Dynamic Interferometry for On-Machine Metrology

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.

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

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

Dynamic transient analysis of squealing vibration of a reciprocating sliding system

In this paper, the first experimental results of tests with a new model support designed for simulations of high frequency and high amplitude pitching maneuvers are presented. A generic missile model with a blunt nose was used for which static test data from earlier experiments with a conventional model support were existing. At the beginning, static tests were done for comparison purposes to judge the influence of the new setup (model support, sting for the model, pivot arm) on the measured forces and moments. Afterwards, dynamic tests with sine oscillations at frequencies of $$f_{\rm a}=0.05\ldots 4\,\hbox{Hz}$$ and angles of attack varying between $$\alpha = 0^{\circ} \ldots 45^{\circ}$$ were performed. Beside the qualification of this new test rig, the tests were used to study the “Phantom Yaw Effect” and to prove an interactive method of its control. This phenomenon is characterized by unwanted yawing moments resulting from asymmetric vortices which can occur on slender bodies at high angles of attack. In the tests, a lee-vortex control device with symmetrically arranged longitudinal slot nozzles producing “air-jet strakes” was demonstrated to decrease the yawing moments both under static and dynamic conditions.

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.

The relative casing motion can significantly influence the turbine blade tip aerothermal performance. In this study, experimental investigation was conducted in a newly developed high-speed disk rotor rig which can mimic engine realistic high-speed casing relative motion while enabling full optical access to a transonic turbine blade tip surface. Spatially-resolved tip heat transfer data, including heat transfer coefficient and film cooling effectiveness, were obtained for a cooled transonic squealer tip by infrared transient thermal measurement. Combined with closely coupled Reynolds-averaged Navier–Stokes computational fluid dynamics (CFD) analysis, this paper reveals an interesting interaction mechanism between the cooling injections from the pressure side and the cavity floor with and without the effect of relative casing motion. Both experimental data and CFD results show a consistent trend in both heat transfer and cooling performance. With cavity cooling only, the cooling performance reduces with the effect of relative casing motion. However, with additional cooling injection from the pressure side, a significant improvement in the combined cooling performance with the relative casing motion can be observed. Such opposite trend highlights the importance of relative casing motion when ranking different tip cooling designs. With the consideration of relative casing motion, extra tip cooling benefit can be obtained by combining cooling injections from two different locations.

A numerical approach based on the particle discrete element method, in which the rock matrix is represented as flat joint contacts and weak planes are conceptualized as a set of parallel continuous smooth joint contacts, was adopted to simulate the transversely isotropic rocks. Firstly, this approach was validated through the comparison in the strength and fracture patterns of typical anisotropic rocks between simulation and experimental test results. Then, the influence of micro-structure of rock matrix and micro-parameters of weak planes on the mechanical behaviors of transversely isotropic rocks under uniaxial compression was studied. The results show that (1) good agreement is obtained between the numerical and experimental results in terms of strength and fracture patterns for typical U type or shoulder type rocks; (2) the types for the variation of uniaxial compression strength as a function of the weak plane-loading angles and the fracture patterns are slightly influenced by the tensile strength of weak planes but greatly influenced by the pre-existing micro-cracks in rock matrix, the stiffness and shear strength of weak planes; (3) shear and tensile micro-cracks in rock matrix are prone to occur in congregated region of pre-existing micro-cracks for the poor integrity in these regions. While the pre-existing micro-cracks in rock matrix has little influence on the occurring position of shear and tensile cracks on weak planes.

Prediction of thermal expansion coefficients of sandwiches using finite elements methods validated by experimental test results

Assessment of geogrids in gravel roads under cyclic loading

An experimental study has been carried out on a single-stage compression–absorption system for simultaneous heating and cooling with R22 and E181 (DMETEG) as the working fluid pair. An absorber, being the major component of the system, is designed to absorb the amount of vapour that can be handled by the selected refrigerant compressor. The designs of the other components of the system are based on the design result of the absorber. The experimental test results have been compared with the results obtained from the theoretical analysis of the system. Though the experimental results are found to match the theoretical results qualitatively, the performance of the experimental test rig is found to be lower than that of the theoretical predictions due to various heat losses from the system and non-ideal compression. Copyright © 2007 John Wiley & Sons, Ltd.

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.

High Voltage Transmission Line Electromagnetic Field’s (HVTL-EMF) impact on solar PV performance is analyzed in the proposed work. Depending on HV-EMF, the electrical characteristics and conversion process of PhotoVoltaic (PV) panels are analyzed. Electromagnetic (EM) field from HV lines has a partially positive and somewhat negative impact on solar PV. When absorption probability is low, one photon and one phonon are required. Phonons are vibrational energy units. A solar PV cell made of Silicon (Si) semiconductor material requires phonons to have high conversion efficiency and electric field from HV transmission line induces phonon. In addition, electric field from HV line increases the solar cell temperature (10 to 15°C) to the ambient temperature. Because of high solar PV cell temperature and high EM field, solar PV power generation is affected by increasing panel temperature. The proposed system uses unnatural Phase Change Material (PCM-Glauber salt (Na2SO4.10 H2O)) coated to the backside of solar PV to normalize the temperature. The impact of electromagnetic fields produced by HV lines on solar cells coated with PCM is validated with experimental testing results. The experiment considers a HVTL of 230kV and solar PV rating of 20 W. The experimental results are measured at various distance ranging from 12 to 22 meters between solar PV and HV transmission lines. Conversion efficiency of solar PV with PCM coating under the impact of HVTL- EMF has increased by 3%.

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.

Concrete filled steel columns in multistorey buildings provide outstanding constructability and economy when compared to traditional steel sections. However, minimal research work and insufficient design guidance is available throughout the world, particularly concerning slender composite columns, although they are becoming increasingly used in multistorey buildings. This paper is concerned with the behaviour and design of high strength concrete filled slender box columns. A series of tests were carried out which included four slender composite columns, four slender steel columns, four short composite columns and additional material property tests. Two different steel hollow section types were chosen for this study together with two nominal concrete strengths of 60 and 80 MPa. The columns were tested under concentric axial force and the experimental results are presented and discussed. The results of these experiments, and of experiments conducted elsewhere, have been calibrated successfully with the numerical solution developed herein. Furthermore, comparisons have been carried out between predicted column strengths, as provided by Eurocode 4, BS5400, AS4100 and experimental test results. Recommendations are then made which may be amenable for the designs of slender composite columns when using high strength concrete.