Thin-walled members are increasingly used in structural applications, especially in light structures like in constructions and aircraft structures because of their high strength-to-weight ratio. Perforations are often made on these structures for reducing weight and to facilitate the services and maintenance works like in aircraft wing ribs. This type of structures suffers from buckling phenomena due to its dimensions, and this suffering increases with the presence of holes in it. This study investigated experimentally and numerically the buckling behavior of aluminum alloy 6061-O thin-walled lipped channel beam with specific holes subjected to compression load. A nonlinear finite elements analysis was used to obtain the buckling loads of the beams. Experimental tests were done to validate the finite element results. Three factors namely; shape of holes, opening ratio D/Do and the spacing ratio S/Do were chosen to study their effects on the buckling strength of the channel beams. Finite elements results were obtained by using Taguchi method to identify the best combination of the three parameters for optimum critical buckling load, whereas determining the contribution of each parameter on buckling strength was implemented by using the analysis of variance technique (ANOVA) method. Results showed that the combination of parameters that gives the best buckling strength is the hexagonal hole shape, D/Do=1.7 and S/Do= 1.3 and the opening ratio (or size of holes) is the most effective on buckling behavior.
This paper deals with the preparation of new monomers and polymers which including heterocyclic unit. The diacid chlorides compounds [1-3] were prepared from the reaction of glutaric acid, adipic acid, terephthalic acid with thionyl chloride. Succinic acid reacted with ethanol to produce compound [4]. Compound [4] reacted with hydrazine hydrate to obtain succinic hydrazide [5].Compound [5] reaction with CS2 and KOH in absolute ethanol to produce compound [6].The polymers [7-12] have been created by reacting diacid chlorides compounds [1-3] with compound[5] or [6] in dry pyridine with some drops of DMF. The topology of produced compounds has characterized through their spectral and analytical data as in FT-IR spectra, Thermal analysis [DSC,
... Show MoreA field experiment was carried out at the research station of the College of Agriculture - Wasit University / Kut, during the fall season 2021 in soil with texture (sandy mixture) using the RCBD design in the arrangement of splintered plates and with three replications, to study the effect of spraying different combinations of organic emulsion (Appetizer) and NPK nano fertilizer with urea fertilizer on the growth of synthetic cultivars of yellow corn. The main panels included three synthetic varieties of yellow corn (Fajr1, Sumer and Baghdad3), which symbolized by (V1,V2,V3) in sequence, while the secondary panels included five fertilization treatments in which mineral fertilizer (urea) was used 46% nitrogen with the full recomme
... Show MoreThe study included the collection of samples of raw cow milk to isolate Leuconostoc bacteria, samples were sub cultured on De-Man Rogosa Sharpe-Vancomycin medium, the pure colonies were selected and subjected to the cultural and microscopically tests, according to that 25 cocci bacterial isolates were obtained, then isolates were subjected to biochemical tests. Result of tests showed that 12 isolates belong to the genus Leuconostoc out of 25 cocci bacterial isolates, Vitek2 system was used as a supplementary step. Results of final identification showed that 3 sub species were obtained included Leuconostoc mesenteroides ssp. cremoris 9 out of 12 isolates, while it was 2 isolates of Leuconostoc mesenteroides ssp. mesenteroides and one isol
... Show MoreBackground: The final stage of endodontic therapy is complete obturation of the root canal system to provide as perfect as possible at the cementodentinal junction of the apical foramen. The purpose of this in vitro study was to evaluate the sealing ability of injection molded thermoplasticized gutta percha and lateral condensation techniques with and without the use of sealers. Materials and Methods: Forty freshly extracted adult human maxillary central incisors with complete formed apices were utilized in this study. The teeth were randomly divided into four groups for evaluation of the apical seal. Group (1) lateral condensation gutta percha technique without sealer, (2) lateral condensation gutta percha technique with sealer, (3) Inject
... Show MoreThe study was conducted to identify the toxicity of chromium on scenedesmus quadricauda algae alone and in the presence of nutrient metal (Nitrogen). Different concentrations of chromium (0.5, 1.5 , 2.5, 3.5 , 4.5mg/L) were used and the presence nitrogen is (5 ,10 ,50 ,100mg/L) on cultur media(chu-10) with used for cultivation of the algae in controlled conditions(25oC , light intensity 380 –?E/m2 /s. The results showed increasing in the toxicity of the metal when is alone , excess of concentrations an time of exposure. The growth rate decreased from 0.44 to 0.06 cell/ hour after 12 day of the biging of the experiment and of concentrate 4.5 mg/L of chromium. The intermediate active concentrations of the chromium(EC50) was increase
... Show MoreThe chamomile is one of the most important medicinal plants recommended for treatment of asthma and some respiratory system diseases. This research was designed to research the effects of aqueous extract of chamomillarecutita on histological structure of Diaphragm of albino mice. The study included 40 male albino mice Musmusculus, their age ranged from (5-7) weeks.The mices were divided randomly to 5 groups and oral administered with 1 ml every day for 10 days:- First Group G1: consider as control group and treated with normal saline,Second Group G2: was treated with aqueous extract of chamomile with concentration of 3 gm /100 ml D.W, Third Group G3: was treated with aqueous extract of chamomile with concentration of 5 gm /100 ml D.W.Fourth
... Show MoreIn this study; the genus of Sinoxylon Duftschmid, 1825 (Coleoptera, Bostrichidae) was revised. There were 3 species registered in our investigations: S. anale Lesne, 1897; S. ceratoniae (Linnaeus, 1758) and S. muricatum (Olivier, 1790), the last species was redescribed as being found for the first time for the Iraqi faunal insects. Key to the species were constructed and supported by figures of the main diagnostic characters and some morphological features.