Deformation and rupture of stainless steel under cyclic, torsional creep

Copyright 2008 @ Engineering Integrity Society.Recent results from a long-term, strain-limited, cyclic creep test program upon stainless steel tubes are given. The test conditions employed were: constant temperature 500 °C, shear stress Ƭ = ± 300 MPa and shear strain limits ƴ = ± 4%. It is believed that a cyclic creep behaviour for the material has been revealed that has not been reported before in the literature. That is, the creep curves for stainless steel under repeated, shear stress reversals shows two basic square root dependencies: one upon time and the other upon cycle number. Consequently, the combined effect is such that the shear creep strain depends upon the square root of the product of cycle number and the time elapsed within that cycle. Despite extended times of cycling, with the test running into a period of over a year, no secondary or tertiary creep stages were ever observed within individual creep curves. Thus both the forward and reversed creep curves were exclusively primary in nature, within which the only visible evidence of a slow degradation of the deforming material was that the creep interval reduced successively between the imposed strain limits. However, it was found that the creep curve, when plotted within axes of cumulative creep strain and time, did recover a "pseudo-tertiary" stage. This stage concords with earlier results that showed tertiary creep to be a dominant contributor to the creep curve for this material under a steady torque. Given either the tensile ductility of the material or, a tensile creep rupture time, it is shown how final failure is predicted from the phenomenological square root law and an equivalence criterion

Creep in fibre-reinforced polymer mat composites

Tensile creeps have been conducted upon a woven, glass-fibre laminated epoxy composite and a 0/90° cross ply, carbon fibre reinforced epoxy composite. For the laminate loading was aligned with a fibre direction. For the ply the loading was inclined to the fibres (off-axis). Testing to stress levels up to 200 MPa and temperatures in the range 20°- 200°C has revealed a form of creep in each material. The creep observed is essentially primary in nature but with extended time •1000 h, it may exhaust or resemble a pseudo-secondary regime with a low rate. Where the load carrying capacity is lost, through fibre breakage or tab slip, the creep rate accelerates suddenly to infinity in a few hours. Smooth creep curves apply to successful tests but many irregular curves resulted from grip failure. A phenomenological approach was used to model smooth curves using a summation of instantaneous, primary and secondary strain terms. For the mat reinforcement a consistent trend was not found between the secondary creep rate and a stress that was raised incrementally upon the same testpiece. However the cumulative instantaneous strain provided the correct elastic modulus. Creep in the solid laminate was believed to be due to a fibre straightening that yielded a limiting strain in a time beyond which the process exhausts. Creep in cfrc was only evident when the fibres were inclined to the stress axis, indicating a viscous flow in the matrix. Moreover, it is believed that a viscous shear sliding between laminates or plies is more likely to contribute to an off-axis deformation mode which is not strain limited.http://www.brunel.ac.uk/about/acad/sed/sedstaff/design/DavidRee

The introduction of an holistic design approach through a teaching company scheme

Traditional design approaches separate the various functions of design such as material selection, performance modelling and tolerance specification into discrete entities. Whilst this allows more focused methods to be used at each stage, areas of conflict or benefit may be overlooked, and the designer is left to bring the loose ends together. This paper looks at a synthesis approach that draws upon a number of current design themes. The design process is considered along with various aspects such as product development, design-for-`X' methodologies and material selection. The need for the preservation of design knowledge and reasoning, the so called wh-? questions, within the process are considered along with various models of the design process. The paper draws these various aspects together to form a more holistic approach to design. The application of this technique within the Teaching Company Scheme is briefly discussed

Legal Policy for Management of Criminal Action of Narcotics in Low Education

The objectives of this research are: To know and analyze how legal handling of narcotics crime among low education.To find out and analyze obstacles and solutions prevention of narcotics crime among low education. The results of this study areWays to Overcome the Law on Narcotics Crime Among Low Education, among others: 1) Preventive, namely policies that see the root causes of the main causes of crime through a social approach, a situational approach and a community approach to eliminate the elements of potential interference (Correlative Criminogen Factors); 2) Preventive (prevention), namely to form a society that has resistance and immunity to drugs. Prevention is better than eradication .; and 3) Repressive (repression), namely taking action against and eradicating drug abuse through legal channels and based on law, which is carried out by law enforcers or security forces assisted by the community. Internal obstacles are the lack of resources for sophisticated technology equipment to match the technological sophistication of drug network syndicates in distributing and producing drugs, while external obstacles that come from outside are the confusion of articles in the Narcotics Law regarding sanctions against victims of abusers, lack of participation and public participation as police intelligence to provide information and information in order to uncover and uncover cases of illicit traffic and narcotics abuse. Future efforts will be made to overcome obstacles in overcoming narcotics crime among low education. Drug Crime Unit personnel are given education or training on the use of technology so that they can use IT tools in order to detect narcotics offenders and networks; Narcotics Crime Unit personnel carry out vocational education in the field of combating narcotics crime. And the personnel of the Narcotics Crime Unit are required for investigators to continue their education to higher education so that their insight and understanding of the Narcotics Law can better understand so that they can carry out investigations into a more organized modus operandi

