Connecting accuracy of interchanged prosthetic abutments to different dental implants using scanning electron microscopy

The present study evaluated the interchangeability of prosthetic components for external hexagon implants by measuring the precision of the implant/abutment (I/A) interface with scanning electron microscopy. Ten implants for each of three brands (SIN, Conexão, Neodent) were tested with their respective abutments (milled CoCr collar rotational and non-rotational) and another of an alternative manufacturer (Microplant) in randomly arranged I/A combinations. The degree of interchangeability between the various brands of components was defined using the original abutment interface gap with its respective implant as the benchmark dimension. Accordingly, when the result for a given component placed on an implant was equal to or smaller then that gap measured when the original component of the same brand as the implant was positioned, interchangeability was considered valid. Data were compared with the Kruskal-Wallis test at 5% significance level. Some degree of misfit was observed in all specimens. Generally, the non-rotational component was more accurate than its rotational counterpart. The latter samples ranged from 0.6-16.9 µm, with a 4.6 µm median; and the former from 0.3-12.9 µm, with a 3.4 µm median. Specimens with the abutment and fixture from Conexão had larger microgap than the original set for SIN and Neodent (p<0.05). Even though the latter systems had similar results with their respective components, their interchanged abutments did not reproduce the original accuracy. The results suggest that the alternative brand abutment would have compatibility with all systems while the other brands were not completely interchangeable.

Caratterizzazione meccanica di materiali compositi mediante attrezzatura CLC

L'obiettivo della tesi è diradare, almeno parzialmente, le incertezze che potrebbero essere presenti nella caratterizzazione a compressione di materiali compositi. Per quanto concerne la compressione, in un primo momento, non essendo ritenuta una caratteristica troppo rilevante, si considerava che il materiale composito avesse proprietà equivalenti a quelle in trazione. Solo successivamente, dai primi anni ’70, si sono iniziate ad indagare in modo approfondito e mirato le proprietà meccaniche a compressione di tali materiali. Si sono sviluppati e normati nel tempo vari metodi che vengono classificati in base al modo di applicazione del carico sul provino. Ci si è quindi proposti, basandosi anche sulle richieste mosse dalla Scuderia Toro Rosso di Faenza, di determinare, dopo aver analizzato tutti i vantaggi e gli svantaggi di ciascuna metodologia, quella migliore a cui attenersi per tutte le prove di compressione che seguiranno. A tale scopo, dopo una attenta e approfondita analisi dei vari metodi di prova, si è scelto di utilizzare il Combined Loading Compression (CLC) Test Fixture: attrezzatura leggera e molto compatta, che dimostra una affidabilità dei risultati superiore alle altre tecnologie. Si è, inoltre, deciso di testare laminati non unidirezionali, evitando così molte problematiche quali, ad esempio, quelle dovute all’utilizzo di tabs o al possibile insorgere di microbuckling delle fibre. Si è risaliti, poi, al valore di resistenza a compressione della lamina unidirezionale attraverso il metodo di calcolo indiretto del Back-Out Factor (BF). Di tale metodo si sono indagate le basi teoriche, a partire dalla teoria classica dei laminati, e si sono ricavate le formule necessarie per l'applicazione pratica sperimentale. Per quanto riguarda la campagna sperimentale, svolta presso i laboratori ENEA di Faenza – Unità Tecnica Tecnologie dei Materiali Faenza (UTTMATF), sono stati realizzati 6 laminati di materiale composito, ognuno con differente sequenza di laminazione e percentuale di fibre nelle diverse direzioni. Due laminati sono stati ottenuti impilando lamine unidirezionali preimpregnate, in modo da ottenere una configurazione cross-ply (0°\90°), due in configurazione angle-ply (0°\90°\±45°) e due materiali unidirezionali (0° e 90°). Da questi 6 laminati sono stati ricavati 12/13 provini ciascuno. I provini cross-ply e angle-ply sono stati testati per ricavarne la resistenza a compressione, da cui, poi, risalire a quella della lamina unidirezionale a 0° mediante il BF. Dal confronto dei risultati ottenuti attraverso l'applicazione combinata di CLC e Back-Out Factor, con i dati riportati nel datasheet ufficiale, si è avuta conferma dell'affidabilità della metodologia scelta. Per quanto concerne l'elaborazione dei dati ricavati dalle prove sperimentali, è stato utilizzato un opportuno programma realizzato con il software Matlab. Con l'estensione GUI, poi, è stata creata un'interfaccia grafica per agevolare la comprensione delle fasi di elaborazione anche ad un utente non esperto.

