Quasi-Static Folding and Deployment of Ultrathin Composite Tape-Spring Hinges

Deployable structures made from ultrathin composite materials can be folded elastically and are able to selfdeploy by releasing the stored strain energy. This paper presents a detailed study of the folding and deployment of a tape-spring hinge made from a two-ply plain-weave laminate of carbon-fiber reinforced plastic. Aparticular version of this hinge was constructed, and its moment-rotation profile during quasi-static deployment was measured. The present study is the first to incorporate in the simulation an experimentally validated elastic micromechanical model and to provide quantitative comparisons between the simulations and the measured behavior of an actual hinge. Folding and deployment simulations of the tape-spring hinge were carried out with the commercial finite element package Abaqus/Explicit, starting from the as-built unstrained structure. The folding simulation includes the effects of pinching the hinge in the middle to reduce the peak moment required to fold it. The deployment simulation fully captures both the steady-state moment part of the deployment and the final snap back to the deployed configuration. An alternative simulation without pinching the hinge provides an estimate of the maximum moment that could be carried by the hinge during operation. This is about double the snapback moment

A SyR and IPM machine design methodology assisted by optimization algorithms

The design optimization of synchronous reluctance (SyR) machine and its extension to internal permanent magnet (IPM) motors for wide speed ranges is considered in this paper by means of a Finite Element Analysis-based multi-objective genetic algorithm (MOGA). The paper is focused on the rotor design, that is controversial key aspect of the design of high saliency SyR and IPM machines, due to the difficult modeling dominated by magnetic saturation. A three step procedure is presented, to obtain a starting SyR design with the optimal torque versus torque ripple compromise and then properly include PMs into the SyR geometry, given the desired constant power speed range of the final IPM machine. The designed rotors have been extensively analyzed by computer simulations and two SyR prototypes have been realized to demonstrate the feasibility of the design procedur

Contemporary landscape and the archaeological record. An integrated approach to the study of the Etruscan-Samnite site of Pontecagnano (SA)

Pontecagnano is a large Etruscan-Samnite settlement located 8 km SE of Salerno, at the northern edge of the Sele plain. The well-investigated necropolis provided data that made it possible to analyse the structure of the ancient community and reconstruct its long-term development. Over the last few years, after archaeological investigations carried out during roadwork to widen the Salerno-Reggio Calabria highway, a more systematic study of the site was begun. The analysis of archaeological data was combined with environmental and landscape studies, shedding light on the reasons behind the spatial organisation of the settlement, which was influenced by natural or man-made landscape elements such as streams, non-uniform dislocation of geological formations, terraces, roads, canals, etc. The aim of this paper is to illustrate the methods and instruments we used to develop a system that can dynamically combine archaeological and geomorphological data. The paper focuses particularly on the reconstruction of paleo-topographical areas of the ancient settlement. Our investigation outlined the physical and environmental limits within which the old town developed, especially as regards the archaic and classical period. Part of the work was devoted to reconstructing in detail the connections between the modern and the ancient landscape, not only by reading and interpreting the aerial photographs from 1945 to the present-day, but also by analyzing the evidence from the excavations. This approach allowed us to draw up a detailed geomorphologic map of the area of the ancient settlement - part of the GIS platform - and develop a three-dimensional model of the ground (DEM)

Levantamento de dados secundários sobre o acúmulo de carbono orgânico em solos brasileiros sob pastagens.

Este contexto justifica a intensificação de pesquisa na área de mitigação e adaptação do setor pecuário às mudanças do clima e, neste sentido, o presente trabalho se propôs a criar uma base de dados secundários existentes na literatura acerca do acúmulo de carbono orgânico em solos sob pastagens de diversas regiões pecuaristas do Brasil. Com isto, pretende-se contribuir para a criação de padrões e correlações entre as principais causas de variação de carbono sob diferentes formas de manejo de pastagens

Photo-oxidative and soil burial degradation of irrigation tubes based on biodegradable polymer blends

Irrigation tubes based on biodegradable polymers were prepared via an extrusion-drawing process by Irritec and compared to conventional pipes made of high-density polyethylene (HDPE). A commercial polylactide/poly (butyleneadipate-co-butyleneterephthalate) (PLA/PBAT) blend (Bio-Flex®) and Mater-Bi® were used. The polymers were characterized from rheological and mechanical points of view. Irrigation pipes were subjected to photoaging with continued exposure to UV radiation up to 22 days. The degradability in the soil of irrigation tube samples was studied. The influence of temperature and UV irradiation on soil burial degradation was investigated. A soil burial degradation test was carried out at 30 °C and 50 °C for up to 70 days. The degree of degradation was evaluated from the weight loss percentage. The degradation rate of irrigation tube samples based on Mater-Bi® was higher at 30 °C and was stimulated after 14 days of UV irradiation. Higher temperatures or UV aging encouraged the disintegration in soil of Bio-Flex®-based irrigation tubes. Furthermore, tube samples, before and after UV and soil burial degradation, were analyzed by Attenuated Total Reflection-Fourier Transform Infra-Red (ATR-FTIR) spectroscop

Automatic design of Synchronous Reluctance motors focusing on barrier shape optimization

The automated design of Synchronous Reluctance motors based on Multi-Objective, Genetic Optimization and Finite Element Analysis is considered in this paper. Three types of barrier shapes are considered, all described by an effective, limited set of input variables. The three solutions are investigated to establish which of the geometries can give the best torque output and also which one represents the best compromise between output performance and computational time. The analysis presented in this paper shows that Synchronous Reluctance motors designed automatically can give a good performance, can be designed in a reasonable time and it is also shown that not all design degrees of freedom are useful in terms of motor performance. Two prototypes of automatically designed machines have been fabricated and experimentally compared to a third prototype designed according to state-of-the-art design principle

Design of synchronous reluctance motors with multiobjective optimization algorithms

The automatic design of Synchronous Reluctance (SyR) machines is considered in this paper by means of Finite Element Analysis and Multi-Objective Optimization Algorithms (MOOA). The research focuses on the design of the rotor geometry which is the key aspect of the SyR machine design. In particular, the performance of three popular MOOAs is analyzed and compared in terms of quality of the final design and computational time. A procedure to minimize the computational burden of the optimized design process is introduced and applied to a three layer and to a five layer rotors. Two prototypes demonstrate experimentally the feasibility of the design procedure

Deployment Dynamics of Composite Booms with Integral Slotted Hinges

This paper considers a lightweight boom with an integral hinge consisting of a thin-walled tube made of carbon fibre reinforced plastic with two longitudinal slots. The dynamic deployment of this boom is studied both experimentally and by means of detailed finite-element simulations. The deployment of the boom can be divided into three phases: deployment; incomplete latching, buckling of the tape springs and large rotation of the boom; and vibration of the boom in latched configuration. The simulations show that the most critical phase is the second one, as the highest strains in both the fibres and the matrix occur at this stage. Through the simulations it is found that the deployment of the particular boom design studied in this paper is quite sensitive to the details of the gravity offload system