Automated procedure for determination of friction grip and bearing joint strength used for space missions

This paper presents an algorithm that calculates the nominal torque for friction grip joints, followed by its implementation in a Microsoft Excel worksheet that is automated by a macro written in Visual Basic. The algorithm outputs not only the optimum nominal torque (the value for which the margin of safety is maximum) but also the interval of acceptable values so that the user can easily choose the torque according to his preferences

End-to-end process of hollow spacecraft structures with high frequency and low mass obtained with in-house structural optimization tool and additive manufacturing

In the space sector the most decisive elements are: mass reduction, cost saving and minimum lead time; here, structural optimization and additive layer manufacturing (ALM) fit best. The design must be driven by stiffness, because an important requirement for spacecraft (S/C) structures is to reduce the dynamic coupling between the S/C and the launch vehicle. The objective is to create an end-to-end process, from the input given by the customer to the manufacturing of an aluminum part as light as possible but at the same time considerably stiffer while taking the full advantage of the design flexibility given by ALM. To design and optimize the parts, a specialized in-house tool was used, guaranteeing a load-sufficient material distribution. Using topological optimization, the iterations between the design and the stress departments were diminished, thus greatly reducing the lead time. In order to improve and lighten the obtained structure a design with internal cavities and hollow beams was considered. This implied developing of a procedure for powder evacuation through iterations with the manufacturer while optimizing the design for ALM. The resulted part can be then manufactured via ALM with no need of further design adjustments. To achieve a high-quality part with maximum efficiency, it is essential to have a loop between the design team and the manufacturer. Topological optimization and ALM work hand in hand if used properly. The team achieved a more efficient structure using topology optimization and ALM, than using conventional design and manufacturing methods

An impact study of a capsule with a rigid wall using the SPH approach

Impact problems have always been of interest in the Aerospace industry because events such as “bird-strikes” occur quite often and necessary studies must be performed to observe the behavior of structures during the impact. This paper performs a study of an impact between a capsule filled with a liquid, modeled with SPH approach (Smoothed-Particle Hydrodynamics), and a rigid wall using the explicit nonlinear analysis. We also apply a rotation to the capsule to study how it affects different values such as impact pressures and structural stress. Another important aspect of this problem is the fluid-structure interaction and how different parameters influence the spill pattern of the fluid. We present some numerical results obtained for the above-mentioned cases

New Urban Vertical Axis Wind Turbine Design

This paper develops a different approach for enhancing the performance of Vertical Axis Wind Turbines for the use in the urban or rural environment and remote isolated residential areas. Recently the vertical axis wind turbines (VAWT) have become more attractive due to the major advantages of this type of turbines in comparison to the horizontal axis wind turbines. We aim to enhance the overall performance of the VAWT by adding a second set of blades (3 x 2=6 blades) following the rules of biplane airplanes. The model has been made to operate at a maximum power in the range of the TSR between 2 to 2.5. The performances of the VAWT were investigated numerically and experimentally and justify the new proposed design

The validation of an aerospace structure through the sine vibration analysis

Sinusoidal vibrations represent an ideal case. Technically, it is quite hard to generate pure sinusoidal vibrations without containing other spectral components, called harmonics. Sinusoidal vibrations can appear on propeller, propulsion and turbofan aircraft as well as on helicopters and aerospace structures. They can occur during different phases of flight (take-off, ascent, cruise, landing, etc.). The aim of this article is to present how a structure can be validated by using the mathematical formulas or a FEM software such as PATRAN-NASTRAN (and the equations behind it). As an application, an aerospace structure such as thruster brackets will be analyzed. A sinusoidal signal of 1g was applied on the attachment points and the response was read from the center of gravity of the thrusters

Comparative Analysis Program for Experimental and Calculated Data

This article aims to provide an interactive in-house tool to quickly asses the stress in the critical points of the aeronautical structures. The software compares the results between the stress values obtained from the experimental tests using the resistive electrical tensometry technique (RET) and the stress values calculated with FEM software. RET refers to the stress and strains measured by strain gauges applied to the critical points of the structures. The finite element analysis was carried-out with MSC. PATRAN/ NASTRAN using shell and solid elements in order to identify the critical points based on the stress and strain results. The validation of the results obtained by the finite element modelling has been made experimentally using the resistive electrical tensometry method. The results from these two methods have been compared with the in-house software developed in Visual Basic with Excel interface. The program evaluates the relative error between the experimental and calculated data at critical points