Analisi numerica e sperimentale del comportamento a compressione di materiali compositi

L’obbiettivo di questa tesi è ottenere un modello agli elementi finiti che simuli la prova a compressione su un campione di materiale composito a matrice polimerica rinforzata con fibre di carbonio unidirezionali (UD), mediante l’utilizzo di una attrezzatura denominata Combined Loading Compression (CLC) Test Fixture. Il programma utilizzato per realizzare il modello agli elementi finiti è Abaqus della Simulia. Il materiale oggetto dello studio è un prepreg UD di interesse nel settore automobilistico, e fa seguito ad una campagna di prove sperimentali (caratterizzazione a compressione) svolta nei laboratori ENEA di Faenza, dove opera l’Unità Tecnica Tecnologie dei Materiali Faenza (UTTMATF).

Correlation of Pullout Force of Kirschner (K-) Wire to Other Factors Indicative of Bone Quality

More than 250,000 hip fractures occur annually in the United States and the most common fracture location is the femoral neck, the weakest region of the femur. Hip fixation surgery is conducted to repair hip fractures by using a Kirschner (K-) wire as a temporary guide for permanent bone screws. Variation has been observed in the force required to extract the K-wire from the femoral head during surgery. It is hypothesized that a relationship exists between the K-wire pullout force and the bone quality at the site of extraction. Currently, bone mineral density (BMD) is used as a predictor for bone quality and strength. However, BMD characterizes the entire skeletal system and does not account for localized bone quality and factors such as lifestyle, nutrition, and drug use. A patient’s BMD may not accurately describe the quality of bone at the site of fracture. This study aims to investigate a correlation between the force required to extract a K-wire from femoral head specimens and the quality of bone. A procedure to measure K-wire pullout force was developed and tested with pig femoral head specimens. The procedure was implemented on 8 human osteoarthritic femoral head specimens and the average pullout force for each ranged from 563.32 ± 240.38 N to 1041.01 ± 346.84 N. The data exhibited significant variation within and between each specimen and no statistically significant relationships were determined between pullout force and patient age, weight, height, BMI, inorganic to organic matter ratio, and BMD. A new testing fixture was designed and manufactured to merge the clinical and research environments by enabling the physician to extract the K-wire from each bone specimen himself. The new device allows the physician to gather tactile feedback on the relative ease of extraction while load history is recorded similar to the previous procedure for data acquisition. Future work will include testing human bones with the new device to further investigate correlations for predicting bone quality.

Razor Thin Win: The 1972 Constitution Ballot, Campaign, Ratification & the Courts -- Mae Nan (Robinson) Ellingson & Mick McKeon “In the Crucible of Change”

