This paper presents the effects of Friction Stir Welding (FSW) and Linear Friction Welding (LFW) on aluminium based metal matrix composites (MMCs) containing a ceramic particulate reinforcement. The FSW process has been carried out on two types of composite obtained by means of stir casting, extruded and T6 heat-treated: AA6061/20%vol.Al2O3p and AA7005/10%vol.Al2O3p. LFW joints have been realized on an aluminum based MMC obtained by powder metallurgy, forged and T4 heat-treated: AA2124/25%vol.SiCp. Optical Microscopes (OM) and Scanning Electron Microscopes (SEM) with Energy Dispersive Spectroscopy (EDS) microprobe have been used to characterize the effects of the welding processes on the microstructural properties of the joints. Instrumented impact strength tests have been carried out on Charpy samples and fractographic examination has been performed by SEM analysis of fracture surfaces. Both the welding processes permitted to obtain joints substantially defect-free. The microstructures of the joints were found to be dependent on both the initial microstructure of the composites and the welding process. With respect to the base metal, an increase on impact strength properties of AA6061/20%Al2O3p and AA7005/10%Al2O3p joined by FSW have been measured, due to the reduction of the grain size, aspect ratio and mean size of the reinforcement particles. The impact strength of the base AA2124/25%SiCp composite and LFW joints were found to be comparable, due to the limited effects of the welding process on the microstructure, which was already very fine in the base material.

Based on the experience of more than a quarter of century on the analysis of the endurance characteristics of materials using thermographic methodologies, the present paper deals on a proposal of a new procedure for the quality control on mechanical components in processing line. The procedure methodology was already patented by some of the authors. The work described is included in the research programme FIRB Smartflex, particularly regarding the activity of the DIIM about the advanced control of the reliability of automotive elements and systems. A control cell, inside the processing line, able to evaluate the presence of defects in the automotive components by the application of defined cyclic loads and the analysis of the induced thermal maps, is proposed. The results, in this first step found in laboratory, could be easily transferred to the processing line, considering the possibility of realizing a structured environment control cell, with ambient conditions very similar to those created in the laboratory, reducing the noise effects affecting the thermal data in a non-structured environment.

Starting from the observation that previously damaged specimens have a fatigue limit differences (see Miner), the behavior of a steel, subject to series of fatigue loads, was examined to verify the resulting thermal response. The review, by thermal analysis, fatigue tests on samples of steel C40 damaged in varying degrees, provides valuable insights on the role of loads applied in relation to the possibility of producing damage in the material. The temperature, therefore the energy consumed, is an element indicative of the state of the material. The fatigue curves and the curves of temperature of smooth specimens, subjected to different load histories have been reported. These are demonstrated that a valid law of linear damage (Sini/Ni= cost), but the curve defined under the rule of Miner-Manson (Sini/Ni=1), which takes into account only the number of times the stress exceeds the fatigue limit of the material (smooth specimens), however, does not always reflect the actual state of damage. Especially when the loads are close to the fatigue limit, for the sequence of the application, loads can become fatiguing.

There are many problems in Solid Mechanics, Physics of Solids and Materials Science that can not been solved using conventional approaches. Besides the effective properties of non-homogeneous bodies, there is an increasing need for incorporating more physical information about small-scale mechanisms of deformation and damage into phenomenological models of plasticity and rupture of materials which are usually considered homogeneous. Cavitation, local stress or strain concentrations at small scale are essential to explain nonlinear phenomena, such as fatigue or ductile rupture, which are not understandable from the simple point of view of average stresses or strains. Precise determination or accurate estimation of local fields is the domain of micromechanics. This work treats the basic concepts of the micromechanics in a simple way, with some practical suggestion on the most commonly used modelling techniques and some applications made by the author on various nodular cast iron microstructures.

In the present paper the structural failure of a crane arm is analysed and discussed. During inspections, a significant pre-existing crack was observed, which extended to about half the cross section of one of the main tubular elements which constitute the arm frame. In order to determine the failure cause, a model for the crack growth analysis and a model for the plastic collapse were developed; the model for the analysis of crack growth is based on the weight functions method. The analyses allowed to conclude that the failure was due to plastic collapse and to asses how, for a considerable part of the life, the crack propagated under stable conditions with an almost constant rate.

In the present work we present some results of numerical experiments obtained with a variational model for quasi-static Griffith-type brittle fracture. Essentially the analysis is based on a recent formulation by Francfort and Marigo the main difference being the fact that we rely on local rather than on global minimization. Propagation of fracture is obtained by minimizing, in a step by step process, a form of energy that is the sum of bulk and interface terms. To solve the problem numerically we adopt discontinuous finite elements based on variable meshes and search for the minima of the energy through descent methods. We use a sort of mesh dependent relaxation of the interface energy to get out of small energy wells. The relaxation consists in the adoption of a carefully tailored cohesive type interface energy, tending to the Griffith limit as the mesh size tends to zero.

In this research paper we compare two different methods to estimate the fatigue life of spot welded joints: the method of fiction notch radius and the implicit gradient approach. The first requires a radius of curvature at the weld toe or at the weld root that is different from zero, the second simply considers the weld as a sharp notch. The comparison is made on the ability to predict the reliability of spot welded joints made of steel with a thickness ranging from 0.8 to 1.5 mm. These joints are subjected to shear loading (lap joints) or to tensile loading (circular cup joints). Finally, we discuss the convergence condition of the numerical analysis needed, in both methods, for the calculation of equivalent stress to be used in the fatigue analysis.

The numerical modeling and wave theory are used in tsunami mitigation analysis. It is assumed sea forest is simulating offshore structure submitted to wave loads. The sea forest acts simulate break waves in conservation of coastal territory and facility installed over there. The result reveal that mathematical modeling and numerical simulation can be used to understand tsunami ability in design and urban construction, the research indicates reduction of water deep by sea forest resulted in reducing geometry and all wave ability.