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Lillehei, Peter Thomas. "Single molecule mechanical testing". Diss., Georgia Institute of Technology, 2001. http://hdl.handle.net/1853/31044.
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Johnston, James Duncan. "Mechanical testing of the scapholunate ligament". Thesis, National Library of Canada = Bibliothèque nationale du Canada, 2002. http://www.collectionscanada.ca/obj/s4/f2/dsk3/ftp05/MQ65628.pdf.
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Rioux, Robert A. "Mechanical Testing of Coated Paper Systems". Fogler Library, University of Maine, 2008. http://www.library.umaine.edu/theses/pdf/RiouxRA2008.pdf.
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Fahd, Aly. "Mechanical and ultrasound testing of bone". Ann Arbor, Mich. : ProQuest, 2006. http://gateway.proquest.com/openurl?url_ver=Z39.88-2004&rft_val_fmt=info:ofi/fmt:kev:mtx:dissertation&res_dat=xri:pqdiss&rft_dat=xri:pqdiss:1434828.
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Thesis (M.S. in Mechanical Engineering)--S.M.U.Title from PDF title page (viewed May 23, 2007). Source: Masters Abstracts International, Volume: 44-06, page: 2967. Adviser: Yildirim Hurmuzlu. Includes bibliographical references.
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Robusto, Francesco. "Accelerated life testing in mechanical design". Doctoral thesis, Università degli studi di Padova, 2019. http://hdl.handle.net/11577/3424672.
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The introduction of new products on the market is a time-consuming process, which typically includes both design and testing phases. Often, the experimental validation phase significantly affects the overall process time. Indeed, in many industrial sectors, the product development procedure is based on trial and error methodologies. Intermediate validation tests are performed on full-scale physical prototypes and, based on their outcome, the design is updated (in the case of a negative result) or validated (if the result is positive). The efficiency of this method in terms of time-resources is notoriously sub-optimal.
To improve the efficiency of this process it is, for example, possible to exploit accelerated test methodologies, which consist in subjecting the product to test conditions that exceed its actual working conditions. In this way, a reduction in the number of cycles necessary to bring the component to final failure can be achieved, with obvious beneficial effects on the efficiency of the process. Another way to accelerate the test is to switch from testing the top-level assembly to performing tests on subassemblies or individual components.
It is however mandatory, to ensure that the results obtained with these test methods are useful for the design, to take appropriate precautions. For example, it is essential to preserve the original failure mode of the component. To do this, it is necessary, among other things, to know the relationship between the boundary conditions of the entire assembly and the stresses of the individual components. In the present paper, the methodology described above is illustrated with reference to its application to locking industry components (demonstrator).
Several experimental tests have been carried out, in order to characterize the fatigue life and wear resistance of the materials involved in the construction of the demonstrator.
Numerical FEM models were also developed to determine the stresses of the sub-assemblies and components of the demonstrator during the test phase.
Combining the experimental results with the numerical ones, it was possible to develop an analytical model. Such model allows estimating the endurance of the demonstrator when subjected to accelerated tests. The model has shown a good correlation with experimental results.
The principles underlying this procedure can be applied, without any loss in terms of generality, to many sectors of the industry.L'introduzione di nuovi prodotti sul mercato è un processo di lunga durata, che comprende tipicamente sia fasi di progettazione che di sperimentazione. Sovente, la fase di validazione sperimentale condiziona notevolmente i tempi complessivi del processo. Infatti, in molti settori industriali, la procedura di sviluppo prodotto è basata su metodologie di tipo trial and error. Prove di validazione intermedie vengono eseguite su prototipi fisici in scala reale, ed in base all'esito di queste il design viene rielaborato (in caso di esito negativo) o validato (se l'esito è positivo). L'efficienza di tale metodo sotto il profilo temporale è, notoriamente, sub-ottimale. Per migliorare l'efficienza di tale processo è, ad esempio, possibile sfruttare metodologie di prova accelerate, che consistono nel sottoporre il prodotto ad una condizione di prova più gravosa rispetto alle normali condizioni di lavoro. In tale modo, si può conseguire una riduzione del numero di cicli necessari a portare a rottura il componente, con evidenti ricadute vantaggiose sull'efficienza del processo. Un'ulteriore modalità di accelerazione della prova consiste nel passare da prova sull'assieme globale a prova sui sottoassiemi o singoli componenti. È tuttavia obbligatorio, affinché i risultati ottenuti mediante tali metodologie di prova siano utili per la progettazione, adottare opportune precauzioni. Ad esempio, è fondamentale preservare la modalità di rottura originaria del componente. Per fare ciò, si rende necessario, fra le altre cose, conoscere la relazione tra le condizioni al contorno dell'intero assieme e le sollecitazioni dei singoli componenti. Nel presente elaborato, la metodologia sopra descritta viene illustrata facendo riferimento alla sua applicazione a componenti del settore serraturiero (dimostratore). Sono stati effettuati numerosi test sperimentali, per caratterizzare la vita a fatica e la resistenza all'usura dei materiali coinvolti nella costruzione del dimostratore. Sono inoltre stati sviluppati modelli numerici FEM per determinare le sollecitazioni dei sottoassiemi e componenti del dimostratore durante la fase di test. Combinando i risultati sperimentali con quelli numerici, è stato possibile sviluppare un modello analitico in grado di stimare con buona approssimazione la vita effettiva del dimostratore, quando sottoposto a prove accelerate. I principi alla base di questa procedura possono essere applicati, senza perdita di generalità, a numerosi settori dell'industria.
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Connally, John Arnold. "Micromechanical fatigue testing". Thesis, Massachusetts Institute of Technology, 1992. http://hdl.handle.net/1721.1/12756.
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Poissant, Jeffrey. "Microscale mechanical testing of individual collagen fibers". Thesis, McGill University, 2010. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=95075.
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Collagen is a key constituent for a large number of biological materials including bone, tendon, cartilage, skin and fish scales. Understanding the mechanical behavior of collagen's microscale structural components (fibers and fibrils) is therefore of utmost importance for fields such as biomimetics and biomedical engineering. However, the mechanics of collagen fibers and fibrils remain largely unexplored. The main research challenges are the small sample sizes (diameters less than 1 µm) and the need to maintain physiologically relevant conditions. In this work, a microscale mechanical testing device (MMTD) capable of measuring the stress-strain response of individual collagen fibers and fibrils was developed. The MMTD consists of: (i) a transducer from a commercial nanoindenter to measure load and displacement, (ii) an optical microscope to observe the deformation of the sample in-situ and (iii) micromanipulators to isolate, position and fix samples. Collagen fibers and fibrils were extracted from fish scales using a novel dissection procedure and tested using the MMTD. A variety of tensile tests were performed including monotonic loading and cyclic tests with increasing loading rate or maximum displacement. The monotonic test results found that the elastic modulus, ultimate tensile strength and strain at failure range from 0.5 to 1.3 GPa, 100 to 200 MPa and 20% to 60%, respectively. The cyclic tests revealed that the largest increase in damage accumulation occurs at strains between 10% and 20%, when hydrogen bonds at the molecular level are ruptured. Further straining the fibril causes little additional damage accumulation and signals the approach of failure. The addition of water is shown to increase damage tolerance and strain to failure.Le collagène est un constituant clé pour plusieurs matériaux biologiques incluant les os, tendons et écailles de poisson. Bien comprendre le comportement mécanique des composantes microstructurales du collagène (fibres et fibrilles) est important pour les domaines tel que la biomimétique et l'ingénierie biomédicale. Les principales difficultés sont la petite taille d'échantillons (< 1 µm) et le besoin de maintenir l'échantillon hydraté. Dans ce projet, un système de chargement micromécanique (SCMM) capable de mesurer le comportement mécanique de fibres et fibrilles de collagène a été développé. Le SCMM est composé : (i) d'un senseur provenant d'un nanoindenteur pour mesurer les forces et déplacements, (ii) d'un microscope optique pour observer la déformation d'échantillons in-situ et (iii) de micromanipulateurs pour isoler, positionner et fixer les échantillons. Des fibres et fibrilles de collagène ont été extraites d'écailles de poisson par voie d'une nouvelle procédure et ont été chargées par le SCMM. Plusieurs expériences ont été exécutées incluant des chargements en tension monotone et des chargements cycliques qui varieraient soit le taux de chargement ou le déplacement maximal. Les résultats de chargements monotones démontrent que le module d'élasticité, la contrainte ultime et la déformation au point de rupture se retrouvent entre 0.5 et 1.3 GPa, 100 et 200 MPa et 20% et 60%, respectivement. Les chargements cycliques révèlent que la plus grande augmentation d'endommagement du matériel se produit lors de déformations entre 10% et 20%, ce qui correspond à la rupture de ponts d'hydrogène au niveau moléculaire. Des déformations supplémentaires causent peu de dommage additionnel et signalent la rupture. L'ajout d'eau augmente l'endommagement que peut tolérer le matériau et augmente la déformation au point de rupture.
