Low-velocity impact behaviour of fibreglass-aluminium laminates

Low-velocity impact tests were performed on fibreglass–aluminium composites made of 2024 T3 sheets and S2-glass/epoxy prepreg layers, using an instrumented falling weight machine. For comparison purposes, similar tests were carried out on monolithic 2024 T3 sheets of equivalent thickness. In the tests, the impact speed, mass, and energy were varied, to ascertain the influence of these parameters on the material response. From the results obtained, the overall force–displacement curve only depends on the impact energy, rather than on the mass and speed separately. Further, the energy required for penetration is higher for monolithic aluminium than for the fibreglass– aluminium. However, the latter material seems to offer better performance than carbon fibre- and glass fibre-reinforced laminates in terms of penetration energy, damage resistance, and inspectability. The main failure modes of fibreglass – aluminium were assessed by both ultrasonic C-scan and chemical grinding of aluminium sheets. It was found that the energy required for first failure is very low, whereas the energy level resulting in first fibre failure is similar to that inducing first cracking in the 2024 T3 sheets. From the experimental data, simple empirical relationships were found for the calculation of maximum contact force, energy, and residual displacement as a function of the maximum displacement

Human-centred design methods : developing scenarios for robot assisted play informed by user panels and field trials

Original article can be found at: http://www.sciencedirect.com/ Copyright ElsevierThis article describes the user-centred development of play scenarios for robot assisted play, as part of the multidisciplinary IROMEC1 project that develops a novel robotic toy for children with special needs. The project investigates how robotic toys can become social mediators, encouraging children with special needs to discover a range of play styles, from solitary to collaborative play (with peers, carers/teachers, parents, etc.). This article explains the developmental process of constructing relevant play scenarios for children with different special needs. Results are presented from consultation with panel of experts (therapists, teachers, parents) who advised on the play needs for the various target user groups and who helped investigate how robotic toys could be used as a play tool to assist in the children’s development. Examples from experimental investigations are provided which have informed the development of scenarios throughout the design process. We conclude by pointing out the potential benefit of this work to a variety of research projects and applications involving human–robot interactions.Peer reviewe

Damage and energy absorption in GFRP laminates impacted at low-velocity: Indentation model

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Innovative Sandwiches for Civil Applications

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Numerical, Experimental and Analytical Correlation for Predicting the Structural Behavior of Composite Structures under Impact

Abstract In the present work, numerical, experimental and analytical results regarding impact events on composite structure are presented. The test case consists in a classic 24 plies CAI specimen (100×150 mm) subjected to 10 J impact. The work can be divided into two phases. The first phase is finalized to the definition of a procedure able to provide a robust numerical model, which can simulate accurately the structural response of composite plates subjected to impact events. At this phase, the numerical results are compared with analytical ones. In the second phase, both inter- and intra-lamina failure are considered. Regarding the inter-laminar failure, an experimental-numerical procedure is defined in order to set the right parameters related to cohesive behaviour. For both phases, trade-off analyses on the main numerical parameters are performed. All numerical results are compared with experimental ones in terms of both energy balance and damaged area

conventional orthogonal cutting machining on unidirectional fibre reinforced plastics

Abstract The results of orthogonal cutting tests on unidirectional carbon and glass fibre reinforced plastics are presented. The specimens were under shape of rectangular plates, circular disks and cylinders with different fibre architectures and a milling machine, a lathe machine and a five-axis high-speed vertical machining centre, were used for the experimental tests. The cutting speed was varied. During the tests, performed at low cutting speed, avoiding thermal effects, and high speed, to investigate about the effect of the cutting velocity on the cut quality, the fibre orientation respect to the cutting direction, the tool rake angle and the depth of cut were varied to investigate their influence on the phenomenon. A high speed steel tool in different geometries, was used. The mechanisms of chip formation and the cutting quality were investigated. A tentative to correlate the mechanisms of chip formation and cutting forces signals was done. Since the anisotropy, the mechanisms of chip formation consists of different failure modes occurring simultaneously and their identification, on the basis of the cutting force evolution, is very complex. Only in particular conditions, the features of cutting forces allow a precise identification of the chip development and detachment. The results indicated that the fibre orientation respect to the cutting direction determines the mechanisms of chip formation and influences the cutting quality. It was noted that for fibre orientation higher than 60°, the quality of the surface was revealed unacceptable. These conclusions were obtained independently of the particular shape of specimen tested and of the speed adopted

