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The residual strength determination due to fatigue loading by fracture mechanics in notched composite materialsJen, Ming-Hwa Robert January 1985 (has links)
The objective of this investigation is to predict the residual strength of notched composite Iaminates with various layups, subjected to low frequency fatigue loading with constant amplitude at room temperature, by using a material modeling approach, fracture and fatigue mechanics and the finite element method (FEM).
For simplicity, after thousands of cycles, the geometry of a circular hole of the deformed laminate was categorized as (1) uniformly expanded hole into elliptic shape, (2) crack propagation around the hole transversely. Both types were studied for 12 cases of layups with various proportions of 0, 45, -45 and 90 degree plies. The effect of geometry change during fatigue on residual strength was attributed to the elliptical hole, longitudinal splitting, matrix cracking (reduction moduli of plies), crack propagation and local delamination. Due to the thin through-the-thickness notched laminate, two-dimensional FEM was used and interlaminar stresses were not considered.
Reduction of stress concentration is a reason for the increase of the residual strength of the notched laminate. The stress concentration factor decreases while the elliptic hole becomes more slender; that was examined by the FEM. The residual strength and stiffness were determined by the material modeling with moduli reduction and damaged zone, and the numerical result was obtained by FEM. Laminate theory, point stress criterion, polynomial failure criterion, ply discount method, and fatigue and fracture mechanics (Paris' Power Law) were also included in this research.
Geometry change and moduli reduction are two major effects that are considered to predict the notched strength. The WN point stress fracture model is adopted for simplicity, instead of the average stress criterion. K<sub>tg</sub> that corresponds to the unnotched strength in the normalized stress base curve is used to obtain the characteristic length (d<sub>o</sub>). We find that K<sub>tg</sub> decreases when the elliptic hole becomes more slender and more moduli are reduced (more plies crack). At the time d<sub>o</sub> that is determined from K<sub>tg</sub> in the base curve is not necessarily a fixed material constant.
The correlation between the fatigue life and the residual strength as predicted by the model and those determined numerically is found within acceptable errors in comparison with the experimental data. / Ph. D.
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Surface run-off behaviour of bitumen emulsions used for the construction of sealsKashaya, Asiimwe Annie 03 1900 (has links)
Thesis (MScEng)--Stellenbosch University, 2013. / ENGLISH ABSTRACT: Factors influencing surface run-off of bitumen emulsions were studied in order to understand
binders for use in the construction of surfacing seals.
Run-off of the binder from the road surface causes an inconsistent film thickness leading to
ravelling (Johannes, Hanz & Bahia n.d.) and bleeding at the upstream and downstream
regions, respectively.
There is currently no accepted specification for surface run-off viscosity. Practice mainly
relies on empirical tests and experience. As the establishment of such a specification
encompasses performance of the binder in various environments or field conditions, this
study was undertaken to determine performance of the selected binder. Viscosity was kept
constant by spraying the emulsion at a constant temperature and also holding the pavement
temperature constant.
In order to study the run-off behaviour of the binder, run-off tests were conducted at various
gradients, texture depths and spray rates. Surfacing seals of various texture depths were
constructed in the laboratory. Using a spray bar, the emulsion was sprayed at various spray
rates. The sample surfaces were tilted to various gradients.
Results portrayed the effects of the three factors (spray rate, gradient and texture depth) on
the amount of runoff. An increase in the magnitude of the factors resulted in a variation in the
runoff (increase or decrease). One notable finding was that the runoff from the 9.5 mm seal
was less than that from the 13.2 mm seal. The other significant finding was that spray rate
had the largest effect on runoff, followed by texture depth, and gradient. / AFRIKAANSE OPSOMMING: Sekere eienskappe wat oppervlakdreinering van bitumen emulsies op paaie beinvloed, is
bestudeer om sodoende binders wat gebruik word in die konstruksie van die seëls beter te
verstaan.
Afloop van die binder vanaf die padoppervlak kan lei tot die vorming van ‘n laag met
ongelyke dikte wat moontlike rafeling (Johannes, Hanz & Bahia nd) en bloeing vanuit die
onderkant van die pad tot gevolg kan hê.
