| 1. |
- Hajikazemi, Mohammad, et al.
(författare)
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Analysis of cracked general cross-ply laminates under general bending loads : A variational approach
- 2017
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Ingår i: Journal of composite materials. - : Sage Publications. - 0021-9983 .- 1530-793X. ; 51:22, s. 3089-3109
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Tidskriftsartikel (refereegranskat)abstract
- A novel variational model is developed that can predict the stress transfer between plies in cracked general cross-ply laminates subject to general in-plane (Nxx, Nyy, Nxy) and out-of-plane bending (Mxx, Myy, Mxy) loading. The effects of thermal residual stresses are taken into account. Admissible stress systems, which satisfy equilibrium and all boundary and interface conditions, are constructed and the principle of minimum complementary energy is employed to find the optimal solution. The approach yields rigorous lower bounds for stiffness matrices. A methodology based on Levin's theorem is developed to evaluate the effective thermal expansion coefficients of non-symmetric cracked laminates. A ply-refinement technique is used in order that through-thickness variations of the stress components can be precisely taken into account. It is found that the developed method, when used in conjunction with ply refinement technique, results in stress fields and thermo-mechanical properties comparable in accuracy to refined finite and boundary element solutions.
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| 2. |
- Hajikazemi, Mohammad, et al.
(författare)
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Variational analysis of cracked general cross-ply laminates under bending and biaxial extension
- 2015
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Ingår i: International journal of damage mechanics. - : SAGE Publications. - 1056-7895 .- 1530-7921. ; 24:4, s. 582-624
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Tidskriftsartikel (refereegranskat)abstract
- In the current study, a variational model is developed for predicting stress transfer due to ply cracking in general cross-ply laminates subject to out-of-plane bending and biaxial in-plane loading. The model is valid for multiple ply laminates that can be nonsymmetric. Using the principle of minimum complementary energy, an optimal admissible stress field is derived that satisfies equilibrium, boundary, and traction continuity conditions. Natural boundary conditions are derived from the variational principle to overcome the limitations of the existing variational methods on the analysis of cracked general cross-ply laminates. Comparing laminates of glass/epoxy and graphite/epoxy with the available finite element results shows that stress components are in very good accordance with the analytical results. It is also shown that the existing variational models are specific cases of the current formulation. In the next step, the obtained stress field is used in conjunction with the principle of minimum complementary energy to get the effective stiffness modulus of a cracked general cross-ply laminate. It is indicated that the method provides a lower bound for the stiffness modulus of a cracked laminate.
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| 3. |
- Farida, Seyed Hamed Moazzami, et al.
(författare)
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Ethnobotanical Applications and Their Correspondence with Phylogeny in Apiaceae-Apioideae
- 2018
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Ingår i: RESEARCH JOURNAL OF PHARMACOGNOSY. - 2345-5977. ; 5:3, s. 79-97
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Forskningsöversikt (refereegranskat)abstract
- The Apiaceae family includes some of the most known medicinal, food and spice species in the world some of which have been used by humans since antiquity. Local people in different regions use many species of the family but the information regarding their uses is scattered. Traditionally used species are good candidates for bioprospecting. Combining traditional uses with phylogenetic data helps in selecting species for bioprospecting. In the present study, an ethnobotanical literature review was conducted to outline a comprehensive overview of the ethnobotanical importance of the family in Iran. To highlight the most ethnobotanically used groups in the family, ethnobotanical data were overlapped with generic phylogeny tree of the subfamily Apioideae. In total, 72 species (17.27%) from 42 genera (33.87%) were found to have ethnobotanical uses. Main uses of the family members were medicinal purposes (67.30%) followed by culinary (25%) and ethnoveterinary (11.11%) uses. Two categories of potential species groups for further bioprospecting investigations have been identified based on the phylogenetic analysis. Based on the findings of the present study, phylogenetic analysis can help in identifying potential groups for bioprospecting studies. More rigorous phylogenetic analysis that combines chemotaxonomy data, ethnomedicinal data and phylogenetic data are necessary to pinpoint exact lineages for specific medicinal properties.
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