Papers by Keyword: Experimental Test

Abstract: The objective of this work is to study the heat transfer on rectangular perforatedor non-perforatedfins of different geometries and different materials and to see the influence of these holes on the cooling of the structures. Different simulations using the Nastran/Patran software were carried out. In order to validate the numerical results, an experimental part was carried out. To collect the data of the sensed temperatures, circuits were used based on the Arduino programmable board or the Pic 16F8777A microcontroller programmed by the MicroC and Proteus software. In order to visualize, analyse and control the data, Labview software was used and a personalized interface was created. The results obtained show that by increasing the number and the diameter of holes, the temperature decreases. It is shown that the surface area of ​​the holes is more important than the shape of the holes. There are certain hole distributions that give better results compared to others.

Abstract: In this work, the mechanical behaviour of natural composite fibre sandwich panels is experimentally investigated. The composite sandwich panels are composed of a natural core made of Posidonia dried leaves reinforced with aluminium skins. The introduced material system is characterized by good structural behaviour (due to the aluminium skins) combined with the good thermal and acoustical insulation provided by the Posidonia core. Flexural and impact tests, characterized by different impact energies, have been performed on specimens with and without the aluminium skins, to preliminary assess the influence of the Posidonia core densities on the natural fibre sandwich mechanical behaviour.

Abstract: In the framework of the Mediterranean cultural heritage, the term “fictile tubule” identifies a peculiar type of brick, characterized by a cylindrical shape and a hollow core. Its unique geometry and characteristics rank it among the first hollow clay bricks in history. The large-scale production of fictile tubules allegedly began in the Roman provinces of Northern Africa during the 2^nd Century A.D., where they were employed for building vaulted and domed structures without the need of centrings. Over the following Centuries, the construction technique of fictile tubules embedded in mortar was constantly refined and improved. This led to an extensive use of such technique in several buildings - as part of different structural elements (vaults, domes, floors, walls) - all over the Mediterranean area, and especially in Southern Italy. In 1909, after the disastrous earthquake in Messina and Reggio Calabria, Calabrian engineer Pasquale Frezza devised and patented an anti-seismic construction system which evolved the technology of casa baraccata. Frezza’s take on this traditional Calabrian way of erecting buildings involved the use of a specific type of fictile tubule, named carosello, alternated with common bricks in masonry walls, which are then encased in a timber frame. This paper presents an investigation on the structural behavior of Frezza’s evolution of casa baraccata, aimed at its possible revival as a relevant anti-seismic construction technique. Two specimen walls with dimensions equal to 60×60×15 cm³ are built according to Frezza’s patent and experimentally examined through a diagonal compressive test at the Civil Engineering Laboratory of University of Calabria. For the first specimen wall the test is carried out until failure to identify the collapse load. Conversely, for the second specimen wall the test is halted immediately after the formation of the first vertical cracks. The specimen is subsequently repaired using B-FRCM (Basalt Fiber-Reinforced Cementitious Matrix) as reinforcement, and the diagonal compressive test is repeated, this time until failure. The results in terms of collapse load and shear strength for both specimens are then compared and critically discussed, highlighting the increased load-bearing capacity of the wall built according to Frezza’s patent and reinforced with B-FRCM.

Abstract: In this paper, hybrid composite made of carbon woven fibers and flax woven fibers is studied. This hybrid composite structure takes advantages of high resistance, high stiffness of carbon fibers and high damping and low density of flax fibers. Different structures of flax woven composites, carbon woven composites and hybrid composites were fabricated and tested experimentally. With aim of predicting the properties of the hybrid composite, a homogenization model of the composite is established. The homogenization model is based on the rule-of-mixture and iso-strain assumption. The results of the analytical homogenization model (AHM) are then compared with the results of experimental tests. The results show a good agreement between the AHM and the experimental results at the homogenization level of the woven composite. However, at the hybrid composite homogenization level, the experimental results present considerably higher stiffness than analytical results that is explained by hybrid effect on the hybrid composite.

Abstract: The paper presents the comparison of the results between the numerical model developed for the simulation of the fluid-structure interaction problem and the experimental tests. The model is based on the so called “partition scheme” in which the equations governing the fluid’s pressures and the equations governing the displacement of the structure are solved separately, with two distinct solvers. The SPH (Smoothed Particle Hydrodynamics) method is used for the fluid and the standard FEM (Finite Element Method), based on shell elements, is used for the structure. Then, the two solvers are coupled to obtain the coupled behaviour of the fluid structure system. The elasto plastic material model for the structure includes some important nonlinear effects like yielding in compression and tension. Previously experimentally tested (on a shaking table) rectangular tanks with rigid and deformable walls were used for the verification of the developed numerical model. A good agreement between the numerical and the experimental results clearly shows that the developed model is suitable and gives accurate results for such problems. The numerical model results are validated with the experimental results and can be a useful tool for analyzing the behaviour of liquid tanks of larger dimensions.