Abnormal liquor volume and mode of delivery

Introductions: Sonographic assessment of four quadrant measurement of amniotic fluid index (AFI) is an integral part of antenatal evaluation of pregnancies, especially in the third trimester. Decreased (oligohydramnios, AFI 0-9.9 cm) or increased (polyhydramnios >25 cm) increases the risk of intrauterine growth retardation, birth asphyxia and induction or operative interference. The aim of this study was to analyse abnormal liquor volume and mode of delivery. Methods: This retrospective cross-sectional study analysed the cases of abnormal liquor volume in term pregnancies during 2013-2016 at Patan Hospital. Patient's files were traced from medical record section. We analysed the abnormal liquor volume based on amniotic fluid index (AFI) and the mode of deliveries. Results: Among 15,272 term pregnancies scanned, 130 had abnormal AFI, 128 oligohydramnios and 2 polyhydramnios. Out of 128 oligohydramnios, 40 (30.8%) were severe, 54 (41.5%) moderate and 34 (26.2%) mild. Two cases had polyhydramnios. The emergency lower uterine segment caesarean sections (emLSCS) were performed in 99 (76.1%) oligohydramnios. Conclusions: This study suggests that oligohydramnios measured by AFI at term pregnancy required more emLSCS. Keywords: amniotic fluid index, oligohydramnios, polyhydramnios, emergency caesarean sections, spontaneous vaginal deliverie

Congenital anomalies in antenatal ultrasound scan at a tertiary care teaching hospital

Introductions: Early detection of congenital fetal anomalies by ultrasonography (USG) helps to identify the severity and termination of pregnancy in severe cases. Anomalies cause significant perinatal morbidity and mortality. Aim of this study was to analyse real-time USG detection of prenatal anomalies. Methods: This was a cross-sectional descriptive study of fetal anomalies detected during 2nd and 3rd trimester antenatal USG scan done from 2011 to 2015, in Patan Hospital. Age of mother, parity, gestational age when anomalies detected and, anomalies of previous child, use of folic acid were analysed. Descriptive analysis was done. Results: There were 35,571 deliveries in four years period with 134 (0.37%) congenital anomalies, 99 (79.2%) detected during antenatal USG during 2nd and 3rd trimester. Among 99 anomalies, 29 (29.29%) were detected before 22 weeks. Central nervous system (CNS) anomalies were 47, gastrointestinal 23, renal 12, skin and fetal compartment 8 and rest were less common. Young mothers of less than 30 years were 109 (81.34%) and primi were 85 (63.4%). Conclusions: Antenatal ultrasound can detect fetal anomalies in 2nd and 3rdtrimester with higher frequencies belonging to the central nervous system followed by gastrointestinal tract anomalies and renal. Keywords: congenital anomalies, gestational age, prenatal ultrasound sca

Landslide Analysis Using Seismic Refraction Tomography And MASW: a Case Study in Ponorogo, East Java, Indonesia

Ponorogo district morphology form consisting of highlands and hills make this area vulnerable to landslides. Based on the BNPB (National Disaster Management Agency) data from 2013 to 2017, 77 landslides and 35% have occurred in Ngrayun and Slahung sub-districts. One area that has the potential to experience landslides is Tugurejo village in Slahung District. This study aims to determine the physical properties of subsurface rocks using SRT (Seismic Refraction Tomography) and MASW (Multi-channel Analysis of Surface Waves). The seismic velocity distribution defined from the SRT and MASW at the study sites shows a zone with a higher porosity that is interpreted to represent the level and depth of rock mass movement. P-wave velocity and S-wave indicates very low velocity of 500 – 1200 m/s and 100 – 250 m/s at depths up to 5 m

Pemodelan Numerik Data Potensial Diri (Self Potential)