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Basterfield, Robert. "Interpretation of mechanical testing measurements for pastes". Thesis, Imperial College London, 2004. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.409257.
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Jailin, Clément. "Projection-based in-situ 4D mechanical testing". Thesis, Université Paris-Saclay (ComUE), 2018. http://www.theses.fr/2018SACLN034/document.
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L'analyse quantitative de volumes 3D obtenus par tomographie permet l’identification et la validation de modèles. La séquence d’analyse consiste en trois problèmes inverses successifs : (i) reconstruction des volumes (ii) mesure cinématique par corrélation d'images volumiques (DVC) et (iii) identification. Les très longs temps d’acquisition nécessaires interdisent de capter des phénomènes rapides. Une méthode de mesures, Projection-based Digital Volume Correlation (P-DVC), raccourcit la séquence précédente en identifiant les quantités clés sur les projections. Cette technique réduit jusqu'à 2 le nombre de radiographies utilisées pour le suivi de l’essai au lieu de 500 à 1000. Cette thèse étend cette approche en réduisant la quantité d’informations acquises, rendant ainsi accessibles des phénomènes de plus en plus rapides et repoussant les limites de la résolution temporelle. Deux axes ont ainsi été développés : - d’une part, l'utilisation de différentes régularisations, spatiales et temporelles des champs 4D (espace/temps) mesurés généralise la méthode P-DVC (avec volume de référence) à l'exploitation d’une seule radiographie par étape de chargement. L’essai peut désormais être réalisé de façon continue, en quelques minutes au lieu de plusieurs jours; - d’autre part, la mesure du mouvement peut être utilisée pour corriger le volume reconstruit lui-même. Cette observation conduit à proposer une nouvelle procédure de co-détermination du volume et de sa cinématique (sans prérequis), ce qui ouvre ainsi de nouvelles perspectives pour l’imagerie des matériaux et médicale où parfois le mouvement ne peut pas être interrompu. Le développement de ces deux axes permet d’envisager de nouvelles façons de réaliser les essais, plus rapides et plus centrés sur l’identification de quantités clés. Ces méthodes sont compatibles avec les récents développements « instrumentaux » de la tomographie rapide en synchrotron ou laboratoire, et permettent de réduire de plusieurs ordres de grandeurs les temps d’acquisition et les doses de rayonnementThe quantitative analysis of 3D volumes obtained from tomography allows models to be identified and validated. It consists of a sequence of three successive inverse problems: (i) volume reconstruction (ii) kinematic measurement from Digital Volume Correlation (DVC) and (iii) identification. The required very long acquisition times prevent fast phenomena from being captured.A measurement method, called Projection-based DVC (P-DVC), shortens the previous sequence and identifies the kinematics directly from the projections. The number of radiographs needed for tracking the time evolution of the test is thereby reduced from 500 to 1000 down to 2.This thesis extends this projection-based approach to further reduce the required data, letting faster phenomena be captured and pushing the limits of time resolution. Two main axes were developed:- On the one hand, the use of different spatial and temporal regularizations of the 4D fields (space/time) generalizes the P-DVC approach (with a known reference volume) to the exploitation of a single radiograph per loading step. Thus, the test can be carried out with no interruptions, in a few minutes instead of several days.- On the other hand, the measured motion can be used to correct the reconstructed volume itself. This observation leads to the proposition of a novel procedure for the joint determination of the volume and its kinematics (without prior knowledge) opening up new perspectives for material and medical imaging where sometimes motion cannot be interrupted.end{itemize}The development of these two axes opens up new ways of performing tests, faster and driven to the identification of key quantities of interest. These methods are compatible with the recent ``hardware" developments of fast tomography, both at synchrotron beamlines or laboratory and save several orders of magnitude in acquisition time and radiation dose
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Jones, Daniel Brian. "Micro-mechanical testing of interfacially adsorbed protein networks". Thesis, University of Cambridge, 2002. https://www.repository.cam.ac.uk/handle/1810/251831.
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Lewis, John R. "Formation of deformation-induced ferrite during mechanical testing". Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1997. http://www.collectionscanada.ca/obj/s4/f2/dsk3/ftp04/mq29610.pdf.
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Yandt, Scott A. "Development of a thermal-mechanical fatigue testing facility". Thesis, National Library of Canada = Bibliothèque nationale du Canada, 2000. http://www.collectionscanada.ca/obj/s4/f2/dsk1/tape4/PQDD_0020/MQ57745.pdf.
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Boone, Michael James. "Mechanical Testing of Epoxy Adhesives for Naval Applications". Fogler Library, University of Maine, 2002. http://www.library.umaine.edu/theses/pdf/BooneMJ2002.pdf.
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Lewis, John R. 1972. "Formation of deformation induces ferrite during mechanical testing". Thesis, McGill University, 1996. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=27237.
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The effects of austenite grain size, level of undercooling, and strain and strain rate in compression on the austenite-to-ferrite transformation in a 0.1% C, 1.4% Mn steel were investigated. The influence of this transformation on the hot ductility of the steel in question was then examined. Samples were strained at rates from $ rm 3 times 10 sp{-4} s sp{-1}$ to $ rm 3 times 10 sp{-2} s sp{-1}$ after cooling to holding temperatures between the Ae$ sb3$ and the (undeformed) Ar$ sb3$ temperature.Deformation was found to raise the effective Ar$ sb3$ temperature almost to the Ae$ sb3$, and to significantly accelerate the transformation in both fine ($ sim$25 $ mu$m) and coarse ($ sim$200 $ mu$m) grained samples. At relatively small levels of undercooling ($ sim$40$ sp circ$C, it was found that deformation induced ferrite could not form outside the regions of the material that were significantly affected by the applied strain. At low strain rates and in coarse grained material, this meant that ferrite formed in narrow bands near the grain boundaries. No such restriction was found in fine grained material.
In tension, it was found that, if thin bands of grain boundary ferrite were present in the microstructure, failure always occurred in this second phase. The effect of intergranular ferrite on the ductility was found to vary with the amount present; the lowest %RA value was obtained with around 10% ferrite present in the microstructure. The detrimental effect of ferrite lessened slightly as the strain rate was raised.
It is concluded that, from an industrial perspective, unless unbending can be performed at strain rates in excess of $ rm 3 times 10 sp{-2} s sp{-1},$ it would be prudent to carry out this operation either above the Ae$ sb3$ or below the (undeformed) Ar$ sb3$ temperature for the steel in question.
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Greina, Kristine. "IN-SITU FRACTURE MECHANICAL TESTING OF MICROSIZED CANTILEVERS". Thesis, Norges teknisk-naturvitenskapelige universitet, Institutt for materialteknologi, 2014. http://urn.kb.se/resolve?urn=urn:nbn:no:ntnu:diva-25617.
