Diagnosi prenatale di piede torto congenito:importanza dell\u27approccio multidisciplinare.

...Definizione Piede torto: Anomalia strutturale del piede , che risulta da un arresto di sviluppo, che fissa il piede in un atteggiamento che ? proprio del periodo precoce della vita embrionaria, con persistenza dell\u27atteggiamento in equinovaro- supinazione. PREVALENZA 1-3 / 1000 nati M : F 2 : 1 - Bilateralit? 65% cas

Homogenization of elastic–viscoplastic composites by the Mixed TFA

A new homogenization technique, based on the Transformation Field Analysis, able to determine the overall behavior of viscoplastic heterogeneous materials, is proposed. This method is derived developing a variational formulation of the compatibility and evolution equations governing two classical elastic–viscoplastic models, i.e. Perzyna and Perić models. A representation form for the stress field and the plastic multiplier is defined on the representative volume element (RVE) of the composite material, resulting in a significant reduction of the history variables ruling the evolution problem. A numerical procedure is developed integrating the evolution equation by a backward-Euler algorithm and solving the single time step developing a specific form of the predictor corrector technique. The accuracy of the proposed homogenization method is assessed through some numerical examples for elastic–viscoplastic composites. The applications aim to verify the effectiveness of the presented technique in modeling the elastic–viscoplastic composite behavior adopting a reduced number of history variables. The homogenization results are compared with the ones obtained by nonlinear finite element micromechanical analyses

A homogenization technique for elasto-plastic composites

The present study proposes a homogenization technique for the estimation of the overall behavior of composite materials characterized by a nonlinear behavior. A mixed nonuniform TFA procedure is proposed in order to study the mechanical response of periodic composites characterized by linear isotropic hardening plasticity. As the case of periodic composites is considered, the homogenization is performed on a repetitive unit cell that plays the equivalent role of representative volume element for random media. A numerical application is performed to test the effectiveness of the proposed technique. In particular, the homogenization results are compared with the ones carried out by micromechanical nonlinear finite element analyses

Uppror : En begreppshistorisk undersökning av ordet uppror och dess uppkomst i Sverige mellan åren 1525 och 1543

Abstract Hannes Sundkvist: Uppror. En begreppshistorisk undersökning av ordet uppror och dess uppkomst i Sverige mellan åren 1525 och 1543, Uppsala universitet: Institutionen för idé- och lärdomshistoria, C-uppsats, Vårterminen, 2013.   The following thesis is a conceptual historical study of the Swedish word uppror (rebellion) between the years 1525 and 1543. During this period, there occured five conflicts that in modern time have been named as rebellions. In my study I problematize the concept of rebellions and show that it is not possible to apply a contemporary definition to conflicts that erupted in the early 16th centrury. My purpose is to display how the word actually was defined during the time of the five conflicts. These conflicts are important because they coincident with the oldest known source of the word rebellion from 1521. The first conflict that in our days has been named as a rebellion occured in 1525 and the last in 1543 (during the 16th century). To fulfill my purpose, I have studied three actors that used the word rebellion between 1525–1543 and analysed their use of the concept. These actors were King Gustav I, the reformatory friendly bishop Olaus Petri and two catholic bishops from Västergötland; Magnus Haraldsson and Ture Jönsson. My study is based on how they used the word over time to see if it consisted of a continuous pattern. My study of the notion rebellion shows that it in the beginning had weak features, which later came to be reinforced during a conflict in 1529. Hence the characteristics that I found during the 1520s continued to figure until the end of my study in 1543. The result displays the notion’s definition during the 16th century as following: Rebellion was a directed threatful action that originated in conflicts that disputed the question of who followed the one true God, it could also emerge due to infringement of law

Complementary formulation of the TFA for the elasto-plastic analysis of composites

In this paper, a new mixed nonuniform Transformation Field Analysis (TFA) homogenization technique for deriving the overall mechanical response of heterogeneous materials is proposed. The new TFA approach is based on a mixed stress variational formulation of the elasto-plasticity theory, assuming stresses and plastic multiplier as independent variables. The case of periodic composites is considered, so that the homogenization is performed on a repetitive unit cell that plays the equivalent role of representative volume element for random media. The unit cell of the material is divided into subsets and in each subset the weak form of the compatibility condition and of the consistency condition are enforced, leading to a simultaneous evaluation of the stress and of the plastic strain field. It is assumed that the stress field satisfies a priori the equilibrium equations while the inelastic strain distribution is evaluated as function of the assumed stress resulting nonuniform in each subset. Some numerical examples are performed in the framework of plane stress plasticity in order to assess the effectiveness of the proposed technique. In particular, the homogenization results are compared with the ones carried out by micromechanical nonlinear finite element analyses

Multiscale analysis of nonlinear composites via a mixed reduced order formulation

In this paper a new multiscale approach is presented for the analysis of structures made of composite material characterized by elastoplastic or viscoplastic nonlinear response. Scale separation is assumed so that the homogenization theory can be applied: at the structural scale (macroscale) the material appears as homogeneous, while at the microscale it is characterized by a heterogeneous microstructure that affects the global behavior of the structure. The resolution of the micromechanical problem is performed developing a reduced order homogenization technique based on a mixed variational formulation, named Mixed Transformation Field Analysis (MxTFA). The microscopic reduced internal variables are the stress and plastic multiplier parameters of RVE subsets, whose evolution is computed enforcing the weak form of the governing equations for every subset. Some numerical tests are performed to show the accuracy and efficiency of the proposed multiscale technique

Comparison of reduced order homogenization techniques: pRBMOR, NUTFA and MxTFA

The introduction of composites in engineering applications led to a need for tools that can predict the mechanical response with account for the heterogeneities in the materials in order to safely design complex structures. These predictions are required to be sufficiently accurate yet computationally inexpensive, especially when dealing with nonlinear materials: for these the amount of internal variables and the computing times can both become prohibitively high. Here, three model order reduction homogenization methods are compared in detail: the potential-based Reduced Basis Model Order Reduction (pRBMOR), the NonUniform Transformation Field Analysis and the Mixed Transformation Field Analysis (MxTFA). All methods are developed in the framework of the Nonuniform TFA, initially introduced by Michel and Suquet. Two of the illustrated methods, the pRBMOR and the MxTFA, deviate from the TFA of Michel and Suquet in that they are based on mixed variational formulations. The comparison will investigate differences and similarities of the techniques in terms of the reduced degrees of freedom and their evolution law, the storage requirements and the accuracy of the effective constitutive behavior. Numerical tests on three-dimensional periodic composites under complex normal and shear loading paths will show the performances of the techniques