30 research outputs found
EFFECT OF SURFACE FINISH ON THE TENSILE BEHAVIOR OF DACRON© 360 WOVEN
Nel presente lavoro vengono presentate alcune indagini sperimentali mirate alla
caratterizzazione dell’effetto del trattamento superficiale sul comportamento costitutivo di un tessuto in Dacron© 360. Tale tessuto, largamente utilizzato nella realizzazione di vele, è ottenuto dalla tessitura di fili di polietilene tereftalato (PET) e presenta alcune peculiarità dovute al processo manifatturiero. Le prove di trazione realizzate evidenziano le caratteristiche di ortotropia del materiale e l’effetto del trattamento superficiale che si manifesta principalmente in un comportamento più rigido nella direzione dell’ordito ed in quella inclinata e in un aumento della resistenza ultima in tutte le direzioni.In the present paper some experimental analyses effected on Dacron© 360 woven
with and without surface treatment, aimed to characterize the effect of this treatment on the constitutive behavior, are presented. This woven, widely adopted in sail manufacturing, is
obtained by weaving polyethylene terephthalate (PET) yarn and it shows some peculiar features due to the manufacturing process. The experimental tests, in terms of tensile tests,
clearly show the orthotropy features of the material and the effect of the treatment which results in a stiffer behavior especially along the warp and bias direction and in an increment
of ultimate strength in all directions
Experimental Analysis and Numerical Modelling of the Mechanical Behavior of a Sisal-Fiber-Reinforced Geopolymer
The present paper is devoted to the proposal of appropriate numerical modelling able to provide a suitable description of the mechanical behavior of a composite geopolymer. Reference is made to a natural sisal-fiber-reinforced geopolymer. The study is based on the results of appropriate experimental investigations for compressive, flexural and splitting loadings, taking into account different weight percentages of fibers to evidence their role in the mechanical behavior. The main objective of the paper is to calibrate the microplane constitutive model, available in ANSYS software version 18.1, where the numerical analyses are performed. Therefore, the present study is structured in two different steps. Firstly, the mechanical behavior of geopolymers reinforced with sisal fibers is experimentally investigated, and subsequently, the gathered test data are interpreted and utilized to calibrate the relevant constitutive model to be used in the numerical stage. The obtained results are compared with experimental data, yielding good correlations. The paper's results supply the parameters required to obtain an affordable numerical model of the reinforced geopolymer for different percentages of fibers to be adopted for material design with assigned mechanical properties
Improving the Downwind Sail Design Process by Means of a Novel FSI Approach
The process of designing a sail can be a challenging task because of the difficulties in
predicting the real aerodynamic performance. This is especially true in the case of downwind sails,
where the evaluation of the real shapes and aerodynamic forces can be very complex because of
turbulent and detached flows and the high-deformable behavior of structures. Of course, numerical
methods are very useful and reliable tools to investigate sail performances, and their use, also as a
result of the exponential growth of computational resources at a very low cost, is spreading more
and more, even in not highly competitive fields. This paper presents a new methodology to support
sail designers in evaluating and optimizing downwind sail performance and manufacturing. A new
weakly coupled fluid–structure interaction (FSI) procedure has been developed to study downwind
sails. The proposed method is parametric and automated and allows for investigating multiple
kinds of sails under different sailing conditions. The study of a gennaker of a small sailing yacht is
presented as a case study. Based on the numerical results obtained, an analytical formulation for
calculating the sail corner loads has been also proposed. The novel proposed methodology could
represent a promising approach to allow for the widespread and effective use of numerical methods
in the design and manufacturing of yacht sails
A New Automatic Process Based on Generative Design for CAD Modeling and Manufacturing of Customized Orthosis
As is widely recognized, advancements in new design and rapid prototyping techniques
such as CAD modeling and 3D printing are pioneering individualized medicine, facilitating the
implementation of new methodologies for creating customized orthoses. The aim of this paper is
to develop a new automatic technique for producing personalized orthoses in a straightforward
manner, eliminating the necessity for doctors to collaborate directly with technicians. A novel design
method for creating customized wrist orthoses has been implemented, notably featuring a generative
algorithm for the parametric modeling of the orthosis. To assess the efficacy of the developed
algorithm, a case study was conducted involving the design and rapid prototyping of a wrist orthosis
using Fused Deposition Modeling (FDM) technology. Subsequently, the developed algorithm was
tested by clinicians and patients. The results obtained indicate that the implemented algorithm is
user-friendly and could potentially enable non-expert users to design customized orthoses. These
results introduce innovative elements of originality within the CAD modeling, offering promising
solutions to the challenges associated with the design and production of customized orthoses. Future
developments could consist of a better investigation regarding the parameters that influence the
accuracy of the scanning and of the printing processes
Displacement measurement through DIC and DSPI techniques in cold-expanded holes
In this paper, the displacement field induced by the split-sleeve cold expansion of holes was measured using both digital image correlation (DIC) and digital speckle pattern interferometry (DSPI) techniques. Thus, the experimental results, which were evaluated on the inlet surface of a 6082-T6 aluminium plate, were compared with those from theoretical prediction. DIC provided accurate measurements up to the elastic-plastic boundary, whereas the DSPI technique highlighted the changes of displacement in the elastic domain. Prediction of the displacement based on the existing analytical model agreed with the experimental results achieved with both techniques. Possible explanations for the differences are discussed