LOW CYCLE FATIGUE OF T-TUBULAR JOINTS WITH OUT-OF-PLANE BENDING LOADING

ABSTRACT Tubular T-joints were fatigue tested with out-of-plane bending loading. Six models were tested, three models with Rratio of 0 and three with R = -1. Hot spot stress was measured for the brace and for the chord using the ECSC linear extrapolation procedure. Fatigue loading was applied in load control, to obtain through thickness cracking at a number of cycles in the range 4 000 -200 000 cycles. The data were analysed and compared with published data and with current fatigue design criteria for tubular joints. INTRODUCTION Fatigue loading on tubular offshore structures is predominately wave loading. For a design life of 20 years the number of cycles is of the order of 10 8 and the major contribution to the cumulative damage is from stress ranges corresponding to a constant amplitude life above 10 5 cycles. For this reason design SN curves for tubular joints are based on fatigue tests in the high cycle range, i.e. in the range 10 5 -1

Carotid Atherosclerosis and Longitudinal Changes of MRI Visual Rating Measures in Stroke Survivors: A Seven-Year Follow-Up Study

Objectives We aimed to assess longitudinal changes in MRI measures of brain atrophy and white matter lesions in stroke and transient ischemic attack (TIA) survivors, and explore whether carotid stenosis predicts progression of these changes, assessed by visual rating scales. Materials and Methods All patients with a first-ever stroke or TIA admitted to Bærum Hospital, Norway, in 2007/2008, were invited in the acute phase and followed for seven years. Carotid ultrasound was performed during the hospital stay. Carotid stenosis was defined as ≥50% narrowing of lumen. MRI was performed one and seven years after the index event and analyzed according to the visual rating scales Fazekas scale (0-3), Medial Temporal Lobe Atrophy (MTLA) (0-4) score, and Global Cortical Atrophy (GCA) scale (0-3). Patients with MRI scans at both time points were included in this sub-study. Results Of 227 patients recruited, 76 had both MRI examinations. Mean age 73.9±10.6, 41% women, and 9% had ≥50% carotid stenosis. Mean Fazekas scale was 1.7±0.9 and 1.8±1.0, mean MTLA score 1.0 ±1.0 and 1.7±1.0, and mean GCA scale score 1.4±0.7 and 1.4±0.6 after one and seven years, respectively. 71% retained the same Fazekas scale score, while 21% showed progression. Deterioration in GCA scale was seen in 20% and increasing MTLA score in 57%. Carotid stenosis was not associated with progression on Fazekas score, MTLA score or GCA scale. Conclusions Three out of five showed progression on the MTLA score. Carotid stenosis was not associated with longitudinal change of visual rating scales