Nonlinear spectral collocation analysis of imperfect functionally graded plates under end-shortening

S. Amir M. Ghannadpour,Payam Kiani 국제구조공학회 2018 Structural Engineering and Mechanics, An Int'l Jou Vol.66 No.5

An investigation is made in the present work on the post-buckling and geometrically nonlinear behaviors of moderately thick perfect and imperfect rectangular plates made-up of functionally graded materials. Spectral collocation approach based on Legendre basis functions is developed to analyze the functionally graded plates while they are subjected to end-shortening strain. The material properties in this study are varied through the thickness according to the simple power law distribution. The fundamental equations for moderately thick rectangular plates are derived using first order shear deformation plate theory and taking into account both geometric nonlinearity and initial geometric imperfections. In the current study, the domain of interest is discretized with Legendre-Gauss-Lobatto nodes. The equilibrium equations will be obtained by discretizing the Von-Karman’s equilibrium equations and also boundary conditions with finite Legendre basis functions that are substituted into the displacement fields. Due to effect of geometric nonlinearity, the final set of equilibrium equations is nonlinear and therefore the quadratic extrapolation technique is used to solve them. Since the number of equations in this approach will always be more than the number of unknown coefficients, the least squares technique will be used. Finally, the effects of boundary conditions, initial geometric imperfection and material properties are investigated and discussed to demonstrate the validity and capability of proposed method.

Roll Bonding Behaviour of Al-3003/Al-4043 and Al-3003/Zn Sheets

Mojtaba Movahedi,Amir-Hossein Kokabi,Hamid-Reza Madaah-Hosseini,Mahdi Kiani 대한금속·재료학회 2011 METALS AND MATERIALS International Vol.17 No.4

In the present study, the roll bonding behaviour of Al-3003/Al-4043 and Al-3003/Zn sheets were compared. The bi-layer sheets were produced by a roll bonding process at different reductions in thickness and rolling temperatures. The joint strengths of the sheets were evaluated by peel and bend testing before and after supplemental annealing treatment. The peeled surfaces were examined using a scanning electron microscope. The results indicated that the Al-3003/Al-4043 sheets were bonded with higher joint strength and lower threshold reductions in thickness with respect to the Al-3003/Zn sheets. In contrast to the Al-3003/Zn sheets, significant improvement was observed in the joint strength of the Al-3003/Al-4043 sheets after annealing treatment. Moreover, electron microscopy examinations showed that the fracture types of the Al-3003/Al-4043 and Al-3003/Zn sheets were predominantly ductile and brittle, respectively.

Nonlinear spectral collocation analysis of imperfect functionally graded plates under end-shortening

Ghannadpour, S. Amir M.,Kiani, Payam Techno-Press 2018 Structural Engineering and Mechanics, An Int'l Jou Vol.66 No.5

An investigation is made in the present work on the post-buckling and geometrically nonlinear behaviors of moderately thick perfect and imperfect rectangular plates made-up of functionally graded materials. Spectral collocation approach based on Legendre basis functions is developed to analyze the functionally graded plates while they are subjected to end-shortening strain. The material properties in this study are varied through the thickness according to the simple power law distribution. The fundamental equations for moderately thick rectangular plates are derived using first order shear deformation plate theory and taking into account both geometric nonlinearity and initial geometric imperfections. In the current study, the domain of interest is discretized with Legendre-Gauss-Lobatto nodes. The equilibrium equations will be obtained by discretizing the Von-Karman's equilibrium equations and also boundary conditions with finite Legendre basis functions that are substituted into the displacement fields. Due to effect of geometric nonlinearity, the final set of equilibrium equations is nonlinear and therefore the quadratic extrapolation technique is used to solve them. Since the number of equations in this approach will always be more than the number of unknown coefficients, the least squares technique will be used. Finally, the effects of boundary conditions, initial geometric imperfection and material properties are investigated and discussed to demonstrate the validity and capability of proposed method.

Growth, Quality, and Physiological Characteristics of Gerbera (Gerbera jamesonii L.) Cut Flowers in Response to Different NO3‑:NH4+ Ratios

Mohammad Ali Khalaj,Shahram Kiani,Amir Hosein Khoshgoftarmanesh,Reihaneh Amoaghaie 한국원예학회 2017 Horticulture, Environment, and Biotechnology Vol.58 No.4

We investigated the effects of different NO3¯:NH4+ratios in nutrient solution on the yield and growth ofgerbera (Gerbera jamesonii) cut flowers in soilless culture. Two cultivars of gerbera (red ‘Stanza’ and yellow ‘DoubleDutch’) were supplemented with four different NO3¯:NH4+ratios (100:0, 80:20, 60:40, and 40:60). Replacing 20%nitrate in the nutrient solution with ammonium resulted in the higher number of leaves per plant, highest fresh anddry weights of roots and shoots, greatest number of flowers, highest flower stalk diameter and flower disk diameter,longest vase life, highest fresh and dry weight of inflorescences, and highest relative water contents in petals comparedwith the control. Decreasing the NO3¯:NH4+ratio to 60:40 caused a considerable reduction in plant growth and biomass. The chlorophyll and carotenoid contents, as well as catalase (CAT) and peroxidase (POX) activity, increased withincreasing proportion of ammonium-to-nitrate in the nutrient solution. The results suggest that a NO3¯:NH4+ratio of80:20 should be used for gerbera cut flower production to achieve the highest growth and quality.

Intrathecal administration of naringenin improves motor dysfunction and neuropathic pain following compression spinal cord injury in rats: relevance to its antioxidant and anti-inflammatory activities

Sajad Fakhri,Shahryar Sabouri,Amir Kiani,Mohammad Hosein Farzaei,Khodabakhsh Rashidi,Ahmad Mohammadi-Farani,Ehsan Mohammadi-Noori,Fatemeh Abbaszadeh 대한통증학회 2022 The Korean Journal of Pain Vol.35 No.3

Background: Spinal cord injury (SCI) is one of the most debilitating disorders throughout the world, causing persistent sensory-motor dysfunction, with no effective treatment. Oxidative stress and inflammatory responses play key roles in the secondary phase of SCI. Naringenin (NAR) is a natural flavonoid with known antiinflammatory and antioxidative properties. This study aims at evaluating the effects of intrathecal NAR administration on sensory-motor disability after SCI. Methods: Animals underwent a severe compression injury using an aneurysm clip. About 30 minutes after surgery, NAR was injected intrathecally at the doses of 5, 10, and 15 mM in 20 μL volumes. For the assessment of neuropathic pain and locomotor function, acetone drop, hot plate, inclined plane, and Basso, Beattie, Bresnahan tests were carried out weekly till day 28 post-SCI. Effects of NAR on matrix metalloproteinase (MMP)-2 and MMP-9 activity was appraised by gelatin zymography. Also, histopathological analyses and serum levels of glutathione (GSH), catalase and nitrite were measured in different groups. Results: NAR reduced neuropathic pain, improved locomotor function, and also attenuated SCI-induced weight loss weekly till day 28 post-SCI. Zymography analysis showed that NAR suppressed MMP-9 activity, whereas it increased that of MMP-2, indicating its anti-neuroinflammatory effects. Also, intrathecal NAR modified oxidative stress related markers GSH, catalase, and nitrite levels. Besides, the neuroprotective effect of NAR was corroborated through increased survival of sensory and motor neurons after SCI. Conclusions: These results suggest intrathecal NAR as a promising candidate for medical therapeutics for SCI-induced sensory and motor dysfunction.