Mechanical strength of highly preloaded bolts affected by the ovalization of an aircraft wheel

This work presented in this paper concerns the modeling of the tensile and bending behavior of bolts in an airplane wheel. The design of a very rigid airplane tire means that the airplane wheel must be separated into two parts. In order not to have a separation between the two parts, several bolts with high preload are used. The main objective of this work is to predict the mechanical behavior of this assembly in a preliminary design phase with geometrical and global mechanical data. To achieve this objective, a simplified semi-numerical 1D model is developed. The complex geometry of the wheels is modeled by axisymmetric elements, while beam elements define the geometries and mechanical behavior of the bolts. The model is improved in non-axisymmetric cases to include the ring effect due to the wheel ovalization. Different cases are simulated (inflation and rolling). For each load case, the most stressed fastener is examined. Then, a comparison between its static and fatigue stress results and those of the 3D finite element reference model considered is analyzed for the validation of the developed tool. The semi-numerical model is used in the preliminary design phase and permits the geometric and mechanical properties of the aircraft wheel and fasteners to be defined so as to find the best assembly configuration that prevents separation.

Automatic cabin virtualization based on preliminary aircraft design data

Preliminary aircraft design and cabin design are essential and well-established steps within the product development cycle for modern passenger aircraft. In practice, the execution usually takes place sequentially, with the preliminary design defining a basic cabin layout and the detail implementation following in a subsequent step. To enable higher fidelity assessment of the cabin early in the design process—for example by means of virtual reality applications—this paper proposes an interface, which can derive detailed 3D geometry of the fuselage from preliminary design data provided in the Common Parametric Aircraft Configuration Schema (CPACS). This is a key step towards integration of cabin analysis and preliminary design in automated collaborative aircraft design chains, not only in terms of passenger comfort, but also manufacturability or crash safety. Like the TiGL Geometry Library for CPACS, the interface presented acts as a parameter engine, which translates data from CPACS into CAD geometry using the Open Cascade Technology library. However, the scope of TiGL is expanded significantly, albeit with an explicit focus on the fuselage, by including more details such as extruded frame and stringer profiles and floor structures. Furthermore, advanced knowledge management techniques are employed to detect and augment missing data. For virtual reality applications, triangulated representations of the CAD geometry can be provided in established exchange formats, creating an interface to common visualization platforms. Additionally, a new evolution of the cabin definition schema in CPACS is presented, to incorporate models of cabin components such as seats or sidewall panels enabling immersive virtual mock-ups.

Feasibility Study of Solar Powered Unmanned Aerial Vehicle

High Altitude Long Endurance Unmanned Aerial Vehicles (HALE UAVs) could provide an improved service and/or flexibility at a reduced cost over existing systems for a vast number of civil patrol and surveillance applications. This document looks into the Feasibility and Conceptual Design of Solar Powered UAV for HALE applications. It mentions the advancements in technology of the components required to build an efficient solar powered UAV. It also provides a preliminary design methodology that can be adopted for the conceptual design of Solar Powered UAV. It also emphasizes the Aerodynamic difficulties that are faced in HALE configurations.

AN OPTIMIZATION MODEL FOR PRELIMINARY STABILITY AND CONFIGURATION ANALYSES OF SEMI-SUBMERSIBLES

In the modern era of design governed by economics and efficiency, the preliminary design of a semi-submersible is critically important because in an evolutionary design environment new designs evolve from the basic preliminary designs and the basic dimensions and configurations affect almost all the parameters related to the economics and efficiency (e.g. hydrodynamic response, stability, deck load and structural steel weight of the structure, etc.). The present paper is focused on exploring an optimum design method that aims not only at optimum motion characteristics but also optimum stability, manufacturing and operational efficiency. Our proposed method determines the most preferable optimum principal dimensions of a semi-submersible that satisfies the desired requirements for motion performance and stability at the preliminary stage of design. Our proposed design approach interlinks the mathematical design model with the global optimization techniques and this paper presents the preliminary design approach, the mathematical model of optimization. Finally, a real world design example of a semi-submersible is presented to show the applicability and efficiency of the proposed design optimization model at the preliminary stage of design.

ON THE MACRO HYDRODYNAMIC DESIGN OF HIGHLY EFFICIENT MEDIUM- SPEED CATAMARANS WITH MINIMUM RESISTANCE

A new class of fuel-efficient and environmentally friendly twin-hull vessels is currently under development. Compared to high-speed catamarans, a significant reduction in speed combined with an increase in deadweight tonnes will lead to a highly efficient medium-speed catamaran design. Recently-built conventional and high-speed ferries are compared to each other in terms of length, speed, deadweight and transport efficiency to classify the new design. The goal of this study is to find a preliminary macro design point for minimum total resistance by considering the main particulars of the catamaran vessel: block coefficient, prismatic coefficient and slenderness and separation ratios of the demihulls. Publications containing recommendations towards the optimum hull form parameters for moderate Froude numbers are reviewed and existing experimental data analysed to identify parameters for this new class of vessel. Designs with varied L/BOA-ratios and constant deck area are compared to find configurations of low total resistance for carrying a nominated deadweight at a particular speed, the associated change of the light ship weight has been taken into account. Two different model test series of catamaran models have been considered and their resistance curves agreed to each other. Recommendations are made; with the most important being the vessel should not exceed a speed of Fr = 0.35, with optimal prismatic coefficients around CP ≈ 0.5 and low transom immersion. This study presents the preliminary design of medium-speed single and twin-hull vessels for operations close to hump speed.