Zahra Khaji; Mahdi Fakoor; Saeed Shakhesi
Abstract
The design of space operations must be done carefully. Because the smallest mistake in the design and construction of the spacecraft causes heavy financial losses. Electronic boards are one of the most important components of electronic systems in any operation. These boards must continue to operate ...
Read More
The design of space operations must be done carefully. Because the smallest mistake in the design and construction of the spacecraft causes heavy financial losses. Electronic boards are one of the most important components of electronic systems in any operation. These boards must continue to operate under the applied loading. Strong levels of random vibrations can cause damage and fracture in electronic boards. The random vibration field applied to the electronic board can be modeled by mixed-mode I/II loading. Solder joints are very sensitive components of satellites. Fracture of electronic packages often occurs due to cracking in the joint between the electronic board and the solder under mixed-mode I/II loading. In this research, a new fracture criterion based on the maximum tangential stress is presented to predict the fracture for the interfacial crack between the electronic board and the solder. Based on the presented criterion, the direction and moment of crack initiation are predicted for the interfacial crack between isotropic and orthotropic materials. In this way, the fracture limit curve can be drawn. By comparing the presented criterion with the available experimental data, it can be concluded that the presented criterion has sufficient validity to evaluate the prediction of fracture in interfacial cracks between isotropic and orthotropic materials.
Structure
mohammadreza alijani nargesi; hasan haddadpour; Saeed Shakhesi
Abstract
One of the key issues in the operations of on orbit servicing to unmanned satellites is to provide a safe and reliable docking process. This paper investigates the dynamic behavior of a flexible probe in the central docking mechanism of unmanned satellites. For simulating the impact phenomenon, ...
Read More
One of the key issues in the operations of on orbit servicing to unmanned satellites is to provide a safe and reliable docking process. This paper investigates the dynamic behavior of a flexible probe in the central docking mechanism of unmanned satellites. For simulating the impact phenomenon, a dynamic analysis software (MSC. Adams) has been applied and a three-dimensional model has created based on the assumption of a flexible clamped beam as a shock absorber. The results are in good agreement with similar theoretical and experimental results. additionally, it is possible to consider the parameters such as the type of connection between the beam and the concentrated mass, angular and translational velocity of chaser and target satellites, in order to determine the optimum condition to perform a successful docking operation. The results of this study indicate that the use of a spherical joint for the ball attached to the probe, significantly reduces the maximum value of impact force. Also, the rotation of the sphere leads to less change in the linear and angular velocity of the target satellite and increases the probability of successful mating of the satellites. On the other hand, the movement of the conical area relative to the target satellite reduces the maximum impact force and shock resulting on the satellites structure. As a result, the chance of successful docking increases.