Verification and numerical simulation of advanced composite inlet in compliance of airworthiness impact requirements

Bird or hail stone strikes are an important phenomenon which must be considered during aircraft design. Most of major bird or hail strike incidents result from engine ingestion. As engines are the sole thrust providing mechanisms of an aircraft, it is critical to investigate and mitigate the effects of bird or hail strikes on engine inlets and systems to the greatest extent possible. The article presents application of test verified numerical simulation for design and full-scale test verification of advanced composite air inlet for new generation of jet trainer aircraft from point of view of high speed impact resistance. The physical bird and hail impact tests were performed at the Czech Aerospace Research Centre (VZLÚ) according to airworthiness requirements. The measurement during impact test were performed by high-speed camera, Fiber Bragg Grating (FGB) sensors and strain gauges in cooperation with Czech Technical University (CTU) in Prague. The results from full-scale bird and hail strike tests were compared with numerical simulation

Small-and wide-angle X-ray scattering (SAXS/WAXS) in materials science

PING 2019 is organized with the support of funds for specific university research project SVK1-2019-002.Small-angle X-ray scattering (SAXS) is a well-established characterization method for microstructure (in particular, nanostructure) investigations in various materials. It examines electron density differences to provide information about structural inhomogeneities, particles or pores with size from the near atomic scale (~ 1 nm) to the scale of tens or at maximum around 200 nm in case of desktop SAXS instruments or up to micron scale (at maximum ~15 um) in case of synchrotron SAXS instruments. Wide-angle X-ray scattering (WAXS) experimental setup is usually similar to that of SAXS – the difference is that the X-ray scattering/diffraction under higher scattering angles is examined. WAXS gives information about sub-nanometer-scale structure of material, i.e., crystallinity/amorphousness. At New Technologies – Research Centre (NTC) of the University of West Bohemia, SAXSess instrument by Anton Paar (Austria) is available in a configuration enabling to investigate nanostructures on the scale from approximately 1 to 25 nm. The SAXS/WAXS method, its possibilities and the applications of SAXS/WAXS in materials science will be introduced in general. Our SAXSess instrument and selected applications for which the method was applied at NTC so far, will be presented. It includes e.g. investigation of nucleation of a new phase in metakaolin, structure analysis of Nafion-based polymer membranes and other membranes for hydrogen fuel cells and vanadium redox batteries, polyvinyl alcoholbased membranes, and analysis of size distribution changes of Pt catalysts in fuel cells after operational tests

Non-destructive Methods for Damage Assessment of Composite Sandwich Structures

Sandwich structures are capable of absorbing large amounts of energy under impact loads which results in high structural crashworthiness. Comparison of detection capabilities of selected C-scan NDT methods applicable for inspections of sandwich structures was performed using water-squirt, air-coupled and pitch-catch ultrasonic techniques, supplemented by laser shearography. Test results have shown that water-squirt and pitch-catch techniques are the most suitable methods for the core damage evaluation. Air-coupled method showed lower sensitive for detection of some artificial defects and impact damages in honeycomb sandwiches when unfocused transducers were used. The combination of the presented methods was able to reveal most of the defects

Non-destructive Methods for Damage Assessment of Composite Sandwich Structures

Sandwich structures are capable of absorbing large amounts of energy under impact loads which results in high structural crashworthiness. Comparison of detection capabilities of selected C-scan NDT methods applicable for inspections of sandwich structures was performed using water-squirt, air-coupled and pitch-catch ultrasonic techniques, supplemented by laser shearography. Test results have shown that water-squirt and pitch-catch techniques are the most suitable methods for the core damage evaluation. Air-coupled method showed lower sensitive for detection of some artificial defects and impact damages in honeycomb sandwiches when unfocused transducers were used. The combination of the presented methods was able to reveal most of the defects

Bird and hail stone impact resistance analysis on a jet engine composite air inlet

Bird or hail stone impacts are an important phenomenon that must be taken into consideration when designing aircraft. As engines are the sole thrust-providing mechanisms of an aircraft, it is critical that the effects of bird or hail stone strikes on engine inlets and systems be investigated and mitigated to the greatest extent possible. A combination of experiments and numerical simulations is necessary to properly understand the behaviour of a bird or hail stone during impact and the reaction of the impacted material with the structure. A simulation methodology is developed and validated to certify the bird or hail stone strike resistance of composite air ducts designed for a new generation of jet training aircraft. Physical impact tests were performed on real composite parts. Numerical simulation results were compared with test results. Numerical simulation was also used for test preparation and optimization of the test rig design from the point of view of the influence of the stiffness of the surrounding aircraft structure. The validated modelling procedure allows the analysis of numerous impact scenarios, improving the optimization procedures for aircraft component design and reducing the cost of development by reducing the need to manufacture test prototypes

