Dynamic Test Bench Research Articles

Efficient Static and Dynamic Modelling of Machine Structures with Large Linear Motions

Mechatronic structures deform under static and dynamic loads. These deformations lead to deviations at the tool center point (TCP), affecting the reachable accuracy and/or productivity of the machines. The scope of this work is the comparison of calculations and measurements of different static and dynamic errors on a dynamic test bench. A reduced-order modelling approach is applied for the test bench modelling. It uses a combination of modal condensation and moment-matching methods with Krylov subspaces. The different modelling steps and requirements are presented. The same model is used for all static and dynamic evaluations presented within this paper. Static deformations, leading to roll and pitch deviations at the TCP of the test bench structure, are simulated using the described modelling methodology and validated by inclination measurements. The modal behavior of the system is investigated by calculation and compared to the measurements at a single axes position. The spatial change of the frequency response functions of the modelled system is investigated further, by calculation and measurement of the velocity open-loop FRFs of one axis for different machine configurations. In addition, a transient trajectory simulation is performed and compared to the Heidenhain KGM and encoder measurements. The large variety of comparisons shows the efficient applicability of the modelling environment MORe.

Frequency Response of Laser Gyroscopes in a Wide Range of Rotation Velocities

The laser gyro frequency response is studied by means of numerical simulation using a phase equation. The calculation results are compared to the results of experimental measurements on a precision dynamic test-bench. Quantitative relationship between the threshold value of static lock-in zone and frequency response distortions is established. Numerical methods helped to obtain and experimentally confirm the quantitative dependence of frequency response distortion on the amplitude and frequency of meander-shaped dither. It is shown that the dither shape significantly affects the frequency response form. Furthermore, it is demonstrated that frequency-response distortions depend on conditions of its measurement, in particular, on the time. The conducted research allows dither parameters to be optimized with a view to increase the accuracy of measurements using laser gyroscopes.

A 17.5 kWel high flux solar simulator with controllable flux-spot capabilities: Design and validation study

A new High Flux Solar Simulator (HFSS) has been designed and built for the research of medium/ high-temperature solar material testing and solar thermochemical processes in Mexico. The HFSS was designed using seven 2.5 kWel Xenon short arc lamps, each close-coupled to a 2 m focal length truncated ellipsoidal specular reflector made of polished aluminum. A Monte Carlo (MC) ray tracing technique was employed to design the shape of the ellipsoidal reflectors. The estimated radiative flux obtained with the MC ray-tracing was 1700 kW m−2 peak flux for all the seven lamps in a flux spot of 100 mm in diameter. A peak flux of 267 kW m−2 was obtained for a single lamp-reflector unit. The design, dimensions and material specifications are presented. The control system is composed of an attenuator curtain and a servo-controlled dynamic test bench that allows variation of the spot size and irradiance incident in the focal plane. A study to compare the theoretical design and the real ellipsoidal reflector surface was conducted with the use of the photogrammetry technique. This was done in order to know if differences in the theoretical flux compared to that of the measured flux come from defects in manufacturing of the reflector. A data acquisition module and an artificial vision system provide information and allow for a monitoring flux spot. Obtaining an experimental peak flux of 194 kW m−2 and a flux spot diameter of 120 mm per lamp, the results were consistent with the desired design. In addition, in order to quantify the risk of our own installation and implement a safety protocol, an experimental campaign of ultraviolet radiation monitoring was conducted; the assessment of ultraviolet radiation shows that the recommended dose per 8 h is exceeded in a few seconds when close to the focal plane (∼0.2 m). In this paper, due to extension, preliminary design, construction, and validation of the HFSS are presented.

Prediction of exhaust emission in transient conditions of a diesel engine fueled with animal fat using Artificial Neural Network and Symbolic Regression

The objective of this study is the development and evaluation of two models to predict instantaneous exhaust emissions of CO2, NOx, particle number concentration and geometric mean diameter in accumulation mode (30–560 nm) and in nucleation mode (5.6–30 nm) of a 2.0 euro 4 diesel engine fueled with pure diesel and animal fat in different proportions. To acquire data for training, validation and testing, 4 repetitions of the urban part of the New European Driving Cycle and 5 steady-state conditions (15, 30, 50, 70 and 100 km/h) were reproduced in a dynamic engine test bench. The used prediction models were Artificial Neural Networks and Symbolic Regression. Vehicle speed and acceleration, engine speed and torque, air intake temperature, boost pressure, mass air flow and fuel consumption were used as inputs variables. Artificial Neural Networks provided a R2 for testing dataset equal to 0.91, 0.78, 0.87 and 0.81 for CO2, NOx, number of particles in accumulation mode and geometric mean diameter, respectively. Symbolic regression showed a R2 of 0.91, 0.82, 0.87 and 0.82 for the mentioned pollutants. Particle number concentration in nucleation mode presents low correlation with the considered inputs due to the variability of the formation process of this particle mode.

Design and Optimization of Automatic Shifting Mechanism for the Tractor

The stability of the shifting mechanism is the basis of the reliability of the automatic shift system. The gear shifting process of Taishan TG1804 tractor is hard and long. In order to solve this problem, we design a tractor automatic shift system and apply it to the tractor successfully. This paper designs a shifting mechanism, optimizes the shifting mechanism and dose the dynamic bench test. The test results prove that the optimized shifting mechanism is more reliable and more reasonable.

