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Статті в журналах з теми "Paper Dry strength Testing"
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Kiecana, Monika, Piotr Kanty, and Klaudia Łużyńska. "Optimal control time evaluation for “dry DSM” soil-cement composites." MATEC Web of Conferences 251 (2018): 01023. http://dx.doi.org/10.1051/matecconf/201825101023.
Повний текст джерелаАнотація:
Soil improvements with hydraulic binders are a widespread practice in foundation works. They vary depending on the mixing method (jet grouting hydraulic, deep soil mixing -mechanical), medium type (wet/water, dry/air) and binder type (cement, lime, fly ash or mixtures). The produced component’s strength changes in time thus its control should change in time as well. The paper presents the results of laboratory testing of an organic soil component mixed in dry method. The process of samples preparation and testing methodology of compressive strength and stiffness is described. Volatility of the parameters in time is considered. On the basis of the results, recommendation for optimal quality control time and its methodology for soil-cement components might be proposed.
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Jendrysik, Klaudia, Monika Kiecana, and Hubert Szabowicz. "Preliminary results of dry Deep Soil Mixing soil-cement composite testing." MATEC Web of Conferences 251 (2018): 01025. http://dx.doi.org/10.1051/matecconf/201825101025.
Повний текст джерелаАнотація:
This paper provides results of testing made for soil-cement mixtures in dry mixing technology. This technology is greatly dependent on existing soil condition; hence the results are of highly random nature. Material used in testing was distinguished with high organic content and low humidity. Tests were carried out in laboratory of Wroclaw University of Technology on 145 samples as ordered by Menard Polska Ltd. Company. Samples were prepared and stored under laboratory conditions and then, after various maturation time, were destroyed in a testing machine. The purpose was to determine the stress-strain curves used to find strength properties, strain at failure, modulus of elasticity, secondary modulus of elasticity versus cement content. Test confirmed improvement of soil strength properties after addition of cement binder. The results may be used to determine the most economic binder-to-soil ratio.
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Koukis, G., N. Sabatakakis, and S. Papanakli. "Laboratory testing properties of sandstones." Bulletin of the Geological Society of Greece 40, no. 4 (January 1, 2007): 1695. http://dx.doi.org/10.12681/bgsg.17083.
Повний текст джерелаАнотація:
The aim of this paper is to determine the geotechnical properties of clastic sedimentary rocks and especially sandstones which constitute a great part of the flysch formation. Laboratory tests were conducted in samples collected from different sites in western Greece. Physical and mechanical properties were determined including porosity (n), dry density (pf), sound velocities (Vp, Vs), point loading strength (IS(so)) and uniaxial compressive strength (ac). Additionally, the material constant m„ an input parameter for the Hoek and Brown failure criterion, was estimated by analyzing the results from a series of triaxial compression tests under different confining pressures. Regression analyses were also applied to define the relations among the obtained parameters
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Dobrowolska, Ewa, Mateusz Niedbała, and Daniel Tabaczyński. "Testing of the fatigue strength along wood fibres at different moisture contents." Annals of WULS, Forestry and Wood Technology 115 (September 26, 2021): 45–54. http://dx.doi.org/10.5604/01.3001.0015.5133.
Повний текст джерелаАнотація:
Testing of the fatigue strength along wood fibres at different moisture contents. The paper determines the effect of wood moisture content on the fatigue strength in compression along fibres. The method of determining the maximum stress at the proportional limit was used for the measurements. Fatigue strength was investigated for three wood species: pedunculate oak (Quercus robur L.), bearded birch (Betula pendula Roth.) and Norway spruce (Picea abies L.), with two moisture contents: close to the absolutely dry state and above the fibre saturation point. The ratio of fatigue strength to short term strength depends on moisture content and is similar for birch (70.3% in the dry state and 72.1% in the wet state), for oak (67.4% and 69.5% in both states) and for spruce (66.6% in the dry state and 68.1% in the wet state). The moisture content of the wood clearly influences the fatigue strength of the wood. On average, the fatigue strength of wood with moisture contents above the fibre saturation point constitutes about 0.20 of the fatigue strength of wood with moisture contents close to 0%. This tendency was found regardless of the tested species. The simplified method for testing fatigue strength at the limit of proportionality has shown its limited usefulness, requiring further analysis and comparison with other methods in order to be thoroughly tested and possibly improved.
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Varanasi, Swambabu, Hui Hui Chiam, and Warren Batchelor. "Application and interpretation of zero and short-span testing on nanofibre sheet materials." Nordic Pulp & Paper Research Journal 27, no. 2 (May 1, 2012): 343–51. http://dx.doi.org/10.3183/npprj-2012-27-02-p343-351.
Повний текст джерелаАнотація:
Abstract This paper investigates the use of zerospan testing to measure the tensile strength of cellulose nanofibre sheets. The mechanical strength of cellulose nanofibre paper is a key property but tensile strength measurement requires a substantial amount test material, whereas a zero/short span test needs much less material. Sheets made from cellulose nanofibres, microfibrillated cellulose (MFC) and northern bleached softwood fibres were tested at spans ranging from 0 to 0.6 mm and tensile strength spans of 50 and 100 mm. For the cellulose nanofibres or the MFC sheets, strength was constant with span from 0 to 0.6 mm when tested dry and negligible when tested wet, except at zero span. The sheets made from the softwood fibres showed significant strength when tested wet at all spans from 0 to 0.6 mm. The results showed that for nanofibre materials, the zero or short span strength is measuring sheet tensile strength at a smaller sample length. The strength of the nanofibre sheets at 50 or 100 mm was smaller than at zero/short span due to sample size effects and Poisson contraction. The effects of starch and grammage on strength were also studied.
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Wang, Chenfei, Zixiong Guo, and Ditao Niu. "Influence of the Fiber Volume Content on the Durability-Related Properties of Polypropylene-Fiber-Reinforced Concrete." Sustainability 12, no. 2 (January 11, 2020): 549. http://dx.doi.org/10.3390/su12020549.
Повний текст джерелаАнотація:
Polypropylene-fiber-reinforced concrete impacts the early shrinkage during the plastic stage of concrete, and the fiber volume content influences the durability-related properties of concrete. The purpose of this paper was to investigate the influence of fiber volume content on the mechanical properties, durability, and chloride ion penetration of polypropylene-fiber-reinforced concrete in a chloride environment. Tests were carried out on cubes and cylinders of polypropylene-fiber-reinforced concrete with polypropylene fiber contents ranging from 0% to 0.5%. Extensive data from flexural strength testing, dry–wet testing, deicer frost testing, and chloride penetration testing were recorded and analyzed. The test results show that the addition of the fiber improves the failure form of the concrete specimens, and 0.1% fiber content maximizes the compactness of the concrete. The flexural strength of specimen C2 with 0.1% fiber shows the highest strength obtained herein after freeze–thaw cycling, and the water absorption of specimen C2 is also the lowest after dry–wet cycling. The results also indicate that increasing the fiber volume content improves the freeze–thaw resistance of the concrete in a chloride environment. Chlorine ions migrate with the moisture during dry–wet and freeze–thaw cycling. The chlorine ion diffusion coefficient (Dcl) increases with increasing fiber content, except for that of specimen C2 in a chloride environment. The Dcl during freeze–thaw cycling is much higher than that during dry–wet cycling.
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POTTER, F. S., T. L. WRIGHT, C. HAGIOPOL, and J. W. JOHNSTON. "A new perspective on tissue wet strength decay: the real values." January 2013 12, no. 1 (February 1, 2013): 9–15. http://dx.doi.org/10.32964/tj12.1.9.
