Shear-lag analysis of a hybrid, unidirectional composite with fiber damage

Development of a method of analysis capable of predicting accurately the fracture behavior of unidirectional hybrid (buffer strip) composite laminates was studied. Three particular solutions are discussed in detail: broken fibers in a unidirectional half-plane; adjoined half planes of different fiber and matrix properties; and the solution of two half planes bounding a third distinct region of finite width. This finite width region represents a buffer strip and primary attention is given to the potential of this strip to arrest a crack that originates in one of the half planes. A materials modeling approach using the classical shear lag assumption to describe the stress transfer between fibers was analyzed. Explicit fiber and matrix properties of the three regions are retained, and changes in the laminate behavior as a function of the relative material properties, buffer strip width, and initial crack length are discussed

Analysis of a hybrid-undirectional buffer strip laminate

A method of analysis capable of predicting accurately the fracture behavior of a unidirectional composite laminate containing symmetrically placed buffer strips is presented. As an example, for a damaged graphite/epoxy laminate, the results demonstrate the manner in which to select the most efficient combination of buffer strip properties necessary to inhibit crack growth. Ultimate failure of the laminate after the arrest can occur under increasing load either by continued crack extension through the buffer strips or the crack can jump the buffer strips. For some typical hybrid materials it is found that a buffer strip spacing to width ratio of about four to one is the most efficient

Mathematical modeling of damage in unidirectional composites

A review of some approximate analytical models for damaged, fiber reinforced composite materials is presented. Using the classical shear lag stress displacement assumption, solutions are presented for a unidirectional laminate containing a notch, a rectangular cut-out, and a circular hole. The models account for longitudinal matrix yielding and splitting as well as transverse matrix yielding and fiber breakage. The constraining influence of a cover sheet on the unidirectional laminate is also modeled

PROBIOTIC Rhodotorula mucilaginosa ISOLATED FROM FERMENTED FOOD: INVESTIGATION OF PUFA PRODUCTION AND STRATEGY FOR HEALTH IMPROVEMENT

Polyunsaturated fatty acids (PUFAs) are a vital component for human health. PUFA cannot be synthesized by human system and hence dependance on other sources has become inevitable. Though porcine liver and fish oil were the dependable sources for ages past, yet cheaper microbial source was sought after and have gained importance as well. Such microbial oils normally used as biofuels can also be used for several therapeutic purposes. Hence, this study was designed to evaluate the quality and quantity of lipids produced by a probiotic yeast, Rhodotorula mucilaginosa. The lipid production potential of Rhodotorula mucilaginosa has indeed attracted a lot of attention. Isolation and characterization of the probiotic yeast with enhanced lipid production and determining the lipid components have become the aim of the work

Studies on clinical anatomy of the maxillofacial and mandibular regions of the Madras Red sheep (Ovis aries) in India

Background: The present study aimed to study the clinical anatomy of the maxillofacial and mandibular regions of the Madras Red sheep through the morphometric analysis of some clinically important parameters pertaining to the regional anaesthesia.  Materials and methods: The study was conducted in 20 male and 20 female adult Madras Red sheep around 20–25 kg body weight. Eleven parameters re- lated to the clinical regional anaesthesia of the maxillofacial and the mandibular regions were recorded.  Results: The distance between the facial tuberosity to the infraorbital canal was 2.25 ± 0.14 cm in males and 2.14 ± 0.15 cm in females. The distance from the infraorbital canal to the root of the alveolar tooth was 1.73 ± 0.28 cm in males and 1.73 ± 0.13 cm in females. The length and height of the mandibles were 15.37 ± 0.56 cm, 9.00 ± 0.24 cm and in males 14.53 ± 0.24 cm, 9.68 ± 0.16 cm in females, respectively. The maximum height of the mandible to the coro- noid process, width or height of the mandibular foramen and the distance from the condyloid process to the base of the mandible were recorded as 9.0 ± 24, 0.82 ± 0.05, 6.68 ± 0.19 cm in males and 9.68 ± 0.16, 0.83 ± 0.04, 6.25 ± ± 0.28 cm in females, respectively.  Conclusions: The present study revealed that most of the parameters showed statistically significant difference between the sexes i.e. the males had higher values. However, from the practical point of view, these differences were meagre. The results were discussed with regard to their clinical applications in various regional anaesthesia performed in maxillofacial and mandibular regions of the Madras Red sheep.

Thermal and Mechanical Response of Inner Cone Sample of ZrB₂-SiC Ceramic under Arc-Jet Conditions

Under arc-jet test conditions, ZrB2-SiC ceramic will undergo high temperature oxidation and develop an external glassy layer (SiO2), zirconia sub-layer (ZrO2) and SiC-depleted diboride layer (ZrB2). This study relates to finite element modeling of the effects of oxidation on heat transfer and mechanical behavior of ZrB2-SiC ceramic under arc-jet test conditions. A steady-state heat transfer FE method was employed to conduct the heat transfer analysis to obtain the temperature distribution in the inner body of the cone. The surface thermal conditions available in the literature were used in the heat transfer analysis. The resulting temperature distribution in the inner body of the cone is then applied to the thermomechanical finite element analysis to calculate the thermal stress distribution. The results show that the oxide layers affect both thermal and mechanical response of the ZrB2-SiC ceramic under arc-jet high temperature test conditions. Due to the mismatch of material properties between the bulk ZrB2-SiC and its new products after oxidation, the outer oxide layers constrain the thermal deformation of the inner bulk ZrB2-SiC thereby putting it in compression and outside oxide layers in tension

COMPOSITION OF THE ESSENTIAL OIL FROM MIMOSA PUDICA LINN.