Beyond the challenge of crafting a new state Constitution that empowered the people and modernized and opened up state and local government in Montana, the Constitutional Convention delegates, as they signed the final document, looked forward to the arduous task of getting it ratified by the electorate in a short ten week period between the end of the convention on March 24 and the ratification election of June 6, 1972. While all 100 delegates signed the draft Constitution, not all supported its adoption. But the planning about how to get it adopted went back to the actions of the Convention itself, which carefully crafted a ballot that kept “hot political issues” from potentially killing the entire document at the polls. As a result, three side issues were presented to the electorate on the ballot. People could vote for or against those side issues and still vote to ratify the entire document. Thus, the questions of legalizing gambling, having a unicameral legislature and retaining the death penalty were placed separately on the ballot (gambling passed, as did the retention of the death penalty, but the concept of a one-house legislature was defeated). Once the ballot structure was set, delegates who supported the new Constitution organized a grassroots, locally focused effort to secure ratification – thought hampered by a MT Supreme Court decision on April 28 that they could not expend $45,000 in public monies that they had set aside for voter education. They cobbled together about $10,000 of private money and did battle with the established political forces, led by the MT Farm Bureau, MT Stockgrowers’ Assn. and MT Contractors Assn., on the question of passage. Narrow passage of the main document led to an issue over certification and a Montana Supreme Court case challenging the ratification vote. After a 3-2 State Supreme Court victory, supporters of the Constitution then had to defend the election results again before the federal courts, also a successful effort. Montana finally had a new progressive State Constitution that empowered the people, but the path to it was not clear and simple and the win was razor thin. The story of that razor thin win is discussed in this chapter by the two youngest delegates to the 1972 Constitutional Convention, Mae Nan Ellingson of Missoula and Mick McKeon, then of Anaconda. Both recognized “Super Lawyers in their later professional practices were also significant players in the Constitutional Convention itself and actively participated in its campaign for ratification. As such, their recollections of the effort provide an insider’s perspective of the struggle to change Montana for the better through the creation and adoption of a new progressive state Constitution “In the Crucible of Change.” Mae Nan (Robinson) Ellingson was born Mae Nan Windham in Mineral Wells, TX and graduated from Mineral Wells High School in 1965 and Weatherford College in Weatherford, TX in 1967. Mae Nan was the youngest delegate at the 1972 Convention from Missoula. She moved to Missoula in 1967 and received her BA in Political Science with Honors from the University of MT in 1970. She was a young widow known by her late husband’s surname of Robinson while attending UM graduate school under the tutelage of noted Professor Ellis Waldron when he persuaded her to run for the Constitutional Convention. Coming in a surprising second in the delegate competition in Missoula County she was named one of the Convention’s “Ten Outstanding Constitutional Convention Delegates,” an impressive feat at such a young age. She was 24 at the time, the youngest person to serve at the ConCon, and one of 19 women out of 100 delegates. In the decade before the Convention, there were never more than three women Legislators in any session, usually one or two. She was a member of the American Association of University Women, a Pi Sigma Alpha political science honorary, and a Phi Alpha Theta historical honorary. At the Convention, she led proposals for the state's bill of rights, particularly related to equal rights for women. For years, Ellingson kept a copy of the preamble to the Constitution hanging in her office; while all the delegates had a chance to vote on the wording, she and delegate Bob Campbell are credited with the language in the preamble. During the convention, she had an opportunity that opened the door to her later career as an attorney. A convention delegate suggested to her that she should go to law school. Several offered to help, but at the time she couldn't go to school. Her mom had died in Texas, and she ended up with a younger brother and sister to raise in Missoula. She got a job teaching, but about a year later, intrigued with the idea of pursuing the law as a career, she called the man back to ask about the offer. Eventually another delegate, Dave Drum of Billings, sponsored her tuition at the UM School of Law. After receiving her JD with Honors (including the Law Review and Moot Court) from the UM Law School Ellingson worked for the Missoula city attorney's office for six years (1977-83), and she took on landmark projects. During her tenure, Missoula became the first city to issue open space bonds, a project that introduced her to Dorsey & Whitney. The city secured its first easement on Mount Sentinel, and it created the trail along the riverfront with a mix of playing fields and natural vegetation. She also helped develop a sign ordinance for the city of Missoula. She ended up working as bond counsel for Dorsey & Whitney, and she opened up the firm's full-fledged Missoula office after commuting a couple of years to its Great Falls office. She was a partner at Dorsey Whitney, working there from 1983 until her retirement in 2012. The area of law she practiced there is a narrow specialty - it requires knowledge of constitutional law, state and local government law, and a slice of federal tax law - but for Ellingson it meant working on great public projects – schools, sewer systems, libraries, swimming pools, ire trucks. At the state level, she helped form the Montana Municipal Insurance Authority, a pooled insurance group for cities. She's shaped MT’s tax increment law, and she was a fixture in the MT Legislature when they were debating equal rights. As a bond lawyer, though, Ellingson considers her most important work for the state to be setting up the Intercap Program that allowed local governments to borrow money from the state at a low interest rate. She has been a frequent speaker at the League of Cities and Towns, the Montana Association of Counties, and the Rural Water Users Association workshops on topics related to municipal finance, as well as workshops sponsored by the DNRC, the Water and Sewer Agencies Coordination Team, and the Montana State University Local Government Center. In 2002, she received an outstanding service award from the Montana Rural Water Users Association. In addition to being considered an expert on Montana state and constitutional law, local government law and local government finance, she is a frequent teacher at the National Association of Bond Lawyers (NABL) Fundamentals of Municipal Bond Law Seminar and the NABL Bond Attorney’s Workshop. For over 30 years Mae Nan has participated in the drafting of legislation in Montana for state and local finance matters. She has served on the Board of Directors of NABL, as Chairman of its Education Committee, was elected as an initial fellow in 1995 to the American College of Bond Counsel, and was recognized as a Super Lawyer in the Rocky Mountain West. Mae Nan was admitted to practice before the MT and US Supreme Courts, was named one of “America’s Leading Business Lawyers” by Chambers USA (Rank 1), a Mountain States Super Lawyer in 2007 and is listed in Best Lawyers in America; she is a member and former Board Member of NABL, a Fellow of the American College of Bond Counsel and a member of the Board of Visitors of the UM Law School. Mae Nan is also a philanthropist who serves on boards and applies her intelligence to many organizations, such as the Missoula Art Museum. [Much of this biography was drawn from a retirement story in the Missoulian and the Dorsey Whitney web site.] Mick McKeon, born in Anaconda in 1946, is a 4th generation Montanan whose family roots in this state go back to the 1870’s. In 1968 he graduated from Notre Dame with a BA in Communications and received a Juris Doctorate degree from the University of Montana Law School in 1971. Right after graduating from law school, Mick was persuaded by his father, longtime State Senator Luke McKeon, and his uncle, Phillips County Attorney Willis McKeon, to run for delegate to Montana’s Constitutional Convention and was elected to represent Deer Lodge, Philipsburg, Powell, and part of Missoula Counties. Along with a coalition of delegates from Butte and Anaconda, he fought through the new Constitution to eliminate the legal strangle hold, often called “the copper collar,” that corporate interests -- the Anaconda Company and its business & political allies -- had over state government for nearly 100 years. The New York Times called Montana’s Constitutional Convention a “prairie revolution.” After helping secure the ratification of the new Constitution, Mick began his practice of law in Anaconda where he engaged in general practice for nearly 20 years. Moving to Butte in 1991, Mick focused has practice in personal injury law, representing victims of negligence and corporate wrongdoing in both Montana district courts and federal court. As such, he participated in some of the largest cases in the history of the state. In 1992 he and his then law partner Rick Anderson obtained a federal court verdict of $11.5 million -- the largest verdict in MT for many years. Mick’s efforts on behalf of injured victims have been recognized by many legal organizations and societies. Recently, Mick was invited to become a member of the International Academy of Trial Lawyers - 600 of the top lawyers in the world. Rated as an American Super Lawyer, he has continuously been named one of the Best Lawyers in America, and an International Assn. of Trial Lawyers top 100 Trial Lawyer. In 2005, he was placed as one of Montana’s top 4 Plaintiff’s lawyers by Law Dragon. Mick is certified as a civil trial specialist by the National Board of Trial Advocacy and has the highest rating possible from Martindale-Hubble. Mick was awarded the Montana Trial Lawyers Public Service Award and provided pro bono assistance to needy clients for his entire career. Mick’s law practice, which he now shares with his son Michael, is limited to representing individuals who have been injured in accidents, concentrating on cases against insurance companies, corporations, medical providers and hospitals. Mick resides in Butte with his wife Carol, a Butte native. Mick, Carol, Michael and another son, Matthew, who graduated from Dartmouth College and was recently admitted to the Montana bar, enjoy as much of their time together in Butte and at their place on Flathead Lake.