The association between dyslipidemia and lethality of suicide attempts: A case-control study

Evidence supports the existence of an association between dyslipidemia, psychiatric disorders, and suicide risk due to the effects of altered lipid profiles on serotoninergic neuron membranes. The aim of this study was to investigate the differences in c-reactive protein (CRP), thyroid functioning, total cholesterol, high lipoprotein density cholesterol (HDL-c), low-lipoprotein density cholesterol (LDL-c), and triglycerides (TG) serum levels in low lethality (LLSA) vs. high lethality suicide attempters (HLSA) within 24 h fromthe suicide attempt and inpatients who never attempted suicide (NAS). After attempting suicide, subjects were admitted to the emergency ward of the IRCCS Ospedale Policlinico San Martino and later to the section of Psychiatry from 1st August 2013 to 31st July 2018. Socio-demographic and clinical characteristics, serum lipids profile, CRP, and thyroid functioning were collected. The sample consisted of 133 individuals with a HLSA, 299 subjects with LLSA, and 200 patients NAS. HLSA subjects were more likely to be males and diagnosed as having a bipolar disorder. Furthermore, HLSA subgroup showed significantly lower total cholesterol and LDL-c levels and higher CRP serum levels compared to LLSA and control group, respectively. LLSA subgroup showed higher HDL-c levels compared to HLSA subgroup (no differences between HLSA and control group were observed). Additionally, the control group reported higher triglycerides levels compared to patients admitted to psychiatric ward for a suicide attempt. Only male gender, having a diagnosis of bipolar disorder, lower total cholesterol, and higher CRP serum levels predicted HLSA. Investigating the relation between dyslipidemia and the severity of suicide attempts may contribute to reveal the complex determinants underlying at-risk behaviors such as suicide, thus playing a relevant role in the possible prevention of this disabling phenomenon

Integrated seismic and energy retrofitting of existing buildings: A state-of-the-art review

Ageing of the building stock is an issue affecting many regions in the world. This means a large proportion of existing buildings being considered energy inefficient, with associated high energy use for heating and cooling. Through renovation, it is possible to improve their energy-efficiency, hence reducing their significant impact on the total energy household and associated greenhouse gas emissions. In seismic regions, additionally, recent earthquakes have caused significant economic losses, largely due to the vulnerability of older buildings not designed to modern standards. Addressing seismic and energy performance by separate interventions is the common approach currently taken, however to achieve better cost-effectiveness, safety and efficiency, a novel holistic approach to building renovation is an emerging topic in the scientific literature. Proposed solutions range from integrated exoskeleton solutions, over strengthening and insulation solutions for the existing building envelope or their replacement with better materials, to integrated interventions on horizontal elements like roof and floor slabs. To identify pathways to combined seismic and energy retrofitting of buildings, a state-of-the-art review of all materials and solutions investigated to date is presented. This is followed by a critical analysis of their effectiveness, invasiveness, building use disruption as well as their impact on the environment. The assessment of current combined retrofitting research highlights a great potential for their application, with a potential to provide cost-effective renovation solutions for regions with moderate to high seismic risk. Still, to-date there is a lack of experimental research in this field, a need for further work on truly integrated technologies and their validation through applications on existing large-scale buildings. Moreover, there is a need for adequate design methods, regulations and incentives that further the implementation of integrated retrofitting approaches

Evaluation of different dietary lipid supplements on oxidatively generated biomarkers in periparturient dairy goats