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The arctic is an appealing new ventures area for the oil and gas industry. However the climate is extremely demanding, and more technically challenging than any other environment. With design temperatures down to -60°C the ductile to brittle transition temperature (DBTT) is an important concern. The propagation of a brittle fracture in iron and steel requires much less energy than that associated with a ductile fracture. Once a material is cooled below the DBTT, it has a much greater tendency to shatter on impact instead of bending or deforming. The brittle-ductile behavior of BCC crystals has long been an area of intensive study, however the fundamental mechanisms that control the transition have not yet been explained. The rapid development within nanotechnology has made it possible to conduct small scale fracture experiments. The development of innovative nanomechanical testing techniques could lead to a better understanding of fracture properties at low temperatures, quantitative information on local stress requirements for crack propagation and subsequently explain the fundamental mechanisms that control the ductile to brittle transition. Advanced fracture experiments of pure iron at a micron scale have been completed. Electron Backscatter Diffraction analysis were conducted in order to determine the crystal orientation of the surface grains. Micro-cantilevers with dimensions of approximatly 2x2x10 μm were fabricated, in grains with preferred crystal orientation, by means of Focused Ion Beam (FIB) milling. The cantilevers were then loaded in a controlled manner to obtain load displacement data using a Picoinenter. The use of a picoindenter combine with a Scanning Electron Microscope (SEM) has shown to be a valuable tool since it allows events observed in the mechanical data to be correlated directly with the corresponding deformation mechanisms witnessed through the electron microscope. Extensive work has been put in to designing and constructing a cooling system, in order to conduct micro fracture experiments at low temperatures. The developed cooling system consists of a liquid nitrogen tank mounted on an SEM port, which is mechanically connected to the sample through a coldfinger. The thermal conductivity of the cooling system proved be sufficient; after approximately 1,5h a temperature of -90°C was reached, and loading of cantilevers at room temperature, -70°C and -90°C were successfully conducted. All cantilever were plastically deformed during loading, but no fracture occurred. Due to the absence of fracture the critical stress intensity factor, i.e. fracture toughness, could not be determined. However the preliminary stress intensity, (KQ) was calculated using five different methods. The results showed a drop in the preliminary stress intensity values between -70°C and -90°C. The KQ values may indicate the stress causing the first deviation from ideal elastic behavior by dislocation movement and plastic deformation. By this, the stress at which plastic deformation starts, decrease with decreasing temperature. It was not possible to measure the Crack Tip Opening Displacement (CTOD) directly during in-situ experiments, due to low image resolution. However, CTOD was calculated with two different methods: the hinge model and the double gauge model, both relying on the measurements of CMOD during loading. CTOD values for the two different methods were compared, however, they did not correlate. The double gauge model is probably the most accurate method since it is a direct approach and independent of the global behavior, whereas the hinge model relies on accurate values for the rotational center.
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Yandt, Scott A. (Scott Andrew) Carleton University Dissertation Engineering Mechanical and Aerospace. "Development of a thermal-mechanical fatigue testing facility". Ottawa, 2000.
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Hyatt, Daniel (Daniel Elliot). "Proposed testing method for foam padding". Thesis, Massachusetts Institute of Technology, 2011. http://hdl.handle.net/1721.1/69778.
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Thesis (S.B.)--Massachusetts Institute of Technology, Dept. of Mechanical Engineering, 2011.Cataloged from PDF version of thesis.
Includes bibliographical references (p. 31).
One very basic necessity for foam padding testing technology is the ability to test two different padding samples and compare the results. The current standard for testing is to use a steel anvil backing for the padding, create an impact and record the parameters of the collision. The standardized method of testing with a steel anvil backing may not truly depict which foam or padding is actually the most protective, and this project aims to demonstrate how using a more humanlike backing produces more accurate test results. The experimentation setup used a projectile shot with a known velocity at various padding samples, where both a steel anvil and urethane foam are used as separate backings for the experiment. The steel anvil represents the current industry testing standard, whereas the urethane foam is meant to physically replicate the characteristics of human flesh. Using a load cell which is calibrated with an oscilloscope, a curve of the force applied over time will be recorded for each test run. From this force curve, the peak force, total impulse, and energy dissipated were calculated for each collision. By comparing these metrics across different foam padding specimens using the two padding backings across different velocities, the effect of varying the padding backing are demonstrated in the experimental results. Although using the steel anvil backing lead to generally similar recommendations for the best padding, it does not capture a lot of the details which are necessary to truly understand how different foam specimens compare with each other. Two main conclusions are drawn regarding the difference between the steel anvil and urethane foam setups: the difference in the shape of the force over time curves and the significance of changing the velocity of the impact. Using the urethane foam backing also established two different regimes which define whether or not the padding user would feel a significant impact. The parameters of these regimes provide the best data for deciding on appropriate foam specimens. The steel anvil backing lacks any capacity to test or predict which impacts are severe enough to cause serious injury.
by Daniel Hyatt.
S.B.
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Kohlhöfer, Walter. "Dynamic hardness testing challenges conventional tests". Master's thesis, University of Cape Town, 1993. http://hdl.handle.net/11427/15981.
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Bibliography: pages 69-71.The design and use of a portable dynamic hardness tester is described. The thesis begins with a description of the more common static hardness tests and the usefulness of such tests in industry. It shows a correlation between the different types of hardness and also between hardness and other material parameters such as tensile strength. A thorough investigation of the principles involved in the indentation processes using conical and spherical indenters under static and dynamic loading is given so that the reasons for the correlations may be more clearly understood. A series of test specimens tested by conventional static hardness tests (Brinell, Vickers and Rockwell) are used as calibration specimens for the dynamic tester. Both a spherical and conical tip are used. The results of these tests are compared and analyzed. The dynamic tester may then be programmed so that it correlates with the results of the static tests. A set of guidelines for the use of such a portable tester is then given.
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Alsaedi, Mohammed Abbas Soudai. "Development of 3D Accelerometer Testing System". PDXScholar, 2016. https://pdxscholar.library.pdx.edu/open_access_etds/3371.
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Accelerometers are used in numerous industries including aircrafts and missile navigations systems, rotary machines, and electronic devices such as tablets, cell phones, and cameras. Accelerometers of different purposes and specifications are being produced in large quantities. The large demand for accelerometers forces the need for accelerometer testing methodology that is more convenient and accurate. Inertial Micro-Electromechanical Systems Accelerometer (MEMS) require a series of tests that include physical stimuli. One of the key challenges is the cost associated with testing. Therefore, the accurate prediction of the sensor functions not only reduces the testing time but also more importantly contributes to reducing testing cost.
Shaker accelerometer calibrators are widely used to test accelerometers. Shakers use sinusoidal acceleration input, and their testing acceleration range could be as small as 0.1 g1 and as high as 20 g. These devices test accelerometers in one axis at a time. In this study, the 3-D MEMS accelerometer testing method and system have been developed to reduce the testing time cycle significantly by testing 3D axes simultaneously. The theoretical study shows that an acceleration sensor is rotating about a fixed axis experiences tangential and normal accelerations.
The objective of this project is to develop a testing methodology and equipment to test accelerometers along all three axes simultaneously over a range of ± 50 g while reducing testing time. These accelerations are related to the distance from the center of rotation and the angular velocity. The angular velocity can be controlled by the amount of the voltage that is given to the DC motor from the power supply which is adjusted by a speed controller. By varying either the angular velocity with the speed controller or varying the distance from the axis of rotation, it is possible to expose an accelerometer to the desired acceleration value.
The equipment uses a rotating turntable where the center of the table marks the axis of the rotation. The accelerometer being tested was mounted at a known distance from the center of the table. The resulted normal and tangential accelerations were calculated from the angular velocity of the turntable and the position of accelerometer from the axis of rotation. A high precision encoder was used to determine the angular velocity of the turntable. The range of the angular velocity that can be measured accurately by the encoder affects the range of acceleration amplitude the system can be used to test. The encoder used can sense an angular velocity as low as 0.0144º/s. This corresponds to the normal acceleration value of 2.32 x 10-9 g.