Effects of decontamination and implant surface characteristics on re-osseointegration following treatment of peri-implantitis

BACKGROUND: Although considerable bone fill may occur following treatment of peri-implantitis, re-osseointegration appears to be limited and unpredictable. Objectives: To evaluate the effects of various decontamination techniques and implant surface configurations on re-osseointegration of contaminated dental implants. MATERIAL AND METHODS: Three months after tooth extraction, implants consisting of a basal part and an exchangeable intraosseous implant cylinder (EIIC) were placed in the mandibles of dogs. The EIIC was machined (M), sandblasted and acid-etched (SLA), or titanium plasma sprayed (TPS). Ligature-induced peri-implantitis was initiated 8 weeks post-implantation and lasted until bone loss reached the junction of the two implant parts. Three treatment modalities were applied: (T1) the EIIC was exchanged for a pristine EIIC; (T2) the EIIC was sprayed in situ with saline; and (T3) the EIIC was removed, cleansed outside the mouth by spraying with saline, steam-sterilized, and remounted. A collagen barrier was placed over each fixture, and 3 months later, samples were processed for histology and histomorphometry. RESULTS: T2 revealed the highest bone-to-implant contact (BIC) level (significantly better than T1 and T3). T2 also yielded the highest bone crest level (significantly better than T1), followed by T3 (significantly better than T1). SLA showed the highest BIC level (significantly better than M), followed by TPS. There were no statistically significant differences in bone crest height between implant types. CONCLUSIONS: Both SLA implants and in situ cleansing resulted in the best re-osseointegration and bone fill of previously contaminated implants.

Test Blueprints - Exposing Side Effects in Execution Traces to Support Writing Unit Tests

Writing unit tests for legacy systems is a key maintenance task. When writing tests for object-oriented programs, objects need to be set up and the expected effects of executing the unit under test need to be verified. If developers lack internal knowledge of a system, the task of writing tests is non-trivial. To address this problem, we propose an approach that exposes side effects detected in example runs of the system and uses these side effects to guide the developer when writing tests. We introduce a visualization called Test Blueprint, through which we identify what the required fixture is and what assertions are needed to verify the correct behavior of a unit under test. The dynamic analysis technique that underlies our approach is based on both tracing method executions and on tracking the flow of objects at runtime. To demonstrate the usefulness of our approach we present results from two case studies.

Using Dynamic Analysis for API Migration

When changing the API of a framework, we need to migrate its clients. This is best done automatically. In this paper, we focus on API migration where the mechanism for inversion of control changes. We propose to use dynamic analysis for such API migration since structural refactorings alone are often not sufficient. We consider JExample as a case-study. JExample extends JUnit with first-class dependencies and fixture injection. We investigate how dynamically collected information about test coverage and about instances under test can be used to detect dependency injection candidates.

