Integrated Design and Manufacturing Analysis for Automated Fiber Placement Structures

Automated fiber placement provides many advancements beyond traditional hand layups in terms of efficiency and reliability. However, there are also a variety of unique challenges that arise with automated fiber placement technology. In particular, steering of tows over doubly-curved tool surfaces can result in material overlaps and gaps due to path convergence/divergence, fiber angle deviation, as well defects in the tows themselves such as puckers and wrinkles. Minimization of these defects is traditionally considered a task for the manufacturing discipline. Manufacturing specifications are often created for these defects based on laminate testing and can be inflexible to avoid more tests. Recent efforts have been made under the National Aeronautics and Space Administration (NASA) Advanced Composites Project (ACP) to develop software tools and processes that provide automated coupling between design and manufacturing disciplines. The objective of this coupling is to provide information to the design discipline on the manufacturability of a laminate while the laminate is being designed. A variety of software tools, both existing commercial tools and research tools under development, will be used to achieve this objective: HyperSizer for laminate optimization, the Computer Aided Process Planning module for selection of manufacturing process parameters, Vericut Composite Programming for tow path simulation, and COMPRO for deposition and cure defects. The newly developed Central Optimizer tool will be used to tie the modules together and drive the design for manufacturing process

Democracy and/or Stability? The Lebanese Parliamentary Elections of 2000

The first and second issue of four volumes, this volume addresses elections in the Middle East. Contributors include: Assia Boutaleb, Judith Harik, Mona Markram-Ebeid, Christopher Parker, Curtis Francis Doebbler, Maye Kassem, Baskin Oran, Sami Zemni.https://fount.aucegypt.edu/faculty_book_chapters/2026/thumbnail.jp

The Economics of Tax Reform

The contributors discuss the issuess of taxation and tax reform from diverse perspectives and show that tax reform is an ongoing process that doesn\u27t end with the signing of a specific piece of legislation.https://research.upjohn.org/up_press/1205/thumbnail.jp

CHARACTERIZATION OF DEFECTS IN METAL SHEETS VIA INFRARED THERMOGRAPHY

Defects in Aluminum, Stainless steel and galvanized steel sheets are studied in reflection mode infrared thermography. The effect of material properties, surface finish, heating intensity, heater emission spectra, pixel size and defect size are studied. Contrast is governed by heat quality, emissivity and defect geometry—which follows a logarithmic trend. The diameter detected via infrared thermography is found to be at least 30% larger than the measured diameter and sub-pixel defects can be detected. The use of gradient and Laplacian of temperature is introduced as a means of increasing defect contrast and mitigating heater variation

Keuhkosyöpäpotilaan kuvantaohjattu sädehoito : isosentrin paikan yhteys potilaskohtaisiin siirtoihin

Opinnäytetyön tarkoituksena oli selvittää kuvantaohjatusti sädehoidettujen keuhkosyöpäpotilaiden (N=30) päivittäisiä siirtoja sekä isosentrin (is) paikan yhteyttä tehtyjen siirtojen suuruuteen. Työn tavoitteena oli saada käsitys keskiarvoisesta hoidon osuvuudesta Turun yliopistollisen keskussairaalan (TYKS) sädehoitoyksikössä ulkoisten ihomerkkien ja luisten rakenteiden suhteen. Mikäli isosentrillä on yhteys hoidon osuvuuteen, voidaan annossuunnittelussa mahdollisesti välttää tiettyjä alueita isosentrin paikalle, jolloin hoidon asettelu ihomerkkien mukaan tulee tarkemmaksi. Opinnäytetyön toteutuksessa käytettiin tilastollista analyysia. Työhön saatiin valmis aineisto potilaskohtaisista siirroista. Kaikkien suuntien yhteenlaskettujen siirtojen lukumääräksi saatiin 1767, joita analysoitiin Excel-tilastointiohjelman avulla. Potilassiirtoja tarkasteltiin korkeus (vrt)-, pituus (lng)- ja poikittaissuunnassa (lat). Kunkin suunnan siirroista laskettiin minimi- ja maksimiarvot sekä keskiarvot ja –hajonnat. Potilaiden isosentrien paikkaa koskevat tiedot kerättiin heille tehdyistä sädehoidon suunnitelmista. Isosentrin paikan yhteyttä potilaskohtaisiin siirtoihin tarkasteltiin korrelaatiokertoimen avulla. Tuloksissa tarkasteltiin kunkin suunnan siirron minimi- ja maksimiarvoja sekä siirtojen keskiarvoja ja keskihajontoja. Minimiarvoksi saatiin kaikissa suunnissa 0 cm ja maksimiarvoiksi 1,5 cm (vrt), 1,4 cm (lng) ja 1,3 cm (lat). Keskiarvoiksi saatiin 0,35 cm (vrt), 0,37 cm (lng) ja 0,29 cm (lat) ja keskihajonnoiksi 0,31 cm (vrt), 0,30 (lng) sekä 0,24 cm (lat). Tarkastellessa isosentrin yhteyttä potilaskohtaisiin siirtoihin, saatiin keskeiseksi tulokseksi, että mitä kaudaalisemmin isosentri sijaitsee, sitä suurempia ovat siirrot pituussuunnassa ja mitä ventraalisemmin isosentri sijaitsee, sitä pienempiä ovat siirrot korkeussuunnassa. Tutkimustulosten perusteella voidaan päätellä, että kuvantaohjaus on tärkeä menetelmä sädehoidon osuvuuden varmentamisessa ja laadun arvioinnissa. Keuhkosyöpäpotilaiden kuvantaohjatun sädehoidon osuvuutta muissa sädehoitoyksiköissä voidaan verrata näihin tutkimustuloksiin vain, kun käytetään samaa potilasfiksaatiota ja hoitoasentoa. Jatkotutkimusaiheena voisi vertailla jonkin muun sädehoitoyksikön saamia tuloksia tässä työssä saatuihin tuloksiin.The purpose of this thesis was to determine the daily displacements of lung cancer patients (N=30) who were treated with image-guided radiation therapy and also to clarify if the isocenter has a connection to patient-specific displacements. The aim was to identify the average treatment accuracy with relation to skin tattoos and bony anatomy at the Turku University Hospital department of radiotherapy. Provided the isocenter has a connection to the treatment accuracy, treatment can be planned so as to avoid unfavourable regions for isocenter placement. This would improve treatment accuracy when solely using skin tattoos. The thesis was carried out by using statistical analysis. Patient displacement data was collected beforehand. The total number of displacements was 1767 and these were analyzed using Microsoft Excel. Displacements were examined in vertical (vrt), longitudinal (lng) and lateral (lat) directions. The minimum, maximum and mean values were calculated in each respective direction. Standard deviations were also calculated. The locations of the isocenters were collected from patient treatment plans and the isocenters connection to patient-specific displacements was examined using a correlation coefficient. Results included the minimum, maximum and mean values of displacements as well as their standard deviations. The minimum value in every direction was 0 cm and maximum values were 1,5 cm (vrt), 1,4 cm (lng) and 1,3 cm (lat). Mean values were 0,35 cm (vrt), 0,37 cm (lng) and 0,29 (lat) and standard deviations were 0,31 cm (vrt), 0,30 cm (lng) and 0,24 cm (lat). When examining the correlation between isocenter location and patient-specific displacements, two major observations were made: if the isocenter has a more pronounced caudal location it results in larger displacements in the longitudinal direction, whereas if it is more ventral, smaller displacements occur in the vertical direction. Primary conclusions were that image-guidance is an important procedure in improving the accuracy and quality evaluation of radiotherapy. Conclusions based on results produced during this thesis are only applicable in other radiotherapy units when using the same immobilization device and treatment position. Further studies could, for example, involve the comparison of results produced in similar studies from other radiotherapy units