The accelerometer mounted on a turntable in a way that all three of its axes are exposed to the input acceleration to test an accelerometer in all three axes at the same time. A program written in LabVIEW operated the system and collected the test data. This program was able to collect acceleration readings along all three axes of the accelerometer with position and velocity information of the input motion. The collected data set were processed by MATLAB. This testing methodology provides a way to use multiple input accelerations unlike traditional accelerometer testing method. The test methodology developed in this study provides a way to use a constant acceleration input over a wide range (± 50 g). Its lowest acceleration range is 2.32 x 10-9 g. This reduces the time it takes to align the accelerometer in different axes and eliminates errors that may result during a manual repositioning of the accelerometer to align it in a different axis. Error models for MEMS accelerometer sensors have used Kalman filters to perform complete accelerometer sensor test.
The accelerometer error model must be constructed, and the coefficients in the error equations must be determined. Therefore, Kalman filter in the analysis of visual motion has been documented frequently. The filter is constructed as a mean squared error minimizer. The purpose of filtering is to extract the required information from a signal, ignoring everything else.
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Custer, Erica M. "Cortical Bone Mechanics Technology and Quasi-static Mechanical Testing Sensitivity to Bone Collagen Degradation". Ohio University Honors Tutorial College / OhioLINK, 2019. http://rave.ohiolink.edu/etdc/view?acc_num=ouhonors1556281791006274.
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Makowka, Steven Robert. "Development of a Gripping Fixture for Micro-Tensile Testing of Bonded Ceramic Dumbbells". Thesis, State University of New York at Buffalo, 2018. http://pqdtopen.proquest.com/#viewpdf?dispub=10793930.
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It is proposed that both the adhesive interface geometry and the mismatch of elastic moduli influence the tensile strengths of dental bonds attaching restorative ceramics to dentin. Prior calculations indicate this to be due to peripheral interface stress singularities. A physical testing approach to examine and validate the theoretical conclusions utilizing a microtensile testing system is presented.
Considering the choice of shear versus tensile and then macro versus micro tensile testing, reasons were identified for choosing micro tensile testing. Specimen dimensions and shapes were developed to optimize the adjustment of the interface geometries and information that could be obtained therein. Here a dumbbell structure is best suited to the testing needs.
Dumbbell specimens were first fabricated using the ceramic press technique, and then mini-CNC machining. Specimens fabricated by each technique were examined, showing that the mini-CNC machining methodology was superior.
Significant problems in instrumentation were overcome by the design and fabrication of two testing fixtures: 1. A collet based design with independent upper and lower mechanical grips for each end of the dumbbell, to be used in conjunction with a loading device; 2. A screw based clamping design similar to previous jigs, using two screw clamps on V-channels connected by sliding rods. Testing revealed that the collet-based design shows the most promise because of its distributed gripping load. Further tests that can evaluate the effectiveness of this device for microtensile testing are outlined.
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Becker, Wolfgang. "Mechanical response of unidirectional Boron/Aluminum under combined loading". Thesis, Virginia Polytechnic Institute and State University, 1987. http://hdl.handle.net/10919/91079.
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Three test methods were employed to characterize the response of unidirectional Boron/Aluminum metal matrix composite material under monotonic and cyclic loading conditions, namely: Iosipescu Shear, Off-Axis Tension and Compression. The characterization of the elastic and plastic response includes the elastic material properties, yielding and subsequent hardening of the unidirectional composite under different stress ratios in the material principal coordinate system. The elastic response is compared with the prediction of the transformation theory, based on the far field stress ōₓₓ, the Pagano-Halpin Model, and finite element analysis. Yield loci were generated for different stress ratios and were compared for the three different test methods, taking into account residual stresses and specimen geometry. The yield locus for in-plane shear was compared with the prediction of an analytical micromechanical model. The influence of the scatter in the experimental data on the predicted yield surface was also analyzed. Likewise the experimental material strength in tension and compression was compared with the Maximum Stress and the Tsai-Wu failure criterion.M.S.
23
Shanmugam, Arun Kumar. "Dynamic mechanical analysis and impact testing of phenolic composites". Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1997. http://www.collectionscanada.ca/obj/s4/f2/dsk2/ftp03/MQ31638.pdf.
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Lakshmana, Rao Anand. "Dynamic mechanical analysis and impact testing of phenolic resin". Thesis, National Library of Canada = Bibliothèque nationale du Canada, 2001. http://www.collectionscanada.ca/obj/s4/f2/dsk3/ftp05/MQ63532.pdf.
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Firlotte, Nicolas. "Mechanical testing and biodegradation of an alternative dibenzoate plasticizer". Thesis, McGill University, 2008. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=116041.
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Plasticizers are ubiquitous environmental contaminants. Biodegradation of some of these chemicals, such as di(2-ethylhexyl) phthalate (DEHP or DOP), has been shown to lead to the accumulation of toxic metabolic breakdown products. As a result there is a desire to produce new, fully biodegradable, "green" plasticizers. With this goal in mind, a series of tests were developed to be used to measure the plasticizing efficiency of potential green plasticizers. The base resin selected for the study was poly(vinyl chloride) (PVC). The glass transition temperature (Tg) of the plasticized polymer was measured by temperature-modulated differential scanning calorimetry (TMDSC). Tensile tests were carried out on samples of the material from which the tensile strength and the strain at break of the material were measured. The aforementionned properties were measured for PVC plasticized with the commercial plasticizers DEHP, diethylene glycol dibenzoate (DEGDB) and dipropylene glycol dibenzoate (DPGDB) at several plasticizer concentrations.1,5 pentanediol dibenzoate (PDDB) was synthesized and evaluated as a plasticizer by comparing results for this compound with those for the commercial plasticizers using the developed tests. The depression in Tg and tensile properties were comparable at a fixed composition for blends with PDDB relative to blends with DEHP, DEGDB, and DPGDB. PDDB was subjected to biodegradation unsing co-metabolism by the common soil bacterium Rhodococcus rhodocrous (ATCC 13808). After 16 days of growth, nearly all the PDDB was degraded and only small amounts of transient, unidentified, metabolites were observed in the growth medium during the experiment.
26
Brayanov, Jordan 1981. "Design and implementation of nanoscale fiber mechanical testing apparatus". Thesis, Massachusetts Institute of Technology, 2004. http://hdl.handle.net/1721.1/32799.
Pełny tekst źródłaStreszczenie:
Thesis (S.B.)--Massachusetts Institute of Technology, Dept. of Mechanical Engineering, 2004.Includes bibliographical references (leaf 26).
The rapid growth in the synthetic manufacturing industry demands higher resolution mechanical testing devices, capable of working with nanoscale fibers. A new device has been developed to perform single-axis tensile tests on fibers with diameter ranging from 50 nm to 10 [micro]m. The device is capable of performing simple extension tests to determine the fiber's strength as well as high-frequency dynamic tests to look at fiber recovery rates, dampening, and fatigue. The force resolution obtained using a quartz strain gauge and a Zeaman interferometer was in the order of 1 nN and the forces measured by the instrument ranged over 10 orders of magnitude. This paper will present the design the Nanofiber tester, which offered better performance than any currently available commercial instruments and will discuss the subtleties around the implementation of the instrument, which is yet to be completed.
by Jordan Brayanov.
S.B.
27
Van, den Heuvel Louise E. "Improved mechanical design and thermal testing of MIT Solarclave". Thesis, Massachusetts Institute of Technology, 2014. http://hdl.handle.net/1721.1/92211.
Pełny tekst źródłaStreszczenie:
Thesis: S.B., Massachusetts Institute of Technology, Department of Mechanical Engineering, 2014.Cataloged from PDF version of thesis.
Includes bibliographical references (page 65).
