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CFD Approach to Modelling Hydrodynamic Characteristics of Underwater Glider

Abstract

Autonomous underwater gliders are buoyancy propelled vehicles. Their way of propulsion relies upon changing their buoyancy with internal pumping systems enabling them up and down motions, and their forward gliding motions are generated by hydrodynamic lift forces exerted on a pair of wings attached to a glider hull. In this study lift and drag characteristics of a glider were performed using Computational Fluid Dynamics (CFD) approach and results were compared with the literature. Flow behavior, lift and drag forces distribution at different angles of attack were studied for Reynolds numbers varying around 105 for NACA0012 wing configurations. The variable of the glider was the angle of attack, the velocity was constant. Flow velocity was 0.5 m/s and angle of the body varying from −8° to 8° in steps of 2°. Results from the CFD constituted the basis for the calculation the equations of motions of glider in the vertical plane. Therefore, vehicle motion simulation was achieved through numeric integration of the equations of motion. The equations of motions will be solved in the MatLab software. This work will contribute to dynamic modelling and three-dimensional motion simulation of a torpedo shaped underwater glider.

Open access
Comparative Analysis of Macro- and Microstructure of Printed Elements in the FDM, SLS and MJ Technologies

Abstract

The article presents research conducted with the project: ‘Additive manufacturing in conduction with optical methods used for optimization of 3D models’’ [2]. The article begins with the description of properties of the materials used in three different additive technologies – Fused Deposition Modelling (FDM), Selective Laser Sintering (SLS) and Material Jetting (MJ). The next part focuses on the comparative analysis of macro- and microstructure of specimens printed in order to test selected materials in additive technologies mentioned above. In this research two types of specimens were used: dumbbell specimens and rectangular prism with hole specimens. In order to observe macrostructure specimens, they were subjected to load test until it broke. In the case of observing microstructure, they were cut in some places. Each of described additive technologies characterizes by both different way of printing and used materials. These variables have a significant influence on macro- and microstructure and fracture appearance. FDM technology specimens printed of ABS material characterized by texture surface appearance. SLS technology specimens printed of PA12 material characterized by amorphous structure. MJ technology specimens printed of VeroWhite Plus material characterized by fracture appearance which had quasi- fatigue features. The microstructure of these specimens was uniform with visible inclusions.

Open access
Comparison of Composite Laminates Machining Methods and its Influence on Process Temperature and Edge Quality

Abstract

The article presents the description of technological trials and the results of three methods of machining carbon fiber reinforced composites panels. It also reviews the literature concerned heat affected zone in composites and its influence on material properties. As a part of the research, the cutting method using diamond coated saw was tested, as well as the milling method with two different types of carbide milling cutters. The processing of the panels was done using 4-axis CNC machine with special adapter for cutting discs in Composite Testing Laboratory (Center for Composite Technologies, Warsaw Institute of Aviation). The methods were compared in terms of machined edge quality and panel temperature during the processes. For this purpose, thermocouples were mounted into panels. Records from thermocouples were included. Edge quality and surface roughness have been checked by microscopic observation. Additionally, samples machined by each evaluated processing method were tested using differential scanning calorimetry (DSC). The method was used to determine the glass transition temperature of the tested material. The article conclusions contain a comparison of three processing methods in terms of cutting quality, process temperature, processing method productivity as well as DSC tests results.

Open access
Janus – A New Approach to Air Combat Pilot Training

Abstract

Advanced jet training still relies on old concepts and solutions that are no longer efficient when considering the current and forthcoming changes in air combat. The cost of those old solutions to develop and maintain combat pilot skills are important, adding even more constraints to the training limitations. The requirement of having a trainer aircraft able to perform also light combat aircraft operational mission is adding unnecessary complexity and cost without any real operational advantages to air combat mission training.

Thanks to emerging technologies, the JANUS project will study the feasibility of a brand-new concept of agile manoeuvrable training aircraft and an integrated training system, able to provide a live, virtual and constructive environment. The JANUS concept is based on a lightweight, low-cost, high energy aircraft associated to a ground based Integrated Training System providing simulated and emulated signals, simulated and real opponents, combined with real-time feedback on pilot’s physiological characteristics: traditionally embedded sensors are replaced with emulated signals, simulated opponents are proposed to the pilot, enabling out of sight engagement. JANUS is also providing new cost effective and more realistic solutions for “Red air aircraft” missions, organised in so-called “Aggressor Squadrons”.