Daar is tans geen aanvaarde spesifikasies wat hierdie verskynsels inperk nie. Konstruksie
praktyk berus hoofsaaklik op empiriese toetse en ondervinding. Hierdie studie is dus
onderneem om prestasie van die geselekteerde binder vas te stel. Viskositeit was konstant
gehou deur die aangewende emulsie en padtemperatuur konstant te hou.
Ten einde die afloopgedrag van die binder te bestudeer, is toetse uitgevoer op verskeie
hellings, tekstuurdieptes en aanwendingskoerse. Seëls van die verskillende tekstuurdieptes
is gebou in die laboratorium, en emulsies op hierdie oppervlaktes aangewend. Die
toetsoppervlakte is gekantel om die vereiste helling te kry.
Resultate vir die drie faktore wys die invloed op afloop. ‘n Toename in die grootte van die
faktore het gelei tot 'n variasie in die afloop (toename of afname). Een noemenswaardige
bevinding was dat die afloop van die seël van 9,5 mm minder was as dié van die seël van
13,2 mm. Belangrike bevindinge sluit ook in dat die spuitkoers die grootste invloed het op
afloop, gevolg deur die tekstuur diepte en die gradiënt.
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Novel assessment test for granular road foundation materialsLambert, John Peter January 2007 (has links)
Drivers for sustainability have made it necessary for the construction industry to adapt its traditional processes to become both more efficient and produce less waste. Performance based design and specification in the UK for motorways and trunk roads permits a very flexible approach to pavement design, material selection and performance related testing aimed at utilising materials to their maximum potential. However, it is clear that within the emerging philosophy of using materials that are 'fit for purpose' there are many technical challenges for design and specification. There is a need to develop suitable methods of evaluating materials prior to their being used on site. This project was born out of this requirement, with a particular emphasis on coarse granular materials due to their common role in capping construction and also their unique difficulty for measurement under laboratory conditions due to their large range of particle size. A novel assessment test for coarse capping materials for roads that can be used to indicate their likely short-term in situ performance, under controlled laboratory conditions before construction on site, has been developed during this research programme. Key findings relating to the behaviour of coarse capping materials, the use of stiffness measuring devices and variables that influence the measurement of composite stiffness are discussed in detail. The research highlights the necessity for adequate drainage and protection of foundation materials against increase in water content. When adopting a performance specification the timing of the pavement assessment is critical, both on site and in the laboratory. The performance measured on site should perhaps only be considered as a 'snapshot' relating to the stress state in the material at the time of testing.
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Variable frequency microwave curing of polymer dielectrics on metallized organic substratesSung, Taehyun 01 December 2003 (has links)
No description available.
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Experimental verification of the finite element analysis of a dynamically loaded semi-trailerDebesay, Teclemicael Tewelde 04 1900 (has links)
Thesis (MScEng)--University of Stellenbosch, 2004. / ENGLISH ABSTRACT: The aim of the thesis is to compare results obtained from a finite element analysis method (FEM) to
experimental results of a 12.2m long semi-trailer driven off-road. Semi-trailers are of great
importance in the transport industry. Furthermore, the need to obtain optimum and reliable semitrailers
in this crucial stream of industry is indispensable. The work focuses on comparing the two
results so that the finite element method may be used as design analysis and redesigning tool as a
substitute to testing.
The semi-trailer was driven on a relatively rough off-road at different speeds, at 70kmlh, 50kmlh
and 40kmlh loaded with about 12 tonnes of brick pallets. The forces at the suspension of the semitrailer
and strains at different parts were measured with the help of strain gauges and other data
acquisition equipment.
A finite element model of the semi-trailer was modelled in Nastran for Windows. The trailer
parameters in the finite element were tuned to curve fit the test results. A comparison of the two
/'
results was made based on the average of absolute values and standard deviation, to verify the
validity of the finite element model. / AFRIKAANSE OPSOMMING: Die doel van die tesis is om die resultate wat verkry is deur eindige element metodes (EEM) met
eksperimentele resultate van 'n 12.2 m lang leunwa wat bestuur is op 'n grondpad te vergelyk.