Solarclave is a solar-powered autoclave designed for use in rural health clinics in developing countries. The autoclave must sufficiently sterilize medical instruments to ensure that they can safely be used in providing patient care. The medical instruments are sterilized in a pressure cooker that is heated by concentrated sunlight from a parabolic reflective surface. Previous iterations and testing of the Solarclave proved that sunlight and a pressure cooker could sufficiently sterilize equipment. However, usability problems and cost constraints require that the design be further improved before dissemination can occur. Critical design decisions that this work makes include updating the reflective structure, the pressure cooker, and the pressure cooker insulation. The combination of choices must meet user needs and provide sufficient sterilization at a minimum cost. A reflective structure was selected based on its low cost and listed ability to meet existing power consumption needs. A mathematical model was created to estimate the actual usable power output of the selected reflective structure based on its dimensions and reflectivity, as well as expected intensity of solar radiation. Furthermore, a thermal circuit model was developed to predict the temperature over time inside the pressure cooker as a function of input power, pressure cooker dimensions, and insulation material choice. The mathematical model was evaluated by measuring the temperature outside the pressure cooker over time, recording all relevant parameters, and comparing the results to those predicted by the model. The results indicated that the theoretical input power estimate was too high, but that the thermal circuit was an appropriate approach to modeling the heat loss of the system. The usability of the system showed major improvements in terms of ease-of-use, but needs further design in terms of its aesthetics.
by Louise E. van den Heuvel.
S.B.
28
Gudlavalleti, Sauri 1978. "Mechanical testing of solid materials at the micro-scale". Thesis, Massachusetts Institute of Technology, 2002. http://hdl.handle.net/1721.1/29741.
Pełny tekst źródłaStreszczenie:
Thesis (S.M.)--Massachusetts Institute of Technology, Dept. of Mechanical Engineering, 2002.Includes bibliographical references (p. 145-149).
Successful design and fabrication of structures and systems at the micro-scale requires a sound theoretical understanding and reliable experimental data on the mechanical behavior of materials at that scale. Generation of experimental data requires accurate, robust, reliable, versatile and yet simple micro-scale mechanical testing devices. This thesis describes the design, development and applications of materials testing technologies at the micro-scale. Using the rectilinear travel characteristics of compound flexures, two novel testing machines have been designed and built to conduct tension, bending and indentation tests in the force regime of 10 pN - 35 N and displacement regime of 20 nm - 6 mm. These machines have been used in measuring the mechanical properties of free-standing gold thin films, rolled metallic foils, elastomeric fibers and other materials. Numerical simulations of the mechanical behavior of gold thin films and rolled copper foils have been conducted and compared with experimental results. Microstructural investigations into deformation mechanisms of the free-standing gold thin films have also been conducted.
by Sauri Gudlavalleti.
S.M.
29
Martin, Rachel (Rachel M. ). "Mechanical testing of rapid-prototyping refractory ceramic print media". Thesis, Massachusetts Institute of Technology, 2012. http://hdl.handle.net/1721.1/86278.
Pełny tekst źródłaStreszczenie:
Thesis: S.B., Massachusetts Institute of Technology, Department of Materials Science and Engineering, February 2013.Page 30 blank. Cataloged from PDF version of thesis.
Includes bibliographical references.
Additively manufactured (3D-printed) refractory alumina-silica ceramics were mechanically tested to ascertain their ultimate tensile strengths and observed to determine their dimensional consistency over the printing and post-printing process. The equipment used to perform tensile testing was designed and built for use with custom-designed tensile test samples. Two ceramic powders, V18 (electronic-grade alumina, colloidal silica, and organic content) and 403C (200-mesh mullite, organic content, and magnesium oxide), were printed into test samples on ZCorporation ZPrinter® 310 and 510 machines, before being infiltrated with tetraethylorthosilicate (TEaS), and in some cases infiltrated again with a 40% by weight suspension of silica in water (Ludox). Ludox-infiltrated V18 proved to be the strongest medium, with a UTS of 4.539 ± 1.008 MPa; non-Ludox-infiltrated V18 had a UTS of 2.071 ± 0.443 MPA; Ludox-infiltrated 403C was weakest with a UTS of 1.378 ± 0.526 MPa. Within V18, greater silica content lead to greater tensile strength, but this did not hold true for 403C. 403C displayed volumetric shrinkage of about 1.5%, while V18's volumetric shrinkage ranged from 7% to 14%.
by Rachel Martin.
S.B.
30
Judnick, Daniel Clemente Louis. "Modeling and testing of a mechanical counterpressure BioSuit system". Thesis, Massachusetts Institute of Technology, 2007. http://hdl.handle.net/1721.1/39489.
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Thesis (S.M.)--Massachusetts Institute of Technology, Dept. of Aeronautics and Astronautics, 2007.This electronic version was submitted by the student author. The certified thesis is available in the Institute Archives and Special Collections.
Includes bibliographical references (p. 189-190).
The President's Vision for Space Exploration calls for a returned human presence on the Moon, followed by human missions to Mars. The astronauts on these missions will require a more robust and flexible spacesuit than currently exists to conduct exploration and science operations as well as maintain a base on planetary surfaces. The BioSuit system is a modular spacesuit concept based on the theory of mechanical counterpressure (MCP). Considerable experimental work has been conducted in the field of MCP, but there has been no analysis of the hypothetical best level of uniformity of pressure production for this type of spacesuit design. Therefore, computer modeling has been undertaken to verify the feasibility of such a design, which is based on not only providing the required pressure on the skin, but also limiting the variation of pressure production around a cross-section of the body. Given the data sets available, which exclusively consist of legs under normal atmospheric pressure, not mechanical counterpressure, the modeling work indicates that a MCP-based design can meet these requirements.
(cont.) This thesis advances the BioSuit design by laying out the system level requirements, and also by setting requirements for the fabric and closure mechanism in order to design a working prototype. As part of this design process, the team has further developed the elastic bindings concept, which previously was designed to produce pressure only on the calf. Now the team has extended the design to protect the entire leg in an underpressurized environment. Based on blood pressure, skin temperature, heart rate, and qualitative comfort ratings, the bands have proven successful at protecting the leg (with the exception of some minor edema on the knee) at the desired underpressure (-225 mm Hg) over a full hour. A simple knee brace which filled the concavities of the knee was also tested, and proved successful in preventing edema in one trial. While the design is not yet capable of operational testing due to limitations in mobility, it is a valuable stepping point towards developing a full BioSuit system.
by Daniel Clemente Louis Judnick.
S.M.
31
Herrmann, Ariel Marc. "Instrumentation for multiaxial mechanical testing of inhomogeneous elastic membranes". Thesis, Massachusetts Institute of Technology, 2006. http://hdl.handle.net/1721.1/35671.
Pełny tekst źródłaStreszczenie:
Thesis (S.M.)--Massachusetts Institute of Technology, Dept. of Mechanical Engineering, 2006.Includes bibliographical references (p. 93-100).
This thesis presents the design, development, and construction of an instrument for biaxial mechanical testing of inhomogeneous elastic membranes. The instrument incorporates an arrangement of linear motion stages for applying arbitrary deformation profiles on the material under test, purpose-built two-axis force transducers for high-resolution measurement of applied loads, and a digital imaging system for full-field strain measurement. The components described herein provide the foundation for a sophisticated biaxial testing platform for determining the mechanical properties of anisotropic, inhomogeneous membrane materials.
by Ariel Marc Herrmann.
S.M.
32
Hu, Yuan. "Friction-Stir Riveting: Mechanical Testing of Friction-Stir Riveting". University of Toledo / OhioLINK, 2015. http://rave.ohiolink.edu/etdc/view?acc_num=toledo1430393133.
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Allen, Katherine Ruth. "Methods of testing the mechanical properties of orthodontic wires /". Title page, table of contents and summary only, 1994. http://web4.library.adelaide.edu.au/theses/09DM/09dma427.pdf.
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Grant, Caroline. "Mechanical testing and modelling of a bone-implant construct". Thesis, Queensland University of Technology, 2012. https://eprints.qut.edu.au/62191/1/Caroline_Grant_Thesis.pdf.
