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Surface Strain Measurement for Non-Intrusive Internal Pressure Evaluation of a CannonRausch, Brennan Lee 29 August 2022 (has links)
The U.S. Army has recently developed cutting edge designs for gun barrels, projectiles, and propellants that require testing. This includes measuring the internal pressure during fire. There are concerns with the current method of drilling to mount pressure transducers near the breech and chamber of the gun barrel where pressure is highest. An alternative, non-intrusive strain measurement method is introduced and discussed in the present work. This focuses on determining the feasibility and accuracy of relating tangential strain along the sidewall of a gun barrel to the drastic internal pressure rise created during combustion.
A transient structural, numerical modal was created using ANSYS of a 155 mm gun barrel. The pressure gradient was derived using a method outline in IBHVG2 (Interior Ballistics of High Velocity Guns, version 2), and the model was validated using published experimental tangential strain testing data from a gun of the same caliber. The model was used to demonstrate the ideal location for strain measurement along the sidewall of the chamber. Furthermore, three different pressure ranges were simulated in the model. The behavior of the tangential strain in each case indicates a similar trend to the internal pressure rise and has oscillation due to a dominant frequency of the barrel. A method to predict internal pressure from external tangential strain was developed. The internal pressure predicted is within 4% of the pressure applied in the model. A sensitivity study was performed to determine the primary factors affecting tangential strain. The study specifically looked at material properties and geometry of the gun barrel. The thickness and elastic modulus of the gun barrel were determined the most relevant. Overall, the present work helps to understand tangential strain behavior on the sidewall of a large caliber gun barrel and provides preliminary work to establish an accurate prediction of internal pressure from external tangential strain. / Master of Science / Innovative technology for large gun systems require testing to evaluate safety and performance. The most recent designs from the U.S. Army for long range artillery require higher pressures. Currently, large gun barrels are drilled to mount pressure transducers for internal pressure testing, but the new generation of weapons require a way to measure internal pressure of the gun without introducing these high stress locations. External strain offers a means to measure displacement of the barrel caused by the internal pressure change with minimal alteration to the gun barrel.
The present work focuses on modelling a large gun barrel using finite elements to understand the behavior of strain on the external surface due to internal pressure during fire. Measurements were taken near the chamber of the gun barrel model. The strain behavior is comprised of two components, a linear change due to a pressure increase and vibrations introduced due to the sharp pressure increase over a short amount of time. Three cases were evaluated at different pressure ranges and a method was developed to predict internal pressure from the tangential strain with a maximum error of 4% for all cases studied. The model also indicates that the strain results are most sensitive to a change in thickness and the elastic modulus of the gun barrel material.
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[en] GIANT MAGNETOSTRICTIVE MATERIALS APPLIED TO CONTACTLESS DISPLACEMENT SENSORS / [pt] APLICAÇÃO DE MATERIAIS COM MAGNETOSTRICÇÃO GIGANTE EM SENSORES DE DESLOCAMENTO SEM CONTACTOCLARA JOHANNA PACHECO 13 December 2007 (has links)
[pt] A magnetostricção é a propriedade dos materiais
ferromagnéticos de se
deformarem pela presença de um campo magnético externo.
Trata-se de uma
propriedade inerente ao material, que não muda com o
tempo. Materiais que
apresentam deformações da ordem de 10-3 são conhecidos
como materiais de
magnetostricção gigante (GMM). Esta dissertação de
mestrado estuda a
aplicação destes materiais em sensores de deslocamento
onde não há contacto
entre o elemento cursor (um ímã) e o elemento sensor
(GMM). O princípio de
funcionamento consiste em aplicar um gradiente de campo
magnético ao GMM
que está fixo. O gradiente de campo magnético é gerado por
um ímã preso ao
componente ou estrutura na qual se quer medir o
deslocamento. As variações no
campo magnético no material GMM originados pelo
deslocamento do ímã
(estrutura), provocam uma deformação no GMM, que é
detectada com
extensômetros do tipo Strain Gauge ou Redes de Bragg.
