Experimental studies on a compression–absorption system for heating and cooling applications

Experimental and numerical studies of ultra high performance fibre reinforced concrete (UHPFRC) two-way slabs

The main scope of this dissertation has been to give a contribution to the evaluation of seismic performance of CFS structures and in particular of diagonal strap braced walls. To this end, two main objectives are pursued in this work: the study of the seismic behaviour of diagonal strap braced walls in terms of global response and the study of local behaviour of connections to understand their influence on the global seismic behaviour of walls. In the context of ReLUIS-DPC project, a wide experimental program was planned and carried out. It consists of full-scale experimental tests on walls to investigate the global behaviour and small-scale experimental tests on materials, simple mechanical joints and connections to investigate the influence of the local behaviour on the global seismic behaviour. The experimental tests have been performed at the Dist Laboratory (Department of Structures for Engineering and Architecture, Naples), of the University of Naples Federico II. The obtained results demonstrate a satisfactory experimental response in terms of stiffness, strength and deformation capacity, largely confirming the theoretical predictions. Since the final scope of the whole study, and in particular of the experimental campaign, is to provide appropriate design criteria for diagonal strap braced CFS structures to be introduced in Italian seismic code, considerations about design criteria were presented, on the basis of the design assumptions and the experimental test results, in comparison with the prescriptions of national and international seismic codes. The attention is focused on the behaviour factor, the diagonal brace verifications and the overstrength of fragile elements.

Since the energy crisis and the environmental issue have been focused due to excessive fossil fuel consumption, the wind power has been considered as an important renewable energy source. Recently, several MW class large scale wind turbine systems have been developed in some countries. Even though the large scale wind turbine can effectively produce the electrical power, the small scale wind turbines have been continuously developed due some advantages, for instance, it can be easily built by low cost without any limitation of location, i.e. even in city. In case of small scale wind turbines, the vertical axis wind turbine (VAWT) is used in city having frequent wind direction change, even though it has a bit lower efficient than the horizontal axis wind turbine. Furthermore, most small scale wind turbine systems have been designed at the rated wind speed of around 12m/s. This work is to design a high efficiency 500W class composite VAWT blade which is applicable to relatively low speed region. In the aerodynamic design of blade, the parametric studies are carried out to decide an optimal aerodynamic configuration. The aerodynamic efficiency and performance of the designed VAWT is confirmed by the CFD analysis. The structural design is performed by the load case study, the initial sizing using the netting rule and the rule of mixture, the structural analysis using FEM, the fatigue life estimation and the structural test. The prototype blade is manufactured by the hand lay-up and the matched die molding. The experimental structural test results are compared with the FEM analysis results. Finally, to evaluate the prototype VAWT including designed blades, the performance test is performed using a truck to simulate the various range wind speeds and some measuring equipments. According to the performance evaluation result, the estimated performance is well agreed with the experimental test result in all operating ranges.

The paper addresses the methodologies required to derive a reliable and representative simulation environment for virtual shaker testing to predict the outcome of Spacecraft vibration tests numerically prior to its physical execution. The simulation environment needs to comprise the coupled dynamical models of the testing facility, structure under test and control system active during test. Especially, the paper focuses on modelling and experimental validation techniques for coupled test specimen models using the coupled head expander and beam test specimen system as validation test case. The main focus is set on the derivation of experimental test structure models which will be used in the future for modal coupling by applying Component Mode Synthesis and to assess the added value against alternative sub structuring techniques w.r.t. frequency bands and residual compensation, analysis of the measurement of required interface and connection point degrees-of-freedom and consideration of damping. Consequently, those experimental results are used to derive preliminary methodologies and guidelines to couple structural sub component models, and use them in further numerical closed-loop vibration control simulations. Consequently, the developed and experimentally derived structural dynamic models are coupled with a multi-physical electrodynamic shaker and sine controller model to virtually replicate sine control tests, followed by a validation with experimental test results and to be used in preliminary numerical investigations for vibration control performance enhancement.

In this paper, the compressive behavior of a carbon fiber composite pyramidal lattice cylinder has been predicted based on initial failure criteria and progressive damage. To this end, the 3D Hashin failure criteria have been employed with instantaneous and gradual unloading models using the user subroutine UMAT in ABAQUS/Standard. In the gradual unloading model, progressive damage has been controlled by exponential damage function. In addition, a new mold has been designed and manufactured for the experimental test of composite pyramidal lattice cylinders, which allows the use of the maximum essential strength of the fiber-reinforced composite. The predicted load-displacement curves using the finite element models are in good agreement with the experimental test results.