Machine Learning Based AFP Inspection: A Tool for Characterization and Integration

Automated Fiber Placement (AFP) has become a standard manufacturing technique in the creation of large scale composite structures due to its high production rates. However, the associated rapid layup that accompanies AFP manufacturing has a tendency to induce defects. We forward an inspection system that utilizes machine learning (ML) algorithms to locate and characterize defects from profilometry scans coupled with a data storage system and a user interface (UI) that allows for informed manufacturing. A Keyence LJ-7080 blue light profilometer is used for fast 2D height profiling. After scans are collected, they are process by ML algorithms, displayed to an operator through the UI, and stored in a database. The overall goal of the inspection system is to add an additional tool for AFP manufacturing. Traditional AFP inspection is done manually adding to manufacturing time and being subject to inspector errors or fatigue. For large parts, the inspection process can be cumbersome. The proposed inspection system has the capability of accelerating this process while still keeping a human inspector integrated and in control. This allows for the rapid capability of the automated inspection software and the robustness of a human checking for defects that the system either missed or misclassified

Automated Fiber Placement of Composite Wind Tunnel Blades: Process Planning and Manufacturing

The ability to accurately manufacture large complex shapes in a consistent and repeatable manner has led to Automated Fiber Placement (AFP) being the predominant mode of manufacturing for large composite aerospace structures today. Currently, AFP is being considered for medium- and small-scale parts. Composite wind tunnel blades have traditionally been fabricated by hand layup for pre-impregnated or dry fabrics with resin infusion. Though well proven, the traditional fabrication method is laborious and tedious, and hence expensive. The project described in this paper used the Integral Structural Assembly of Advanced Composites (ISAAC) facility at the NASA Langley Research Center to build a manufacturing demonstration unit (MDU) with a shape representative of a wind tunnel blade. This MDU is used to discuss tooling, process planning, and fabrication. Additionally, details of the generic manufacturing workflow are presented

Development of a Design for Manufacturing Tool for Automated Fiber Placement Structures

Existing design processes for laminates constructed with automated fiber placement lack significant integration between the various software tools that compose the process. Tools for finite element analysis, computer aided drafting, stress analysis, tool path simulation, and manufacturing defect prediction are all critical parts of the design process. With traditional hand-layup laminates, the analysis performed with each of these tools could be fairly well decoupled from one another. However, for laminates generated by automated fiber placement, the disciplines can become significantly coupled, especially on structures with curvature. This gives rise to a need for integrated design for manufacturing software tools that are able to balance the competing objectives from each discipline. This paper describes the preliminary development of such a tool

Automated Fiber Placement Defect Identity Cards: Cause, Anticipation, Existence, Significance, and Progression

Automated Fiber Placement (AFP), a major composite manufacturing process, can result in many defects during the layup process that often require manual corrective action to produce a part with acceptable quality. These defects are the main limitation of the technology and can be hard to categorize or define in many situations. This paper provides a thorough definition and classification of all AFP defects. This effort constitutes a comprehensive and extensive library relevant to AFP defects. The defects selected and defined in this work are based on understanding and experience from the manufacture and research of advanced composite structure. Proper classification of these defects required an in-depth literature review and consideration of various viewpoints ranging from designers, manufacturers, analysts, and inspection professionals. Collectively, these sources were utilized to develop the most accurate view of each of the individual defect types. The results are presented as identity cards for each defect type, intended to provide researchers and the manufacturing industry a clear understanding of the (1) cause, (2) anticipation, (3) existence, (4) significance, and (5) progression of the defined AFP defects. The link between AFP defects and process planning, layup strategies, and machining was also investigated. Categorization of all important automated fiber placement defects is presented