A coupled homogenisation-damage model for masonry cracking

Cracking is responsible for the vast majority of masonry non-linear behaviour, due to the low tensile strength of the material. Masonry features orthotropic behaviour with material axes normal and parallel to the bed joints, being the response straightforward for tension normal to the bed joints and rather complex for tension parallel to the bed joints. This paper addresses the formulation and implementation of coupling between a micro-mechanical homogenisation model and an isotropic damage model for the masonry components. The non-linear homogenisation formulation requires an improved internal deformation mode of the masonry basic cell, with respect to previous works. Finally, the model is validated with a comparison with numerical results available in the literature, using interface modelling

Mechanics of masonry in compression : results from a homogenisation approach

Despite considerable experimental and analytical research in the past, modern regulations still adopt very conservative simplified formulas for the compressive strength of masonry. The present paper contributes to the understanding of masonry under compression, using a novel non-linear homogenisation tool that includes the possibility of tensile and compressive progressive damage, both in the unit and mortar. The simplified homogenised model uses an iterative procedure and a few ingenious micro-deformation mechanisms, being able to accurately reproduce complex simulations carried out with non-linear continuum finite element analysis, at a marginal cost of CPU time and with no convergence difficulties. In addition, the comparison of the model with experimental results available in the literature indicates that an estimation of the compressive strength of masonry better than the one provided by the codes is possible, using the mechanical and geometrical properties of the masonry components

Homogenization of masonry using a micro-mechanical model : compressive behaviour

Despite considerable experimental and analytical research in the past, modern regulations still adopt very conservative simplified formulas for the compressive strength of masonry. The present paper contributes to the understanding of masonry under compression, using a novel non-linear homogenisation tool that includes the possibility of tensile and compressive progressive damage, both in the unit and mortar. The simplified homogenised model uses an iterative procedure and a few ingenious micro-deformation mechanisms, being able to accurately reproduce complex simulations carried out with non-linear continuum finite element analysis, at a marginal cost of CPU time and with no convergence difficulties

Recent advances in masonry homogenization

Homogenization remains a popular subject in masonry research. Usually the complex geometry of the basic cell is replaced by a simplified geometry so that a close-form solution of the homogenization problem is possible. Many other approaches involving different approximations and ingenious assumptions have been sought. To overcome the weak approximation, a micromechanical homogenization model that consider additional internal deformation mechanisms and a model based on the polynomial expansion of the stress field inside the R.V.E. are presented

Homogenisation approaches for structural analysis of masonry buildings

Modern methodologies for the conservation of architectural heritage require structural analysis for the purpose of diagnosis and safety evaluation. This is not an easy task, as masonry structures usually feature a very low tensile strength, thus rendering the tool usually adopted for design of new structures (linear elastic analysis) of very limited use. Non-linear analysis of ancient masonry structures is a popular field in masonry research and homogenisation techniques play presently a major role, despite the mathematical and conceptual difficulties inherent to the approach. The paper addresses different homogenisation techniques available in the literature, with a focus on micro-mechanical models and on the polynomial expansion of the stress field. These seem promising and accurate strategies for advanced structural analysis

Fracture Mechanics of Thin, Cracked Plates Under Tension, Bending and Out-of-Plane Shear Loading

Cracks in the skin of aircraft fuselages or other shell structures can be subjected to very complex stress states, resulting in mixed-mode fracture conditions. For example, a crack running along a stringer in a pressurized fuselage will be subject to the usual in-plane tension stresses (Mode-I) along with out-of-plane tearing stresses (Mode-III like). Crack growth and initiation in this case is correlated not only with the tensile or Mode-I stress intensity factor, K(sub I), but depends on a combination of parameters and on the history of crack growth. The stresses at the tip of a crack in a plate or shell are typically described in terms of either the small deflection Kirchhoff plate theory. However, real applications involve large deflections. We show, using the von-Karman theory, that the crack tip stress field derived on the basis of the small deflection theory is still valid for large deflections. We then give examples demonstrating the exact calculation of energy release rates and stress intensity factors for cracked plates loaded to large deflections. The crack tip fields calculated using the plate theories are an approximation to the actual three dimensional fields. Using three dimensional finite element analyses we have explored the relationship between the three dimensional elasticity theory and two dimensional plate theory results. The results show that for out-of-plane shear loading the three dimensional and Kirchhoff theory results coincide at distance greater than h/2 from the crack tip, where h/2 is the plate thickness. Inside this region, the distribution of stresses through the thickness can be very different from the plate theory predictions. We have also explored how the energy release rate varies as a function of crack length to plate thickness using the different theories. This is important in the implementation of fracture prediction methods using finite element analysis. Our experiments show that under certain conditions, during fatigue crack growth, the presence of out-of-plane shear loads induces a great deal of contact and friction on the crack surfaces, dramatically reducing crack growth rate. A series of experiments and a proposed computational approach for accounting for the friction is discussed