Neste trabalho
apresenta-se a caracterização da deformação de GMM em
relação a um campo
constante aplicado, e análises do seu comportamento para
diferentes
geometrias. Efeitos de pressão, polarização com um segundo
ímã, e diferentes
gradientes de campo magnético são também estudados. É
observado um
comportamento local para a deformação quando a medida é
realizada em
diferentes regiões do GMM. Os resultados obtidos
permitiram a medição de
deslocamentos de alguns micra estando o elemento sensor a
até 10 mm de
distância do elemento cursor. / [en] Magnetostriction is a property of ferromagnetic materials
to deform in the
presence of a magnetic field. Magnetostriction is an
inherent property of magnetic
materials, which is unchangeable with time. Materials
exhibiting strains in the
order of 10-3 are known as giant magnetostrictive
materials (GMM).In this
dissertation we study the application of these materials
in displacement sensors
where there is not contact between the cursor element
(magnet) and sensor
element (GMM). Its principle of operation consists of
applying a magnetic field
gradient to a GMM located at a fixed position. The
magnetic field gradient is
produced by a magnet attached to the component or
structure in which the
displacement will be measured.The variation on the
magnetic field in the GMM
position originated from the displacement of the magnet,
results in a strain in the
GMM that can be detected with a Strain Gauge or Bragg
Grating extensometers.
In this work is presented the characterization of the
strain on GMM cuboids
against a constant magnetic field and the analysis of its
behavior for different
geometries. Effects of pressure, polarization with a
second magnet, and different
gradients of magnetic field are also studied. It is
observed a local behavior for
strains when it is measured in different regions of GMM
cuboid. The results
obtained allow us to measure displacements of about few
micra when the sensor
is at a distance of 10 mm from the cursor element.
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Redesign and Development of HotRot1811 Composting Unit and Ancillary ItemHarris, Daniel January 2012 (has links)
This project investigated alternative materials, methods and processes to reduce manufacturing costs while improving the marketability and performance of the HotRot1811 compost machine. Some of the redesign aspects include investigating alternative insulation materials, corrosion within the vessel, stress and strain gauge testing of the shaft and tines, and alternative design considerations.
Another aspect of the project is to test and develop a compost classifier. The compost classifier is used for separating contaminants from compost which could be an alternative technology HotRot Organic Solutions Ltd may produce.
This report describes the findings, recommendations and conclusions of these investigations.
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Deformações geradas no intermediário e região peri-implantar após aplicação de cargas inclinadas em coroas unitáriasAlbarracín, Max Laurent 31 July 2015 (has links)
A reabilitação protética de pacientes desdentados é uma área da Odontologia amplamente estudada por pesquisadores do mundo todo, e com o desenvolvimento dos implantes osseointegrados surgiram muitas perguntas sobre o desempenho das próteses instaladas sobre estes. Conhecer o comportamento mecânico do conjunto coroa unitária, intermediário, implante e tecido de suporte é importante para entender o processo de transmissão de forças e suas consequências, processos estes que ainda não estão totalmente compreendidos. O objetivo deste trabalho foi verificar a deformação gerada no intermediário e no osso peri-implantar após aplicação de uma carga inclinada sobre coroas unitárias metalocerâmicas. Foi utilizado um modelo mestre de poliuretano, simulando o osso mandibular, com um implante hexágono externo de 3,75mm x13 mm de comprimento, no qual foi fixado um intermediário multi-unit. O trabalho foi realizado com 3 grupos de 4 coroas cada, divididos de acordo com o tipo de cilindro e liga de fundição (cilindros de ouro sobrefundidos com liga de PdAg, cilindro de acrílico fundido com liga de NiCoCr e cilindros de CoCr usinado sobrefundidos com liga de NiCoCr). Cada corpo de prova foi submetido cinco vezes à aplicação de carga oblíqua de 15 e 30 graus no centro da oclusal de cada coroa com uma força de 300N em uma máquina universal de ensaios. Foram realizadas leituras das deformações geradas no intermediário e no poliuretano, com o uso de extensômetros lineares elétricos (strain gauges) os quais foram colados em três faces do intermediário (Disto lingual, Mesio lingual, Vestibular) e nas superfícies mesial, vestibular, distal e lingual do osso simulado ao redor do implante. Os dados obtidos foram submetidos à análise de variância a 3 critérios (ANOVA) e o teste de Tukey, utilizando um nível de significância (p<0,05). Os resultados mostraram que entre as duas angulações utilizadas existiram