Leunwaens is baie belangrik vir die vervoer industrie. Verder is die behoefte om optimum en
betroubare leunwaens in die industrie te vervaardig baie nodig. Die werk fokus daarop om die 2
resultate te vergelyk sodat die EEM gebruik kan word as ontwerp analiese en herontwerp
gereedskapstuk en as 'n vervanging vir toetsing.
Die leunwa was op 'n redelike rowwe pad teen verskillende snelhede nl. 70km/h, 50km/h en
40km/h met 'n 12 ton baksteen vrag gery. Die kragte by die suspensie van die leunwa en die
vervorming by verskillende onderdele is gemeet met behulp van rekstrokies en ander data
versamelings toerusting
'n Eindige element model van die leunwa is gemodelleer in "Nastran for Windows". Die sleepwa
parameters in die eindige element model is verstel d.m.v krommepassing van die toets resultate. 'n
Vergelyking van die 2 resultate is gebasseer op die gemiddelde van die absolute waardes en
standaard afwykings, om die geldigheid van die eindige element model te kontroleer.
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Development of a simple trixial test for characterising bitumen stabilised materialsMulusa, William Kapya 03 1900 (has links)
Thesis (MScEng (Civil Engineering))--University of Stellenbosch, 2009. / The need for a more reliable testing procedure for the characterisation and Quality Assurance/
Control of Bitumen Stabilised Materials (BSMs), besides UCS and ITS testing, has long been
recognised by the roads industry. In fact, at CAPSA 2004 and CAPSA 2007, discussions of improved
test methods for granular materials, i.e. possible replacement tests for CBR procedures, were
conducted in workshops. Triaxial testing for the evaluation of shear parameters is widely recognised
as a reliable method of measuring these critical performance properties of granular and Bitumen
Stabilised Materials (BSMs). However, the triaxial test in its current state as a research test has little
chance of extensive use by practitioners and commercial laboratories, because of complexity, cost
and time issues. Major adaptations to the research triaxial test are necessary, before this useful test
can have a chance of being accepted by road practitioners.
The main aim of this study is to investigate possibilities of developing a simple, affordable, reliable
and robust test for characterizing granular and bitumen stabilized materials thus linking test outcome
with in-situ performance. This is achieved through the innovative design and manufacture of a
prototype triaxial cell capable of accommodating 150 mm diameter by 300 mm deep specimens. The
cell is simpler than the research (geotechnical) triaxial cell and the operational protocols have been
streamlined, thereby reducing the time and steps required in assembling specimens and testing them.
In order to ensure the development of an appropriate triaxial cell for industry, a survey was
conducted aimed at investigating currently available facilities, testing capacity and resources within
civil engineering laboratories in South Africa. Findings of the survey (Appendix 4) have provided
guidance with regard to the nature and sophistication of any new tests to be developed. The survey
highlighted some of the limitations and lack of sophistication of the current loading frames used for
CBR and UCS testing such as lack of electronic LVDTs, limited overhead space, limited loading
capacity and others. Most laboratories would need to invest in new loading facilities to carry out
triaxial tests.
A review of the test procedure for monotonic triaxial test showed that two main factors contribute to
the complexity of the research (geotechnical) triaxial cell namely, time taken to assemble the
specimen accurately in the cell and secondly the inherent design of the cell which makes it water
and/or air tight at relatively high pressures.
The design of the Simple Triaxial Test, therefore, was aimed at overcoming the drawbacks of
research triaxial test e.g. fitting a membrane to each specimen to be tested, through considerable
simplification by means of a new structure design and procedure of assembly of specimen into the
cell. The advantage of addressing these issues would be reduction in the number of steps required in the test procedure and therefore reduction in testing time. The design of the cell particularly was
preceded by a conceptualization process that involved investigation of numerous options. Concepts
such as the bottle, encapsulated-tube, bottle and sandwich concepts were considered and given
reality checks. In addition, available triaxial procedures of a similar nature e.g. Texas Triaxial, were
evaluated and analyzed.
