Modelling and simulations of ductile iron solidification-induced variations in mechanical behaviour on component and microstructural level

The mechanical behaviour and performance of a ductile iron component is highly dependent on the local variations in solidification conditions during the casting process. Here we show a framework which combine a previously developed closed chain of simulations for cast components with a micro-scale Finite Element Method (FEM) simulation of the behaviour and performance of the microstructure. A casting process simulation, including modelling of solidification and mechanical material characterization, provides the basis for a macro-scale FEM analysis of the component. A critical region is identified to which the micro-scale FEM simulation of a representative microstructure, generated using X-ray tomography, is applied. The mechanical behaviour of the different microstructural phases are determined using a surrogate model based optimisation routine and experimental data. It is discussed that the approach enables a link between solidification- and microstructure-models and simulations of as well component as microstructural behaviour, and can contribute with new understanding regarding the behaviour and performance of different microstructural phases and morphologies in industrial ductile iron components in service.

The well-being of relatives of patients with atrial fibrillation: a critical incident technique analysis

BACKGROUND: The well-being of relatives of patients having chronic heart diseases (CHD) has been found to be negatively affected by the patient's condition. Studies examining relatives of patients with atrial fibrillation (AF) indicate that their well-being may be affected in a similar manner, but further research is needed. AIM: To explore and describe critical incidents in which relatives of patients experience how AF affects their well-being and what actions they take to handle these situations. DESIGN AND METHOD: An explorative, descriptive design based on the critical incident technique (CIT) was used. Interviews were conducted with 19 relatives (14 women and five men) of patients hospitalised in southern Sweden due to acute symptoms of the AF. RESULTS: The well-being of relatives was found to be affected by their worries (patient-related health), as well as the sacri-ficing of their own needs (self-related health). In handling their own well-being, these relatives adjusted to and supported the patient (practical involvement), along with adjusting their own feelings and responding to the mood of the patients (emotional involvement). CONCLUSION: The well-being of relatives of patients with AF was affected depending on the patients' well-being. In their attempt to handle their own well-being, the relatives adjusted to and supported the patients. Further research is needed in order to evaluate the effects of support to relatives and patients respectively and together.