Objectives: To determine the composition of the essential oil obtained from Mimosa pudica L. (Mimosaceae) Methods: The essential oil   of M. pudica was obtained by hydro distillation using a Clevenger apparatus and the chemical composition was determined by GC-MS analysis. Results: About 23 compounds were identified from the essential oil which constitutes about 98.92 % of the oil. Among the compounds identified phthalic acid dioctyl ester (27.76 %), α-Linolenic acid (20.34 %), Cinnamaldehyde (16.24 %) are the major compounds.  α-Linolenic acid is an n-3 fatty acid. Conclusion: α-Linolenic acid is one of the essential fatty acids, which is necessary for health and cannot be produced within the human body. Mimosa pudica L. (Mimosaceae) appears to be a promising herb to undergo a wide exploratio

COMPARATIVE STUDY OF EFFICACY AND SAFETY OF AZITHROMYCIN ALONE AND IN COMBINATION WITH PROBIOTIC IN THE TREATMENT OF IMPETIGO IN CHILDREN

Objective: Impetigo is a superficial infection of the skin that involves only the epidermis. It affects mostly children, usually on exposed areas of the body (eg. The face and the legs). Staphylococcus aureus is the most important causative organism. Streptococcus pyogenes (i.e.) group A beta-hemolytic streptococcus) causes fewer cases, either alone or in combination with S. aureus. The objective of this study is to find out the efficacy and safety of azithromycin alone and in combination with probiotic among children suffering from impetigo.Methods: This prospective, randomized, single-blinded interventional study was conducted for a period of 6 mo in pediatric OPD and dermatology OPD in Rajah Muthiah Medical College and Hospital. A total of 100 patients, randomly divided into two groups with 50 patients in each group. Group, I patients treated with Azithromycin 10 mg/kg/d for 5 d. Group II patients treated with Azithromycin 10 mg/kg/d for 5 d with probiotic (50 million spores of Lactobacillus sporegens, Streptococcus faecalis 30 million spores, clostridium butyricum 2 million spores, Bacillus mesentericus 1 million spores) twice daily for 5ds.Results: Reduction in a number of lesions and wound area, clinical response were highly significant in Azithromycin with the probiotic-treated group.Conclusion: In this study, probiotic bacteria may counteract the inflammatory process beyond the intestinal milieu. The results of this study indicate that Azithromycin with probiotic is effective in the treatment of impetigo

Failure Investigation of the Steel Strut of Paseo Suspension Bridge

A vertical strut of the 1232-foot long, self-anchored Paseo Suspension Bridge fractured when the temperature hit at a record low of 9°F below zero. During inspection the following day, it was found that its lower pin was frozen and did not allow for free movement of the superstructure. The objective of this study is to pinpoint one of the four reasons for this incidence or their combination: overstressing, thermal contraction, fatigue, and reduction in fracture toughness at low temperatures. To achieve this objective, material property and fatigue testing was performed on samples of strut material while the bridge and strut were analyzed under service loading conditions. This study indicated that the strut material practically has an infinite life under normal conditions. The root cause of the failure is overstressing of the vertical strut due to a frozen pin that became frozen because the design of the bridge did not allow the pin to be maintained. The mechanically frozen pin condition was attributable to salt and sand accumulation in the strut housing. To prevent this to the new struts and other similar structures, it is recommended that both upper and lower pins be greased during special inspections and the lower housings be partially sealed to prevent salt and sand accumulation near the pins. Alternatively, a rotation monitoring system can be installed to remotely monitor the rotation of all four vertical struts and alert officials should the pins become mechanically frozen

Load shifting and peak clipping for reducing energy consumption in an indian university campus

This paper analyzes the intelligent use of time-varying electrical load via developing efficient energy utilization patterns using demand-side management (DSM) strategies. This approach helps distribution utilities decrease maximum demand and electrical energy billing costs. A case study of DSM implementation of electric energy utility for an educational building Alagappa Chettiar Government College of Engineering and Technology (ACGCET) campus was simulated. The new optimum energy load model was established for peak and off-peak periods from the system's existing load profile using peak clipping and load shifting DSM techniques. The result reflects a significant reduction in maximum demand from 189 kW to 170 kW and a reduction in annual electricity billing cost from $11,340 to$10,200 (approximately 10%) in the upgraded system. This work highlights the importance of time of day (TOD) tariff structure consumers that aid reduction in their distribution system's maximum demand and demand charges. Copyright