International Journal of Computational Materials Science and Engineering

Extended finite element method (XFEM) and second-order perturbation technique (SOPT) were combinedly utilized using interaction integral (M-integral) through partition of unity method to find out the mean and variance of mixed mode stress intensity factor (MMSIF). Uncertain system parameters are considered in material properties, crack length, crack orientation, gradient coefficients in the present study. MMSIF in a numerical example with center crack is computed to validate the accuracy of the presented model. Finally, typical numerical results are presented to examine the different modulus ratios, crack angle, crack length, position of crack and tensile, shear and combined loadings with uncertain system properties on the MMSIF.

The basic mechanical properties of a diaphragm under various temperatures in hot diaphragm preforming of composites are obtained by uniaxial tensile tests. A constitutive model considering the influence of temperature is accordingly developed to characterize its large deformation behavior. Model parameters are obtained by nonlinear fitting experiment data. The constitutive model is implemented in ABAQUS through the user material subroutine UHYPER. The developed constitutive model is verified by simulating the covering deformation of the diaphragm over a C-type mold. Finally, as an application of the developed hyperelastic model, an optimal design of a support bar in the hot diaphragm preforming process is implemented. The constitutive model lays a solid foundation for the finite element simulation and process optimization of the hot diaphragm forming (HDF) of carbon composites.

The paper studies the effect of temperature ($T$), ($T=300$, 3200, 4000, 5000, 6000, 7000K) at pressure $P=0$GPa; pressure ($P$), ($P=0$, 100, 200, 300, 350, 400GPa) at $T=7000$K and thermal annealing time ($t$), $t=47.8$ps (after 10⁵ steps) at $T=7000$K, $P=400$Gpa) on the structure of MgSiO₃ bulk 3000 atoms by Molecular Dynamics (MD) simulation using Born–Mayer (BM) pair interaction potential and periodic boundary conditions. The structural results are analyzed through the Radial Distribution Function (RDF), the Coordination Number (CN), the angle distribution, size ($l$), total energy of the system ($E_{\mathrm{\text{tot}}}$) and the bonding lengths. The results show that the temperature and pressure had influenced the structural properties of MgSiO₃ bulk and formation process geology of the Earth. In addition, the center of the Earth with $T=7000$K and $P=350$GPa has appearance and disappearance of the Si–Si, Si–O, O–O, Si–Mg, O–Mg, Mg–Mg bonds and SiO₄, SiO₅, SiO₆, MgO₃, MgO₄, MgO₅, MgO₆, MgO₇, MgO₈, MgO₉, MgO${}_{10}$, MgO${}_{11}$, MgO${}_{12}$ angle distributions. When increasing the depth of the Earth’s surface $(h)$ lead to size $(l)$ of MgSiO₃ decreases, total energy of the system ($E_{\mathrm{\text{tot}}}$) increases, position of first peak of Radial Distribution Function (RDF) is $(r)$, height of RDF is $g(r)$ varies greatly with $h$ from $h=0$km to $h=1820$km, gradually decreasing with $h$ from $h=2000$km to $h=3200$km and the smallest structural change with $h>3200$km that shows has influence affects on the geological formation of the Earth.

There is increasing demand for Carbon Fiber Reinforced Polymers (CFRP) especially in aerospace engineering. Due to their high specific strength-to-weight ratio, these composites offer more characteristics and considerable advantages when compared to metals. Metals, unlike composites, offer plasticity effects to evade high stress concentrations during post-buckling. Under compressive load, composite structures show a wide range of damage mechanisms where a set of damage modes combined together may lead to the structural collapse. The numerical analysis is conducted to investigate the effect of the dual cracks growth for the cracks embedded between plies of the skin and between plies of the stiffener hat. The dual fractured configuration is loaded to study the impact of dual cracks on load carrying capacity of the skin–stiffener joint and mode of fracture initiation and growth. Numerical method of Virtual Crack Close Technique is applied for predicting interlaminar crack initiation and interlaminar crack growth as well as in-plane crack mechanisms to predict the design of crack free joint.

Piezocomposite design for dedicated ultrasonic imaging applications requires precise homogenization models for predicting the electromechanical characteristics of the new material. Thus, several homogenization models have been developed. As part of this work, we applied several analytical homogenization models for piezocomposite of 2–2 and 1–3 connectivities. To validate these analytical models, a comparative study was made between various models and experimental measurements. As a result, these homogenized electromechanical properties are effectively used for the calculation and comparison of electroacoustic response for typical transducers aimed at ultrasound imaging applications. An optimal design of transducer aimed at ultrasound imaging applications is proposed as a dedicated imaging performance index, elaborated through a trade-off between sensitivity and bandwidth.

This paper deals with approximate homotopy series solution of imbibition phenomenon occurring in multiphase flow during the secondary oil recovery process. In heterogeneous porous media, the geometry of pores is irregular while in homogeneous porous media, the geometry of pores is uniformly same. The comparative study of counter-current imbibition phenomenon in heterogeneous and homogeneous porous medium has been also discussed. The governing partial differential equation obtained by mathematical formation of imbibition phenomenon has been solved by the optimal homotopy analysis method. The numerical as well as graphical interpretation of the solution have been given.