Efficient Finite Element for Evaluation of Strain Concentrations

ABSTRACT MARINTEK has developed software for detailed analysis of pipelines during installation and operation. As part of the software development a new coating finite element was developed in cooperation with StatoilHydro enabling efficient analysis of field joint strain concentrations of long concrete coated pipeline sections. The element was formulated based on sandwich beam theory and application of the Principle of Potential Energy. Large deformations and non-linear geometry effects were handled by a Co-rotated "ghost" reference description where elimination of rigid body motion was taken care of by referring to relative displacements in the strain energy term. The nonlinearity related to shear interaction and concrete material behaviour was handled by applying non-linear springs and a purpose made concrete material model. The paper describes the theoretical formulation and numerical studies carried out to verify the model. The numerical study included comparison between model and full-scale tests as well as between model and other commercial software. At last a 3000 m long pipeline was analysed to demonstrate the strain concentration behaviour of a concrete coated pipeline exposed to high temperature snaking on the seabed

Strength Analysis Modelling of Flexible Umbilical Members for Marine Structures

This paper presents a 3-dimensional finite element formulation for predicting the behaviour of complex umbilical cross-sections exposed to loading from tension, torque, internal and external pressure including bending. Helically wound armours and tubes are treated as thin and slender beams formulated within the framework of small strains but large displacements, applying the principle of virtual displacements to obtain finite element equations. Interaction between structural elements is handled by 2-and 3-noded contact elements based on a penalty parameter formulation. The model takes into account a number of features, such as material nonlinearity, gap and friction between individual bodies, and contact with external structures and with a full 3-dimensional description. Numerical studies are presented to validate the model against another model as well as test data

Systematic review of the factors affecting cat and dog owner compliance with pharmaceutical treatment recommendations

© 2018 British Veterinary Association. The aim of this systematic review is to describe and assess the quality of the existing evidence base concerning factors that influence the compliance of cat and dog owners to pharmaceutical and specifically polypharmacy treatment recommendations. PubMed, CAB Abstracts and Google were searched to identify relevant literature and search results were filtered according to predetermined inclusion and exclusion criteria. Standardised data extraction and critical appraisal were carried out on each included study, and a Centre for Evidence-Based Medicine level of evidence grading was applied. Of the 8589 studies, eight studies were included in the review. Majority (five of eight) of the included studies were examining compliance with short-term antimicrobial therapies and none examined polypharmacy. Multiple definitions of compliance, methods of measurement and different factors potentially affecting compliance were used. Factors reported to have affected compliance in at least one study were dosing regimen, discussion of dosing regimen in light of owners' circumstances, consultation time, disease, month of consultation/treatment, physical risk, social risk and method of administration. The evidence available regarding factors affecting client compliance with pharmaceutical treatment recommendations in cats and dogs is scarce and of poor quality

Mortality due to trauma in cats attending veterinary practices in central and south-east England

Objectives: To identify important demographic and spatial factors associated with the risk of trauma and, more specifically, road traffic accident‐related mortality, relative to other diagnoses in cats. Methods: A sample of 2738 cats with mortality data derived from the VetCompass primary‐care veterinary database was selected for detailed study. Generalised linear models investigated risk factors for mortality due to trauma and due to road traffic accidents versus other causes

A new human challenge model for testing heat-stable toxin-based vaccine candidates for enterotoxigenic Escherichia coli diarrhea - dose optimization, clinical outcomes, and CD4+T cell responses

Enterotoxigenic Escherichia coli (ETEC) are a common cause of diarrheal illness in young children and travelers. There is yet no licensed broadly protective vaccine against ETEC. One promising vaccine development strategy is to target strains expressing the heat-stable toxin (ST), particularly the human ST (STh), since infections with these strains are among the leading causes of diarrhea in children in low-and-middle income countries. A human challenge model based on an STh-only ETEC strain will be useful to evaluate the protective efficacy of new ST-based vaccine candidates. To develop this model, we experimentally infected 21 healthy adult volunteers with the epidemiologically relevant STh-only ETEC strain TW10722, identified a suitable dose, assessed safety, and characterized clinical outcomes and immune responses caused by the infection. Doses of 1x10(10) colony-forming units (CFU) of TW10722 gave a suitable attack risk of 67% for moderate or severe diarrhea and an overall diarrhea attack risk of 78%. Non-diarrheal symptoms were mostly mild or moderate, and there were no serious adverse events. During the first month after ingesting the challenge strain, we measured significant increases in both activated CD4+ T cells and levels of serum IgG and IgA antibodies targeting coli surface antigen 5 (CS5) and 6 (CS6), as well as the E. coli mucinase YghJ. The CS5-specific CD4+ T cell and antibody responses were still significantly elevated one year after experimental infection. In conclusion, we have developed a safe STh-only ETEC-based human challenge model which can be efficiently used in Phase 2B trials to evaluate the protective efficacy of new ST-based vaccine candidates

CALIBRATION OF A FLEXIBLE PIPE TENSILE ARMOUR STRESS MODEL BASED ON FIBRE OPTIC MONITORING

ABSTRACT The present paper addresses calibration of a flexible pipe tensile armour stress model based on fibre optic monitoring. A full-scale flexible pipe was instrumented with fibreoptic Bragg grating (FBG) strain sensors in the inner tensile armour, enabling measuring the axial stress due to friction effects and the bending stresses due to bending about the strong axis of the tensile armour tendon. The measurements were used to study the dynamic stress as a function of global loading providing data for model calibration. A brief description is given of the applied sensor technology, how the sensor was integrated in a flexible riser, the test set-up and the test program. The paper focus on how these data were used and which parameters that are critical in order to provide a model that gives a best fit estimate of the dynamic stress distribution. A simple theory of shear interaction is presented. The theoretical model was implemented into the computer code BFLEX and comparisons made in terms of stress history plots including both the tested and predicted values

Fatigue damage analysis of dynamic power cables by laboratory testing and FE analysis

The study presents a comparison of models that can be used for fatigue life prediction of dynamic subsea power cables. It compares and discusses the modelling of fatigue damage degradation mechanisms that may be critical. Results from cyclic tension-bending laboratory tests were used to compare the numerical models and hypotheses on governing fatigue damage mechanisms. The BFLEX fine element software developed by SINTEF Ocean was used to model and simulate the laboratory tests. The model was developed based on the hypothesis that the conductor’s fatigue life is mainly governed by longitudinal stress ranges where the fatigue life can be predicted using SN-data for individual wires. The comparison of the results between the numerical simulations and tests showed that the numerical model overestimated the fatigue life. Hence, a model for fretting analysis between the wires was developed. The results from this model showed better agreement with the test results compared to the former model. It was concluded that the fatigue damage process of the conductors tested in the cyclic bending-tension tests was induced and governed by fretting, especially for small bending radii, with a clear superposition of damage caused by cyclic longitudinal stress ranges