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Finite Element modelling of bone fracture fixation systems allows computational investigation of the deformation response of the bone to load. Once validated, these models can be easily adapted to explore changes in design or configuration of a fixator. The deformation of the tissue within the fracture gap determines its healing and is often summarised as the stiffness of the construct. FE models capable of reproducing this behaviour would provide valuable insight into the healing potential of different fixation systems. Current model validation techniques lack depth in 6D load and deformation measurements. Other aspects of the FE model creation such as the definition of interfaces between components have also not been explored.
This project investigated the mechanical testing and FE modelling of a bone– plate construct for the determination of stiffness. In depth 6D measurement and analysis of the generated forces, moments and movements showed large out of plane behaviours which had not previously been characterised. Stiffness calculated from the interfragmentary movement was found to be an unsuitable summary parameter as the error propagation is too large.
Current FE modelling techniques were applied in compression and torsion mimicking the experimental setup. Compressive stiffness was well replicated, though torsional stiffness was not. The out of plane behaviours prevalent in the experimental work were not replicated in the model.
The interfaces between the components were investigated experimentally and through modification to the FE model. Incorporation of the interface modelling techniques into the full construct models had no effect in compression but did act to reduce torsional stiffness bringing it closer to that of the experiment. The interface definitions had no effect on out of plane behaviours, which were still not replicated.
Neither current nor novel FE modelling techniques were able to replicate the out of plane behaviours evident in the experimental work. New techniques for modelling loads and boundary conditions need to be developed to mimic the effects of the entire experimental system.
35
Krull, Alexander G. (Alexander Gerhard). "Experimental testing of LIGO vibration isolation system". Thesis, Massachusetts Institute of Technology, 2007. http://hdl.handle.net/1721.1/40439.
Pełny tekst źródłaStreszczenie:
Thesis (S.B.)--Massachusetts Institute of Technology, Dept. of Mechanical Engineering, 2007.Includes bibliographical references (leaf 29).
The LIGO (Laser Interferometer Gravitational-wave Observatory) project is designed to detect gravitational waves using precision interferometry. The detection from astrophysical sources has the potential to test Einstein's Theory of General Relativity, and additionally open a new window into the universe and its origin. The Initial LIGO detectors are currently operating at a strain sensitivity of 10-21 Hz, or equivalently 1018 m/ [square root of] Hz, at 100 Hz. In order to attain improved sensitivity required for guaranteed detection of astrophysical sources, e.g. coalescing neutron star binaries and black holes, pulsars, and supernovae collapses, improvements of the strain sensitivity must be achieved. Next generation detectors such as Advanced LIGO are under development, which aims to improve the sensitivity by more than a factor of 10 at all frequencies, compared to initial LIGO. This improvement in sensitivity will be achieved in part by improved seismic isolation one component of which is an active vibration isolation platform. Currently, research and development is being conducted at MIT on a prototype of this vibration isolation system. The work described in this thesis focuses on the Internal Seismic Isolation (ISI) system under development for Advanced LIGO.
(cont.) This system consists of a three-stage in-vacuum seismic isolation system which is supported by an external hydraulic actuation stage known as the Hydraulic External Pre-Isolation (HEPI) stages of the active vibration control system. HEPI uses forces generated by hydraulic pressure to cancel low frequency seismic noise, primarily due to forces from ground vibration. The ISI is an actively controlled platform, in which each stage is supported by three maraging steel blade springs. The vibration is sensed in six degrees of freedom and reduced by applying forces through a control feedback loop. In order for the feedback loop to function properly, it is important to know and be able to predict the position of the ISI stages to within a few thousandths of an inch. Since the load being applied to the spring blades is known, the compliance of each spring along with various shim thicknesses will determine the final position of the stages. Although compliance is a material and geometric property, and should remain constant from spring to spring, due to imperfections of the fabrication process and variation in the material properties, small variations in the long and short spring compliance value were detected using a Spring Tester.
(cont.) The blades were designed based on their resonant frequencies and the load which they would be supporting - more specifically, their geometry (length, width, and thickness) were defined such that the load each supported brought them to a 1/3 of their failure stress. For my undergraduate thesis, I determined the compliance of multiple long and short springs was determined using a specially designed apparatus - the "Spring Tester." Ideally, three blade springs of identical compliance should be used to eliminate system imbalance, but to variation during fabrication may be difficult to achieve Using the Spring Tester the mean values for each set of long and short spring linear compliance data were found to be 0.729 +.008 mils/lb and 0.670 ±.027 mils/lb, respectively, while the means for the long and short angular compliance data were 0.078 + .001 mrad/lb and 0.089 ±.003 mrad/lb, respectively.
by Alexander G. Krull.
S.B.
36
Muto, Andrew (Andrew Jerome). "Device testing and characterization of thermoelectric nanocomposites". Thesis, Massachusetts Institute of Technology, 2008. http://hdl.handle.net/1721.1/44915.
Pełny tekst źródłaStreszczenie:
Thesis (S.M.)--Massachusetts Institute of Technology, Dept. of Mechanical Engineering, 2008.This electronic version was submitted by the student author. The certified thesis is available in the Institute Archives and Special Collections.
Includes bibliographical references (p. 67-68).
It has become evident in recent years that developing clean, sustainable energy technologies will be one of the world's greatest challenges in the 21st century. Thermoelectric materials can potentially make a contribution by increasing energy efficiency of some systems. Thermoelectric materials may play a role in the large scale energy industry, specifically in the applications of refrigeration and waste heat recovery. In this work a novel thermoelectric material will be tested for conversion efficiency. A Bi₂Te₃ nanocomposite has been developed by the joint effort of Prof. Gang Chen's group at MIT and Prof. Zhifeng Ren's group at Boston College. The material exhibits enhanced thermoelectric properties from optimized nanoscale structures and can be easily manufactured in large quantities. In order to better characterize its performance a novel power conversion measurement system has been developed that can measure the conversion efficiency directly. The measurement system design will be described in detail; important design considerations will be addressed such as measuring heat flux, optimizing the load matching condition and reducing electrical contact resistance. Finally the measured efficiency will be compared to the calculated efficiency from a temperature-dependent properties model. It will be shown that a Ni layer must be attached to the nanocomposite to allow soldering and power conversion testing. Results of this work will show that the nanocomposite efficiency is higher than the commercial standard. Electrical contact remains a challenge in realizing the potential efficiency.
by Andrew Muto.
S.M.
37
Dewell, Elizabeth A. (Elizabeth Anderson) 1980. "Tilt bed testing of the subjective horizontal". Thesis, Massachusetts Institute of Technology, 2002. http://hdl.handle.net/1721.1/69235.
Pełny tekst źródłaStreszczenie:
Thesis (S.B.)--Massachusetts Institute of Technology, Dept. of Mechanical Engineering, 2002.This electronic version was submitted by the student author. The certified thesis is available in the Institute Archives and Special Collections.
Includes bibliographical references (leaf 25).
Mittelstaedt (1987) suggested that inversion illusions which caused space sickness in astronauts was associated with a net headward bias in the body's gravireceptor organs, which could be measured on Earth using a tilting bed. Mittelstaedt showed that when individual subjects were asked to repeatedly position themselves to the gravireceptive subjective horizontal, individuals showed a small (<5 deg.) but consistent head up or head down bias that remained stable when retested weeks, months or even years later. A correlation with inversion illusion was noted in a small number of astronauts. The purpose of the present project was 1) to construct a new bed of slightly different design and 2) to verify Mittelstaedt's findings using a different subject population. Nine subjects each lay on their left side with their head immbobilized using a bite bar. They positioned the bed (and themselves) at the subjective horizontal ten successive times starting from standardized initial tilt angles which ranged from +/- 10 degrees. Tests were then repeated on right side. Four subjects returned a day later for retesting. Results showed that subjects repeatedly positioned themselves at their own subjective gravitational horizontal, which differed from true horizontal by several degrees a head down direction. Results of tests on the left and right side had similar means for most of the nine subjects; however 4 were statistically different. Left and right sides were combined, noting the above error. Mean biases in the subjective horizontal varied from -3.26 to -0.82 degrees head down between subjects, with overall mean -1.65 and s.d. 0.80. There was a statistically significant difference between responses of some subjects. Data from four subjects tested on both days was compared. A statistically significant correlation was not found, perhaps due to the small subject retest population. The differences between Mittelstaedt's data and present results are discussed.
by Elizabeth A. Dewell.