Ultimately, with some trials and innovation, a design was developed for a simple triaxial cell
comprising a steel casing with a latex tube which is then introduced around the specimen sitting on a
base plate. It is based on the ‘tube concept’ in which the specimen acts like a ‘rim’ and the cell acts
like a ‘tyre’ providing confinement to the triaxial specimens for testing, within the tube. This approach
eliminates the use of O-rings and membranes for the specimen and tie-rods for the triaxial cell, thus
reducing testing time considerably. The overall dimensions of the cell are 244 mm diameter by 372
mm height (Appendix 5).
The cell was manufactured at Stellenbosch University Civil Engineering workshop and preliminary
tests were conducted under this study. Parallel tests were also conducted with the Research Triaxial
Test setup at Stellenbosch University in order to determine if preliminary results obtained with the
Simple Triaxial Test setup were comparable therefore providing a means of validating the data.
Results of analysis of variance (ANOVA) show that variability between Simple Triaxial Test (STT) and
Research Triaxial Test (RTT) results is less significant whilst that within samples of STT and RTT
results is quite significant. Comparisons also show that good correlation were obtained from
Reclaimed Asphalt Pavement (RAP) Hornfels + 3.3 % Emulsion + 0 % Cement mix and mixes with
the G2 base course aggregate whilst completely different correlation was obtained from RAP + 3.3 %
Emulsion + 1% Cement. It is evident however that the differences observed stem from material
variability i.e. random variability to one degree or the other and not to the STT apparatus. It is
recommended for future research that more STT versus RTT testing be done especially on a mix with
known mechanical properties when compacted to a specified dry density, e.g. graded crushed stone
(G1) compacted to 100% mod. AASHTO.
In summary, a locally made, low cost, relatively durable triaxial cell with relatively easy and quick
specimen assembly procedures has been developed. It is now possible to perform triaxial tests on
150 mm diameter by 300 mm high specimen relatively easily and quickly. However, the challenge of
validating results obtained, as well as improving the manufacture process of its main component, the
tube, still remains.
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Rheology of polymer modified binders : a comparative study of three binders and three binder/filler systemsBurger, A. F. January 2001 (has links)
Thesis (MEng)--University of Stellenbosch, 2001. / ENGLISH ABSTRACT: The use of polymer modified binders have increased drastically over the past twenty
years. It is generally accepted that current empirical specification tests do not adequately
characterise the improvement in binder properties when bitumen is modified with
polymers.
At the University of Stellenbosch, a programme was initiated to relate binder properties
to asphalt mix performance. This study forms part of that programme.
This study focuses on three binders and is an attempt to characterise binder properties
fundamentally. The binders that were tested are:
• 60/70 penetration grade bitumen
• SBS modified 60/70 bitumen
• Bitumen-Rubber
Two rheometers were used to characterise the binder properties:
• Sliding Plate Rheometer (SPR)
• Dynamic Shear Rheometer (DSR)
The Sliding Plate Rheometer was modified to allow testing at elevated temperatures. The
modification is described in this thesis.
Three types of testing were used to test the binders:
• Creep tests (SPR and DSR)
• Dynamic tests (Strain and Frequency Sweeps - DSR)
• Flow tests (high temperature viscosity tests - DSR) The results of the tests were used to characterise differences between the binders. Shear
susceptibility lines were plotted and viscosities calculated from the creep test results;
Master Curves and Black Diagrams were plotted from frequency sweep results; flow test
results were used to characterise high temperature behaviour.
A further development in the asphalt industry is the move towards the development of
performance based specifications. A programme has been initiated in this regard and this
study forms part of the programme.
As a step towards the development of performance based specifications filler was
included in this study. BinderlFiller systems were subjected to the same test programme
the binders were, to characterise the influence on binder properties of filler addition.
Some of the conclusions that were drawn at the end of the study are:
• Polymer modification improves binder properties related to rutting.
• Filler addition does not affect binder properties negatively.
• Shear rate is very important during production of asphalt mixes and construction
of asphalt layers containing polymer modified binders. / AFRIKAANSE OPSOMMING: Die gebruik van polimeer gemodifiseerde bitumen het drasties toegeneem oor die
afgelope twintig jaar. Dit word algemeen aanvaar dat die huidige empiriese spesifikasie
toetse nie die verbetering in bindmiddeleienskappe van polimeer modifisering
aanvaarbaar karakteriseer nie.
