Test Bench For Characterization Research Articles

A Multifunctional Characterization Test Bench for Shape Memory Alloy Micro-Wires-Design, Implementation and Validation.

Most relevant to predicting the behavior of shape-memory-alloy (SMA)-based actuator-sensor applications activated by Joule heating are the electro-mechanical characteristics of the material under consideration. For a comprehensive characterization, a single setup that is able to provide all relevant data and information is desirable. This work covers the design, implementation and validation of such a high-end test bench for the holistic characterization of SMA micro-wires. In addition, the setup provides the possibility of application simulation experiments. Key elements of the design are the clamping mechanism guided on air bearings, a linear direct drive, a high-resolution load cell, a high-precision constant current source and a stress-controlled in-line wire sample installation. All measurements take place inside an isolated, temperature-controlled chamber. With the presented setup, the electro-mechanical and thermal characteristics of SMA wire samples with diameters from 20 µm to 100 µm can be determined. Via hardware-in-the-loop (HiL) implementation, the outputs with different biasing mechanisms and additional end-stops can be simulated even at high ambient temperatures. The generated results facilitate the prediction of the exact characteristics of SMA-driven actuator-sensor systems in a variety of applications and lead to a better general understanding of the alloy's properties. All functionalities and features of the setup are presented by discussing the results of exemplary experiments.

A new method for characterizing piezoelectric properties of hexagonal boron nitride nanoflakes activated by focused ultrasound

Piezoelectric nanomaterials wirelessly activated by ultrasound have been studied for biomedical applications. However, the quantitative measurement of piezoelectric effects in nanomaterials and the correlation between the ultrasound dose and the piezoelectric amplitude are still explored. We demonstrated the synthesis of boron nitride nanoflakes by mechanochemical exfoliation and employed the electrochemical method to quantitatively evaluate the piezoelectric performance of the nanoflakes under ultrasonic circumstances. The change of voltametric charge, current, and voltage in response to different acoustic pressure was obtained in the electrochemical system. The charge was reached up to 69.29 μC with a net increase of 49.54 μC/mm2 under 2.976 MPa. The output current was measured up to 597 pA/mm2 and positive shift of output voltage shifted from −600 mV to −450 mV. Additionally, the piezoelectric performance linearly increased with acoustic pressure. The proposed method could be a standardized evaluation test bench for characterization of ultrasound-mediated piezoelectric nanomaterials.

Millimeter-Wave Permittivity Variations of an HR Silicon Substrate from the Photoconductive Effect.

The photoinduced microwave complex permittivity of a highly resistive single-crystal silicon wafer was extracted from a bistatic free-space characterization test bench operating in the 26.5–40 GHz frequency band under CW optical illumination at wavelengths of 806 and 971 nm. Significant variations in the real and imaginary parts of the substrate’s permittivity induced by direct photoconductivity are reported, with an optical power density dependence, in agreement with the theoretical predictions. These experimental results open the route to ultrafast system reconfiguration of microwave devices in integrated technology by an external EMI-protected and contactless control with unprecedented performance.

30 K to 2 K vibration free remote cooling systems

Absolut System has built a 30 K and a 10 K remote Helium cooling loops used as a vibration free cooling source, respectively for IR detectors electro-optical characterization test bench and two-stage optical cryostat. The circulation loops are based on a by-passed flowrate from either a two-stage Gifford–McMahon cryocooler or a two-stage Pulse Tube cryocooler. Dedicated compact and high efficiency tubes & shell heat exchangers have been designed and produced for the recuperators. The paper describes the design and the performances of the vibration free cooling system produced. The current work towards a 4 K low vibration cooling source will be introduced as well.

