found.
Infertility is a global health problem caused by various environmental and genetic factors. Male infertility accounts for 40-50% of all cases of infertility and approximately half of them are grouped as idiopathic with no definitive causes. Previous studies have suggested an association between some SNPs and infertility in men. In this study, an attempt was made to investigate the association of 7 different SNPs of 4 genes involved in common cell functions with male infertility.MTHFR rs1801131 (T>G), MTHFR rs2274976 (G>A), FASLG rs80358238 (A>G), FASLG rs12079514 (A>C), GSTM1 rs1192077068 (G>A), BRCA2 rs4987117 (C>T), and BRCA2 rs11571833 (A>T) were genotyped in 120 infertile men with idiopathic azoospermia or severe oligospermia and 120 proven fertile controls using ARMS-PCR methods. Next, 30% of SNPs were regenotyped to confirm the results. Odds ratios (ORs) with 95% confidence intervals (CIs) were calculated using SPSS statistical software to evaluate the strength of association. The p<0.05 were considered statistically significant.Statistical analysis revealed significant association between MTHFR rs-2274976 AA variant (OR: 10.00, CI: 3.203-31.225), FASLG rs12079514 AC variant (OR: 0.412, CI: 0.212-0.800), and BRCA2 rs11571833 TT variant OR: 6.233, CI: 3.211-12.101) with male infertility, but there was no significant difference between case and control groups in MTHFR rs1801131 (p= 0.111), GSTM1 rs1192077068 (p=0.272), BRCA2 rs4987117 (p=0.221), and FASLG rs80358238 (p=0.161).Our findings suggested that some novel polymorphisms including MTHFR rs2274976, FASLG rs12079514, and BRCA2 rs11571833 might be the possible predisposing risk factors for male infertility in cases with idiopathic azoospermia.
In forging process, formability is limited by ductile fracture. In many cases forgeability is determined by the occurrence of ductile fracture and therefore limitations are set by the appearance of surface or internal cracks within regions that are highly strained due to extensive material flow. In this paper, the continuum damage mechanics framework for ductile materials developed by Lemaitre has been utilized numerically. A constitutive elastic‐plastic‐damage model has been implemented inside the finite element code ABAQUS. In forming process, crack closure effects have a strong influence on damage evolution. Therefore, it is necessary to split the tensile and compression stresses in damage evolution and deal with them separately. A modified version of Lemaitre model has been implemented and utilized through the study. The prediction of the surface cracks in forging is analyzed numerically. The results could correctly predict the location of surface cracks in the forging process.
A three-dimensional, implicit gradient-enhanced, fully coupled thermomechanical constitutive model is developed within the framework of thermodynamic principles for NiTi shape memory alloys. This work focuses on unstable behaviors of NiTi samples under different thermomechanical loading conditions. Temperature variation and its coupling effect on non-local behavior of a shape memory alloy during a loading–unloading cycle at different strain rates are considered. The proposed constitutive equations are implemented into the finite element software ABAQUS, and the numerical investigations indicate that the used procedure is an effective computational tool for simulation of several behaviors of NiTi samples including phase front nucleation and propagation, stress–strain–temperature responses, and transformation-induced stress relaxation. The obtained results are shown to be in a good agreement with available experimental and numerical findings in the literature. The effectiveness of the model in removing mesh sensitivity is evaluated by investigating the mesh-dependence issue for the low strain rate problems through numerical examples.
In this paper the plastic deformation of single phase and two-phase polycrystal materials is studied both experimentally and by a FEM model computation, taking into account crystal plasticity. A fully coupled constitutive elastic-plastic crystal plasticity model is developed and implemented in the finite element model to define the single crystal material. A polycrystal lattice as an aggregate of single crystal grains with various orientations is both simulated and analyzed by means of unit cell method. The user-subroutine has been written for single crystals materials. Many experimental tests of polycrystal materials have been performed to trust the results of simulations. The stress versus strain dependence as obtained from this FEM-model appears to be in good accordance with experimental results.
This Special Issue gathers research from different branches of science and engineering disciplines working on experiments and modelling of nanocomposites into one volume. The Guest Editor welcomes papers dedicated to experimental, computational, and theoretical aspects dealing with many important state-of-the-art technologies and methodologies regarding the synthesis, fabrication, characterization, properties, design, and applications, and both finite element analysis and molecular dynamic simulations, of nanocomposite materials and structures. Full papers covering novel topics, extending the frontiers of the science and technology of nanoreinforced composites are encouraged. Reviews covering topics of major interest will be also considered.
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