'n Program is geïnisieer by die Universiteit van Stellenbosch om 'n verband te vind
tussen bindmiddeleienskappe en asfaltmengseleienskappe. Hierdie studie vorm deel van
die program.
Hierdie werk fokus op drie bindmiddels en is 'n poging om die bindmiddeleienskappe
fundamenteel te karakteriseer. Die bindmiddels wat gebruik is in hierdie werk, is:
• 60/70 penetrasiegraad bitumen
• SBS gemodifiseerde 60/70 bittimen
• Bitumen-Rubber
Twee reometers is gebruik om bindmiddeleienskappe te karakteriseer:
• Glyplaat Reometer (SPR)
• Dinamiese SkuifReometer (DSR)
Die glyplaat reometer is aangepas om toetse by hoër temperature te doen en die
aanpassing wat gemaak is word in die tesis beskryf.
Drie tipes toetse is uitgevoer om die bindmiddels mee te toets:
• Kruiptoetse (SPR en DSR)
• Dinamiese toetse (DSR)
• Vloei toetse (DSR) Die resultate van die toetse is gebruik om die verksille tussen die bindmiddels te
kwalifiseer. Verskillende grafieke en figure is getrek van die resultate om die onderskeie
bindmiddels te karakteriseer.
Die beweging weg van empmese spesifikasies na werkverrigting gebaseerde
spesifikasies in die asfalt industrie is 'n verder nuwe ontwikkeling. 'n Program is
geïnisïeer ten opsigte hiervan en hierdie werk vorm deel van die program.
As 'n stap in die ontwikkeling van die werkverrigting gebaseerde spesifikasies is 'n
vuIler ingesluit in die toetsprogram. Bindmiddel/vuIler stelsels is onderwerp aan dieselfde
toetse waaraan die bindmiddels onderwerp is om die invloed van die vuIler op die
bindmiddels te karakteriseer.
Sommige van die gevolgtrekkings waartoe gekom is aan die einde van die tesis, is:
• Polimeer modifisering verbeter bindmiddeleienskappe met betrekking tot
wielsporing.
• Die toevoeging van vuIler affekteer nie die bindmiddeleienskappe negatiefnie.
• Die vervormingstempo is van groot belang wanneer asfaltmengsels gemeng en lae
gebou word van mengsels wat polimeer gemodifiseerde bitumen bevat.
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Development of a plane strain compression test to simulate the hot rolling of carbon manganese plate steelsBanks, Kevin Mark 10 June 2016 (has links)
A dissertation submitted to the Faculty of Engineering, University of the
Witwatersrand, Johannesburg, in fulfilment of the requirements for the degree
of Master of Science in Engineering.
,Department of Metallurgy and Materials Engineering
University of the Witwatersrand
Johannesburg, 1990. / An instrumented hot deformation simulator was desLgned, cons'.:ructedand
commissioned at Iscor's Pilot Plant. A modified servohydraulic machine,
using plane strain compression, simulated industrial plate rolling
schedules. The simulation test included induction heating, multiple pass
plane strain compression and either air cooling or quenching. The
movement of the specimen between the different test stages was computer
controlled. Accurate control of specimen temperature, strain atrain rate
and interpass hold times was achieved by means of sophisticated data
acquds i+Lon equipment. A comput er programme was written to simulate the
hot. rolling of plate in t erms of roll sepa ratIng f.orces, ffiE.\tallurgical
changes during deformation as well as the final microstructure and
mechanical properties of SGa carbon manganese steel. Multiple linear
regression was pe.rformed on the results obtained from mUlti-pass plane
strain compression tests. It was found that themical composition, finish
temperature and finish strain were the most important process parameters
affecting yield strength and impact energy of air cooled place. A
computer model was developed to simulate the temperature distribution in
the deformation zone of a plane strain compressLon specimen at any point
during or after a mUlti-pass test.