High frequency model describing the noise transfer behaviour of automotive hydraulic engine mounts

To further decrease carbon dioxide emissions, efficiency of combustion engines in passenger cars needs to increase. Measures enhancing efficiency in combustion engines significantly increase engine vibrations. In order to provide a high level of comfort and low interior noise levels, isolation properties of engine mount systems have to compensate these increasing excitations. As existing analogous models of hydraulic mounts describe their behaviour only at low frequencies, we elaborate a model describing the isolation properties in a frequency range relevant for dominant engine orders. We deduce this model from parameter variation tests on hydraulic engine mounts using an electrodynamic test bench for characterisation. The parameters in the proposed model represent geometric properties as well as physical properties of springs, masses and dampening effects. Using the elaborated model helps to tune the parameters of engine mounts to the specific demands of different vehicles and to increase isolation properties.

High frequency model describing the noise transfer behaviour of automotive hydraulic engine mounts

To further decrease carbon dioxide emissions, efficiency of combustion engines in passenger cars needs to increase. Measures enhancing efficiency in combustion engines significantly increase engine vibrations. In order to provide a high level of comfort and low interior noise levels, isolation properties of engine mount systems have to compensate these increasing excitations. As existing analogous models of hydraulic mounts describe their behaviour only at low frequencies, we elaborate a model describing the isolation properties in a frequency range relevant for dominant engine orders. We deduce this model from parameter variation tests on hydraulic engine mounts using an electrodynamic test bench for characterisation. The parameters in the proposed model represent geometric properties as well as physical properties of springs, masses and dampening effects. Using the elaborated model helps to tune the parameters of engine mounts to the specific demands of different vehicles and to increase isolation properties.

Multifractal Analysis of Stack Voltage Based on Wavelet Leaders: A New Tool for PEMFC Diagnosis

AbstractTo achieve a fast and low cost diagnostic, we propose a new tool based on wavelet leaders in which the proton exchange membrane fuel cell (PEMFC) diagnosis is made by the observation of the one and only stack voltage. The steps of our strategy are the following ones: (i) the PEMFC is operated under a variety of conditions (nominal or severe) using a characterization test bench developed in lab. The severe operating conditions refer either to single fault types or to different combinations of faults; (ii) the recorded stack voltages are analyzed using a wavelet leader based multifractal analysis (WLMA) in order to identify their singularity spectra as fault signatures. This novel method based on leader discrete wavelet coefficients for the estimation of the singularity spectrum is a well‐suited technique for non‐stationary and non‐linear signals; (iii) a feature selection method is used to select the most relevant singularity features and to remove the redundant ones; (iv) the selected singularity features are classified using Support Vector Machine and K‐Nearest Neighbors techniques according to the considered operating situations (faults and combinations of faults).Our results show that the proposed PEMFC diagnosis tool allows identifying simple operating failure cases and even more complicated situations that contain several failure types.

Simple test bench for characterisation of high‐intensity discharge lamps in the frequency domain

A simple electronic circuit for the characterisation of high-intensity discharge (HID) lamps in the frequency domain by obtaining the transfer function of the lamp impedance is presented. The circuit uses a low cost power amplifier to apply a sinewave to the current and the voltage in the lamp. Also, this circuit employs an ordinary igniter based on a high voltage transformer. This circuit is a good alternative when a ballast designer prefers to get a lamp model from experimental Bode plots, and when a low budget is available to build a test bench to characterise HID lamps. Simulations and experimental results obtained from an HPS lamp are shown.

Spectrally-resolved measurement of concentrated light distributions for Fresnel lens concentrators.

A test method that measures spectrally resolved irradiance distribution for a concentrator photovoltaic (CPV) optical system is presented. In conjunction with electrical I-V curves, it is a means to visualize and characterize the effects of chromatic aberration and nonuniform flux profiles under controllable testing conditions. The indoor characterization test bench, METHOD (Measurement of Electrical, Thermal and Optical Devices), decouples the temperatures of the primary optical element (POE) and the cell allowing their respective effects on optical and electrical performance to be analysed. In varying the temperature of the POE, the effects on electrical efficiency, focal distance, spectral sensitivity, acceptance angle and multi-junction current matching profiles can be quantified. This work presents the calibration procedures to accurately image the spectral irradiance distribution of a CPV system and a study of system behavior over lens temperature.