Multiobjective optimization of the LASER aircraft wing’s composite structural design

Purpose Aircraft wings, one of the most important parts of an aircraft, have seen changes in its topological and design arrangement of both the internal structures and external shape during the past decades. This study, a numerical, aims to minimize the weight of multilaminate composite aerospace structures using multiobjective optimization. Design/methodology/approach The methodology started with the determination of the requirements, both imposed by the certifying authority and those inherent to the light, aerobatic, simple, economic and robust (LASER) project. After defining the requirements, the loads that the aircraft would be subjected to during its operation were defined from the flight envelope considering finite element analysis. The design vector consists of material choice for each laminate of the structure (20 in total), ply number and lay-up sequence (respecting the manufacturing rules) and main spar position to obtain a lightweight and cheap structure, respecting the restrictions of stress, margins of safety, displacements and buckling. Findings The results obtained indicated a predominance of the use of carbon fiber. The predominant orientation found on the main spar flange was 0° with its location at 28% of the local chord, in the secondary and main web were ±45°, the skins also had the main orientation at ±45°. Originality/value The key innovations in this paper include the evaluation, development and optimization of a laminated composite structure applied to a LASER aircraft wings considering both structural performance and manufacturing costs in multiobjetive optimization. This paper is one of the most advanced investigations performed to composite LASER aircraft.

Mitigation of Thermal Effects in End Pumping of Nd : YAG and Composite YAG/Nd : YAG Laser Crystas, Modelling and Experiments-=SUP=-1-=/SUP=-

In this work, we have presented a finite element (FE) numerical modelling simulations to study and analyze the thermal effects in Nd : YAG and composite YAG/Nd : YAG laser rods. We have calculated the temperature distributions, stress intensity and thermal focal lengths at different pump powers for both rods. The FE simulations showed that using composite laser rod of undoped cap reduces the maximum value of stress intensity and thermal focal length by ~35% and ~ 50%, respectively. We have verified the FE calculations experimentally by direct measurement of focal length of thermally induced lens by using Hartmann-Shack wavefront sensor. Good agreement was obtained between FE calculations and experimental measurements. Keywords: Nd : YAG lasers, Thermal lens, Wavefront sensing, solid state lasers.