diferenças estatísticas significantes. Os valores médios de deformação se mantiveram dentro dos padrões de normalidade, na janela fisiológica descrita por Frost entre 50 με e 1500 με independente do tipo de cilindro utilizado, com exceção dos valores de compressão obtidos na carga oblíqua de 30 graus onde nos três tipos de cilindro ultrapassaram a janela de sobrecarga patológica com mais de 4000 με. / The prosthetic rehabilitation of edentulous patients is a dental area widely studied by worldwide researchers, and through the development of dental implants, appear many questions about the performance of prostheses installed on them. Knowledge of the mechanical behavior of the integration between single crown, abutment, implant and support tissue is very important to understand the forces transmission process and its consequences but these processes are not fully understood. The objective of the present study was to evaluate the deformation generated in the abutment and simulated peri-implant bone after application of an oblique load on metal-ceramic crowns. A polyurethane master model was used to simulate the jawbone with an implant external hexagon 3.75 mm x13 mm length, which was fixed in a multi-unit abutment. The study was conducted with twelve metal ceramic crowns divided according to type of cylinder and casting alloy, Group 1: Gold cylinder cast with PdAg alloy; Group 2: Acrylic cylinder cast with NiCoCr alloy; Group 3: CoCr cylinder cast with NiCoCr alloy, thus forming three groups of four sample each. Each specimen was subjected five times the application of oblique load of 15 and 30 degrees in the center of the occlusal of each crown with a 300N force in a universal testing machine. Readings were taken of the deformations generated in the abutment and bone simulated by polyurethane, with the use of electric linear strain gauges which have been positioned on three sides equidistant to each other to measure microstrains at abutment (disto-lingual, meso-lingual, Vestibular) and the simulated bone around each implant received four strain gauges, positioned on the mesial, distal, buccal and lingual aspects. The data were submitted to analysis of variance to 3 criteria (ANOVA) and Tukey test, using a significance level (p <0.05). The results showed that between the two angles tested there were significant statistical differences. The deformation average values remained within normal limits, at the adapted state described by Frost between 50 με and 1500 με independent of the type of cylinder used, with the exception of compression values in oblique load of 30 degrees where the three types of cylinder surpassed the pathological overhead state with over 4,000 με.
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Avaliação da deformação do intermediário e região perimplantar de próteses implanto-suportada unitárias parafusada: estudo através da extensometria / Evaluation of abutment and perimplantar region deformation of implant-supported screwed prostheses: an study using strain gaugesMoretti Neto, Rafael Tobias 05 August 2010 (has links)
O implante dental depende do osso de suporte para sua estabilidade e ongevidade funcional. O comportamento mecânico e a estrutura trabecular do osso afetam a interface com o implante. Tal conhecimento pode fornecer uma base para melhoramentos na função e desenho dos implantes atuais minimizando a reabsorção da crista óssea e falha na junção osso-implante. Desta forma a correta quantificação das forças que atuam sobre o sistema de implante e principalmente no osso de suporte ao qual ele está inserido é importante para o entendimento da biomecânica possibilitando que intervenções possam ser realizadas pelos profissionais visando assim à longevidade das próteses implanto-suportadas bem como dos implantes que as sustentam. Por essa razão, a proposta deste trabalho foi avaliar, com auxílio de extensômetros elétricos, se o processo laboratorial de confecção de coroas metalocerâmicas resulta em alterações das tensões no osso ao redor dos implantes. Para isto foi utilizado um modelo de poliuretano em forma de U simulando o osso mandibular com dois implantes de hexágono externo de 3,75mm de diâmetro por 13 mm de comprimento, nos quais foram fixados intermediários multi-unit. Os corpos de prova foram confeccionados com dois tipos de ligas odontológicas - Cobalto-Cromo e Paládio-Prata - e três tipos de cilindros protéticos calcinável, usinado de Cobalto-Cromo e usinado de Ouro. As leituras de deformação foram realizadas em dois momentos: 1- após a fundição das infra-estruturas e 2 após estas infra-estruturas terem recebido cobertura cerâmica. Os testes foram realizados parafusando os corpos de prova sobre os intermediários utilizando-se para isto um dispositivo eletrônico de torque com força máxima de 10 Ncm. Os resultados mostraram que, após a aplicação da cobertura cerâmica, ocorreu piora da condição de assentamento aos intermediários. O mesmo não foi detectado quando se avaliou a deformação do osso simulado, já