Повний текст джерелаАнотація:
The measurement of two key properties of bath tissue (paper wet strength after 5 s and 5 min of soaking in water) were performed on a broad selection of samples from retail shelves. The importance of the experimental errors and their distribution on the interpretation of the physical testing data is evaluated. Examining the data in this manner allows for a new way to look at the relationship between dry strength, initial wet strength, and the decay rate of the paper. The importance of chemistry is revealed and discussed, giving a new perspective with respect to paper properties and the strength relationships in tissue.
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Tamošiūnas, Tadas, and Šarūnas Skuodis. "Non-cohesive Soil Direct Shear Strength Affected with Hydrostatic Pressure." Mokslas - Lietuvos ateitis 9, no. 5 (December 27, 2017): 520–23. http://dx.doi.org/10.3846/mla.2017.1078.
Повний текст джерелаАнотація:
This paper presents first results of noncohesive soil direct shear tests with hydrostatic pressure. To reach this aim, it was chosen the Baltic Sea Klaipėda sand, due to granulometry composition and particles shape. According to this, investigated Baltic Sea sand can be called Lithuanian standard sand for scientific testing. Analysis of results revealed, that when it is increased hydrostatic pressure, the shearing strength is also increasing. Comparing air dry sand results with fully saturated sand and affected with 100 kPa of hydrostatic pressure, the angle of internal friction increased for 21,24%. Meanwhile, the cohesion was not changing so dramatically according to hydrostatic pressure change. Obtained results allows to proceed this research work more detailed with different loading types, testing procedures and hydrostatic pressures.
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Guan, Yongsheng, Zhixiang Zhang, Xiaorui Zhang, Junqing Zhu, Wen Zhou, Qi Huang, and Yuqing Zhang. "Effect of superabsorbent polymer on mechanical properties of cement stabilized base and its mechanism." Transportation Safety and Environment 2, no. 1 (April 2020): 58–68. http://dx.doi.org/10.1093/tse/tdaa001.
Повний текст джерелаАнотація:
Abstract Superabsorbent polymers (SAPs) are cross-linked polymers that can absorb and retain large amounts of water. In recent years, a growing interest was seen in applying SAPs in concrete to improve its performance due to its efficiency in mitigating shrinkage. This paper presents findings in a study on effect of SAPs on performance of cement-treated base (CTB), using the experience of internal curing of concrete. CTB specimens with and without SAPs were prepared and tested in the laboratory. Tests conducted include mechanical property testing, dry shrinkage testing, differential thermal analysis, mercury intrusion porosimetry and scanning electron microscope testing. It was found that 7-day and 28-day unconfined compressive strength of CTB specimens with SAPs was higher than regular CTB specimens. 28d compressive strength of CTB specimens with SAPs made by Static pressure method was 5.87 MPa, which is 27% higher than that of regular CTB specimens. Drying shrinkage of CTB specimens with SAPs was decreased by 52.5% comparing with regular CTB specimens. Through the microstructure analysis it was found that CTB specimens with SAPs could produce more hydration products, which is also the reason for the strength improvement.
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Lachance-Tremblay, Éric, Michel Vaillancourt, Daniel Perraton, and Hervé Di Benedetto. "Comparison of the moisture damage of bituminous binder coupled with glass and limestone substrate using pull-off test." Canadian Journal of Civil Engineering 46, no. 3 (March 2019): 188–94. http://dx.doi.org/10.1139/cjce-2018-0152.
Повний текст джерелаАнотація:
In this paper, the moisture susceptibility of different bituminous binders with two substrates (glass and limestone) was investigated. To that end, the tensile strength of different combinations of bituminous binder–substrate bond was measured using a pull-off test. This test was adapted from the pneumatic adhesion tensile testing instrument (PATTI) test to improve repeatability. Samples were tested in dry condition and after a 7-day conditioning in hot water bath (60 °C). An analysis of variance (ANOVA) was performed on the test results. Overall, the results show that in dry condition, the pull-off strength is a function of the bituminous binder type rather than of the substrate type. After water conditioning, an increase in the pull-off strength was observed for the bituminous binder without polymers and coupled with glass substrate. This was associated with an increase in binder stiffness. For the limestone substrate, the effect of water conditioning was significant only for one type of binder.
Дисертації з теми "Paper Dry strength Testing"
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Sakaemura, Takushi. "Effect of distributions of polyacrylamide-based dry strength resin within paper and a fiber wall on development of strength properties of paper." Kyoto University, 2010. http://hdl.handle.net/2433/120914.
Повний текст джерелаАнотація:
Kyoto University (京都大学)0048
新制・課程博士
博士(農学)
甲第15586号
農博第1836号
新制||農||984(附属図書館)
学位論文||H22||N4459(農学部図書室)
28107
京都大学大学院農学研究科森林科学専攻
(主査)教授 木村 恒久, 准教授 山内 龍男, 教授 髙野 俊幸
学位規則第4条第1項該当
2
Magnusson, Mikael S. "Testing and Evaluation of Interfibre Joint Strength under Mixed-Mode Loading." Licentiate thesis, KTH, Hållfasthetslära (Inst.), 2013. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-116700.
Повний текст джерелаАнотація:
The failure properties of interfibre bonds are the key for the build-up of strength in fibrous materials such as paper and paperboard. In order to tailor the properties of such materials by chemical or mechanical treatments and to learn how such modifications influence the properties at a microscopic level, direct measurement of individual fibre--fibre crosses are typically performed. However, the state of loading in the interfibre joint, in testing of individual fibre--fibre crosses, is in general very complex and a greater understanding for how to evaluate the mechanical properties of interfibre joints is desirable. In Paper A, a method for manufacturing multiple fibre--fibre cross specimens and a procedure for testing interfibre joints at different modes of loading is presented. The method is applied to investigate the strength of fibre-fibre crosses with different geometry and at two principally different modes of loading. Also, an investigation on the influence of drying pressure, the drying method as well as a comparison of pulp fibres from two different degrees of refining is presented. The force at rupture is scaled in terms of different geometric parameters; nominal overlap area, length and width of the joint region. It is shown that neither of the methods of scaling unambiguously reduced the coefficient of variation of the mean strength and that the force at rupture in a peeling type of loading was about 20% of the ones tested in the conventional shearing type of loading. In Paper B, a procedure for evaluating interfibre joint strength measurements in terms of resultant forces and moments at rupture is presented. The method is applied to investigate the state of loading in fibre-fibre crosses tested in two principally different modes of loading. It is shown that for a typical interfibre joint test, the modes of loading other than pure shear, cannot in general be neglected and is strongly dependent on the structural geometry of the fibre-fibre crosses. Also, the stress state in the interface centroid was estimated in order to quantify how the mode of loading influence the amount of normal stresses that develop in relation to the amount of shear stresses in the interfibre joint.De brottmekaniska egenskaperna hos fiberfogar är nyckeln för uppbyggnaden av styrka hos fibrösa material såsom papper och kartong. För att effektivt skräddarsy sådana materials egenskaper genom kemisk eller mekanisk behandling och för att förstå hur sådana modifieringar påverkar egenskaperna på en mikroskopisk nivå är provning av individuella fiber-fiber-kors en allmänt använd metod. Belastningen i en fiberfog vid provning av individuella fiber-fiber kors är dock generellt mycket komplicerad och ytterligare kunskap om hur fiberfogars mekaniska egenskaper skall utvärderas är önskvärd. I Artikel A, presenteras en metod för samtidig tillverkning av flera fiber-fiber kors samt en metod för mekanisk provning av dessa med olika typer av belastning. Metoden tillämpades för att studera styrkan av fiber-fiber-kors med olika geometri och vid två olika lastfall. En undersökning av hur torktrycket, torkmetoden samt graden av malning inverkar på fogstyrkan presenteras. De uppmätta brottlasterna skalades med olika karakteristiska längder för fogen; nominell överlapparea samt fogens längd och bredd. Resultaten visade att ingendera av normaliseringsmetoderna reducerade variationskoefficienten (av medelvärdet av styrkan) samt att brottlasten för en globalt fläkande belastning var omkring 20 % av brottlasten för prov utförda med den konventionella skjuvande belastningen. I Artikel B, presenteras en metod för utvärdering av mätningar av styrkan hos fiberfogar med hänseende på kraft- och moment- resultanterna i gränsytan mellan fibrerna. Metoden används för att studera belastningsmoden hos fiber-fiber--kors provade i två principiellt olika lastfall. Resultaten visar att för ett typiskt fiberfogsprov av isolerade fiber-fiber-kors med långa fria fibersegment, så kan inte belastningsmoderna vid sidan av skjuvning försummas och att de är starkt beroende av fiber-fiber-korsets geometri. För att kunna jämföra fiberfogar av olika storlek och kvantifiera förhållandet mellan normal- och skjuvbelastningen i fogen skalades de resulterande krafterna och momenten med tvärsnittsstorheter baserade på en approximation av fogareans utformning.