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Avaliação histomorfométrica da biocompatibilidade do enxerto bovino misto (OrthoGen®) em tecido subcutâneo e o potencial osteogênico em defeito ósseo craniano / Histomorphometric evaluation of biocompatibility of integral bovine graft (Orthogen®) implanted in subcutaneous tissue and osteogenic potential in cranial bone defectOliveira, Tamiris Vallim Zambaldi de 20 March 2014 (has links)
O desenvolvimento atual de materiais ósseo-substitutos com potencialidade de promover o fechamento completo de um defeito ósseo crítico tem levantado questões quanto à sua atuação biológica. Uma opção de material ósseo utilizado são os enxertos ósseos de origem animal, pois possuem propriedades físicoquímicas similares ao osso humano. O osso bovino misto que preserva a estrutura colagênica e o mineral ósseo tem sido proposto e utilizado como material ósseosubstituto. O objetivo desse estudo foi avaliar a biocompatibilidade e o potencial osteogênico de um enxerto bovino ósseo subistituto, OrthoGen® (Baumer S.A.), na forma de partículas (OGp) e blocos (OGb). Para a avaliação da biocompatibilidade, 100 mg de OrthoGen® nas formas de partícula e bloco, foram implantados no subcutâneo de ratos (n=25) e o tecido reacional foi avaliado aos 7, 14, 21, 30 e 60 dias (n=5 animais/período) após a implantação. Para a análise do potencial osteogênico foram implantados 100 mg de Orthogen® nas formas de partícula e bloco em defeito critico na calvária de ratos (n=30), e a formação óssea foi mensurada aos 1, 3 e 6 meses (n=10/período) após a implantação. A análise radiográfica e histomorfométrica revelaram que no tecido subcutâneo o OGb foi melhor aceito pelo organismo quando comparado ao OGp com uma frequência menor de células gigante multinucleadas entre os períodos avaliados (OGb 0,23% vs OGp 2,19%) e consequentemente uma média de reabsorção também menor (OGb 13% vs OGp 38%). Em ambos os implantes não foi encontrado focos de infiltrado inflamatório composto por leucócitos polimorfonucleares, linfócitos e plasmócitos. Na calvária o OGb mostrou níveis de reabsorção inferiores e uma maior taxa de formação óssea quando comparado ao OGp após 6 meses (OGb 70 mm³ vs OGp 17 mm³). Baseado no modelo experimental utilizado neste estudo, concluímos que ambas as formas do Orthogen® são biocompatíveis em tecido subcutâneo, no entanto, sua forma em bloco promove uma maior formação óssea, possuindo uma capacidade osteogênica superior à forma em partícula, no modelo experimental avaliado. / The current development of bone graft materials with the potential to promote the complete closure of a critical size bone defect has raised questions as to its biological activity. An option of bone material used, are animal bone grafts since the human bone have similar physicochemical properties. Among the materials is the integral bone substitute of bovine origin, which preserves the organic and inorganic compound of the bone tissue, has been proposed and used as bone graft. The aim of this study was to evaluate the biocompatibility and osteogenic potential of a new integral bone substitute OrthogenTM (Baumer S.A.) in the form of particles (OGp) and block (OGb). For biocompatibility evaluation, 100mg OrthogenTM was implanted into dorsal subcutaneous pocket of rat (n= 25) and the reactional tissue was analyzed at 7, 14, 21, 30 and 60 days (n=5animals/period) after implantation. For osteogenic potential evaluation, 100mg OrthogenTM was implanted into critical-size defect in parietal bones of rat (n=30) and the bone formation, biomaterial reabsorption, connective tissue formation and osteoclast activity was evaluated at 1, 3 and 6 months (n=10/period) after implantation. Radiographic and histomorphometrical analysis showed that, in the subcutaneous tissue the OGb was more accepted by the host compared to OGp, with lower density of the multinucleated giant cells (OGb 0.23% vs. OGp 2.19%) and consequently a lower rate of matrix resorption (OGb 13%, vs. OGp 38%). In both implants was not found focus of inflammatory infiltrated composed by polymorphonuclear leucocytes, lymphocytes and plasmocytes. In rat calvaria the OGb showed lower rate of reabsorption and more volume of bone formation compared to OGp after 6 months (OGb 70 mm3 vs OGp 17 mm3). Based on experimental models used in this study we concluded that both forms of the OrthogenTM was biocompatible in subcutaneous tissue, however, its form of porous block promoted greater bone formation and has a higher osteogenic capacity than the particle shape, in the evaluated experimental model.