Open access
Theoretical and Experimental Review of Applied Mechanical Tests for Carbon Composites with Thermoplastic Polymer Matrix

Abstract

This article has a theoretical and experimental character. It presents the characteristics of two main thermoplastics used in the aerospace industry – poly ether ether ketone (PEEK) and poly phenylene sulphide (PPS). The selected materials are compounds for the production of thermoplastic polymer matrix composites. The paper presents a literature review of the application of thermoplastic polymer matrix composite materials in aviation. Additionally, the paper focuses on the characteristics of carbon fibre-reinforced polymer (CFRP) which plays an important role in the production of aerospace components. Testing methods have been chosen on the basis of the type of composite matrix. The article contains the most important mechanical properties and general characteristics of thermoplastics used as a matrix for CFRP type composites used in the aerospace industry. Individual test procedures which allow for the evaluation of mechanical properties of composite materials on a thermoplastic polymer matrix, have been described. Mechanical tests such as static tensile test and bending of short beams were carried out in order to examine CFRP composites.

Open access
Validation of Numerical Models Used for Designing the Composite Blade for ILX-27 Rotorcraft

Abstract

The paper presents the validation procedure of the model used in the analysis of the composite blade for the rotor of the ILX-27 rotorcraft, designed and manufactured in the Institute of Aviation, by means of numerical analyses and tests of composite elements. Numerical analysis using finite element method and experimental studies of three research objects made of basic materials comprising the blade structure – carbon-epoxy laminate, glass-epoxy composite made of roving and foam filler – were carried out. The elements were in the form of four-point bent beams, and for comparison of the results the deflection arrow values in the middle of the beam and axial deformations on the upper and lower surfaces were selected. The procedure allowed to adjust the discrete model to real objects and to verify and correct the material data used in the strength analysis of the designed blade.

Open access
The Analysis of Hospital Helicopter Landing Sites Location in Terms of their Vibroacoustic Impact

Abstract

According to the applicable regulations, in the case of a decision on the location of an investment consisting in the construction and commissioning of a helicopter landing field, it is necessary to carry out an environmental impact assessment. At the same time, due to the emission of noise related to the expected change of acoustic climate parameters, the indicators required under the applicable law related to building acoustics and also impact of vibration on the structure of buildings should be taken into account. The article discusses particular groups of issues related to the assessment of the impact of helicopter landing field on the environment and the hospital building. On the basis of the presented results of analyzes, a postulate concerning the necessity of introducing a comprehensive assessment methodology, including specific groups of issues, was formulated.

Open access
A Concept of Suborbital Scientific Mission and Technology Validation

Abstract

Suborbital platforms are one of alternatives for satellites. They offer cheaper access to space to perform broad range of scientific and technology R&D. One of suborbital platforms are sounding rockets, which are suitable for these applications. A concept of scientific mission utilizing the sounding rocket is presented by author in this paper. The novelty of this mission is the operational responsive launch approach, which presents the example of the mission which responds for payload user needs, not payload contest approach, which is often in scientific community competing for payload space in space agency sounding rocket launch campaigns. The main mission goal is to perform astronomical observation of NEO using IR/VIS telescope. The secondary goal is to qualify the instrument for use on astronomical satellite observatory and raise its technology readiness level from TRL 6 to TRL 8. The expected mission output is to gain scientific data on NEO object and perform new IR/VIS optoelectronic instrument technology validation.

Open access
Determination of In-Plane Shear Properties of Laminate with V-Notch Rail Shear Test and Digital Image Correlation

Abstract

This article presents the results of the application of Digital Image Correlation (DIC) to measurements of in-plane shear modulus and strength of three different carbon fiber reinforced laminates. Three different approaches to shear strain calculations via DIC are evaluated and compared with standard strain gage measurements. Calculation of shear strain based on averaging DIC strain values of strain gages area in most cases yielded results closest to strain gages, while measurements based on single point strain measuring differed the most from strain gages. These results are attributed to shear strain distribution in the center area of the specimen. Thermoplastic matrix fabric reinforced composite had the lowest shear strength at 5% of shear strain, but the highest ultimate shear strength and strain at failure. Of thermosetting materials, laminate reinforced with unidirectional carbon fiber had shear modulus about 10% lower, than fabric reinforced laminate, but higher ultimate strength and strain at failure. This behavior is attributed to the presence of weaves in fabric reinforcing the laminate, causing shear stiffening of the material, but lowering its ability to deform under shear loading.

Open access
Influence of Honeycomb Core Stabilization on Composite Sandwich Structure Geometry

Abstract

Authors showed the influence of stabilization of the honeycomb core on shape of the composite sandwich test panel. Adhesive film laid on core ramps and cured with suitable cure cycle served as core stabilizer. Test panel geometry included different ramp angles (20° and 30°). To verify stabilization process a technology trial was performed. Three test panels were manufactured (3-stage, 1-stage and 1-stage with stabilized core). All test panels were manufactured in OoA process (Out of Autoclave). Panel surfaces were scanned with 3D scanner and compared with the reference CAD model. Both outer skin and inner skin were manufactured in Automated Fiber Placement Laboratory of Warsaw Institute of Aviation.

Open access