QC 20130125
BiMaC Innovation
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Khan, Kashif. "Development and evaluation of a puncture strength test method for sterilization paper." Thesis, Karlstads universitet, Avdelningen för kemiteknik, 2011. http://urn.kb.se/resolve?urn=urn:nbn:se:kau:diva-8585.
Повний текст джерелаАнотація:
The main objective of this research project, carried out at Karlstad University was to investigate which paper property has the best correlation with the package integrity failure (puncture hole). To achieve this goal, a simple equipment was designed at Karlstad University. This research project was divided into two phases, more precisely first a test design with investigation of suitable parameters to carry out the tests with the newly designed equipment and secondly with the help of those parameters the investigation of paper properties which will have direct connection with puncture strength. Results showed that Tensile Energy Absorption (TEA) has the best correlation with puncture strength as compared to other paper properties used in this research project i.e. burst strength, strain at break, tear strength, and tensile strength. In real it seems to be reasonable as tensile energy absorption (TEA) is the amount of energy absorbed during straining until it breaks. Higher the tensile energy absorption, higher will be the resistance against puncture. Furthermore sack paper proved to be the type of paper grade that has the strongest resistance against package integrity failure, as it has the highest tensile energy absorption (TEA) as compared to other paper grades used in this research project. It was also observed that paper in a package should be stretched in order to minimize the risk of puncture hole.
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Murray, Eric B. "Dry Stacked Surface Bonded Masonry - Structural Testing and Evaluation." Diss., CLICK HERE for online access, 2007. http://contentdm.lib.byu.edu/ETD/image/etd2188.pdf.
Повний текст джерела
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Silva, Deusanilde de Jesus. "Química da parte úmida em processo de fabricação de papel - interações em interfaces sólido-líquido." Universidade de São Paulo, 2010. http://www.teses.usp.br/teses/disponiveis/3/3137/tde-13082010-115730/.
Повний текст джерелаАнотація:
Um polieletrólito catiônico (poliamina), com baixo peso molecular e elevada densidade de carga, normalmente aplicado como agente coagulante do lixo aniônico, foi usado para estudos de retenção e drenagem na fabricação de papel. O uso do carboximentil celulose de sódio para simulação do teor de lixo aniônico e seu efeito na retenção de cargas minerais foi uma característica importante para este trabalho. Pode ser observado que o aumento da dosagem do polímero catiônico tanto melhora a retenção de cargas minerais, avaliada pela turbidez do filtrado, quanto melhora a drenagem do sistema, avaliada pela velocidade de escoamento. Entretanto, elevadas dosagens deste polímero comprometeram os resultados destes parâmetros devido à inversão de carga do sistema. Pode também ser confirmado que forças de cisalhamento excessivas prejudicam a retenção de cargas minerais. Ademais, um polianfótero, com peso molecular e densidade de carga elevados, contendo grupos positivo (N-[3-(N,N-dimetilamino)propil]acrilamida), negativo (ácido metileno butanodióico) e nulo (acrilamida) na mesma cadeia, foi testado como agente de resistência a seco do papel. Todos os estudos em nível molecular sobre o comportamento do polianfótero em solução e o seu comportamento de adsorção sobre superfícies modelos carregadas, em diferentes condições de pH e de força iônica, foram importantes para explicar tanto dos fenômenos de adsorção, envolvendo fibras celulósicas e polianfótero, quanto o seu efeito na resistência mecânica do papel. Foi observado que a solubilidade do polímero aumenta à medida que o pH se distancia do seu ponto isoelétrico, pHPIE 7,3, e reduz para valores de pH próximos ao pHPIE. O tamanho das estruturas do polianfótero depende do pH do meio de dispersão. As características de tamanho do polianfótero tanto sob a forma de cadeias individuais ou quanto sob a forma de agregados, foram medidas através da técnica de espalhamento dinâmico de luz. As propriedades viscoelásticas das camadas adsorvidas e a quantidade de polímero adsorvida foram medidas através da técnica da balança microgravimétrica com dissipação de energia. Estas duas determinações, associadas às imagens no microscópio de força atômica, foram importantes para o entendimento dos resultados práticos do uso do polianfótero como agente de resistência a seco do papel. Maiores resultados de resistência do papel, avaliada através da resistência à tração, foram alcançados para valores de pH próximos ao ponto isoelétrico onde foram encontrados o seguinte: (1) maiores tamanhos para as estruturas do polímero em solução, (2) maior quantidade de massa nas camadas adsorvidas e (3) a formação de camadas mais viscoelásticas. O fenômeno de separação de fases, associado à mudança da solubilidade do polímero em solução devido ao balanço dos grupos positivos e negativos ionizados ao longo da faixa de pH estudada, foi considerado o principal aspecto para a variação em tamanho dos agregados. Embora este polímero tenha apresentado comportamento antipolieletrólito devido à expansão da sua cadeia e ao aumento da densidade de carga com o aumento da força iônica, considerando o efeito da força iônica para pH 4,3, o comportamento de adsorção do polianfótero foi avaliado como o comportamento de um polieletrólito monocarregado de alta densidade de carga. Maiores e menores quantidades de massas adsorvidas foram encontradas para valores intermediários e extremos de força iônica, respectivamente. As interações eletrostáticas foram consideradas as principais responsáveis pela adsorção do polímero sobre superfícies carregadas. Entretanto, a blindagem de cargas foi considerada a explicação para os baixos valores de massa adsorvida para valores mais elevados de força iônica.A cationic polyelectrolyte (polyamine), with low molecular weight and high charge density, usually applied as anionic trash coagulant, was used for the retention and drainage studies in the papermaking. The use of sodium carboxymethyl cellulose to simulate the anionic trash content and its effect on the filler retention was an important feature of the work. It could be noted that the increasing of the cationic polymer dosage improves both the filler retention, evaluated by the turbidity of the filtrate, and the system drainage, evaluated by the flow speed. However, high dosages of this polymer compromised the results of these parameters due to the reversal of the system charge. It can also be confirmed that excessive shear forces affect the filler retention. Furthermore, a polyampholyte, with high molecular weight and charge density, containing positive (N-[3-(N,N- dimethylamino)propyl]acrylamide), negative (methylene butanedioic acid), and neutral (acrylamide) groups in the same chain, was tested as a dry strength agent. All of the studies at molecular level concerning to the polyampholyte behavior in the solution and its adsorption behavior on charged model surfaces at different conditions of pH and ionic strength, were important to explain both the adsorption phenomena, involving cellulosic fibers and polyampholyte, and its impact on the paper strength. It was observed that the polymer solubility increases as the pH moves away from its isoelectric point, pHIEP 7.3, and decreases when the pH approaches close to pHIEP. The sizes of the structures of the polyampholytes depend on the pH of the dispersion medium. Also the size characteristics of polyampholyte, both in individual and aggregated forms, were measured by dynamic light scattering technique. The viscoelastic properties of adsorbed layers, as well as the amount of the adsorbed polymer, were measured by quartz crystal microbalance technique with energy dissipation. These two measurements, associated with the atomic force microscopy images, were important to understand the practical results of polyampholyte usage as a dry strength agent. Best results of paper strength, evaluated by paper strength index, were achieved at pH close to the isoelectric point on which one were found the following features: (1) larger sizes of the polymer structures in solution, (2) higher amount of mass in the adsorbed layers, and (3) the formation of more viscoelastic layers. The phase separation phenomenon, associated with the change in the solubility of the polymer due to the balance of the positive and negative groups throughout the studied pH range, was considered the main aspect for the variation in size of the aggregates. Although this polymer shows antipolyelectrolyte behavior due to the expansion of the its chain and the increasing in charge density with the ionic strength, considering the effect of ionic strength at pH 4.3, the adsorption behavior of polyampholyte was evaluated as a monocharged polyelectrolyte behavior with high charge density. Major and minor amounts of adsorbed masses were found for intermediates and extremes values of ionic strength, respectively. The electrostatic interactions were considered the main cause of the adsorption on charged surfaces. However, the electrostatic screening was considered the explanation for the low values of adsorbed mass at higher values of ionic strength.