A prospective, randomized, controlled study using OsseoSpeed™ implants placed in maxillary fresh extraction socket: soft tissues response

PURPOSE The aim of this work was to study the peri-implant soft tissues response, by evaluating both the recession and the papilla indexes, of patients treated with implants with two different configurations. In addition, data were stratified by tooth category, smoking habit and thickness of buccal bone wall. MATERIALS AND METHODS The clinical trial was designed as a prospective, randomized-controlled multicenter study. Adults in need of one or more implants replacing teeth to be removed in the maxilla within the region 15-25 were recruited. Following tooth extraction, the site was randomly allocated to receive either a cylindrical or conical/cylindrical implant. The following parameters were studied: (i) Soft tissue recession (REC) measured by comparing the gingival zenith (GZ) score at baseline (permanent restoration) with that of the yearly follow-up visits over a period of 3 years (V1, V2 and V3). (ii) Interdental Papilla Index (PI): PI measurements were performed at baseline and compared with that of the follow-up visits. In addition, data were stratified by different variables: tooth category: anterior (incisors and canine) and posterior (first and second premolar); smoking habit: patient smoker (habitual or occasional smoker at inclusion) or non-smoker (non-smoker or ex-smoker at inclusion) and thickness of buccal bone wall (TB): TB ≤ 1 mm (thin buccal wall) or TB > 1 mm (thick buccal wall). RESULTS A total of 93 patients were treated with 93 implants. At the surgical re-entry one implant was mobile and then removed; moreover, one patient was lost to follow-up. Ninety-one patients were restored with 91 implant-supported permanent single crowns. After the 3-year follow-up, a mean gain of 0.23 mm of GZ was measured; moreover, 79% and 72% of mesial and distal papillae were classified as >50%/ complete, respectively. From the stratification analysis, not significant differences were found between the mean GZ scores of implants with TB ≤ 1 mm (thin buccal wall) and TB > 1 mm (thick buccal wall), respectively (P < 0.05, Mann-Whitney U-test) at baseline, at V1, V2 and V3 follow-up visits. Also, the other variables did not seem to influence GZ changes over the follow-up period. Moreover, a re-growth of the interproximal mesial and distal papillae was the general trend observed independently from the variables studied. CONCLUSIONS Immediate single implant treatment may be considered a predictable option regarding soft tissue stability over a period of 3 years of follow-up. An overall buccal soft tissue stability was observed during the GZ changes from the baseline to the 3 years of follow-up with a mean GZ reduction of 0.23 mm. A nearly full papillary re-growth can be detectable over a minimum period of 2 years of follow-up for both cylindrical and conical/cylindrical implants. Both the interproximal papilla filling and the midfacial mucosa stability were not influenced by variables such as type of fixture configuration, tooth category, smoke habit, and thickness of buccal bone wall of ≤ 1 mm (thin buccal wall).