que os valores de deformação não ndicaram diferenças antes e após a aplicação da cerâmica. / The dental implant depends on the supporting bone for its stability and functional longevity. Mechanical behavior and trabecular bone structure affect the interface with the implant. Such knowledge may provide a basis for improvements in the current implant function and design, decreasing bone crest resorption and failure at bone-implant junction. Adequate quantification of forces that act upon the implant system and mainly on the supporting bone is important for understanding the biomechanics, allowing the intervention by professionals with the purpose of achieving the longevity of implant-supported prostheses. Therefore, this work aims at evaluating, with the aid of strain gauges, whether the laboratorial process of metal ceramic crown fabrication results in changes of the tensions around the implants. A U-shaped polyurethane model simulating the mandibular bone with two 3.75-mm diameter and 13-mm length external hexagon implants were used with fixed multi-unit abutments. Specimens were prepared with two types of dental alloys - cobalt-chromium and silver-palladium - and three types of prosthetic cylinder castable plastic, prefabricated in cobalt-chromium or gold. The deformation readings were performed in two moments: 1- after framework casting and 2- after ceramic layering of the framework. The tests were performed with the framework screwed onto the abutments at 10Ncm using an electronic torque device. The results showed that the ceramic layering worsened the fit between the crowns and the abutments. The same was not detected when bone deformation was evaluated since the values were not statistically different.
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Towards 4D MVCBCT for lung tumor treatmentChen, Mingqing 01 July 2012 (has links)
Currently in our clinic, a mega-voltage cone beam computed tomography (MVCBCT) scan is performed before each treatment for patient localization. For non-small cell lung cancer (NSCLC) patients, a strain gauge is used as an external surrogate to indicate tumor motion in both the planning stage and the treatment stage. However, it is likely that the amplitude of tumor motion varies between treatment fractions without a corresponding change in the surrogate signal. Motion amplitude larger than what was planned may underdose the tumor and overexpose normal tissues.
The overall objective of this project is to extend the capabilities of MVCBCT for respiratory motion management by taking advantage of 2D projection images. First, a new method was developed to detect ipsi-lateral hemi-diaphragm apex (IHDA) motion along superior-inferior (SI) direction in 3D. Then a respiratory correlated reconstruction method was implemented and verified. This method is able to create MVCBCT volume in the full exhale (FE) and the full inhale (FI) phases, respectively. The diaphragm to tumor motion ratio (DTMR) was derived by quantifying the absolute position of the tumor and IHDA in these two volumes. The DTMR and the extracted IHDA motion were further used to calibrate the strain gauge signal.
Second, an organ motion detection approach was developed, in which the detection is converted into an optimal interrelated surface detection problem. The framework was first applied to tumor motion extraction, which enables accurate detection for large tumors (with a diameter not smaller than 1.9cm). The framework was then applied to lung motion extraction and the extracted lung motion model was used to create a series of displacement vector fields for a motion compensated (MC) reconstruction. The accuracy of both tumor extraction and the MC approach was validated, which shows their clinical feasibility.
Last but not least, a novel enhancement framework was developed. The aim of this approach is to eliminate the overlapping tissues and organs in the CBCT projection images. Though scattering and noise is the major problem, the proposed method is able to achieve enhanced projection images with a higher contrast to noise ratio (CNR) without compromising detection accuracy on tumors and IHDA.
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Distribution Of Bending Moments In Laterally Loaded Passive Pile Groups A Model StudyOzturk, Sevki 01 February 2009 (has links) (PDF)
In this study, bending moment distributions developed in laterally loaded passive pile and passive pile groups in cohesionless soil were investigated in laboratory conditions through model pile experiments. Different from the active pile loading, the lateral load was given directly to the piles using a movable large direct shear box. In these experiments strain gauges fastened to the piles and a computer based data reading system were used. The strain values were measured at five levels on the piles. The behavior of a single pile and a pile group having five piles were investigated through strain measurements in order to observe bending moment distribution on the piles.