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JHANG, MENG-CI, and 張孟騏. "An Investigation of Applying Both Dry- and Wet-strength Agents to Papermaking Wet End and the Effects on Paper Bulk and Physical properties." Thesis, 2013. http://ndltd.ncl.edu.tw/handle/04167030194911623840.
Повний текст джерелаАнотація:
碩士大葉大學
環境工程學系碩士班
101
This study investigated different doses and modes of applying dry- and wet-strength chemicals of different charge characteristics; the 3 modes deployed included single chemical addition, sequential chemical addition, and pre-mixed chemical addition. The experimental results indicated that at the phase I single chemical addition, adding wet-strength agent caused ca. 5% variation in paper bulk; tensile index of the paper increased 23%; and tear index increased 37%. When dry-strength agent was added, the paper bulk varied by 2%; tensile index of the paper increased 26%; and tearing index also increased 37%. Results of this phase suggested that adding wet-strength agent had better paper bulk advantage than that of dry-strength agent. In addition, along with increased doses, tensile and tear index of the paper also gradually increased; change in paper bulk, however, tended to level off with the chemical doses. In phase II, the wet-strength agent was reacted with pulp stock first, and then dry-strength agent added subsequently. The paper bulk showed a gain of 6%; paper tensile index increased 30%; and tear index increased 46%. Conversely when dry-strength agent was added first and then add the wet-strength agent, the paper bulked increased 4%; paper tensile index increased 20%; and tear index increased 32%. Thus, the results suggested that adding wet-strength agent first, dry-strength agent second would confer better benefits to paper bulk, tensile index and tear index than did the reverse order of addition. In phase III of the study, the dry- and wet-strength chemicals were premixed and added to pulp. Pouring dry-strength agent to wet-strength agent before mixing with pulp produced 6% bulk gain, 23% tensile index increase, and 37% increase in tear index in the resulting paper. The reverse order of premixing wet-strength agent with the dry-strength one led to paper bulking gain of 5%; tensile index increase of 20%; and tear index increase of 41%. The results suggested that premix the 2 chemicals before addition produced benefits in paper bulk and tensile index than those of single additions. Transmission electron micrographic observations indicated that wet-strength agent was irregularly shaped; while the dry-strength agent was long-chain molecules. Therefore, the bulking effect of dry-strength agent was inferior to that of wet-strength agent. When the 2 chemicals were premixed, however, wet-strength agent would cover the dry-strength agent, which rendered more effective in both bulking and strength improvements than did the single chemicals.
Книги з теми "Paper Dry strength Testing"
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Wet, and Dry Strength Short Course (1988 Chicago Ill ). 1988 Wet and Dry Strength Short Course, Palmer House and Towers, Chicago, IL, April 13-15. Atlanta, GA, USA (P.O. Box 105113, Atlanta 30348): TAPPI Press, 1988.
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Sneider, Cary Ivan. Paper towel-testing: Teacher's guide. Berkeley, Calif: Lawrence Hall of Science, University of California, 1987.
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Sneider, Cary Ivan. Paper towel testing: Teacher's guide. Berkeley, CA: Lawrence Hall of Science, University of California, 1998.
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Sneider, Cary Ivan. Paper towel testing: Teacher's guide. Berkeley, CA: Lawrence Hall of Science, University of California, 1990.
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Pulp and paper chemistry and technology: Paper products physics and technology. Berlin: Walter de Gruyter, 2009.
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Salt, Mehmet Tekin. Effects of fiber length, starch addition, and fiber modification on the development of paper strength during press drying. 1988.
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Rathi, Mahesh Shrikant. Application of polyallylamine as a dry strength agent. 1999.
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Gupta, Bharti. Interaction between cationic starches and papermaking fibers: Effect of starch and pulp characteristics on fiber surface charge behavior. 1994.
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Barber, Jacqueline, and Cary I. Sneider. Paper Towel Testing. Gems, 1990.
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Ranjan, Gyan. Development of models for predicting opacity, Hercules Size Test and tensile strength of paper produced on the Miami University pilot paper machine. 2000.
Знайти повний текст джерелаЧастини книг з теми "Paper Dry strength Testing"
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Marton, J. "Dry-strength additives." In Paper Chemistry, 83–97. Dordrecht: Springer Netherlands, 1996. http://dx.doi.org/10.1007/978-94-011-0605-4_6.
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Marton, J. "Dry-strength additives." In Paper Chemistry, 63–75. Dordrecht: Springer Netherlands, 1991. http://dx.doi.org/10.1007/978-94-011-6474-0_5.
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Jenkins, S. N. "The improvement of dry strength by synthetic polymers." In Applications of Wet-End Paper Chemistry, 91–101. Dordrecht: Springer Netherlands, 1995. http://dx.doi.org/10.1007/978-94-017-0756-5_6.
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Jenkins, Stan. "The Improvement of Dry Strength by Synthetic Polymers." In Applications of Wet-End Paper Chemistry, 137–46. Dordrecht: Springer Netherlands, 2009. http://dx.doi.org/10.1007/978-1-4020-6038-0_7.
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Gratchev, Ivan, Sinnappoo Ravindran, Dong Hyun Kim, Chen Cui, and Qianhao Tang. "Mechanisms of Shallow Rainfall-Induced Landslides from Australia: Insights into Field and Laboratory Investigations." In Progress in Landslide Research and Technology, Volume 1 Issue 1, 2022, 113–22. Cham: Springer International Publishing, 2023. http://dx.doi.org/10.1007/978-3-031-16898-7_7.
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AbstractThis paper presents and discusses the mechanisms of rainfall-induced shallow landslides that commonly occur in South East Queensland (SEQ) and northern New South Wales (NSW), Australia. The major factors causing the formation of landslide mass such as geology, weathering, and rainfall patterns were discussed. Results from field surveys and laboratory testing of rock/soil material from landslide masses were presented, and relationships between the material strength and landslide occurrence were drawn. It was found that most of shallow slides were related to sandstone deposits. Those failures occurred on natural slopes and road cuts with the inclination of the failure plane being in the range of 35–45°. For natural slopes where the landslide mass mostly consisted of coarse-grained soil, the relationship between the soil strength and water content was established. In addition, the relationship between rainfall patterns such as intensity and duration, and the landslide occurrence was presented. Based on the data from field work and laboratory results including a series of flume tests, the mechanism of shallow landslides triggered by rainfall events was identified and discussed.
