A. T. Marques

Interface element including point‐to‐surface constraints for three‐dimensional problems with damage propagation

An interface finite element for three‐dimensional problems based on the penalty method is presented. The proposed element can model joints/interfaces between solid finite elements and also includes the propagation of damage in pure mode I, pure mode II and mixed mode considering a softening relationship between the stresses and relative displacements. Two different contact conditions are considered: point‐to‐point constraint for closed points (not satisfying the failure criterion) and point‐to‐surface constraint for opened points. The performance of the element is tested under mode I, mode II and mixed mode loading conditions.

Modeling Compression Failure after Low Velocity Impact on Laminated Composites Using Interface Elements

Low velocity impact damage can significantly reduce the residual strength of laminated composites. This kind of damage (mostly delaminations) is very dangerous for the structures because it is not apparent to the naked eye and, in some cases, it can reduce the compressive residual strength up to 60%. In this work, a numerical model for predicting the compression failure of laminated composites containing delamination caused by low velocity impact was developed. An interface finite element, previously developed by the authors, was used. This element is compatible with twenty-seven node isoparametric hexahedral elements and enables modeling the behavior of the damaged interface, taking into account a three-dimensional stress state, the interpenetration constraint and the propagation of delamination. In order to verify the numerical model, some experimental work was done. The experimental work, performed on carbon-epoxy (04, 904)5 and (904, 04), laminates, included low velocity impact tests using a drop weight testing machine, followed by X-Ray damage characterization and compression tests using a fixture system similar to IITRI system. The numerical and experimental results were compared and good agreement was obtained.

Caloric intake and weight gain in a neonatal intensive care unit

The aim of this paper was to study the weight gain in very-low-birthweight (VLBW) infants by adopting earlier and higher intake of proteins and earlier intake of lipids. We studied 28 VLBW infants admitted to Neonatal Intensive Care Unit during the year 2004 (group 1) and 18 during the first semester of 2006 (group 2). Dietary intakes for group 1 were: 1xa0g kg−1 day−1 of proteins started at postnatal day 2 (P2) and 0.5–1xa0g kg−1 day−1 of lipids at P3; for group 2, 1–1.5xa0g kg−1 day−1 of proteins and 0.5–1xa0g kg−1 day−1 of lipids, both started at P1. Caloric intake was significantly higher in group 2 (pu2009<u20090.05), whereas cumulative nutritional deficit was higher in group 1 (p ≤ 0.01). Weight z scores were significantly lower at discharge comparing with z scores at birth for each group (p ≤ 0.01), with no differences between the two groups. Despite a higher protein intake which resulted in a lower nutritional deficit, the weight z score did not improve significantly at discharge.

The Influence of Prestressing on the Mechanical Behaviour of Uni-directional Composites

The influence of pre-stressing the roving fibres upon the mechanical properties, namely the tensile strength and the modulus of an uni-directional composite was studied. The influence of strain rate upon the mentioned properties was also studied and a fractographic analysis was carried out seeking to caracterize the types of rupture and to assess the manual moulding technique used.

Fracture and Fatigue Damage in a CSM Composite

This paper presents a study on the mechanical properties, mode I fracture toughness and on the kinetics of fatigue crack growth in a CSM (chopped strand mat) E glass reinforced polyester resin composite. The environmental influence was studied through the immersion of the composite in an aquous solution of merthiolate tincture. The absorption kinetics of the composite when fully immersed in the aquous solution was also examined.

Echo endoscopy in the local staging of gastric cancer.

OBJECTIVESnto evaluate the accuracy of endoscopic ultrasonography (EUS) in the pre-operative T and N staging of gastric cancer.nnnPATIENTS AND METHODSn41 consecutive patients with gastric cancer (35 carcinomas and 6 lymphomas) underwent EUS using an Olympus GF-UM20, with 360 degrees sector scan and interchangeable frequency (7.5-12 MHz). They were classified as T1-T4 and N0-N2, according to the TNM system. These results were then compared with the surgical and pathological staging (SP), by the weighted K statistic (Kw).nnnRESULTSnIn 2 patients EUS staging was not possible due to cardiac stenosis and in other 4 patients, information about SP staging was not available. In the remaining 35 patients the EUS/SP agreement was good (Kw = 0.80) for stage T and moderate (Kw = 0.49) for stage N. Non-agreement was mostly due to EUS understaging, both T and N.nnnCONCLUSIONSn1) EUS is the most accurate procedure for pre-operative local staging of gastric cancer, and 2) EUS should preferably be performed by endoscopists with sonographic experience and a particular interest in the method.