نشریه فناوری در مهندسی هوافضا
سال هفتم شماره 1 (پیاپی 24، بهار 1402)

Space debris is considered a serious problem for space operational missions. Many methods of capturing space debris have been proposed in the last decade and have been tested by various ground-based and sub-orbital flight methods. Space debris is usually an unusual and unknown object, and capturing and collecting them differs significantly from the objectives of conventional space missions in orbit and is considerably challenging. One of the most important considerations is how to safely capture and remove the unusual and unknown target without generating other space debris. In this article, we have tried to present the different methods and activities performed for the capturing of space debris along with their advantages and disadvantages.

The selection of suitable biological sample for space studies has vital importance. Plant cell suspension culture containing a homogenous population of proliferating cells prepares the proper situation to study various cell responses under stress conditions, especially microgravity. Cell culture systems in the laboratory can be performed in the two-dimensional (2D) and 3D culture models. In the 2D culture model, cells are cultured as a monolayer and show different growth and differentiation responses compared to normal conditions. While in the 2D model, cells are cultured in conditions that are similar to the normal conditions of cells and tissues in the living organisms and are used for medicinal purposes, production of secondary metabolites and biomass on a large scale. In this research, recent advancements and technologies used for 3D cell culture will be studied.

The aim of this study was to investigate the effects of three parameters including secondary flow injection angle, secondary flow injection location and bypass section geometry on the deflection angle of the thrust vector. The model is simulated in both two and three dimensional for a Dual Throat Nozzle. The results show that by increasing injection angle of the secondary flow, the deflection angle of the thrust vector decreases by about 27%. Also, by placing the location of secondary flow injection after the throat, we can see the deviation of the thrust vector angle is more than the flow injection before the throat. The largest difference between the injection mode in the throat and the injection after the throat is about 25% and the largest deviation of the thrust vector angle occurred at an angle of 45 degrees at the injection position in the throat.

According to friction stir processing For production of surface composites with constant progress and rotational speed, samples are made in different number of passes (1,3.5) and to obtain the stress range and adjust the device and apply the fatigue and tensile test is performed. Results of micro-structure study showed that with increasing number of passes, the distribution of underlying particles is improved, and maximum yield strength is for one sample and five samples have the longest low cycle life fatigue. The goal is improve the metal micro-structure with the new friction stirring technique, result shown the strength of the metal is improved, and resistance to wear, fatigue and corrosion is increased, it causes improvement of form-ability, which results increase in the number of The pass has led to a homogeneous and uniform distribution of reinforcing particles, in fact, increasing the number of passes in the process has led to a better distribution and separation of silicon-carbide particles in ground phase.

Purpose of paper is to use a nonlinear dynamic absorber as beam with concentrated mass at its end to reduce the amplitude of resonant nonlinear oscillator vibration. Primary vibration system consists of mass, nonlinear spring, and viscous damping, and harmonic force is applied to it and causes the system to intensify. Nonlinear dynamic absorber has been used to reduce vibration amplitude. First, the kinetic energy and potential energy of system are calculated, and then governing equations of the system are extracted using Lagrange's equations. To solve the governing equations, the method of multiple scales is used. Numerical solution, in the negligible case of considering the mass of the absorber and the stiffness of the nonlinear Duffing spring, the validation of results is done. The effect of nonlinear dynamic vibration absorber on reducing the amplitude of resonant oscillator vibration can be seen well. Influence of the main parameters of the nonlinear dynamic absorber on vibration amplitude of primary system is investigated.

In this paper, the flutter analysis of a CNT-reinforced composite beam carrying an attached mass in the supersonic flow under different boundary conditions is presented. Also, the analysis of the mentioned beam has been investigated taking into account of the first-order shear deformation theory. The aerodynamic Piston theory has been used to estimate the aerodynamic pressure. The equations governing the vibrations of this dynamic system have been determined based on the Hamilton principle. Then, by solving the equations using the generalized differential quadrature method, the natural frequencies of the dynamic system are calculated. In this work, the results have been compared and validated with similar studies. Then, the effects of carbon nanotube reinforcement and the effects of the attached mass on the frequency and stability of the beam have been investigated. The obtained results show that for uniform distribution of CNT the non-dimensional frequency decreases by increasing the ratio of length to thickness for all boundary conditions.