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Mansoor, Moiz, Muhammad Waqar Khan, Syed Sajjad Hussain Rizvi, Manzoor Ahmed Hashmani, and Muhammad Zubair. "Adaptation of Modern Agile Practices in Global Software Engineering." In Research Anthology on Agile Software, Software Development, and Testing, 280–99. IGI Global, 2022. http://dx.doi.org/10.4018/978-1-6684-3702-5.ch013.
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Software engineering has been an active working area for many decades. It evolved in a bi-folded manner. First research and subsequently development. Since the day of its inception, the massive number of variants and methods of software engineering were proposed. Primarily, these methods are designed to cater the time-varying need of modern approach. In this connection, the Global Software Engineering (GSE) is one of the growing trends in the modern software industry. At the same time, the employment of Agile development methodologies has also gained the significant attention in the literature. This has created a rationale to explore and adopt agile development methodology in GSE. It gained rigorous attention as an alternative to traditional software development methodologies. This paper has presented a comprehensive review on the adaptation of modern agile practices in GSE. In addition, the strength and limitation of each approach have been highlighted. Finally, the open area in the said domain is submitted as one of the deliverables of this work.
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"6. On the Mechanisms behind the Action of Dry Strength and Dry Strength Agents." In Paper Products Physics and Technology, 169–84. De Gruyter, 2009. http://dx.doi.org/10.1515/9783110213461.169.
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"AAC2.2 Determination of compressive strength of AAC from cubes in a dry state." In RILEM Technical Recommendations for the testing and use of construction materials, 312. CRC Press, 1994. http://dx.doi.org/10.1201/9781482271362-70.
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Li, Shuaiheng, Chen Zhu, Zhousheng Huang, and Haiyan Sun. "Experimental Study on Strength and Deformation Characteristics of Cement Soil Under Wet and Dry Cycle." In Advances in Transdisciplinary Engineering. IOS Press, 2022. http://dx.doi.org/10.3233/atde220931.
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Jiangsu province, located in the middle and lower reaches of the Yangtze River, suffers from rainfall and temperature and humidity changes, which has a significant impact on the structure of road base and foundation soil in the cyclic wet and dry cycle process, impacting and endangering the strength and deformation characteristics of soil. This paper studies the road base filling in Shanghai-Shaanxi Expressway for strength characteristics and change rules of cement improved foundation soil under the wet and dry cycle, and discusses the influence of cement admixture, age and number of dry and wet cycles on the strength of cement improved road base soil. The results show that the higher the cement admixture and the longer the curing age, the higher the compressive strength of cured foundation soil; the cured foundation soil tends to slow down gradually in strength growth with the increase of age, and slows down obviously after 28 d; the wet and dry cycle process will have an irreversible impact on the structure of cured foundation soil, slowing down or even reversing the strength growth rate of cured foundation soil, which can be reduced by increasing cement admixture.
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"AAC 2.4 Determination of compressive strength for whole units of AAC in air dry condition." In RILEM Technical Recommendations for the testing and use of construction materials, 324–26. CRC Press, 1994. http://dx.doi.org/10.1201/9781482271362-74.
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Qamhia, Issam, Maximilian Orihuela, Scott Schmidt, Erol Tutumluer, Maziar Moaveni, Colin Basye, and Dingqing Li. "Railway Ballast Strength and Permeability Affecting Track Performance Under Dry and Wet Conditions." In 2018 Joint Rail Conference. American Society of Mechanical Engineers, 2018. http://dx.doi.org/10.1115/jrc2018-6256.
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Railway ballast is a major structural component of railroad track that also facilitates the drainage of water. Particle breakage and abrasion due to dynamic loading and environmental impacts causes ballast to age and degrade. The finer materials generated from ballast degradation can adversely affect the track stability especially under wet conditions. This paper investigates through laboratory testing the effect of moisture on the behavior and performance of in-service ballast. The tested ballast samples were initially subjected to an artificial rain system as well as train loadings in the Facility for Accelerated Service Testing (FAST) at the Transportation Technology Center, Inc. (TTCI). The rainy test section experiment applied realistic dynamic freight train loads and continuously monitored the test sections to determine the effects of moisture and saturation conditions on the field performance trends of ballasted track. Accordingly, ballast samples at varying levels of degradation were collected from the test locations to investigate ballast gradations as well as strength and permeability characteristics at dry and wet conditions. Shear strength tests were performed using a large-scale triaxial test machine, known as the TX-24, to study ballast degradation effects on the strength of dry ballast. Materials finer than the 3/8 in. (9.5 mm) were then collected and studied for the moisture-density behavior using a modified Proctor type compactive effort. Shear strength samples with the same gradations and degradation levels were prepared and tested at varying moisture contents of the 3/8 in. (9.5 mm) fraction ranging from 3% to 9%, with the latter being the optimum moisture content of these finer materials. The wet ballast triaxial test samples had strength values only in the range of 38% to 65% of the dry strengths. In addition to the strength tests, constant head permeability tests were also conducted on the ballast samples which demonstrated quite low and negligible horizontal flow amounts through ballast under static pressure heads and at various hydraulic gradients.
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Jadhav, Rahul, and Thomas Pisklak. "Liquid Strength Retrogression Control Additive." In SPE/IADC Middle East Drilling Technology Conference and Exhibition. SPE, 2021. http://dx.doi.org/10.2118/202104-ms.
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Abstract To mitigate strength retrogression at temperatures, higher than 230°F, well cement designs typically include strength retrogression control additives (SRCAs). Solid siliceous materials (e.g., silica flour, fume, and sized-sands) are commonly used SRCAs that are incorporated into cements using dry-blending techniques. This study highlights liquid silica compositions as alternative SRCAs to dry-blended silica for high-temperature cementing. Liquid additives can be managed easily, delivered accurately, and offer a reduced on-site footprint, thus making them particularly advantageous for operations offshore and in remote locations. This paper presents a study on the use of liquid silica compositions as SRCAs and their effect on cement slurry properties, such as thickening time, mixability, fluid loss, rheology, and free water. The cement slurry used during the current study was prepared and tested according to API RP 10B-2 (2005). The performance of the liquid silica composition was tested at temperatures up to 400°F. Set cement samples were prepared using the liquid silica composition and silica flour, cured for up to 14 days at different temperatures. In addition, permeability testing was also performed on the samples. This paper presents the findings of this research, including strength and permeability test results on cement blends cured at temperatures of 300, 330, 350, and 400°F. The liquid silica composition, which provided silica to the cement formulation equivalent to 35% BWOC dry silica (48% BWOC liquid SRCA), functioned effectively as an SRCA at temperatures up to 330°F. Signs of strength retrogression were observed at 350°F and were more pronounced at 400°F. A greater concentration of the liquid silica composition may be necessary to prevent strength retrogression at temperatures higher than 330°F. The liquid silica composition also demonstrated mild retardation and a dispersing effect on the slurry. However, it helped enable improved slurry stability and suspension, thus providing improved control over free water without adverse effects on fluid loss and sedimentation. The study results demonstrate that a liquid SRCA can help improve the performance of annular cement designs to provide dependable barriers and effective zonal isolation during high-temperature cementing applications. The improved performance enabled by this liquid silica composition verifies its potential use as an alternative SRCA for high-temperature oil well cementing operations.
