Closed form solutions for the elastic and elastic-plastic stress fields created by circumferential notches in an axisymmetric shaft under torsional loading are developed. The linear elastic boundary value problem has been formulated by an approach using complex potential functions and some curvilinear coordinate systems. The solutions obtained for the shear stresses have a wide range of applicability, both in terms of the size and shape of the notches and the diameter of the shafts. Conversely the elastic-plastic problem has been solved in closed-form by using the hodograph transformation technique, which reduces the non-linear governing equations into a linear equation system. The present paper is a synthesis of some contributions recently published the same authors.

In this investigation the extent of the plastic zone size ahead of a crack-tip in single edge notched tension (SENT), compact tension (CT) specimens has been examined experimentally by micro-hardness technique and by elastic-plastic finite element analyses at different applied load levels. The magnitudes of the plastic zone size (PZS), rp ahead of crack-tip in the investigated specimens have been compared using normalized J-integral (J/a?y, where, a-crack length and ?y-yield stress of the material). The results show the dependence of PZS on specimen geometry due to varied in-plane crack-tip constraint. The results also demonstrate that the existing analytical models do not explain the experimental results of PZS satisfactorily.

Dealing with composites in polymeric matrix, the pultruded ones are among the more suitable for large production rates and volumes. For this reason, their use is increasing also in structural applications in civil and mechanical engineering. However, their use is still limited by the partial knowledge of their fatigue behaviour; in many applications it is, indeed, required a duration of many millions of cycles, while most of the data that can be found in literature refer to a maximum number of cycles equal to 3 millions. In this paper a pultruded composite used for manufacturing structural beams is considered and its mechanical behaviour characterized by means of static and high-cycle fatigue tests. The results allowed to determine the S-N curve of the material and to assess the existence of a fatigue limit. Observations at the scanning electronic microscope (SEM) allowed to evaluate the damage mechanisms involved in the static and fatigue failure of the material.

The main objective of this research is improvement of red soil with addition of construction materials. This method could provide a scientific way to create a soil foundation with sufficient stability against geo-technical problems or instabilities. Laboratory tests have been conducted to assess the behavior of red soil, when amended with different types of gravels, soils and sand under compacted conditions with Optimum Moisture Content (OMC). Safe bearing capacity of all models, have been calculated to identify best and worst soil mixed model.

A brief description of surface nanosrystallization process via severe plastic deformation is presented. To come to the point different shot peening methods which have proved to be able to create nanocrystalline layers are demonstrated clarifying the actual state of the art. Then the influence of the process is reviewed on material behavior and a wide range of affected properties are investigated. On this basis some possible addresses for future research in this field are drawn and underlined.

Dealing with composites in polymeric matrix, the pultruded ones are among the more suitable for large production rates and volumes. For this reason, their use is increasing also in structural applications in civil and mechanical engineering. However, their use is still limited by the partial knowledge of their fatigue behaviour; in many applications it is, indeed, required a duration of many millions of cycles, while most of the data that can be found in literature refer to a maximum number of cycles equal to 3 millions. In this paper a pultruded composite used for manufacturing structural beams is considered and its mechanical behaviour characterized by means of static and high-cycle fatigue tests. The results allowed to determine the S-N curve of the material and to assess the existence of a fatigue limit. Observations at the scanning electronic microscope (SEM) allowed to evaluate the damage mechanisms involved in the static and fatigue failure of the material.

The problem of assessing the ductility of reinforced concrete (RC) structural elements in bending or under the action of eccentric forces has been largely investigated from both the experimental and the analytical point of view during the last decades. Since the development of ductility is influenced by several design parameters, it is difficult to develop a predictive model able to fully describe the mechanical behaviour of the structural element. In particular, the role of the size-scale effect, which has been evidenced by some experimental tests, is not yet completely understood. One of the main reasons is the inadequacy of the traditional models based on ad hoc stress-strain constitutive laws. In the present contribution, a new model based on the concept of strain localization is proposed, which is able to describe both cracking and crushing growths during the loading process. In particular, the nonlinear behaviour of concrete in compression is modelled by the Overlapping Crack Model, which describes the strain localization due to crushing by means of a material compenetration. With this numerical algorithm in hand, it is possible to effectively capture the flexural behaviour of RC structural elements by varying the reinforcement percentage and/or the structural size. Numerical applications regard the analysis of the post-peak nonlinear response of concrete specimens subjected to eccentric compression tests and the evaluation of the plastic rotation of RC beams under three-point bending. An extensive comparison with experimental results is also proposed, fully demonstrating the effectiveness of the proposed approach.

The main objective of this research is improvement of red soil with addition of construction materials. This method could provide a scientific way to create a soil foundation with sufficient stability against geo-technical problems or instabilities. Laboratory tests have been conducted to assess the behavior of red soil, when amended with different types of gravels, soils and sand under compacted conditions with Optimum Moisture Content (OMC). Safe bearing capacity of all models, have been calculated to identify best and worst soil mixed model.

In this investigation the extent of the plastic zone size ahead of a crack-tip in single edge notched tension (SENT), compact tension (CT) specimens has been examined experimentally by micro-hardness technique and by elastic-plastic finite element analyses at different applied load levels. The magnitudes of the plastic zone size (PZS), rp ahead of crack-tip in the investigated specimens have been compared using normalized J-integral (J/a?y, where, a-crack length and ?y-yield stress of the material). The results show the dependence of PZS on specimen geometry due to varied in-plane crack-tip constraint. The results also demonstrate that the existing analytical models do not explain the experimental results of PZS satisfactorily.