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1 – 10 of 13Evan Hanks, Anthony Palazotto and David Liu
Experimental research was conducted on the effects of surface roughness on ultrasonic non-destructive testing of electron beam melted (EBM) additively manufactured Ti-6Al-4V…
Abstract
Purpose
Experimental research was conducted on the effects of surface roughness on ultrasonic non-destructive testing of electron beam melted (EBM) additively manufactured Ti-6Al-4V. Additive manufacturing (AM) is a developing technology with many potential benefits, but certain challenges posed by its use require further research before AM parts are viable for widespread use in the aviation industry. Possible applications of this new technology include aircraft battle damage repair (ABDR), small batch manufacturing to fill supply gaps and replacement for obsolete parts. This paper aims to assess the effectiveness of ultrasonic inspection in detecting manufactured flaws in EBM-manufactured Ti-6Al-4V. Additively manufactured EBM products have a high surface roughness in “as-manufactured” condition which is an artifact of the manufacturing process. The surface roughness is known to affect the results of ultrasonic inspections. Experimental data from this research demonstrate the ability of ultrasonic inspections to identify imbedded flaws as small as 0.51 mm at frequencies of 2.25, 5 and 10 MHz through a machined surface. Detection of flaws in higher surface roughness samples was increased at a frequency of 10 MHz opposed to both lower frequencies tested.
Design/methodology/approach
The approach is to incorporate ultrasonic waves to identify flaws in an additive manufactured specimen
Findings
A wave frequency of 10 MHz gave good results in finding flaws even with surface roughness present.
Originality/value
To the best of the authors’ knowledge, this was the first attempt that was able to identify small flaws using ultrasonic sound waves in which surface roughness was present.
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Mel Siegel, Priyan Gunatilake and Gregg Podnar
Aircraft flight pressurization/depressurization cycling causes the skin to inflate and deflate, stressing it around the rivets that fasten it to the airframe. The resulting…
Abstract
Aircraft flight pressurization/depressurization cycling causes the skin to inflate and deflate, stressing it around the rivets that fasten it to the airframe. The resulting strain, exacerbated by corrosion, drives the growth of initially microscopic cracks. To avoid catastrophe, aircraft are inspected periodically for cracks and corrosion. The inspection technology employed is ∼90 percent naked‐eye vision. We have developed and demonstrated robotic deployment of both remote enhanced 3D‐stereoscopic video instrumentation for visual inspection and remote eddy current probes for instrumented inspection. This article describes the aircraft skin inspection application, how robotic deployment may alleviate human performance problems and workplace hazards during inspection, practical robotic deployment systems, their instrumentation packages, and our progress toward developing image enhancement and understanding techniques that could help aircraft inspectors to find cracks, corrosion, and other visually detectable damage.
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An overview of the advances in understanding the impact of corrosion on structural integrity and the associated tools available for inspection, assessment and repair is presented…
Abstract
An overview of the advances in understanding the impact of corrosion on structural integrity and the associated tools available for inspection, assessment and repair is presented. A comprehensive set of these tools would allow for a significant shift in aircraft maintenance concepts.
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In a letter to the Federal Aviation Administration, the National Transportation Safety Board expressed its concern about multiple tyre failures in wide‐bodied aircraft, such as…
Abstract
In a letter to the Federal Aviation Administration, the National Transportation Safety Board expressed its concern about multiple tyre failures in wide‐bodied aircraft, such as that experienced by the Continental Air Lines DC‐10 at Los Angeles International Airport on March 1st, 1978. Several actions the FAA had underway or was planning to initiate. The Safety Board acknowledges these actions as a step toward reducing the potential risk of tyre failures. However, the Safety Board's public hearing, which was convened on May 30th, 1978, as part of the investigation of the DC‐10 accident, elicited much testimony regarding factors which can affect tyre safety and reliability; and as a result, we believe that additional regulatory or advisory actions are needed in the areas of design standards, qualification testing, quality control during manufacture, and operational limits. Our concerns apply to retreaded tyres as well as new tyres.
This paper aims to document the approach, effort and cost of advance composite technology implementation suited for small and medium enterprises on the example of composite main…
Abstract
Purpose
This paper aims to document the approach, effort and cost of advance composite technology implementation suited for small and medium enterprises on the example of composite main rotor blade development for ILX-27 helicopter.
Design/methodology/approach
This work was carried out as part of a development project for main rotor blades used on the ILX 27 helicopter. The paper presents all stages of the design of the blade structure in parallel with composite technology development. The data were gathered and documented during project execution. The stages of R&D work in terms of labor intensity and important processes influencing quality and efficiency were assessed.
Findings
The paper provides key aspects for successful composite capability introduction. The incurred cost of equipment and staff training is evaluated. The paper also summarized the cost of composite parts manufactured with developed technology.
Practical implications
The paper provides detail example of composite capability development including basic technologies, processes, equipment and cost of the project. Presented details can be great guidelines for small and medium enterprises with the goal of composite technology introduction for aerostructures design and manufacturing.
Originality/value
This paper present clear, complete and verified process of composite capability development for aerostructures design and build suited for small and medium enterprises. It presents detail cost, calculated in Polish economy environment, of each phase and final cost of the product.