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Salama, Mamdouh M. "Fiber Augmented Steel Technology Pipe (FAST-Pipe™): An Alternative to High Strength Steel." In ASME 2010 29th International Conference on Ocean, Offshore and Arctic Engineering. ASMEDC, 2010. http://dx.doi.org/10.1115/omae2010-20568.
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A key imperative to the transportation of natural gas for long distance is the continued technological advances to reduce the development and life cycle cost of high pressure gas pipeline while maintaining the required high level of safety, reliability and environmental stewardship. Therefore, advances in high strength steels such as X100 and X120 have been pursued by several companies. This paper presents an alternative solution namely FAST-Pipe™ (Fiber Augmented Steel Technology - Pipe). The FAST-Pipe™ Concept involves wrapping a conventional strength steel pipe (X70) whose thickness is selected to satisfy axial and bending load requirement with dry fiberglass to achieve the pressure load requirement. The FAST-Pipe™ offers several technical and economical advantages over High strength steel concepts. The paper presents the results of the proof of concept validation program that included cost analysis and performance testing. The paper also summarizes the results of the rigorous qualification program that was implemented subsequent to the successful results of the proof of concept phase.
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Michopoulos, John G., John C. Hermanson, and Athanasios Iliopoulos. "First Industrial Strength Multi-Axial Robotic Testing Campaign for Composite Material Characterization." In ASME 2012 International Design Engineering Technical Conferences and Computers and Information in Engineering Conference. American Society of Mechanical Engineers, 2012. http://dx.doi.org/10.1115/detc2012-71064.
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In this paper we are reporting on the first successful campaign of systematic, automated and massive multiaxial tests for composite material constitutive characterization. The 6 degrees of freedom system developed at the Naval Research Laboratory (NRL) called NRL66.3, was used for this task. This was the in-augural run that served as the validation of the proposed overall constitutive characterization methodology. It involved accomplishing performing 1152 tests in 12 business days reaching a peak throughput of 212 tests per day. We describe the context of the effort in terms of the reasoning and the actual methods behind it. Finally, we present representative experimental data and associated constitutive characterization results for representative loading paths.
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Sches, Ce´line, Roy Shilling, Steve Shademan, Jacky Massaglia, Mike Payne, and Arnaud Gateaud. "Development of Fatigue Resistant Heavy Wall Riser Connectors for Deepwater HPHT Dry Tree Riser Systems." In ASME 2009 28th International Conference on Ocean, Offshore and Arctic Engineering. ASMEDC, 2009. http://dx.doi.org/10.1115/omae2009-79518.
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BP is currently looking at the next generation of dry tree development projects in the US Gulf of Mexico (GOM) deepwater operating region. Some HPHT wells call for the design of 15 ksi or greater riser systems with sour service requirements. Over the last 10 years, NACE compliant high strength steels (HSS) together with fatigue resistant threaded and coupled connectors have proved to be reliable technical solutions top tensioned riser (TTR). Today their light weight and increased performance capabilities enable cost effective dry tree systems for water depths up to 10,000 feet. In the frame of BP xHPHT development projects, the design and qualification of Heavy Wall Threaded and Coupled (T&C) riser connectors for TTR applications was launched. Comprehensive development programs were built, involving numerous design variations, Finite Element Analysis evaluation and optimization — including parametric studies —, followed by intensive full scale static and fatigue testing campaigns. Those developments benefited from the design and field running experience accumulated with previous TTR projects, where innovative fatigue enhancement techniques and premium fatigue compliant sealing devices were engineered. In addition, combined static, dynamic and corrosion testing of base material is being conducted to assess and qualify the fatigue resistance of HSS up to 140 ksi under those conditions. This paper will present results and conclusions from these developments and will report the performance levels reached by Heavy Wall High Pressure T&C riser connectors and the associated high strength base material. Forward work plans on riser connectors for xHPHT, SCR and flowlines will also be discussed.
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Qian, Yu, Debakanta Mishra, Erol Tutumluer, Youssef M. A. Hashash, and Jamshid Ghaboussi. "Moisture Effects on Degraded Ballast Shear Strength Behavior." In 2016 Joint Rail Conference. American Society of Mechanical Engineers, 2016. http://dx.doi.org/10.1115/jrc2016-5840.
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Ballast consisting of large sized aggregate particles with uniform size distribution is an essential component of the track substructure, to facilitate load distribution and drainage. As freight tonnage accumulates with traffic, ballast will accumulate an increasing percentage of fines due to either aggregate breakdown or outside contamination such as subgrade soil intrusion and coal dust collection. According to the classical text by Selig and Waters [1], ballast degradation from traffic involves up to 76% of all fouling cases; voids will be occupied by fines from the bottom of ballast layer gradually causing ballast clogging and losing its drainage ability. When moisture is trapped within ballast, especially fouled ballast, ballast layer stability is compromised. In the recent studies at the University of Illinois, the focus has been to evaluate behavior of fouled ballast due to aggregate degradation using large scale triaxial testing. To investigate the effects of moisture on degraded ballast, fouled ballast was generated in the laboratory through controlled Los Angeles (LA) abrasion tests intended to mimic aggregate abrasion and breakdown and generate fouled ballast at compositions similar to those observed in the field due to repeated train loadings. Triaxial shear strength tests were performed on the fouled ballast at different moisture contents. Important findings of this preliminary study on characterizing wet fouled ballast are presented in this paper. Moisture was found to have a significant effect on the fouled ballast strength behavior. Adding a small amount of 3% moisture (by weight of particles smaller than 3/8 in. size or smaller than 9.5 mm) caused test specimens to indicate approximately 50% decrease in shear strength of the dry fouled ballast. Wet fouled ballast samples peaked at significantly lower maximum deviator stress values at relatively smaller axial strains and remained at these low levels as the axial strain was increased.
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Li, Zhong, Yuan Fu, Jianyu Zhang, Liancheng Lin, Jianping Huang, Wenyu Mao, Dongsheng Yang, Dandan Zhao, and Xiao Wang. "Design and Test for a High-Temperature Molten Salt Pump." In ASME/NRC 2014 12th Valves, Pumps, and Inservice Testing Symposium. American Society of Mechanical Engineers, 2014. http://dx.doi.org/10.1115/nrc2014-5024.
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A high-temperature molten salt pump, described as mechanical, free-surface, centrifugal, vertical-shaft, sump type, working at 500°C [932°F] to 600°C [1112°F], has been developed for the Thorium-Based Molten Salt Reactor (TMSR). Flow passage components of the pump are made of Hastelloy C-276 to ensure sufficient strength and corrosion resistance at high temperature. Also, a heat shield plug with air-cooled channels was designed to separate the drive motor, seal elements, and bearings from intense radioactivity and to keep the temperature of the flange seal below 150°C [302°F] and the temperature of the bearing below 80°C [176°F]. A dry gas seal was used so that there is zero leakage. Furthermore, some analysis of hydraulics characteristics, temperature field, thermal stress, and strain was performed to research the pump’s performance, and then the temperature field and the hydraulics were measured to validate the analysis results. The results show that the hydraulics, thermal stress, and strain meet the design value very well. The pump has been successfully operated on a LiF-NaF-KF test loop for over 250 hr. at temperatures of 500°C [932°F] to 600°C [1112°F], speeds of 1050 to 1450rpm, and flows of 15 m3/h [66 gpm] to 25 m3/h [110 gpm]. Paper published with permission.
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D'Antino, Tommaso, and Marco A. Pisani. "Durability of glass FRP reinforcing bars: a state of the art." In IABSE Symposium, Guimarães 2019: Towards a Resilient Built Environment Risk and Asset Management. Zurich, Switzerland: International Association for Bridge and Structural Engineering (IABSE), 2019. http://dx.doi.org/10.2749/guimaraes.2019.0611.