Structural, Thermal and Viscoelastic Properties of Nanodiamond-Reinforced Poly (vinyl alcohol) Nanocomposites

PING Junior 2021 is organized with the support of funds for specific university research project SVK1-2021-008 and ERDF "Research of additive technologies for future applications in the machinery industry - RTI plus" (No. CZ.02.1.01/0.0/0.0/18_069/0010040).Advanced polymer nanocomposites comprising polyvinyl alcohol (PVA) and nanodiamonds (NDs) were developed using a single-step solution-casting method. The properties of the prepared PVA/NDs nanocomposites were investigated using Raman spectroscopy, small- and wide-angle X-ray scattering (SAXS/WAXS), scanning electron microscopy (SEM), transmission electron microscopy (TEM), thermogravimetric analysis (TGA), differential scanning calorimetry (DSC) and dynamic mechanical analysis (DMA). It was revealed that the tensile strength improved dramatically with increasing ND content in the PVA matrix, suggesting a strong interaction between the NDs and the PVA. SEM, TEM and SAXS showed that NDs were present in the form of agglomerates with an average size of ~60 nm with primary particles of diameter ~5 nm. These results show that NDs can act as a good nanofiller for PVA in terms of improving its stability and mechanical properties

Bird and hail stone impact resistance analysis on a jet engine composite air inlet

Bird or hail stone impacts are an important phenomenon that must be taken into consideration when designing aircraft. As engines are the sole thrust-providing mechanisms of an aircraft, it is critical that the effects of bird or hail stone strikes on engine inlets and systems be investigated and mitigated to the greatest extent possible. A combination of experiments and numerical simulations is necessary to properly understand the behaviour of a bird or hail stone during impact and the reaction of the impacted material with the structure. A simulation methodology is developed and validated to certify the bird or hail stone strike resistance of composite air ducts designed for a new generation of jet training aircraft. Physical impact tests were performed on real composite parts. Numerical simulation results were compared with test results. Numerical simulation was also used for test preparation and optimization of the test rig design from the point of view of the influence of the stiffness of the surrounding aircraft structure. The validated modelling procedure allows the analysis of numerous impact scenarios, improving the optimization procedures for aircraft component design and reducing the cost of development by reducing the need to manufacture test prototypes

Preparation and characterization of PVA nanocomposites with bio-functionalized nanodiamonds

PING 2019 is organized with the support of funds for specific university research project SVK1-2019-002.Poly (vinyl alcohol) (PVA) has a long and successful history of applications in the biomedical and pharmaceutical area. At the forefront of multidisciplinary research in nanomedicine, carbon nanomaterials have demonstrated unprecedented potential for a variety of regenerative medicine applications. Nanodiamonds (NDs) are a unique class of carbon nanoparticles that are gaining increasing attention to their biocompatibility, highly functional surfaces, optical properties and intriguing physical properties. In this work, we have developed advanced PVA and NDs based nanocomposite membrane in a single step using a solution-casting method from an aqueous medium and achieved high dispersibility of NDs in the PVA matrix. The resulting nanocomposites have excellent properties derived from NDs and PVA. It has been found that thermal and mechanical properties increase dramatically with increasing NDs content, suggesting a strong chemical interaction between NDs and PVA. We assume that NDs will be a suitable nano-filler for PVA membranes. This work examines properties of PVA matrix reinforced with NDs particles and their potential application in biomedical field

Verification and application of bird strike analysis for the design of high-speed helicopter composite cowlings

Bird strikes are an important phenomenon that must be taken into consideration when designing aircraft. A bird impact experiment provides a direct method to examine the bird strike resistance. However, the design of the aircraft structures usually involves many iterations of design-manufacturing-test and conducting bird impact experiments is not only time consuming but also costly. The aim of this work is to show the application of test verified numerical simulation for the design of composite cowlings of the high-speed helicopter

Non-destructive Inspection of Composite Aileron during Fatigue Test

The operational safety and reliability of an airplane must be an integral part of its design. The use of suitable materials that pass material certification tests is very important for a new aircraft design. The next part is testing specific samples, sub-components, and components such as the aileron. The paper deals with a non-destructive evaluation of composite primary structural part fatigue tests in accordance with damage tolerance philosophy considering impact damage presence. NDT methods such as visual, eddy current, and ultrasonic testing included phased array technique, are used for the inspections. A schedule of inspections was created, and structural durability was verified