Investigation of cohesive FE modeling to predict crack depth during deep-scratching on optical glasses

Dynamic transient analysis of squealing vibration of a reciprocating sliding system

This paper presents experimental monotonic and cyclic test results on small scale sand columns reinforced by means of geosynthetics. The influence of the stiffness of the georeinforcement on the system mechanical response is discussed as well as that of the previous loading history. The experimental test results have also been numerically simulated by employing a 3D finite difference commercial code. A parametric study concerning the georeinforcement stiffness and the soil-column interface friction angle is presented. The results prove the influence of the encasing geosynthetic on the overall stiffness of the system, as well as of the stiffening effect induced by a possible preload applied on the column. The effect of shear stresses at column-soil interface is also observed to play a non negligible role, which is expected to become even more evident for real scale geo-encased columns. Numerical approaches based on standard constitutive models are able to capture the behaviour of the system under virgin load, but they totally fail in reproducing the unload-reloading response.

Assessment of mechanical properties in unirradiated and irradiated zircaloys and steels with non-standard tests and finite element calculations

Numerical and experimental investigations on buckling of steel cylindrical shells with elliptical cutout subject to axial compression

An exergy analysis of a single-stage compression–absorption system with R22-E181 as the working fluid pair is carried out. Theoretical results obtained have been compared with those obtained from the experiment. Results show that the heat of mixing of the refrigerant vapour and solution at absorber and desorber contributes a significant amount to the internal entropy generation rates. A significant part of internal entropy generation rate is also due to non-isentropic compression of refrigerant vapour at higher absorber pressure. The exergetic efficiency of the system increases with the increase in absorber pressure due to reduction in internal irreversibilities. Higher value of weak solution concentration along with the increase in solution concentration difference results in higher exergetic efficiency of the system. Thus, a compression–absorption system performs better when operated at higher absorber pressure, and an improved system performance can also be achieved with higher value of weak solution concentration with higher possible solution concentration difference. Copyright © 2008 John Wiley & Sons, Ltd.

One of the obstacles in laboratory testing is the availability of testing capacity. So that the similitude method was developed which aims to replicate the state of the prototype by scaling the variables so that they can be tested in the laboratory. The purpose of this study was to determine the difference between the results of numerical tests and experimental tests on the response of the open frame portal structure and the braced portal structure to the perpindahan parameters and the driftt ratio of the steel portal structure in earthquake buildings. The method used in this research is the experimental test method. From the analysis results, the largest perpindahan difference between the numerical test and the experimental test of the open frame portal structure is on the 4th floor, with a difference of 21,8 mm, while the largest perpindahan difference in the braced structure is on the 6th floor with a difference of 14,54 mm. The highest perpindahan difference is between numerical tests and experimental tests that occur on the open frame structure are on the 3rd, 4th, and 5th floors while those that occur on the braced structure are on the 5th, 6th, and 7th floors but the experimental perpindahan test is still within the permit limits for structural planning and if reviewed from the driftt ratio results, the results exceed the allowable driftt ratio limit of 2% of the height of each building level located on the 1st and 6th floors of the open frame portal structure and on the 5th floor of the braced portal structure.

Today, there is an increasing use of fiber reinforced polymer (FRP) composites in civil engineering as reinforcement of existing structures. In particular, FRP composites offer higher strength and Young’s modulus than traditional steel devices, also easy handling and installation, excellent resistance to corrosion and they can be plastered after application. When FRP wraps are used to confine compressed pillars, the effective contribution of the composite cannot be accurately evaluated because it begins to work as the stress state of the member grows. In the present paper, some theoretical relationships available in literature and in current international design guidelines, regarding the evaluation of confinement effect on wrapped concrete columns, are analyzed and compared with experimental test results. Based on these considerations, we propose a new formula that is in good agreement with the experimental test results that were produced for the purpose and reported both in the present paper and in a previously published research study. Although empiric, the proposed formula is able to reproduce the structural response of wrapped specimens and the failure mode as observed in the experimental tests.

This article proposes a novel device for wrist motion rehabilitation. The proposed mechatronic architecture is based on a simple user-friendly design, which includes a mobile platform for hand support, which is operated by a single actuator. A dedicated assist-as-needed control is designed to operate the device for the required movements. The proposed control strategy is also integrated into a gaming software for stimulating the exercising by means of various interactions with patients. Experimental tests are carried out with 14 healthy subjects at the Physiotherapy Clinical Hospital of the Federal University of Uberlandia. Also, three patients with stroke have been enrolled in a pilot clinical testing. Each of the patients has been involved in four sessions per month with 15 min of assisted treatment. Results of experimental tests are analyzed in terms of improvements and amplitude gains for the flexion and extension wrist movements. Experimental results are reported as evidence for the feasibility and soundness of the proposed device as a tool to assist professionals in procedures of wrist rehabilitation.

Modeling of micro-CHP (combined heat and power) unit and evaluation of system performance in building application in United States