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<p>Glass fiber reinforced polymer (GFRP) bars represent a valid solution for internal reinforcement of concrete elements. With respect to steel reinforcing bars, GFRP bars have a good resistance to corrosion and a high tensile strength. However, durability of GFRP bars is still an open issue and design guidelines and recommendations provide environmental and long-term reduction factors that strongly limit the tensile stress in the bar. In this paper, a large database of GFRP reinforcing bars exposed to different environmental conditions with and without the application of a sustained load and subjected to tensile testing was collected from the literature. The variation of the bar tensile strength with respect to different exposure conditions, namely hot dry and humid air, different alkali environments, and salt solutions with various concentrations, was analyzed and discussed. Furthermore, the effect of sustained stress on the bar tensile strength was studied. A statistical analysis based on the design by testing approach provided by EN 1990 was performed on the results collected to calibrate characteristics and design values of the product between environmental and long-term reduction factors.</p>
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Faghihi Kashani, Hamed, Carlton L. Ho, and James P. Hyslip. "Evaluating the Effect of Breakdown Fouling and Water Content on the Ballast Degradation Characteristics." In 2017 Joint Rail Conference. American Society of Mechanical Engineers, 2017. http://dx.doi.org/10.1115/jrc2017-2215.
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Railroad ballast as a layer of track substructure performs important tasks such as increasing the bearing capacity of the sleepers, providing large voids for drainage and resisting the forces applied to the super-structure. Contamination of ballast as the result of ballast breakdown known as breakdown fouling can prevent ballast from performing its job and also affects the engineering properties of ballast. This paper discusses the drained static triaxial testing on granite ballast material with different amount of breakdown fouling and water content. Large-scale triaxial equipment was used for this testing program at the University of Massachusetts, Amherst. These tests were performed to study the effect of fouling and water content, on the strength properties and degradation characteristics of railroad ballasted track. Ballast with three different fouling percentages from clean to highly fouled ballast (<5%, 15% and 30%) and four water contents from dry to field capacity were tested under three different confining pressures. The results show that although an increase in moisture degrades the fouled ballast, increase in breakdown fouling at constant moisture conditions increases the strength of the ballast.
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Croccolo, Dario, Massimiliano De Agostinis, Stefano Fini, Giorgio Olmi, Francesco Robusto, and Nicolò Vincenzi. "Effect of Material and Lubrication Conditions on the Underhead Frictional Response in High Strength Socket-Head Screws." In ASME 2020 Pressure Vessels & Piping Conference. American Society of Mechanical Engineers, 2020. http://dx.doi.org/10.1115/pvp2020-21506.
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Abstract The present paper investigates the influence of several design parameters on the frictional response at the underhead in a bolted joint, involving high strength socket-head screws: M8 class 14.9 with black oxidization coating. The experimentation deals with different underhead materials (Steel, Aluminium), lubrication conditions (dry, lubricated) and repeated tightening operations. The awareness of the actual friction coefficients, depending on the current operating parameters, is a useful tool, to support the most proper design of a bolted joint. The experimental campaign has been run by a testing rig for friction coefficient estimation, complying with the recommendations by International Standard ISO 16047 and the automotive Standard VW01131-1 in order to consider the effect of the tightening speed normally adopted in the automotive field. The axial preload generated upon tightening induces a high pressure on the remarkably small underhead surface of the utilized high strength socket-head screws and is therefore likely to affect the tribological response. Consequently, some differences may be expected with respect to the tribological behavior of screws belonging to lower strength grades. This is particularly true, when tightening is done without bearing lubrication, and through several repeated assembly-disassembly operations. The collected data have been processed by the tools of ANOVA and F-Test, in order to assess the significance of each factor, as well as related interactions.
Звіти організацій з теми "Paper Dry strength Testing"
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Shivakumar, Pranavkumar, Kanika Gupta, Antonio Bobet, Boonam Shin, and Peter J. Becker. Estimating Strength from Stiffness for Chemically Treated Soils. Purdue University, 2022. http://dx.doi.org/10.5703/1288284317383.
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The central theme of this study is to identify strength-stiffness correlations for chemically treated subgrade soils in Indiana. This was done by conducting Unconfined Compression (UC) Tests and Resilient Modulus Tests for soils collected at three different sites—US-31, SR-37, and I-65. At each site, soil samples were obtained from 11 locations at 30 ft spacing. The soils were treated in the laboratory with cement, using the same proportions used for construction, and cured for 7 and 28 days before testing. Results from the UC tests were compared with the resilient modulus results that were available. No direct correlation was found between resilient modulus and UCS parameters for the soils investigated in this study. A brief statistical analysis of the results was conducted, and a simple linear regression model involving the soil characteristics (plasticity index, optimum moisture content and maximum dry density) along with UCS and resilient modulus parameters was proposed.
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Moser, Robert, Preet Singh, Lawrence Kahn, Kimberly Kurtis, David González Niño, and Zackery McClelland. Crevice corrosion and environmentally assisted cracking of high-strength duplex stainless steels in simulated concrete pore solutions. Engineer Research and Development Center (U.S.), August 2021. http://dx.doi.org/10.21079/11681/41620.
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This paper presents a study of crevice corrosion and environmentally assisted cracking (EAC) mechanisms in UNS S32205 and S32304 which were cold drawn to tensile strengths of approximately 1300 MPa. The study utilized a combination of electrochemical methods and slow strain rate testing to evaluate EAC susceptibility. UNS S32205 was not susceptible to crevice corrosion in stranded geometries at Cl⁻ concentrations up to 1.0 M in alkaline and carbonated simulated concrete pore solutions. UNS S32304 did exhibit a reduction in corrosion resistance when tested in a stranded geometry. UNS S32205 and S32304 were not susceptible to stress corrosion cracking at Cl⁻ concentrations up to 0.5 M in alkaline and carbonated solutions but were susceptible to hydrogen embrittlement with cathodic overprotection.
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Cao Romero, Julio A., Jorge Reyes-Avendaño, Julio Soriano, Leonardo Farfan-Cabrera, and Ali Erdemir. A Pin-on-Disc Study on the Electrified Sliding Wear of EVs Powertrain Gears. SAE International, March 2022. http://dx.doi.org/10.4271/2022-01-0320.
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In contrast to conventional powertrains from internal combustion engine vehicles (ICEV), the tribological performance of powertrains of electric vehicles (EVs) must be further evaluated by considering new critical operating conditions such as electrical environments. The operation of any type of electric motor produces shaft voltages and currents due to various hardware configurations and factors. Furthermore, the common application of inverters intensifies this problem. It has been reported that the induced shaft voltages and currents can cause premature failure problems in tribological components such as bearings and gears due to accelerated wear and/or fatigue. It is ascribed to effects of electric discharge machining (EDM), also named, sparking wear caused by shaft currents and poor or increasingly diminishing dielectric strength of lubricants. A great effort has been done to study this problem in bearings, but it has not yet been the case for gears. Considering that EVs powertrains can be configurated with an electric motor coupled to a single-speed or multi-speed transmission, it is expected that shaft currents can also affect gears to some extent. The pin-on-disc test has been widely used to study sliding wear of gear materials under comparable or realistic operating conditions. This accelerated test is effective for screening materials, lubricants and operating conditions allowing evaluations of their friction and wear properties. However, it has not been implemented for studying gear materials under electrified environments. Thus, this paper aims to explore the friction coefficient and wear of gear materials under non-electrified and electrified sliding in a pin-on-disc tester applying typical of EVs powertrain shaft currents during sliding. The tests were carried out at two different DC currents under comparable gear dry and lubricated sliding contact conditions. Friction coefficient, wear volumes and morphologies were evaluated and reported in this work.
