Modeling the viscoelasticity of nonwoven material with consideration of the irreversible strain component

2006 ◽  
Vol 38 (1) ◽  
pp. 50-54 ◽  
Author(s):  
V. Yu. Mishakov ◽  
G. Ya. Slutsker ◽  
A. M. Stalevich
Author(s):  
Xijia Wu ◽  
Zhong Zhang ◽  
Leiyong Jiang ◽  
Prakash Patnaik

Nozzle guide vanes (NGV) of gas turbine engines are the first components to withstand the impingement of hot combustion gas and therefore often suffer thermal fatigue failures in service. A lifting analysis is performed for the NGV of a gas turbine engine using the integrated creep–fatigue theory (ICFT). With the constitutive formulation of inelastic strain in terms of mechanism-strain components such as rate-independent plasticity, dislocation glide-plus-climb, and grain boundary sliding (GBS), the dominant deformation mechanisms at the critical locations are thus identified quantitatively with the corresponding mechanism-strain component. The material selection scenarios are discussed with regards to damage accumulated during take-off and cruise. The interplay of those deformation mechanisms in the failure process is elucidated such that an “optimum” material selection solution may be achieved.


Author(s):  
Tao Yang ◽  
Xiaoman Xiong ◽  
Yuanfeng Wang ◽  
Rajesh Mishra ◽  
Michal Petrů ◽  
...  

2018 ◽  
Vol 8 (1) ◽  
Author(s):  
Najib Cheggour ◽  
Theodore C. Stauffer ◽  
William Starch ◽  
Peter J. Lee ◽  
Jolene D. Splett ◽  
...  

2013 ◽  
Vol 821-822 ◽  
pp. 188-194
Author(s):  
Sizo Ncube ◽  
Chu Yang Zhang ◽  
Edison Omollo ◽  
Li Liu

The study examined the effect of heat and time on fabrics made from polyester (PET) and polyvinyl alcohol (PVA) fibres which have different aerial densities and composed of 90% and 10% of PET and PVA respectively. PVA is included in the fabric due to its water solubility and this will allow the PVA to be removed thereby leaving a more porous fabric. The fabrics were passed through needle punching machine and PVA removed by heating in a water bath. The nonwoven fibre was then heated in water at temperatures of 75, 85 and 100 °C in an effort to remove the PVA fibres and leave a more porous fabric. While removing the PVA through heating in a water bath, the effect of heating period and the temperature on the fabric properties was investigated. The strength, elongation and structure of the fabric were investigated and the changes analysed. It was found that there was a significant removal of PVA at longer periods of time when at a high temperature. The effect on the properties was found to be higher with higher temperatures as well with a decrease in strength ranging between 40% and 60% being experienced while an increase in elongation, between 60% and 90% was experienced. Fibre spacing and pore size was found to have increased as well.


2003 ◽  
Vol 37 (5) ◽  
pp. 1008-1012 ◽  
Author(s):  
Maja M. Radetić ◽  
Dragan M. Jocić ◽  
Petar M. Jovančić ◽  
Zoran Lj. Petrović ◽  
Helga F. Thomas

