Journal of Multiscale Modelling

Beneficial effects of the electromagnetic treatment on fatigue resistance were reported on several engineering alloys. These could be linked to the dislocation activity and the rearrangement of the crystal structure of the material under the electromagnetic field (EMF), resulting in delayed crack initiation. This paper presents an experimental study on the effect of pulsed electromagnetic treatment on the fatigue resistance of 2011 aluminum alloy. Circular cantilever specimens with loads at their ends were tested on rotating fatigue machine SM1090. Fatigue lives of treated and untreated specimens were analyzed and compared systematically. It has been found that the effect of the pulsed electromagnetic treatment on the fatigue resistance is dependent on the intensity of the pulsed EMF and the number of the treatment applied. Clear beneficial effect of the pulsed electromagnetic treatment on the fatigue resistance of the aluminum alloys has been observed, demonstrating a potential new technique to industries for fatigue life extension.

BACKGROUND: Malalignment about the knee leads to a pathological-mechanical load that may cause early osteoarthritis of the knee joint and high degree of deformity which may need surgical treatment. Analysis of the leg movements in the experimental cases and comparing acquired results to the normal ones during the gait is used as a practical method to evaluate the effects of the disease.

METHOD: In this study, gait differences between the patients with tibia vara and normal people were studied according to the data obtained from a three-dimensional (3D) motion analyzer. Various parameters, including positions, linear and angular velocities, linear and angular accelerations, total velocity, total acceleration, and path length at different angels were extracted and processed via a 3D motion analyzer. Then the results of the patient and control groups were compared to identify the differences.

RESULTS: The maximum and average values as well as sample entropy were also calculated for all the mentioned parameters. Among all, only nine remarkable differences between these two groups were observed. The results revealed that the great difference between the patients with tibia vara compared to the normal ones in gait cycle lies on the abnormal movement of fibula bone and less irregularities along the $z$-axis.

CONCLUSIONS: These findings may have implications not only for understanding the differences between the tibia vara in the healthy and diseased individuals, but also for providing a practical understanding for the medical and orthopedic experts to propose a better treatment method.

The fiber-reinforced composite materials with periodic cylindrical inclusions of a circular cross-section arranged in a hexagonal array are analyzed. The governing analytical relations of the thermal conductivity problem for such composites are obtained using the asymptotic homogenization method. The lubrication theory is applied for the asymptotic solution of the unit cell problems in the cases of inclusions of large and close to limit diameters, and for inclusions with high conductivity. The lubrication method is further generalized to the cases of finite values of the physical properties of inclusions, as well as for the cases of medium-sized inclusions. The analytical formulas for the effective coefficient of thermal conductivity of the fiber-reinforced composite materials of a hexagonal structure are derived in the cases of small conductivity of inclusions, as well as in the cases of extremely low conductivity of inclusions. The three-phase composite model (TPhM) is applied for solving the unit cell problems in the cases of the inclusions with small diameters, and the asymptotic analysis of the obtained solutions is performed for inclusions of small sizes. The obtained results are analyzed and illustrated graphically, and the limits of their applicability are evaluated. They are compared with the known numerical and asymptotic data in some particular cases, and very good agreement is demonstrated.