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TESTING OF ADDITIVELY MANUFACTURED STAINLESS STEEL MATERIAL AND CROSS-SECTIONS. The Hong Kong Institute of Steel Construction, August 2022. http://dx.doi.org/10.18057/icass2020.p.175.
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Powder bed fusion (PBF) additive manufacturing has the potential for significant impact on the construction industry due to its ability to produce complex and free-form components with high-precision. However, the size of components is limited by the build envelope of PBF machines. Laser welding offers a means of joining small individual PBF parts together to create larger-scale parts. This paper investigates the microstructure and material properties of stainless steel coupons with and without laser-welded joints, in conjunction with the structural performance of stainless steel circular hollow sections (CHS) at the cross-sectional level, with all specimens printed by PBF. The PBF base material exhibited a typical cellular microstructure, while the weld material consisted of equiaxed, columnar and cellular dendrite microstructures. The proof strengths of the weld were lower than those of the base metal, and the strengths of the PBF base metal were dependent on the build direction – the vertically built coupons showed lower proof strengths than the horizontal coupons. The axial resistances of the PBF CHS are safely predicted by the EN 1993-1-4 design provisions and the deformation-based continuous strength method (CSM).
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TENSILE BEHAVIOUR OF TMCP Q690D HIGH-STRENGTH STRUCTURAL STEEL AT STRAIN RATES FROM 0.00025 TO 760 S-1. The Hong Kong Institute of Steel Construction, March 2022. http://dx.doi.org/10.18057/ijasc.2022.18.1.7.
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The application of Q690D high-strength structural steel (HSSS) has been increasing in engineering structures. The lack of knowledge of the strain rate behaviour limits the application to the extreme loading conditions such as blast and impact loadings. This paper presents a series of tensile tests on the dynamic tensile behaviour of Q690D HSSS produced through the thermo-mechanical control process (TMCP). The stress-strain relationships of TMCP Q690D in the strain rate range of 0.00025 to 760 s-1 were measured by using the universal and servo-hydraulic high speed testing machines. The experimental results verified the sensitivity to strain rate of TMCP Q690D and the dynamic increase factor (DIF) for yield stress is identical to that of QT (Quenched and Tempered) S690 HSSS. However, TMCP Q690D behaves in a much different way in the strain hardening stage. The commonly-used Cowper-Symonds model was calibrated for the DIFs of yield stress and ultimate tensile strength. The Johnson-Cook (J-C) model was modified and a new rate-dependent constitutive model was proposed. The proposed model was validated successfully to predict the true stress-strain relationship, providing better prediction results than the modified J-C model.
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SHEAR BEHAVIOR OF NOVEL DEMOUNTABLE BOLTED SHEAR CONNECTOR FOR PREFABRICATED COMPOSITE BEAM. The Hong Kong Institute of Steel Construction, December 2022. http://dx.doi.org/10.18057/ijasc.2022.18.4.2.
Повний текст джерелаАнотація:
Bolted shear connectors offer alternatives to achieve steel-concrete composite action instead of conventional welded headed studs especially for prefabricated constructions and demountable composite structures. This paper firstly proposed a new type of demountable steel-concrete bolted shear connectors based on the double-nut friction-grip high strength bolted connector, which modify the upper nut into conical locking nut. This paper performed ten full scale push-out tests to study shear behaviors of the developed new type of connectors. Testing parameters included bolt configuration, strength, diameter of bolts and strength of infilled grout. Test results indicate that shear behaviors and slip capacity of the conventional bolted connectors are significantly improved when the bolted connector incorporating with conical locking nut. The influences of these studied parameters on shear behaviour of novel bolted shear connectors are revealed and discussed. The developed novel demountable connector exhibits an average 25% improvement in ultimate shear resistance over conventional bolted connectors. Moreover, the shear stiffness of the developed bolted connectors is about six times of the conventional bolted connector through eliminating the clearance between steel flange hole and bolt shank.
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NUMERICAL SIMULATION AND RESEARCH ON WELDING RESIDUAL STRESS OF BOX - TYPE STEEL STRUCTURE. The Hong Kong Institute of Steel Construction, August 2022. http://dx.doi.org/10.18057/icass2020.p.324.
Повний текст джерелаАнотація:
The welding residual stress of the box-plate steel structure is studied in this paper. Q235B steel and Q345B steel are generally used in box plate assembly steel structures, so this paper focuses on the welding residual stress of these two sheets of steel. The welding of Q235B and Q345B steel plates was simulated by ABAQUS associated DFLUX heat source subroutine. The welding residual stress of the steel plates is tested by the ultrasonic testing method. The results show that the yield strength of steel has a significant effect on the welding residual stress. The longitudinal residual stress in the heataffected zone of the weld is mainly strength stress, while the transverse residual stress in the whole welding part is both tensile stress and compressive stress. The results of the steel plate residual stress test are in good agreement with the simulation results, which verifies the reliability of ABAQUS simulated steel plate welding.
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LOW-TEMPERATURE COMPRESSION BEHAVIOUR OF CIRCULAR STUB STAINLESS-STEEL TUBULAR COLUMNS. The Hong Kong Institute of Steel Construction, September 2022. http://dx.doi.org/10.18057/ijasc.2022.18.3.4.
Повний текст джерелаАнотація:
This paper firstly studies mechanical properties of stainless steel (SS) S30408 at the low temperature (T) range of -80~20℃. Further compression tests are carried out on 20 SS stub tubular columns (SSSTCs) at low temperatures of -80, -60, -30, and 20℃ to investigate their low-temperature compression behaviour. Including the testing low temperatures, the wall thickness of SS tube (t) is the other investigated parameters. Test results show that decreasing the T from 20 to -80℃ improves the yield and ultimate strength of stainless steel by 29% and 80%, respectively, but reduces its ductility by about 25%. Under low-temperature compression, elephant foot local buckling occurs to most of SSSTCs and inelastic inward and outward local buckling occurred to specimens with 6 mm-thick SS tube. Test results also show that the decreasing T value increases the strength and stiffness of SSSTCs, but compromises their ductility; the wall thickness of SSSTCs significantly improves their strength, stiffness, and ductility. This paper also develops 3D finite element model (FEM) to estimate the low-temperature compression behaviour of SSSTCs, which considers nonlinearities of material and geometry, geometric imperfections, and influences of low temperatures. The validations show it predicts reasonably well the low-temperature compression behaviours of SSSTCs.
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EXPERIMENTAL STUDY ON TRUSS TYPE STEEL REINFORCED CONCRETE JOINTS. The Hong Kong Institute of Steel Construction, August 2022. http://dx.doi.org/10.18057/icass2020.p.165.
Повний текст джерелаАнотація:
"This paper presents an experimental study on the structural behavior of two truss type steel reinforced concrete (SRC) joints. The objective is to characterize the mechanical behavior of SRC joints subjected to static loading. The specimens were scaled from a concrete core tube connected to a mega steel truss. Mechanical behavior of the joint zone is extremely complicated due to the complex geometry and interactive forces among the connected members. Monotonic loading tests were carried out through a self-balanced loading system. Sparse cracks were observed under design loads. Spalling concrete cover was observed for joint B1. Whereas, only a few cracks were observed in the joint D1 after testing. Based on the measured equivalent strains, the interaction zone of steel sections works elastically under 1.5 times of the design loads. This indicates that the joints have sufficient strength to meet the design requirements. The experimental results presented in this paper provides a better understanding of current truss type composite joints and offers ideas for further research based on the authors' findings."