Desarrollo de software de control y medida para goniofotómetro de tipo B

El proyecto trata del desarrollo de un software para realizar el control de la medida de la distribución de intensidad luminosa en luminarias LED. En el trascurso del proyecto se expondrán fundamentos teóricos sobre fotometría básica, de los cuales se extraen las condiciones básicas para realizar dicha medida. Además se realiza una breve descripción del hardware utilizado en el desarrollo de la máquina, el cual se basa en una placa de desarrollo Arduino Mega 2560, que, gracias al paquete de Labview “LIFA” (Labview Interface For Arduino”), será posible utilizarla como tarjeta de adquisición de datos mediante la cual poder manejar tanto sensores como actuadores, para las tareas de control. El instrumento de medida utilizado en este proyecto es el BTS256 de la casa GigaHerzt-Optik, del cual se dispone de un kit de desarrollo tanto en lenguaje C++ como en Labview, haciendo posible programar aplicaciones basadas en este software para realizar cualquier tipo de adaptación a las necesidades del proyecto. El software está desarrollado en la plataforma Labview 2013, esto es gracias a que se dispone del kit de desarrollo del instrumento de medida, y del paquete LIFA. El objetivo global del proyecto es realizar la caracterización de luminarias LED, de forma que se obtengan medidas suficientes de la distribución de intensidad luminosa. Los datos se recogerán en un archivo fotométrico específico, siguiendo la normativa IESNA 2002 sobre formato de archivos fotométricos, que posteriormente será utilizado en la simulación y estudio de instalaciones reales de la luminaria. El sistema propuesto en este proyecto, es un sistema basado en fotometría tipo B, utilizando coordenadas VH, desarrollando un algoritmo de medida que la luminaria describa un ángulo de 180º en ambos ejes, con una resolución de 5º para el eje Vertical y 22.5º para el eje Horizontal, almacenando los datos en un array que será escrito en el formato exigido por la normativa. Una vez obtenidos los datos con el instrumento desarrollado, el fichero generado por la medida, es simulado con el software DIALux, obteniendo unas medidas de iluminación en la simulación que serán comparadas con las medidas reales, intentando reproducir en la simulación las condiciones reales de medida. ABSTRACT. The project involves the development of software for controlling the measurement of light intensity distribution in LEDs. In the course of the project theoretical foundations on basic photometry, of which the basic conditions for such action are extracted will be presented. Besides a brief description of the hardware used in the development of the machine, which is based on a Mega Arduino plate 2560 is made, that through the package Labview "LIFA" (Interface For Arduino Labview "), it is possible to use as data acquisition card by which to handle both sensors and actuators for control tasks. The instrument used in this project is the BTS256 of GigaHerzt-Optik house, which is available a development kit in both C ++ language as LabView, making it possible to program based on this software applications for any kind of adaptation to project needs. The software is developed in Labview 2013 platform, this is thanks to the availability of the SDK of the measuring instrument and the LIFA package. The overall objective of the project is the characterization of LED lights, so that sufficient measures the light intensity distribution are obtained. Data will be collected on a specific photometric file, following the rules IESNA 2002 on photometric format files, which will then be used in the simulation and study of actual installations of the luminaire. The proposed in this project is a system based on photometry type B system using VH coordinates, developing an algorithm as the fixture describe an angle of 180 ° in both axes, with a resolution of 5 ° to the vertical axis and 22.5º for the Horizontal axis, storing data in an array to be written in the format required by the regulations. After obtaining the data with the instrument developed, the file generated by the measure, is simulated with DIALux software, obtaining measures of lighting in the simulation will be compared with the actual measurements, trying to play in the simulation the actual measurement conditions .

Avaliação do processamento por atrito linear em chapas da liga de titânio Ti-6Al-4V.

Esta tese tem por objetivo a aplicação do processamento por atrito linear na liga de titânio Ti-6Al-4V. Derivado da solda por atrito linear, é um processo recente desenvolvido na década de 90 para união de alumínio. Sua aplicação em outros tipos de materiais como aços e ligas de alto desempenho, em especial o titânio, tem interessado a industria. A metodologia utilizada nesta tese para avaliar o processamento por atrito linear, consistiu na execução de ensaios mecânicos de tração em condições mistas em chapas da liga de titânio Ti-6Al-4V. A máquina utilizada para o processamento das chapas foi um centro de usinagem CNC convencional, adaptado com dispositivos especiais. Além dos ensaios de tração em condições mistas, foram executadas medições de microdurezas nas regiões atingidas pelo processo, avaliação das microestruturas resultantes e medições de tensão residual para uma caracterização mais ampla do processo. As microestruturas na região processada são caracterizadas por uma estrutura totalmente transformada. As temperaturas de pico na região processada excederam a temperatura -transus durante o processamento e a transformação da fase + ocorreu durante a fase de resfriamento. A transformação da fase para resultou na formação de agulhas de fase nos contornos e pelo interior dos grãos da fase . Pequenas regiões com estrutura equiaxial de grãos ( globular) foram observados na zona de processamento. A abordagem dos resultados quantitativos foi feita de forma estatística, visando identificar os parâmetros de maior interação com os resultados observados. Foi identificado nesta tese que a rotação da ferramenta apresentou a maior influência nos resultados de tensão residual, microdureza e tensão de escoamento. Uma importante contribuição à modelagem da tensão de escoamento para materiais anisotrópicos é proposta, baseado em um critério de escoamento ortotrópico. Equações complementares baseadas nos testes mistos de tração e cisalhamento são propostas para modificar o modelo ortotrópico. O intuito deste modelo é indicar em que condições o material tem seu regime de escoamento atingido, podendo servir de base para simulações práticas de peças em condições similares.