S.B.
38
Ambrogi, Robert R. (Robert Raymond). "Testing and analysis of hybrid magnetic bearings". Thesis, Massachusetts Institute of Technology, 1987. http://hdl.handle.net/1721.1/14815.
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Dike, Nnadozie N. F. "Performance of Mechanical and Non-mechanical Connections to GFRP Components". Master's thesis, University of Central Florida, 2012. http://digital.library.ucf.edu/cdm/ref/collection/ETD/id/5187.
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There are presently many solutions to dealing with aging or deteriorated structures. Depending on the state of the structure, it may need to be completely over-hauled, demolished and replaced, or only specific components may need rehabilitation. In the case of bridges, rehabilitation and maintenance of the decks are critical needs for infrastructure management. Viable rehabilitation options include replacement of decks with aluminum extrusions, hybrid composite and sandwich systems, precast reinforced concrete systems, or the use of pultruded fiber-reinforced polymer (FRP) shapes. Previous research using pultruded glass fiber-reinforced polymer (GFRP) decks, focused on behaviour under various strength and serviceability loading conditions. Failure modes observed were specific to delamination of the flexural cross sections, local crushing under loading pads, web buckling and lip separation. However certain failure mechanisms observed from in-situ installations differ from these laboratory results, including behaviour of the connectors or system of connection, as well as the effect of cyclic and torsional loads on the connection. This thesis investigates the role of mechanical and non-mechanical connectors in the composite action and failure mechanisms in a pultruded GFRP deck system. There are many interfaces including top panel to I-beam, deck panel to girder, and panel to panel, but this work focuses on investigating the top panel connection. This is achieved through comparative component level shear, uplift, and flexure testing to characterize failure and determine connector capacity. Additionally, a connection of this GFRP deck system to a concrete girder is investigated during the system-level test. Results show that an epoxy non-mechanical connection may be better than mechanical options in ensuring composite behaviour of the system.ID: 031001297; System requirements: World Wide Web browser and PDF reader.; Mode of access: World Wide Web.; Title from PDF title page (viewed March 7, 2013).; Thesis (M.S.)--University of Central Florida, 2012.; Includes bibliographical references (p. 80-82).
M.S.
Masters
Civil, Environmental, and Construction Engineering
Engineering and Computer Science
Civil Engineering; Structural and Geotechnical Engineering
40
Wang, Zhichao. "Disturbed state constitutive modeling and testing of solders in electronic packaging". Diss., The University of Arizona, 2001. http://hdl.handle.net/10150/279828.
Pełny tekst źródłaStreszczenie:
Accuracy of fatigue life prediction of solder joint materials using the finite element method (FEM) depends on realistic and reliable constitutive models and the FEM procedure itself. The effectiveness and accuracy of a constitutive model to simulate and predict the behavior of materials strongly depends on consistent, reliable and precise experimental data. In this research, a thermomechanical digital image correlation test device has been developed to investigate solder joint material behavior under thermal mechanical and cyclic loading. The test device is composed of two high precision actuators driven by two brushless servo-motors; a vacuum chamber used to prevent the heating and cooling plate from heating and cooling the air in the vacuum chamber and other components to save the energy needed to heat and cool the specimen; a heating and cooling unit composed of four Peltier devices; a digital correlation deformation and displacement measurement system and various load and displacement sensors. The test device is controlled by Labview. Two closed loop system control programs in Labview were developed to control the device and perform tests under specified loads, displacements and temperature profiles. The temperature, loads, and displacements can be applied manually and automatically. A series of tests such as normal load tests, temperature and rate dependent tests, isothermal mechanical fatigue and thermomechanical fatigue tests have been carried out on 63Sn/37Pb and 60Sn/40Pb solder joint materials. The rate and temperature dependent test results are consistent, which shows that newly developed test device is reliable. Material parameters for the HISS and DSC models were computed from the test data, which can be used to investigate the failure mechanism of solder joints in electronic packaging to improve the reliability of electronic packaging. Disturbed State Concept (DSC) constitutive model is a powerful tool for the simulation and prediction of material damage, failure and fatigue. Strain localization and material softening cause negative-semi definite finite element stiffness-matrix, which create numerical difficulties for the calculation of DSC. A new DSC finite element scheme was proposed and implemented to overcome the numerical difficulties. The finite element thermoplastic formulation was modified and implemented based on Drucker's postulate. Thermoplastic deformation and viscoplastic deformation usually happen sequentially or combined. An alternative finite element computational method for viscoplastic problem was proposed and the FE program is modified. Computational examples show the new procedures produce accurate and consistent results and the program is robust. Material parameters for the HISS and DSC models were used to back predict the rate and temperature dependent test results using the modified finite element program. These back predictions showed that the HISS and DSC constitutive models and the FE program can be used to accurately simulate solder joint material behavior and predict solder joint damage and failure.
41
Hentschel, William R. (William Ryan). "Design and construction of a propeller open water testing apparatus and testing of a stereolithography 3D printed model propeller". Thesis, Massachusetts Institute of Technology, 2019. https://hdl.handle.net/1721.1/122139.
Pełny tekst źródłaStreszczenie:
Thesis: Nav. E., Massachusetts Institute of Technology, Department of Mechanical Engineering, 2019Thesis: S.M., Massachusetts Institute of Technology, Department of Mechanical Engineering, 2019
Cataloged from PDF version of thesis.
Includes bibliographical references (page 85).
This thesis describes the design and construction of a propeller open water testing apparatus for educational and experimental use at MIT. This test apparatus was built as an inexpensive alternative to conducted in-house model scale marine propeller testing. A complimentary study was conducted to explore the process of manufacturing a model propeller using additive manufacturing. A propeller open water test apparatus, commonly referred to as a test boat, is used to measure the performance of marine propellers in uniform flow. The test boats performance was validated using a Wageningen B-series aluminum propeller as a benchmark. The test boat measured the open water performance of this benchmark within a small percentage of error. The practicality of using additive manufacturing to produce a model propeller was explored by manufacturing and testing a 3D printed replica of the benchmark propeller. The replica propeller was manufactured using a benchtop stereolithography 3D printer. The open water characteristics of the replica were measured and compared to the benchmark propeller. Results of this testing revealed some limitations of 3D printed model propellers, such as size constraints and imprecision of propeller blade geometry. This research has provided MIT students with an inexpensive method to conduct preliminary marine propeller testing and offers in-sight into the use of additively manufactured model propellers.
by William R. Hentschel.
Nav. E.
S.M.
Nav.E. Massachusetts Institute of Technology, Department of Mechanical Engineering
S.M. Massachusetts Institute of Technology, Department of Mechanical Engineering
42
Zheng, Hang. "Tempcore reinforcing steel : microstructure and mechanical properties". Phd thesis, Department of Civil Engineering, 1998. http://hdl.handle.net/2123/8671.
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Murphy, R. Sean. "Thermo-mechanical reliability of the VSPA package solder joints". Thesis, Georgia Institute of Technology, 1997. http://hdl.handle.net/1853/17119.
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Silberstein, Meredith N. "Mechanics of Notched Izod impact testing of polycarbonate". Thesis, Massachusetts Institute of Technology, 2005. http://hdl.handle.net/1721.1/32917.
Pełny tekst źródłaStreszczenie:
Thesis (S.B.)--Massachusetts Institute of Technology, Dept. of Mechanical Engineering, 2005.Includes bibliographical references (leaf 62).
