G. Milani¹, T. Rotunno², E. Sacco³, A. Tralli^1,4

Structural Durability & Health Monitoring, Vol.2, No.1, pp. 29-50, 2006, DOI:10.3970/sdhm.2006.002.029

Abstract Aim of the present work is the evaluation of the ultimate load bearing capacity of masonry panels reinforced with FRP strips. The investigation is developed performing both experimental and numerical studies. In particular, several panels subjected to different loading conditions are tested in the Tests Laboratory of the University of Florence (Italy). Then, numerical models based on combined homogenization and limit analysis techniques are proposed. The results obtained by numerical simulations are compared with experimental data. The good agreement obtained shows that the proposed numerical model can be applied for the evaluation of the ultimate More >

R.S. Olivito¹, F.A. Zuccarello¹

Structural Durability & Health Monitoring, Vol.2, No.1, pp. 19-28, 2006, DOI:10.3970/sdhm.2006.002.019

Abstract During the last decades FRP materials have been utilized in many civil engineering applications for their good performances in substituting traditional restoration techniques, especially in reinforcing and restoring damaged structures. At present, the use of composite materials is greatly increasing as a consequence of the fact that conservation and restoration of existing historic heritage are becoming key issues for civil engineers and architects. This paper deals with the behavior of brick masonry models subjected to cyclic loads with the aim of studying their performances and durability. Firstly the models were damaged by imposing a strain More >

R. Costa¹, J. Alfaiate²

Structural Durability & Health Monitoring, Vol.2, No.1, pp. 11-18, 2006, DOI:10.3970/sdhm.2006.002.011

Abstract In this paper a numerical simulation is performed on the behaviour of reinforced concrete beams, submitted to initial damage, subsequently strengthened with external steel plates bonded with epoxy. Modelling these structures requires the characterization of the behaviour of different materials as well as the connection between them. Fracture is modelled within the scope of a discrete crack approach, using a formulation in which strong discontinuities are embedded in the finite elements. In this approach, the displacement field is truly discontinuous and the jumps are non-homogeneous within each parent element [Alfaiate, Wells and Sluys (2000)]. More >

D.Taylor¹

Structural Durability & Health Monitoring, Vol.2, No.1, pp. 1-10, 2006, DOI:10.3970/sdhm.2006.002.001

Abstract Current theories of fracture recognize the importance of material length scales, i.e. parameters having the dimensions of length which are included, either explicitly or implicitly, in many methods of fracture prediction. This paper is a review of the development of one particular approach, which we have called the Theory of Critical Distances (TCD). The history of this approach -- which is presented here for the first time - is a story of parallel developments in the areas of fatigue and brittle fracture and in different material fields: metals, polymers, ceramics and composites. A particular milestone More >

E. Viola¹, F. Tornabene²

Structural Durability & Health Monitoring, Vol.1, No.2, pp. 155-170, 2005, DOI:10.3970/sdhm.2005.001.155

Abstract In this paper, generalized differential quadrature techniques are applied to the computation of the in-plane free vibrations of thin and thick non-uniform circular arches in undamaged and damaged configurations, when various boundary conditions are considered. Structural damage is represented by one crack in different positions and with various damage levels. The crack present in a structural member can be considered as a local stiffness reduction at the fracturing section, which changes the dynamic behaviour of the structure. Much effort has been devoted to dealing with in-plane free vibration analysis of circular arches, but only a… More >

C. Braccesi¹, F. Cianetti¹, G. Lori¹, D. Pioli¹

Structural Durability & Health Monitoring, Vol.1, No.4, pp. 277-290, 2005, DOI:10.3970/sdhm.2005.001.277

Abstract This paper describes an original frequency method for fatigue life estimation of mechanical components subjected to random inputs. Currently mechanical components life design under random loads is an important task of the research, due to the increasing importance of virtual simulation in opposition to the experimental tests. The frequency domain approach, in this context, seems to be able to supply reliable estimations with small computational effort. The proposed method belongs to the class of corrective coefficient to narrow-band formula methods and it has been thought for bimodal PSDs. The definition of the generalized bimodal processes and More >

S. Baragetti¹, A. Terranova²

Structural Durability & Health Monitoring, Vol.1, No.4, pp. 267-276, 2005, DOI:10.3970/sdhm.2005.001.267

Abstract Aim of this work is to investigate into the possibility of enhancing the fatigue resistance of CrN PVD coated components. In particular PVD coated spur gears were tested and numerical simulation of crack propagation was carried out. The coating layer micro-hardness and the residual stresses characterising the surface film were measured and the obtained results were introduced in a numerical modelling predicting fatigue life procedure of coated gears used in gearboxes for automotive applications. The number of cycles necessary to reach specified crack depths of coated and uncoated samples was numerically determined and represents a More >

C. Colombo¹, M. Guagliano^1,2, L. Vergani¹

Structural Durability & Health Monitoring, Vol.1, No.4, pp. 253-266, 2005, DOI:10.3970/sdhm.2005.001.253

Abstract In this paper the fatigue crack growth properties of a nitrided and shot-peened steel is dealt with: different peening intensities were considered and the resulting residual stresses measured by means of an X-ray diffractometer. Rotating bending fatigue tests were executed on specimens including a blind micro hole, acting as a pre-existent crack. The fracture surface of broken specimens was observed with a SEM to detect the crack growth initiation point. The run-out specimens were broken after the test and the presence of non-propagating cracks detected. The results allowed to determine the propagation threshold of the More >

L. Fratini¹, S. Pasta²

Structural Durability & Health Monitoring, Vol.1, No.4, pp. 245-252, 2005, DOI:10.3970/sdhm.2005.001.245

Abstract In the last years friction stir welding (FSW) has reached a quite large diffusion in the welding of aluminium alloys, difficult to be welded with traditional technologies. The objective of this investigation was to investigate the influence of FSW process parameters on the fatigue strength of the developed joints. Moreover, in order to improvement the strength of joint, the effect of a post-welding treatment has been highlighted; what is more a surface finish treatment has been developed with the aim to eliminate the stress concentration caused by welding process on the surface of the joints. More >

W. Brocks¹

Structural Durability & Health Monitoring, Vol.1, No.4, pp. 233-244, 2005, DOI:10.3970/sdhm.2005.001.233

Abstract A review on phenomenological fracture criteria is given, based on the energy balance for cracked bodies, and the respective toughness parameters are related to micromechanical processes. Griffith's idea of introducing a "surface energy" and Barenblatt's concept of a "process zone" ahead of the crack tip build the foundation of modern cohesive models, which have become versatile tools for numerical simulations of crack extension. The cohesive strength and the separation energy used as phenomenological material parameters in these models appear to represent a physically significant characterisation of "fracture toughness". Micromechanical interpretations of these parameters can be More >