Equivalent Stress Approach to Life Prediction of Creeping Solids with Initial Defect

High temperature components contain many crack like defects introduced during the fabrication processes. These defects will grow during service under the action of applied stress and elevated temperature. An equivalent stress approach has been developed in this paper which can be effectively used to predict the life of defective materials under creep conditions

Outcome of emergency cerclage for advanced cervical dilatation: a retrospective analysis

Background: The objective was to evaluate the outcome of late second trimester emergency cerclage in patients with advanced cervical dilatation with bulging membranes.Methods: Setting: department of obstetrics and gynaecology, PSG Institute of medical sciences & research, Coimbatore, Tamil Nadu, India. This is a retrospective study of case files of patients who underwent emergency late second trimester cerclage for advanced cervical dilatation with bulging membranes between January 2009 to January 2014. McDonald’s technique was used in all the cases.Results:Altogether, 7 patients (100%) underwent late second trimester  emergency cerclage between 20-28 weeks of gestational age, out of which three  patients (42.86%) had term deliveries (>37w), and 3 patients (42.86 %) carried on their pregnancies to more than 32 weeks resulting in healthy live born babies. Two of them delivered by normal vaginal delivery, 4 underwent LSCS, and one patient had severe abdominal pain with bleeding and draining per vaginum after 3 days of cerclage, in view of which the stitch was removed. Subsequently, the patient expelled a live foetus weighing 620gms, which died in the Neonatal Intensive Care Unit (NICU) after 3 hours. This procedure prolonged the duration of pregnancy in all patients with a mean duration of 70.4 days. The mean gestational age at the time of delivery was 34.33 weeks. The mean birth weight was 2.18 kg and ranged between 1.97 to 2.64 kg. The mean APGAR at one minute was 8/10 and the mean duration of stay in NICU was 1.66 days. All the new-born babies were healthy at the time of discharge. The live birth rate following emergency late second trimester cerclage in this series was 85.75%.  Conclusion:Favourable neonatal outcome can be accomplished in patients with cervical incompetence in the second trimester of pregnancy following emergency cervical suturing, even if performed when the membranes are bulging through the cervix.

Predictions and observations of soft clay foundations stabilized with geosynthetic drains and vacuum surcharge

This chapter starts with an introduction of a revised analytical model of radial drainage with vacuum preloading in both axisymmetric and plane strain conditions. Observed from large-scale radial drainage consolidation tests, the influence of vacuum pressure distribution along the drain length is examined through the dissipation of average excess pore pressure and associated settlement. The details of an appropriate conversion procedure by transforming permeability and vacuum pressure between axisymmetric and equivalent plane strain conditions are described through analytical and numerical schemes. The effects of the magnitude and distribution of vacuum pressure on soft clay consolidation are investigated on the basis of average excess pore pressure, consolidation settlement, and time analyses. The writers describe a multi-drain plane strain finite element method analysis based on permeability conversion, which is employed to study the behavior of embankments stabilized at the site of the Second Bangkok International Airport with vacuum-assisted prefabricated vertical drains. In the field, a constant suction head is not always stable because of the occurrence of air leaks; therefore the magnitude of applied vacuum pressure was adjusted accordingly. The theoretical (numerical) predictions are compared with measured field data such as settlements, excess pore pressures, and lateral movements. The case history analysis employing the writers’ model indicates improved accuracy of the predictions in relation to the field observations. The data indicate that the efficiency of the prefabricated vertical drains depends on the magnitude and distribution of vacuum pressure as well as on the extent of air leak protection provided in practice