Evaluation of different dietary lipid supplements on oxidatively generated biomarkers in periparturient dairy goats. Bellagamba Federica1, Busetto Maria Letizia1, Caprino Fabio1, Invernizzi Guido1, Moretti Vittorio Maria1, Savoini Giovanni1. 1 Dipartimento di Scienze e Tecnologie Veterinarie per la Sicurezza Alimentare, Universit\ue0 degli Studi di Milano, Via Trentacoste 2, 20134 Milano, Italy The study of biomarker of oxidative stress in ruminant is a field of research recently explored [1]. Consequences of high-fat diet and lipid peroxidation on the health of ruminants and quality of their products have been considered and discussed [2]. This study aimed at analyzing the impact of different dietary lipid supplements on oxidative stress status in 26 periparturient Alpine dairy goats. At day 130 of gestation (about 20 days before kidding), goats, chosen homogeneous for parity and milk yield in previous lactation, were housed in single boxes and fed the same diet. Goats were divided in three experimental groups and assigned one of the identical experimental diets just differing in lipid sources: a dietary protected fish oil (FO) group, rich in n-3 long chain polyunsaturated fatty acids (n-3 LC-PUFAs); a dietary calcium stearate (ST) group, rich in 16:0, 18:0 saturated fatty acids (SFAs) and a dietary control group (C), without any supplement. Experimental fatty acid enriched diets (FO and ST) were both formulated to administer 30 g/day and 50 g/day of fatty acid before and after kidding respectively. Blood samples (98 samples) were collected weekly starting from day 130 of gestation until 21 days of lactation; serum and plasma were obtained after sampling and stored at -80\ub0 C until the analysis. Analytical determination of malondialdehyde (MDA) by high performance liquid chromatography (HPLC) and enzyme-linked immunosorbent assay (ELISA) assessment of 8-oxo-7,8-dihydro-2\u2019-deoxyguanosine (8-oxodGuo) have been carried out in serum samples. Since the 8-oxodGuo derives after the ROS attack to DNA, this DNA-adduct is widely used as specific marker of oxidative damage. This DNA adduct can be measured in tissues, serum and urine and often used as prognostic factor in cancer lesions and degenerative diseases. MDA is the most abundant individual aldehyde resulting from lipid peroxidation and commonly employed in studies involving oxidative alteration of lipids. Gas chromatographic determination of plasma fatty acid has been also determined. The same sampling from animals fed without any supplements (C group) has been considered as control and analysed. Data were processed by analysis of variance (ANOVA) and values presented as mean \uf0b1 SEM. data were subjected to a Student\u2013Newman\u2013Keuls post hoc test for homogeneous subsets, and a P value of 64 0.05 was considered as significant. MDA and 8-oxodGuo resulted both highest in FO group (822.02\ub150.45 \u3bcmol ml-1 and 1.83\ub10.24 ng ml-1, respectively), and the 8-oxodGuo levels in serum from FO group were statistical different (P 64 0.05) from other groups. Dietary lipid supplements produced remarkable change in plasma fatty acid (expressed as g/100g total FAs) and particularly, n-3 LC-PUFAs, 20:5 n-3 (2.06 %), 22:5 n-3 (1.94 %) and 22:6 n-3 (1.61 %), in FO group resulted significant different (P 64 0.05) from ST and C groups. In ST group plasma 18:0 fatty acid was the highest value (19.20 %) and significant difference from FO (17.47 %) diet group. The n-6 LC-PUFAs (20:3 n-6; 20:4 n-6) as well as linoleic acid were not different at statistical level. MDA and 8-oxodGuo did not show any significant difference amongst different times of sampling; otherwise the interaction with sampling was evident on fatty acid of plasma, with a significant (P 64 0.05) increase of EPA (20:5 n-3, 3.9 %) and DHA (22:6 n-3, 2.25 %) in FO diet after 21 days of supplementation. Aiming to focus on metabolic variation of peripartum status, we analysed MDA and 8-oxodGuo in serum, as well as plasma fatty acid in samples from 2 until 7 days after kidding. The results did not produce any significance difference at statistical level, however the highest value of 8-oxodGuo was found just in peripartum period of goats receiving FO diet. The present study confirms that modification of dietary fatty acid composition derived from the utilisation of different dietary lipid sources in feed formulations can have appreciable impact on oxidative DNA damage also in ruminant specie and produce valuable variations of plasma fatty acid. Otherwise, no evidence of a significant increase of serum MDA concentrations has been verified. References [1] Celi P. Immunopharmacology and immunology (2011) 33(2): 233-240. [2] Durand D., Scislowski V, Gruffat D., Chilliard Y., Bauchart D. EAAP Pubblication (2005) 112:137-150, Wageningen Academic Publisher