Nonsingular stress and strain fields of dislocations and disclinations in first strain gradient elasticity

The aim of this paper is to study the elastic stress and strain fields of dislocations and disclinations in the framework of Mindlin's gradient elasticity. We consider simple but rigorous versions of Mindlin's first gradient elasticity with one material length (gradient coefficient). Using the stress function method, we find modified stress functions for all six types of Volterra defects (dislocations and disclinations) situated in an isotropic and infinitely extended medium. By means of these stress functions, we obtain exact analytical solutions for the stress and strain fields of dislocations and disclinations. An advantage of these solutions for the elastic strain and stress is that they have no singularities at the defect line. They are finite and have maxima or minima in the defect core region. The stresses and strains are either zero or have a finite maximum value at the defect line. The maximum value of stresses may serve as a measure of the critical stress level when fracture and failure may occur. Thus, both the stress and elastic strain singularities are removed in such a simple gradient theory. In addition, we give the relation to the nonlocal stresses in Eringen's nonlocal elasticity for the nonsingular stresses.Comment: 24 pages, 6 figures, to appear in: International Journal of Engineering Scienc

Speaking the same language: developing a language-aware feedback culture

Research suggests that feedback as part of assessment is often not delivered effectively. A key aspect of effective feedback delivery is that students need to understand feedback and also feel motivated to act on it. This article explores how educational developers can incorporate a language-aware approach to feedback when working with staff involved in learning and teaching in order to enable staff to make appropriate linguistic choices when providing feedback so that it is more comprehensible and motivational for students. It describes a piece of action research which explored and evaluated two teaching activities used on a PG Cert HE with staff at a post-1992 university, designed to promote critical awareness of the language used when giving feedback. We report on the staff evaluation of the activities devised and piloted, and consider how this project could be taken forward in future