After evaluating the test results, the behavior of passive single pile was found to be similar to the results obtained in early studies. Negative bending moments were observed at the specified depths above the shear plane and positive bending moments were measured at the level of the shear plane and below the shear plane. Maximum bending moments were obtained at 0.7L (L: Length of Pile) for single piles and piles in the group. Above the shear plane, maximum bending moments within the pile
group were found to be developed on the piles nearest to the loading. On the shear plane maximum bending moments were developed on the piles farthest from the loading just like active piles. Below the shear plane, maximum bending moments were developed mainly on the piles nearest to the loading.
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EFFECT of the LENGTH of the SUPERFICIAL PLATE in STACKED VETERINARY CUTTABLE PLATE CONSTRUCTS: An IN VITRO STUDY on the BENDING STRENGTH and STIFFNESS, and on the STRAIN DISTRIBUTIONBichot, Sylvain 06 January 2012 (has links)
This thesis investigated the effect of the length of the superficial plate on the mechanical properties of a stacked-plate construct made with 2.0-2.7 Veterinary Cuttable platesTM (VCP). Stacking VCP increases construct stiffness compared to using a single VCP but increases stress protection and concentrates stress at the extremities of the implants. We hypothesized that shortening the superficial plate would not reduce the stiffness of the construct, and would reduce stress concentration at the plate ends.
A fracture gap model was created with a bone surrogate (copolymer acetal rods), stacked 2.0-2.7 VCP and 2.7 screws. The constructs consisted of an 11-hole VCP bottom plate and a 5-, 7-, 9- or 11-hole VCP superficial plate. In phase one, 5 of each construct were randomly tested for failure in 4-point bending and axial loading. Stiffness, load at yield, and work until failure were measured. In phase two, strains were recorded during elastic deformation for each configuration.
During both testing methods, stiffness, load at yield and work to failure progressively decreased when decreasing the length of the superficial plate. No statistically significant differences were obtained for load at yield in 4-point bending and work to failure in axial loading. The strain within the implant over the gap increased as the length of the superficial plate decreased.
Shortening the superficial plate reduces the stiffness and strength of the construct, and decreases stress concentration at the implant ends. As the cross section of the implant covering the gap remained constant, friction between the plates may play a role in the mechanical properties of stacked VCP. / Synthes Canada - OVC Pet Trust Fund
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Thermal output and thermal compensation models for apparent strain in a structural health monitoring-based environmentA-iyeh, Enoch 12 February 2013 (has links)
Structural Health Monitoring (SHM) is widely used to monitor the short and long-term behavior of intelligent structures. This monitoring can help prolong the useful service lives and identify deficiencies before possible damage of such structures.
The sensing systems that are usually deployed are intended to faithfully relay readings that reflect the true conditions of these structures. Unfortunately, this is seldom the case due to the presence of errors in the collected data.
The electrical strain gauges used in SHM environments for instrumentation purposes are susceptible to numerous sources of error. Apparent strain is known to be the most serious of all such errors. However or whichever way temperature variations of the gauge’s environment occurs, apparent strain is introduced.
This work focuses on modeling apparent strain in an SHM environment using National Instruments’ (NI) hard and software. The results of this work are applicable for thermal compensation in current test programs.
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Thermal output and thermal compensation models for apparent strain in a structural health monitoring-based environmentA-iyeh, Enoch 12 February 2013 (has links)
Structural Health Monitoring (SHM) is widely used to monitor the short and long-term behavior of intelligent structures. This monitoring can help prolong the useful service lives and identify deficiencies before possible damage of such structures.
The sensing systems that are usually deployed are intended to faithfully relay readings that reflect the true conditions of these structures. Unfortunately, this is seldom the case due to the presence of errors in the collected data.
The electrical strain gauges used in SHM environments for instrumentation purposes are susceptible to numerous sources of error. Apparent strain is known to be the most serious of all such errors. However or whichever way temperature variations of the gauge’s environment occurs, apparent strain is introduced.
This work focuses on modeling apparent strain in an SHM environment using National Instruments’ (NI) hard and software. The results of this work are applicable for thermal compensation in current test programs.
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