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Jerzy P. Komorowski and David S. Forsyth
The current corrosion maintenance philosophy reflected in aviation regulations and recommended practices does not stimulate progress in corrosion related technology. A US Air…
Abstract
The current corrosion maintenance philosophy reflected in aviation regulations and recommended practices does not stimulate progress in corrosion related technology. A US Air Force (USAF)‐sponsored survey has recommended re‐examination of corrosion maintenance policies and practices to identify lower cost alternatives, and has encouraged research into tools and techniques that reduce maintenance costs while preserving safety. In particular, these include models to predict the impact of existing corrosion damage on structural integrity, methods of predicting corrosion growth rates and nondestructive inspection systems capable of providing corrosion metrics. The Institute for Aerospace Research of the National Research Council Canada (IAR/NRC) has pioneered work on the application of enhanced visual methods for corrosion detection in lap joints and the assessment of the impact of corrosion on lap‐joint structural integrity. The role of these enhanced visual methods in the new corrosion management is described.
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Brant Edward Stoner, Griffin T. Jones, Sanjay Joshi and Rich Martukanitz
The continued improvement of additive manufacturing (AM) processing has led to increased part complexity and scale. Processes such as electron beam directed energy deposition…
Abstract
Purpose
The continued improvement of additive manufacturing (AM) processing has led to increased part complexity and scale. Processes such as electron beam directed energy deposition (DED) are able to produce metal AM parts several meters in scale. These structures pose a challenge for current inspection techniques because of their large size and thickness. Typically, X-ray computed tomography is used to inspect AM components, but low source energies and small inspection volumes restrict the size of components that can be inspected. This paper aims to develop digital radiography (DR) as a method for inspecting multi-meter-sized AM components and a tool that optimizes the DR inspection process.
Design/methodology/approach
This tool, SMART DR, provides optimal orientations and the probability of detection for flaw sizes of interest. This information enables design changes to be made prior to manufacturing that improve the inspectabitity of the component and areas of interest.
Findings
Validation of SMART DR was performed using a 40-mm-thick stainless-steel blade produced by laser-based DED. An optimal orientation was automatically determined to allow radiographic inspection of a thickness of 40 mm with a 70% probability of detecting 0.5 mm diameter flaws. Radiography of the blade using the optimal orientation defined by SMART DR resulted in 0.5-mm diameter pores being detected and indicated good agreement between SMART DR’s predictions and the physical results.
Originality/value
This paper addresses the need for non-destructive inspection techniques specifically developed for AM components.
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Assunta Sorrentino, Fulvio Romano and Angelo De Fenza
The purpose of this paper is to introduce a methodology aimed to detect debonding induced by low impacts energies in typical aeronautical structures. The methodology is based on…
Abstract
Purpose
The purpose of this paper is to introduce a methodology aimed to detect debonding induced by low impacts energies in typical aeronautical structures. The methodology is based on high frequency sensors/actuators system simulation and the application of elliptical triangulation (ET) and probability ellipse (PE) methods as damage detector. Numerical and experimental results on small-scale stiffened panels made of carbon fiber-reinforced plastic material are discussed.
Design/methodology/approach
The damage detection methodology is based on high frequency sensors/actuators piezoceramics system enabling the ET and the PE methods. The approach is based on ultrasonic guided waves propagation measurement and simulation within the structure and perturbations induced by debonding or impact damage that affect the signal characteristics.
Findings
The work is focused on debonding detection via test and simulations and calculation of damage indexes (DIs). The ET and PE methodologies have demonstrated the link between the DIs and debonding enabling the identification of position and growth of the damage.
Originality/value
The debonding between two structural elements caused in manufacturing or in-service is very difficult to detect, especially when the components are in low accessibility areas. This criticality, together with the uncertainty of long-term adhesive performance and the inability to continuously assess the debonding condition, induces the aircrafts’ manufacturers to pursuit ultraconservative design approach, with in turn an increment in final weight of these parts. The aim of this research’s activity is to demonstrate the effectiveness of the proposed methodology and the robustness of the structural health monitoring system to detect debonding in a typical aeronautical structural joint.
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Mohammad I. Albakri, Logan D. Sturm, Christopher B. Williams and Pablo A. Tarazaga
This work proposes the utilization of electromechanical impedance measurements as a means of non-destructive evaluation (NDE) for additive manufacturing (AM). The effectiveness…
Abstract
Purpose
This work proposes the utilization of electromechanical impedance measurements as a means of non-destructive evaluation (NDE) for additive manufacturing (AM). The effectiveness and sensitivity of the technique for a variety of defect types commonly encountered in AM are investigated.
Design/methodology/approach
To evaluate the feasibility of impedance-based NDE for AM, the authors first designed and fabricated a suite of test specimens with build errors typical of AM processes, including dimensional inaccuracies, positional inaccuracies and internal porosity. Two polymer AM processes were investigated in this work: material jetting and extrusion. An impedance-based analysis was then conducted on all parts and utilized, in a supervised learning context, for identifying defective parts.
Findings
The newly proposed impedance-based NDE technique has been proven to be an effective solution for detecting several types of print defects. Specifically, it was shown that the technique is capable of detecting print defects resulting in mass change (as small as 1 per cent) and in feature displacement (as small as 1 mm) in both extruded nylon parts and jetted VeroWhitePlus parts. Internal porosity defects were also found to be detectable; however, the impact of this defect type on the measured impedance was not as profound as that of dimensional and positional inaccuracies.
Originality/value
Compared to currently available NDE techniques, the newly proposed impedance-based NDE is a functional-based technique with the advantages of being cost-effective, sensitive and suitable for inspecting AM parts of complex geometry and deeply embedded flaws. This technique has the potential to bridge the existing gaps in current NDE practices, hence paving the road for a wider adoption of AM to produce mission-critical parts.
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