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Avaliação da influência da técnica de aplicação e manipulação na força de retenção de cimentos resinosos autoadesivos empregados na cimentação intrarradicular de pinos de fibra / Evaluation of the influence of application and handling technique in the retention strength of self-adhesive resin cements used in intra-radicular fiberglass postsShiratori, Fábio Kenji 09 April 2010 (has links)
Atualmente, existem cimentos resinosos que dispensam o uso prévio de sistemas adesivos (autoadesivos) e aliam as vantagens dos cimentos resinosos às dos cimentos não resinosos, sendo recomendados para todas as restaurações indiretas, inclusive a cimentação de pinos intrarradiculares. Devido à falta de conhecimento do comportamento desses cimentos perante as diferentes técnicas de manipulação e aplicação, o objetivo deste trabalho foi avaliar a força de retenção de 3 cimentos autoadesivos, quando empregados na cimentação de pinos intrarradiculares de fibra de vidro. Para isso, foram selecionados 45 caninos humanos, divididos aleatoriamente em três grupos (N=15) diferenciados pelos cimentos: Grupo I - BisCem (Bisco), Grupo II - Breeze (Pentron Clinical Technologies, LLC) e Grupo III Maxcem (Kerr). Esses grupos foram divididos em três subgrupos, variando a técnica de aplicação e de manipulação: Subgrupo A - Ponta automisturadora/Ponta aplicadora, Subgrupo B - Espatulação/Lentulo, Subgrupo C - Espatulação/Centrix. O teste de push-out foi realizado com uma velocidade de 1 mm/min, e a força de retenção foi expressa em Mega Pascal (MPa). O cimento Breeze apresentou os maiores resultados médios para os subgrupos A, B e C (12,27 ± 3,19 Mpa; 13,65 ± 2,51 MPa; 13,64 ± 3,65 MPa), quando comparados aos cimentos Biscem (7,25 ± 2,37 MPa; 13,37 ± 1,80 MPa; 9,48 ± 2,38 MPa), e Maxcem Elite (7,87 ± 1,12 MPa; 7,21 ± 1,43 MPa; 9,89 ± 1,43 MPa. Somente para o cimento Biscem houve diferença estatística significante entre seus subgrupos. Assim, pôde-se concluir que, de acordo com os resultados deste estudo, a técnica de aplicação e manipulação pode influenciar na resistência retentiva, dependendo do cimento autoadesivo utilizado. / Currently, there are resin cements that do not require prior use of adhesive systems (self-adhesive), and combine the advantages of resin cements with that of non-resin cements, and are recommended for all indirect restorations, including intraradicular cementation. Due to the lack of understanding about the behavior of these cements in the presence of the different handling and application techniques, the objective was to evaluate the retention strength of 3 self-adhesive cements, when used in cementing intra-radicular fiberglass posts. For this, 45 human canines were selected and divided randomly into three groups (N = 15) for different cements: roup I - Bisco (Bisco), Group II - Breeze (Pentron Clinical Technologies, LLC) and Group III - Maxcem (Kerr). These groups were divided into three sub-groups by varying the application and handling technique: Sub-group A - Automix/Point tip applicator, Sub-group B - Handmix/ Lentulo, Sub-group C Handmix/ Centrix. The test of push-out was performed with a speed of 1 mm / min, and the retention strength was expressed in Mega Pascal (MPa). The Breeze cement, showed the highest average for sub-groups A, B and C (12.27 ± 3.19 MPa, 13.65 ± 2.5 MPa, 13.64 ± 3.65 MPa)when compared to the Biscem cement (7.25 ± 2.37 MPa, 13.37 ± 1.80 MPa, 9.48 ± 2.38 MPa), and Maxcem Elite (7.87 ± 1.12 MPa, 7.21 ± 1 , 43 MPa, 9.89 ± 1.43 MPa. Only for the Biscem cement was there statistically significant difference between the sub-groups. Thus, one can conclude that according to the results of this study, the application and handling technique may influence the retentive strength depending on the self-adhesive cement used.
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