Evaluation of Surgical Outcome in Rhinoplasty: A Comparison Between Rasp and Osteotome in Dorsal Hump Removal:

Dorsal hump reduction is a crucial point of rhinoplasty, as it has a great impact on the final shape of nasal pyramid. Depending on morphological features of the hump, its removal is usually obtained by the use of an osteotome or a rasp. In our study, we describe a closed rhinoplasty technique performed in 2 groups of patients: the only difference between the groups is the surgical tools used during the dorsal hump removal phase (rasp vs the 5-mm osteotome).We used 2 questionnaires of quality of life (QoL), Nasal Obstruction Symptom Evaluation (NOSE), and Rhinoplasty Outcome Evaluation (ROE) questionnaire, to evaluate postoperative outcome (6 months after surgery).Closed rhinoplasty was performed in 107 patients. Dorsal hump removal was carried out with rasp on 35 patients; while in 72 cases, it was performed using a 5-mm osteotome. All the patients were given 2 copies of NOSE and ROE questionnaires (1 month before surgery and 6 months after surgery) to evaluate postoperative QoL. In our study emerged that the use of osteotome in dorsal hump reduction is associated with a better aesthetic outcome (evaluated by analyzing patients QoL with ROE questionnaire) without any difference between the 2 groups in terms of functional outcome (expressed by NOSE questionnaire), major and minor complications and surgical procedure duration

An Alternative Tool for Intra-Row Weed Control in a High-Density Olive Orchard

none6openAssirelli, Alberto; Ciaccia, Corrado; Giorgi, Veronica; Zucchini, Matteo; Neri, Davide; Lodolini, Enrico MariaAssirelli, Alberto; Ciaccia, Corrado; Giorgi, Veronica; Zucchini, Matteo; Neri, Davide; Lodolini, Enrico Mari

Long-term safety and efficacy of Omnitrope\uae, a somatropin biosimilar, in children requiring growth hormone treatment: Italian interim analysis of the PATRO Children study

Background: PATRO Children is an ongoing observational, longitudinal, non-interventional, global post-marketing surveillance study, which is investigating the long-term safety and effectiveness of Omnitrope\uae, a somatropin biosimilar to Genotropin\uae, in children with growth disturbances. The primary endpoint of PATRO Children is long-term safety and the secondary endpoint is effectiveness, which is assessed by analysing auxological data such as height (HSDS) and height velocity (HVSDS) standard deviation scores. Here, we report the data from the Italian interim analysis of PATRO Children data up to August 2015. Methods: PATRO Children is enrolling children who are diagnosed with conditions of short stature requiring GH treatment and are receiving Omnitrope\uae. Adverse events (AEs) are assessed in all Omnitrope\uae-treated patients. Height is evaluated yearly to near-adult (final) height, and is herein reported as HSDS; height velocity is also assessed and reported as a standard deviation score (HVSDS). Results: Up to August 2015, a total of 186 patients (mean age 10.2 years, 57.5 % males) were enrolled :156 [84 %] had growth hormone deficiency, 12 [6.5 %] were born small for gestational age, seven [3.8 %] had Prader-Willi syndrome, one [0.5 %] had Turner syndrome and one [0.5 %] had chronic renal insufficiency; seven [3.8 %] patients had other indication profiles. The mean treatment duration with Omnitrope\uae was 28.1 \ub1 19.1 months. AEs were reported in 35.6 % of patients and included headache, pyrexia, arthralgia, abdominal pain, leg and/or arm pain and increased blood creatine phosphokinase. Two serious AEs in two patients were thought to be drug-related; one patient experienced a minimal increase in a known residual craniopharyngioma, and another a gait disturbance with worsening of walking difficulties. Similar to investigational studies, Omnitrope\uae treatment was associated with improvements in both HSDS and HVSDS. Conclusions: Omnitrope\uae appears to be well tolerated and effective for the treatment of a wide range of paediatric indications, which is consistent with the outcomes from controlled clinical trials. These results need to be interpreted with caution until the data from the global PATRO Children study are available

Diabetic ketoacidosis at the onset of disease during a national awareness campaign: a 2-year observational study in children aged 0-18 years

After a previous survey on the incidence of diabetic ketoacidosis (DKA) at onset of type 1 diabetes in children in 2013-2014 in Italy, we aimed to verify a possible decline in the incidence of DKA at onset during a national prevention campaign