Polycarbonate is widely used as a transparent protective material because of its low density and excellent mechanical properties. However, when defects such as cracks or notches are introduced, it is subject to catastrophic brittle failure at relatively low loads. Notched Izod testing is a common qualitative measure of toughness of a material, measuring energy absorbed prior to failure under high triaxiality and high rate loading conditions. Much research has been done using Izod testing to compare the fracture energies of blends of Polycarbonate and rubbery materials; however the specific yielding and fracture mechanisms associated with each blend are rarely analyzed. This study presents detailed images, fracture energies, and time durations of the deformation and failure processes actively occurring during the Notched Izod testing of 3.23mm and 6.35mm thick Polycarbonate specimens, as well as of a quasi-static version of Notched Izod bending. The thin specimens were found to yield in a ductile manner followed by tearing across most of the ligament width, resulting in a final failure including a small plastically-deformed ligament hinging the two failure surfaces in both the Notched Izod impact and Quasi-Static tests.
(cont). The thick specimens exhibited slight yielding followed by catastrophic failure, where the crack initiated ahead of the notch and then propagating back towards the notch root as well as across the remaining ligament.. In the thick Izod tests local pre-failure yielding was evident at the notch root resulting in extensive blunting of the notch. The fracture energies per unit thickness for the thin specimens were almost a full order of magnitude larger than those for the thick specimens. A finite element simulation for the Notched Izod Impact test was developed using the Arruda and Boyce(1988) constitutive model of polymers as modified by Mulliken and Boyce(2004) for high rate deformation. The 3.23mm Notched Izod impact test was successfully modeled from initial contact of the pendulum through initiation of failure and early tearing. The yielding patterns and failure occurred along the same lines as in the experiment where diagonal shear bands and lobes initiate plastic deformation from the notch tip and tearing progresses in a horizontal manner across the specimen width. An extensive shear yielded region is observed ahead of the propagating tear. The 6.35mm thick model shows the beginning of the formation pressure concentration which causes brittle fracture, but further refinement of the mesh needs to be performed for more accurate modeling.
by Meredith N. Silberstein.
S.B.
45
Jenks, Kevin P. (Kevin Patrick). "Designing, constructing, and testing an X-ray polarimeter". Thesis, Massachusetts Institute of Technology, 2011. http://hdl.handle.net/1721.1/68903.
Pełny tekst źródłaStreszczenie:
Thesis (S.B.)--Massachusetts Institute of Technology, Dept. of Mechanical Engineering, 2011.Cataloged from PDF version of thesis.
Includes bibliographical references (p. 24).
X-ray astronomy has been an important field since its birth 50 years ago. However, Xray polarization measurements have been almost non-existent, especially when compared to the amount of polarimetry being performed in the other bands of the spectrum. One method of filtering a specific energy of polarized X-rays involves reflecting these X-rays off of a correctly tuned multilayer mirror at a specific grazing angle. A design for a small spacecraft incorporating this type of instrument has been proposed, but the effectiveness of using multilayer mirrors as polarization filters has never been tested in a laboratory setting. A design for using an existing X-ray beamline as a means of testing this method was developed. The necessary modifications to both the source and detector end were made, but due to an inability to completely eliminate small misalignments in the system, the full tests of the multilayer mirrors could not be performed. Further research could be performed to identify and correct the cause of the misalignments and continue the evaluation of the multilayer mirrors as a polarimeter.
by Kevin P. Jenks.
S.B.
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Lee, Dai Gil. "Manufacturing and testing of composite machine tool structures". Thesis, Massachusetts Institute of Technology, 1985. http://hdl.handle.net/1721.1/15265.
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Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Mechanical Engineering, 1985.MICROFICHE COPY AVAILABLE IN ARCHIVES AND ENGINEERING.
Vita.
Includes bibliographical references.
by Dai Gil Lee.
Ph.D.
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Jackson, Justin Reed. "Mechanical Testing and Evaluation of Epoxy Resins at Cryogenic Temperatures". MSSTATE, 2005. http://sun.library.msstate.edu/ETD-db/theses/available/etd-11112005-091310/.
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The objective of this research is to develop a test methodology to be used in determining which material properties affect the ultimate performance of a composite overwrapped pressure vessel (COPV) at liquid nitrogen (LN2) temperatures. The test methodology being evaluated is based on that used for ambient performance of COPVs and includes: resin properties, resin/fiber interface and COPV burst data. The suitability of these tests at LN2 temperatures will be evaluated. The resin properties are investigated by use of tensile tests to determine: strain to failure (%å), failure stress (óys), and elastic modulus (E). TThe objective of this research is to develop a test methodology to be used in determining which material properties affect the ultimate performance of a composite overwrapped pressure vessel (COPV) at liquid nitrogen (LN2) temperatures. The test methodology being evaluated is based on that used for ambient performance of COPVs and includes: resin properties, resin/fiber interface and COPV burst data. The suitability of these tests at LN2 temperatures will be evaluated. The resin properties are investigated by use of tensile tests to determine: strain to failure (%å), failure stress (óys), and elastic modulus (E). The resin/fiber interface is evaluated using short beam shear tests to determine the interlaminar shear strength (ILSS). These properties are compared with actual COPV burst pressures performed at ambient and LN2 temperatures. If a correlation can be found, this research lays the foundation for a method to quickly and efficiently screen candidate material systems for composite overwrapped pressure vessel (COPV) fabrication.he resin/fiber interface is evaluated using short beam shear tests to determine the interlaminar shear strength (ILSS). These properties are compared with actual COPV burst pressures performed at ambient and LN2 temperatures. If a correlation can be found, this research lays the foundation for a method to quickly and efficiently screen candidate material systems for composite overwrapped pressure vessel (COPV) fabrication.
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Vonderheide, Christopher M. "Laser velocimetric flow mapping and characterization of oil mist nozzles used for blade excitation in high cycle fatigue testing". Thesis, Monterey, Calif. : Springfield, Va. : Naval Postgraduate School ; Available from National Technical Information Service, 2005. http://library.nps.navy.mil/uhtbin/hyperion/05Sep%5FVonderheide.pdf.
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Thesis (M.S. in Mechanical Engineering)--Naval Postgraduate School, September 2005.Thesis Advisor(s): Dr. Raymond Shreeve, Dr. Garth Hobson. Includes bibliographical references (p. 61). Also available online.
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Robertson, Galen Charles. "Quantification of Skeletal Phenotype Using Micro-CT and Mechanical Testing". Thesis, Georgia Institute of Technology, 2004. http://hdl.handle.net/1853/4874.
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With the vast array of genetically altered (knockout) mice becoming available there is a need for quantitative, repeatable, and efficient methodologies to characterize the phenotypic consequences of knocking out specific genes. Since knockout animals often have the ability to compensate for a single missing gene, it is important to examine the structural, material and morphological properties to obtain a thorough understanding of the changes occurring. For this project, femurs of knockout mice were first scanned using microcomputed tomography (micro-CT) to obtain high-resolution images of the trabecular bone in the distal femur, as well as cortical bone in the mid-diaphysis. After scanning, the femurs were tested to destruction in four-point bending at the mid-diaphysis about the medial lateral axis of the femur. These methodologies allowed quantification of (1) morphologic properties such as bone volume fraction, trabecular properties and 2nd moment of the area (2) structural properties such as stiffness, maximum load at failure, and post yield deformation and (3) material properties such as bone mineral density, elastic modulus and yield strength.
As part of two independent studies, two different knockout mice, cyclooxygenase-2 (COX-2 -/-) and Apolipoprotein E (APOE -/-), were examined for structure-function relationships using these methodologies. COX-2 knockout mice were found to have decreased mineral content in their femurs, and increased post yield deformation. APOE knockout mice at 10 weeks of age had decreased bone mass and structural properties. However, by 40 weeks of age APOE deficient mice caught up to and exceeded the structural properties and bone mass of their wild type counterparts.
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Chow, Yiu Wa. "Investigation into the bio-mechanical features of neonatal hip testing". Thesis, Queen's University Belfast, 1994. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.241385.
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