Abstract: A reasonably accurate, low-cost system for the monitoring of strains in simple physical models within the field of Structural Engineering, based on Internet of Things, is presented, calibrated and discussed. The system only requires average, economic devices as Arduino microcontroller and strain gauges. Several tests on a case study of a scaled-cantilevered aluminium beam with different loading are conducted. Governing parameters are calibrated aimed at an optimization when benchmarked against theoretical and experimental results obtained with a reference device. Results show great accuracy; however, the need of setting of the parameters campaign-by-campaign, especially aimed at dealing with thermal drift, becomes a shortcoming. Still, its minimum cost and user-friendly management makes it a suitable solution for different applications.

Abstract: This article presents some results of the experimental monotonic bending tests on the behaviour of the tubular columns and the reverse channel, effected based on a parametric variation of the most significant characteristics of the tubular profiles. The parameters considered are the thicknesses and the widths of the tubular columns faces, the filling with concrete and the axial load. The experimental tests program, included in the framework of the Doctoral Program Thesis in the scientific domain of the Steel Composite Structures, were performed on a test layout, corresponds to a framed structure, in the Structural Mechanic Laboratory of the Department of Civil Engineering of the University of Coimbra. The objective is to determine the characteristics of the nonlinear cyclic behaviour of the principal components of the tubular columns and the reverse channel, in this shape of joints. These components are related to the tubular columns walls, and to the web and flanges of the reverse channel yielding, crushing or instability, when submitted to bending, shear, compression and tension. The results of this experimental tests allow correlate the parameters considered with the structural behaviour of the connection, defined by the resistance, the stiffness, and the rotation capability.

Abstract: This paper focuses on the characterization of the behaviour of Concrete Filled Steel Tubular (CFST) columns made with Rubberized Concrete (RuC), and on the development of an accurate numerical model for the simulation of CFST columns under monotonic and cyclic bending. The test campaign involves 18 CFST specimens with different configurations, namely the cross-section slenderness, the concrete strength, the axial load level and the lateral loading type. All CFST members tested exhibited good ductility under monotonic loading. The Eurocode 4 design provisions was verified against the test results and the design capacities of the CFST members were validated to be conservative. A comprehensive 3D Finite Element (FE) model was developed and calibrated based on test results. The FE model proved to be reliable in predicting the bending behaviour of CFST member, in terms of local buckling deformation modes, ultimate capacity and ductility of the CFST columns.

Abstract: The current paper deals with an overview on façade industry with the purpose to be useful for the engineers involved in the structural and architectural design of curtain walls.The research activity has been based on both the structural calculation and the experimental test on the Le Boulevard skylight in Doha (Qatar), measuring 36m by 18m in plan, located at a height of about 42 m and subjected to a wind load of 1.7 KPa. The skylight, composed of steel rectangular curved tubes, glass and aluminium sandwich panels, is designed for a basic wind speed of 25 m/s as per Qatar Construction Standards. Two types of steel frames have been designed, one to support both the glazing and aluminium sandwich panel, and another to transfer all the loads to the main structure. Subsequently, a performance testing on a specimen extracted from the skylight has been performed. The test was carried out by Aluminium Technology Auxilliary Ind. (ALUTEC) on a specimen having length and width of 6.625 m and 3.315 m, respectively. The assessment procedures have been carried out following the “ASTM E283”, “ASTM E331” and “ASTM E330” standards. The results of the test have been found within the acceptable limits for the skylight components specified by the standards and required by the project specification.

Abstract: To meet the need of modernized coal dressing, topology theory was used to build a kind of hybrid mechanism 2PRRR-R which can work as a main excitation mechanism of three freedom degree hybrid vibration screen with two-translation and one-rotation. Next, D′Alembert’s principle was introduced to establish a kinetic model of vibration screen frame and surface, and kinematic equations of directions of vibration screen frame and surface was achieved. Then, ADAMS was used to perform kinetic simulation of vibration screen, and kinetic parameters of the hybrid vibration screen was finally tested on multi-dimensional vibration screening test bench. The research shows that kinetic parameters’ numerical simulation of hybrid vibration screen with two-translation and one-rotation basically agrees with spot test value, which verifies the feasibility of the mechanism design, that the screen frame is of two motion freedom, that screen surface is of three motion freedom degree, that the rotation of the screen surface is relatively independent and controllable. The research provides further study of kinetic properties and development of hybrid vibration screen with two-translation and one-rotation with workable reference.