Diary of Henry Flynt, 1723-1747

This diary, effectively a commonplace book, documents Flynt's daily activities and personal reflections from 1723 to 1747. Many entries concern his dealings with family members, business associates, acquaintances, ministers, and political officials. The diary includes a list of books Flynt loaned to others from 1723 to 1743 and detailed financial entries from 1724 to 1747. These entries provide information about the costs of goods and services, as well as Flynt's consumption habits; they detail where he traveled, what he ate and drank (including, apparently, many pounds of almonds), what he read, and many other aspects of daily life. The diary also contains entries related to Flynt's land holdings and other investments, as well as copies of meeting minutes from several sessions of the Harvard Board of Overseers.

Review of the application of flexible, measurement-assisted assembly technology in aircraft manufacturing

Aircraft assembly is the most important part of aircraft manufacturing. A large number of assembly fixtures must be used to ensure the assembly accuracy in the aircraft assembly process. Traditional fixed assembly fixture could not satisfy the change of the aircraft types, so the digital flexible assembly fixture was developed and was gradually applied in the aircraft assembly. Digital flexible assembly technology has also become one of the research directions in the field of aircraft manufacturing. The aircraft flexible assembly can be divided into three assembly stages that include component-level flexible assembly, large component-level flexible assembly, and large components alignment and joining. This article introduces the architecture of flexible assembly systems and the principles of three types of flexible assembly fixtures. The key technologies of the digital flexible assembly are also discussed. The digital metrology system provides the basis for the accurate digital flexible assembly. Aircraft flexible assembly systems mainly use laser tracking metrology systems and indoor Global Positioning System metrology systems. With the development of flexible assembly technology, the digital flexible assembly system will be widely used in current aircraft manufacturing.

Assembly accuracy analysis for small components with a planar surface in large-scale metrology

Large-scale mechanical products, such as aircraft and rockets, consist of large numbers of small components, which introduce additional difficulty for assembly accuracy and error estimation. Planar surfaces as key product characteristics are usually utilised for positioning small components in the assembly process. This paper focuses on assembly accuracy analysis of small components with planar surfaces in large-scale volume products. To evaluate the accuracy of the assembly system, an error propagation model for measurement error and fixture error is proposed, based on the assumption that all errors are normally distributed. In this model, the general coordinate vector is adopted to represent the position of the components. The error transmission functions are simplified into a linear model, and the coordinates of the reference points are composed by theoretical value and random error. The installation of a Head-Up Display is taken as an example to analyse the assembly error of small components based on the propagation model. The result shows that the final coordination accuracy is mainly determined by measurement error of the planar surface in small components. To reduce the uncertainty of the plane measurement, an evaluation index of measurement strategy is presented. This index reflects the distribution of the sampling point set and can be calculated by an inertia moment matrix. Finally, a practical application is introduced for validating the evaluation index.

The Metrology Enhanced Tooling for Aerospace (META) framework

Aerospace manufacturers typically use monolithic steel fixtures to control the form of assemblies. This tooling is very expensive, has long lead times and has little ability to accommodate product variation and design changes. Since the tool setting and recertification process is manual and time consuming, monolithic structures are required in order to maintain the tooling tolerances for multiple years without recertification. This paper introduces the Metrology Enhanced Tooling for Aerospace (META) Framework which interfaces multiple metrology technologies with the tooling, components, workers and automation. This will allow rapid or even real-time fixture re-certification with improved product verification leading to a reduced risk of product non-conformance and increased fixture utilization while facilitating flexible fixtures.