2021 ◽  
pp. 34-36
Author(s):  
М.А. Долгополова ◽  
Л.Н. Тимакова

Для повышения уровня механизации производства свеклы столовой важное значение имеет признак раздельноплодности, который позволяет исключить проведение прореживания растений в рядках. Создание раздельноплодных сортов и гибридов длительный и трудоемкий процесс, который осложняется не ясным до конца механизмом наследования этого признака. Цель исследований – создать раздельноплодный исходный материал свеклы столовой с комплексом хозяйственно ценных признаков. Исследования проводили в 2015–2020 годах во ВНИИО – филиале ФГБНУ ФНЦО. Изучение и описание линий столовой свеклы проводили согласно «Методическим указаниям ВИР по изучению и поддержанию в живом виде мировой коллекции корнеплодов». Полевые опыты закладывали на Центральной части Москворецкой поймы (Раменский район Московской области). Почва аллювиальная, луговая, среднесуглинистая, хорошо окультуренная, с мощным гумусовым горизонтом. Метеорологические условия 2015–2020 годов складывались благоприятно для формирования корнеплодов и созревания семян свеклы столовой, за исключением условий 2017 и 2018 годов, которые повлияли на сроки вегетации растений, но не помешали получить посевной и посадочный материал. В качестве исходного материала использовали 5 сортов отечественной и зарубежной селекции (Бордо односемянная, Модана, Моника, Фортуна и Хавская односемянная). Агротехнические мероприятия выполнены в соответствии с требованиями, принятыми для Центрального региона Нечерноземной зоны РФ. Оценку поражения церкоспорозом проводили визуально по пятибалльной шкале Н.И. Салунской. Содержание сухого вещества в корнеплодах определяли термостатно-весовым методом; содержание сахаров в соке – рефрактометрическим методом; содержание бетанина – спектрофотометрическим методом. Уровень плодности семенных растений оценивали визуально во время бутонизации до начала цветения. Для проведения самоопыления использовали только растения с уровнем раздельноплодности 99 и 100%. Изолировали растения до начала цветения под индивидуальными изоляторами из нетканого материала спанбонд, плотностью 80 г/м². Выделено две линии из сорта Моника. Степень раздельноплодности у линии №1 составила 97%, у линии №4–90%. Эти линии характеризуются округлой формой корнеплода с темно-красной окраской мякоти. В корнеплодах содержится растворимых сахаров 6,6–6,3%, сухого вещества и бетанина – 11,2–12,8% и 133,3–130,8 мг/100 г соответственно. To increase the level of mechanization of the production of dining beet, the sign of separation is important, which allows to exclude the decimation of plants in rows. The creation of separate fruit varieties and hybrids is a long and time-consuming process, which is complicated by the mechanism of inheritance of this feature that is not fully clear. The purpose of the research is to create a separate source material of canteen beets with a complex of economically valuable features. Research was carried out in 2015–2020 in ARRIVG – branch of FSBSI FSCVG. The study and description of the dining lines of beets was carried out in accordance with the «Methodological Guidelines of the VIR for the study and living maintenance of the world collection of root crops». Field experiments were carried out on the central part of the Moskvoretskaya floodplain (Ramensky district of Moscow region). The soil is alluvial, meadow, medium-grained, well-cultured, with a powerful humus horizon. Meteorological conditions of 2015–2020 developed favorably for the formation of root crops and the ripening of beet seeds in the dining room, with the exception of the conditions of 2017 and 2018, which affected the timing of plant vegetation, but did not prevent the production of sowing and planting material. As a starting material, 5 varieties of domestic and foreign breeding were used (Bordeaux single-seeded, Modana, Monica, Fortuna and Havskaya single-seeded). Agrotechnical measures were carried out in accordance with the requirements adopted for the Central region of the Non-Black Earth Zone of RF. The cercosporosis assessment was evaluated visually on the five-point scale of N.I. Salunskaya. The content of dry matter in root crops was determined by thermostatic-weight method; sugar content in juice – by the refractometric method; betanine content – by the spectrophotometric method. The level of fertility of seed plants was assessed visually during butonization before flowering. To carry out self-pollination, only plants with a separation level of 99 and 100% were used. Plant insulation was carried out before flowering under individual insulators made of Spanbond nonwoven material with a density of 80 g/m². Two lines from the Monica variety were isolated. The degree of separation at line No1 was 97%, at line No4–90%. These lines are characterized by a rounded shape of the root fruit with a dark red color of the pulp. The root crops of soluble sugars contain 6.6–6.3%, dry matter and betanin – 11.2–12.8% and 133.3–130.8 mg/100 g accordingly.


2019 ◽  
Vol 92 ◽  
pp. 05006
Author(s):  
Truong Le ◽  
David Airey ◽  
Jamie Standing

The evolution of the creep strain component in triaxial stress space was investigated through performing a series of multistage drained compression tests on London Clay using a specially designed locally instrumented triaxial apparatus. Experiments along specifically defined stress paths showed significant rotation of the local creep strain component as the samples were sheared towards failure. The results indicate a need for a more complex plastic potential function to correctly predict incremental creep strains at different states in triaxial stress space. Creep deformations for stress path controlled drained compression tests were also found to require a reinterpretation of the classic secondary compression behaviour. Creep strain-rates were found to fall well outside the normal power decay function. Test data and previously reported drained creep test results on London Clay have been combined to provide a complete understanding of the incremental creep component. The experiments show how creep behaviour significantly depends on the stress conditions imposed and the approaching strain rate.


Sign in / Sign up

Export Citation Format

Share Document