Experimental investigation of damage progression and strength of countersunk composite joints

An experimental investigation is conducted into the damage progression and strength of bolted joints with fibre-reinforced composite laminates and countersunk fasteners. The main goal of the experimental investigation is to characterise the effect of the countersink geometry on the load-carrying capacity of single lap joints in comparison to the straight-shank case. The effects of bolt torque, clearance and countersink height ratio on the damage progression and joint strength are also studied. Experimental tests and detailed microscopy studies are conducted on a bearing test specimen with a straight-edged hole, and several single-lap joint configurations with countersunk fasteners. It is found that introduction of the countersunk hole roughly halves the bearing stress, and causes delamination for some configurations. This delamination is primarily located at the start of the countersink region, though is found to be triggered by other damage mechanisms and has only minor influence on the results. Bolt torque increases the density of through-thickness damage though limits its extension from the hole edge, whilst bolt clearance causes localisation of the damage region. Increasing the ratio of the countersink depth to the laminate thickness reduces the extent of bearing and promotes bending, with a change to net section failure at large ratios

The effect of clearance on single lap countersunk composite joints

An experimental investigation was conducted into the effects of bolt-hole clearance on the static strength and damage progression behaviour of single lap countersunk composite bolted joints. Joints were manufactured from carbon/epoxy plain weave fabric and tested with three different bolt clearance levels. The experimental results showed that the bolt-hole clearance had a minimal effect on the ultimate failure load of the bolted joint. However, a significant reduction (approx. 22%) was observed in the bearing damage initiation load, consistent with difference in the through-thickness damage profile. Finite element analysis was conducted, and was able to accurately capture the load-displacement behaviour and through-thickness damage profile of the joints

Characterising fibre compression fracture toughness of composites using bearing tests

In this paper we propose the use of a bearing test with a coupled experimental-numerical approach to characterise the critical strain energy release rate, or "fracture toughness", for fibre compression failure in bearing

Numerical analysis of damage progression and strength of countersunk composite joints

A numerical investigation is conducted into the damage progression and strength of bolted joints between fibre-reinforced composite laminates using countersunk fasteners. Experimental tests were previously conducted on a bearing test specimen and countersunk fastener single-lap joints. In this work, computational models are developed for Abaqus/Explicit, with continuum shells employed to model in-plane ply failure. The bolt-nut assembly is modelled with rigid elements, and the models account for bolt torque and frictional contact. The material properties required in the computational model are determined from standard tests, with the compression fracture toughness of composite plies calibrated against experimental data from the bearing test. The analysis approach captures the load-carrying capability of all configurations, and provides reasonable accuracy in predicting damage patterns. The effects of bolt torque, clearance and countersink height ratio are investigated, and the analysis results compare well with experimental findings. Furthermore, the analysis provides rich insight into the damage progression and joint behaviour at the ply level, with the in-plane and through-thickness damage patterns mapped for increasing applied load. Delamination is incorporated using a cohesive element layer at the start of the countersunk region, though has minimal influence on damage progression and load-carrying capability, which agrees with the experimental results

THERAPEUTIC PROPERTIES OF CAPSAICIN: A MEDICINALLY IMPORTANT BIO-ACTIVE CONSTITUENT OF CHILLI PEPPER

Plants are the source of numerous pharmaceutically important compounds that have been employed to cure various human ailments since ancient times. With the assistance of modern chemistry and materials science, such pharmaceutically important compounds have been identified and isolated to produce new drugs. Alkaloids are one of the most significant classes of naturally occurring secondary-metabolites, which are synthesized and widely distributed in various parts of plants. They regulate various metabolic activities and induce physiological responses in the human body. Capsaicin is a naturally occurring alkaloid found in many species of peppers and is attributed to their spicy nature and pungent flavor. This alkaloid is a member of the Capsaicinoids group, which includes capsaicin, homocapsaicin, homodihydrocapsaicin, dihydrocapsaicin, and nordihydrocapsaicin. Capsaicin has a wide range of therapeutic potential against various human ailments. In this article, we provide a comprehensive overview of the capsaicin molecule as well as an examination of its medicinal properties in a variety of human disorders, including pain, various types of cancer, ulcers, diabetes, obesity, inflammation, cardiovascular diseases, and neurodegenerative diseases

Diagnosis, Treatment, and Outcomes in Children With Congenital Nephrogenic Diabetes Insipidus: A Pediatric Nephrology Research Consortium Study

© Copyright © 2020 D\u27Alessandri-Silva, Carpenter, Ayoob, Barcia, Chishti, Constantinescu, Dell, Goodwin, Hashmat, Iragorri, Kaspar, Mason, Misurac, Muff-Luett, Sethna, Shah, Weng, Greenbaum and Mahan. Background and Objectives: Congenital or primary nephrogenic diabetes insipidus (NDI) is a rare genetic disorder that severely impairs renal concentrating ability, resulting in massive polyuria. There is limited information about prognosis or evidence guiding the management of these patients, either in the high-risk period after diagnosis, or long-term. We describe the clinical presentation, genetic etiology, treatment and renal outcomes in a large group of children (89%) and white (67%). Median age at diagnosis was 4.2 months interquartile range (IQR 1.1, 9.8). A desmopressin acetate loading test was administered to 46% of children at a median age of 4.8 months (IQR 2.8, 7.6); only 15% had a water restriction test. Genetic testing or a known family history was present in 70% of the patients; out of those genetically tested, 89 and 11% had mutations in AVPR2 and AQP2, respectively. No positive family history or genetic testing was available for 30%. The most common treatments were thiazide diuretics (74%), potassium-sparing diuretics (67%) and non-steroidal anti-inflammatory drugs (42%). At the time of first treatment, 70 and 71% of children were below −2 standard deviations (SD) for weight and height, respectively. At last follow-up, median age was 72.3 months (IQR 40.9, 137.2) and the percentage below −2 SD improved to 29% and 38% for weight and height, respectively. Adverse outcomes included inpatient hospitalizations (61%), urologic complications (37%), and chronic kidney disease (CKD) stage 2 or higher in 23%. Conclusion: We found the majority of patients were treated with thiazides with either a potassium sparing diuretic and/or NSAIDs. Hospitalizations, urologic complications, short stature, and CKD were common. Prospective trials to evaluate different treatment strategies are needed to attempt to improve outcomes

Ichthyofauna of Lidder Stream with Emphasis on Haematobiochemical Study of Schizothorax SPP.

Jammu & Kashmir, lying between six mountain ranges and covering an area of 2,22,236 sq. kms. is located between 32° 17' and 36° 58' North latitude, and between 37° 26' and 80° 30' East longitude. The state commonly known as Kashmir is bounded in the north by Afghanistan and China, in the east by China, in the south by the state of Himachal Pradesh and the state of Punjab in India, and in the west by the North-West Frontier Province and the Punjab Province of Pakistan. Jammu and Kashmir geographically comprises of three regions: the foothill plains of Jammu; the lakes and blue valleys of Kashmir rising to alpine passes, the high altitude plains and starkly beautiful mountains of Ladakh which lies beyond narrow passes. Kashmir is rightly said to be the nature's grand finale of beauty. In this masterpiece of earth's creation seasons in strong individuality vary with one another in putting up exquisite patterns of charm and loveliness. This state holds the glorious history of the valiant kings, the placid lakes, the greenery of the forests and the amazing rivers. The sunny gardens, romantic house boats and Lakes add to the beauty of the region. The state of J&K measures about 425 kms from north to south and extends over 520 kms from east to west