Masalah kuantitatif dalam metode potensial diri terkadang masih ditemukan. Beberapa asumsi dan metode inversi digunakan dalam proses pembuatan modelnya agar dicapai error yang sekecil mungkin sehingga makin mendekati kondisi sebenarnya. Telah dilakukan ”Pemodelan Numerik Data Potensial Diri (Self Potential)” untuk menginterpretasi secara kuantitatif anomali dan parameter geometri dari anomalinya. Asumsi model yang digunakan adalah geometri sederhana dari data potensial diri. Program untuk pemodelan numerik ini dibuat di perangkat lunak MATLAB yang meliputi pemodelan kedepan dan pemodelan kebelakang. Metode inversi yang dipakai yaitu metode yang dikembangkan oleh El-Araby (2003). Program yang dibuat selanjutnya diuji pada data sintetik (3 data) dan data sekunder (3 data). Berdasarkan hasil penelitian yang sudah dilakukan, untuk data sintetik, hasil RMS error-nya sebagian besar dibawah 10%. Di samping itu, untuk data sekunder, hasilnya sesuai dengan referensi yang dipakai, dimana data sekunder 1 dan 2 saling memvalidasi karena berada pada daerah yang sama namun beda lintasan pengukuran yang jenis sumber anomalinya adalah bola karena berkaitan dengan mineral tembaga. Sedangkan untuk data sekunder 3, sumber anomalinya adalah vertical cylinder, yaitu rembesan yang berhubungan dengan potensial streaming yang terjadi di daerah bendungan

Correlation of ultrasound imaging with histopathological findings in gestational trophoblastic disease

Introduction:  Gestational trophoblastic diseases (GTD) include a spectrum of pregnancy-related diseases caused by abnormal proliferation of the placenta .  The main aim of this study to study the Correlation of ultrasound imaging with histopathological findings in gestational trophoblastic disease. Method: This is the retrospective study consisting of 155 sonographically diagnosed cases of GTD collected for three years 2016-2019. These patients were evaluated by transabdominal sonography. All these patients underwent Evacuation of product of conception (POC) and samples were subsequently sent for histopathological examination Their histopathological reports were followed up. The Correlation between USG and histopathological findings in GTD was studied. Result :  Among these 155 sonographically diagnosed cases of GTD 141 (91.0%) were  histologically confirmed GTD,  14 (9.0%) were  non-molar miscarriages on histological examination. In 141 cases of histologically confirmed GTD, 110 (71.0 %) were partial mole, 15 (9.7%) complete mole, 12 (7.7%) invasive mole and 3 (1.9 %) persistent mole, 1(0.6%) was choriocarcinoma. Conclusion :  The diagnostic accuracy of ultrasound to be 90% in the diagnosis of GTD, increasing its reliability. Thus ultrasound seems to be an initial modality of choice in the workup of every woman suspected of having GTD

PENDUGAAN POTENSI AIR TANAH DI DAERAH SUMBA TIMUR DENGAN MENGGUNAKAN DATA CITRA SATELIT DAN GEOLISTRIK

Telah dilakukan kajian pendugaan potensi air tanah di daerah Sumba Timur dengan menggunakan data citra satelit SRTM dan geolistrik tahanan jenis. Citra SRTM digunakan untuk analisa morfologi bentang alam sedangkan pengukuran geolistrik bertujuan untuk mendapatkan gambaran litologi bawah permukaan tanah untuk mendapatkan potensi air tanah. Survei sebaran mata air dilakukan untuk menguatkan analisis data. Data SRTM menunjukkan morfologi bentang alam berupa dataran batugamping berundak mulai dari pantai di sisi Timur kearah Barat. Mata air ditemukan berada di kaki dataran berundak yang merupakan perpotongan topografi. Pengolahan data geolistrik menunjukkan bahwa susunan batuan bawah permukaan tanah daerah kajian terdiri dari batugamping terumbu yang merupakan anggota Formasi Kaliangga sebagai lapisan berpori pembawa air dan batupasir tufan anggota Formasi Kananggar sebagai lapisan kedap penahan air. Morfologi berupa perundakan batugamping di sebagian besar area kajian menjadikan keterdapatan mata air berada di kaki undak atau perpotongan topografi. Hal ini menguatkan dugaan bahwa air permukaan meresap kebawah menembus pori batugamping terumbu kemudian tertahan oleh batupasir tufan dan keluar sebagai mata air di perpotongan topografi. Hal ini konsisten dengan hasil pengukuran geolistrik yang menunjukkan dominasi batugamping terumbu di area kajian dan minimnya curah hujan menjadikan daerah kajian menjadi daerah kering