Preliminary validation of a dynamic electrochemical biodegradation test bench in pseudo-physiological conditions

There is a growing interest in the development of next-generation stent materials. In vitro tests that accurately predict in vivo conditions are desired. In this manuscript, a novel approach for the design of a dynamic electrochemical test bench is evaluated for potential characterisation of biodegradable metallic stent materials. The designed dynamic test bench allows for real-time corrosion testing with easy variation of temperature, shear stress and simulated body fluids (SBF), with minimal complications of test sample fabrication. Preliminary tests have shown Tafel generation is feasible and stable. Effect of SBF, shear stress and temperature were evaluated. Variances in the dynamic test bench were higher with the incorporation of temperature and shear stress, with no notable difference between SBF. This dynamic test bench showed to be relatively stable under temperature and SBF modification; however, further optimisation is needed to decrease variances seen throughout fluid velocity analysis.

Dynamic test bench for motocross engines

Simulation of engine components enables early design verification and reduced development time while helping racing teams in getting new knowledge. This article presents a multidiscipline dynamic test bench and a benchmark of two different connecting rods for HONDA CRF250R. The test bench embeds mechanical and control system modeling and simulation including electric starters, ignition timing, power control as well as sensors and actuators enabling closed-loop systems. A non-linear finite element program that combines the traditional separate multi-body simulation and finite element modeling and simulation tasks captures all load cases and dynamic effects in one single run. Model reduction techniques are applied to optimize simulation speed and results accuracy. The virtual test bench captures dynamic engine effects and efficiently provides new knowledge about engine performance and integrity.

Model-Based Control of BMEP and NOx Emissions in a Euro VI 3.0L Diesel Engine

A model-based approach to control BMEP (Brake Mean Effective Pressure) and NOx emissions has been developed and assessed on a FPT F1C 3.0L Euro VI diesel engine for heavy-duty applications. The controller is based on a zero-dimensional real-time combustion model, which is capable of simulating the HRR (heat release rate), in-cylinder pressure, BMEP and NOx engine-out levels. The real-time combustion model has been realized by integrating and improving previously developed simulation tools. A new discretization scheme has been developed for the model equations, in order to reduce the accuracy loss when the computational step is increased. This has allowed the required computational time to be reduced to a great extent. The real-time combustion model has been first calibrated and assessed at both steady-state and transient conditions, on the basis of experimental data acquired at the highly dynamic test bench of ICEAL-PT (Internal Combustion Engines Advanced Laboratory - Politecnico di Torino), in the frame of a research activity in collaboration with FPT Industrial. The model has then been used to realize a model-based control of BMEP and NOx emissions. In particular, the controller provides the injected fuel quantity and the injection timing of the main pulse, for given targets of BMEP and engine-out NOx levels. Finally, the developed controller has been tested on a rapid prototyping device (ETAS ES910) through HiL (Hardware-in-the-Loop) techniques, and demonstrated to have real-time capability.

A numerical model for the prediction of the fluid dynamic and mechanical losses of a Wankel-type expansion device

This paper presents a numerical model of the fluid dynamic processes and mechanical losses of a Wankel-type expansion device for microgeneration purposes. The prototype was built at the University of Pisa using the rotating parts of a gasoline-fueled Wankel engine. Considering the geometrical features of the prototype, the model simulates the fluid-dynamic losses across the valves, the thermal exchange with the outer ambient and the mechanical losses of the whole mechanism. The numerical results were then validated by the comparison with the pressure cycle obtained at the dynamic test bench using compressed air.

Novel AC Servo Rotating and Linear Composite Driving Device for Plastic Forming Equipment

The existing plastic forming equipment are mostly driven by traditional AC motors with long transmission chains, low efficiency, large size, low precision and poor dynamic response are the common disadvantages. In order to realize high performance forming processes, the driving device should be improved, especially for complicated processing motions. Based on electric servo direct drive technology, a novel AC servo rotating and linear composite driving device is proposed, which features implementing both spindle rotation and feed motion without transmission, so that compact structure and precise control can be achieved. Flux switching topology is employed in the rotating drive component for strong robustness, and fractional slot is employed in the linear direct drive component for large force capability. Then the mechanical structure for compositing rotation and linear motion is designed. A device prototype is manufactured, machining of each component and the whole assembly are presented respectively. Commercial servo amplifiers are utilized to construct the control system of the proposed device. To validate the effectiveness of the proposed composite driving device, experimental study on the dynamic test benches are conducted. The results indicate that the output torque can attain to 420 N·m and the dynamic tracking errors are less than about 0.3 rad in the rotating drive. the dynamic tracking errors are less than about 1.6 mm in the linear feed. The proposed research provides a method to construct high efficiency and accuracy direct driving device in plastic forming equipment.

Development and Assessment of Pressure-Based and Model-Based Techniques for the MFB50 Control of a Euro VI 3.0L Diesel Engine

Pressure-based and model-based techniques for the control of MFB50 (crank angle at which 50% of the fuel mass fraction has burned) have been developed, assessed and tested by means of rapid prototyping (RP) on a FPT F1C 3.0L Euro VI diesel engine. The pressure-based technique requires the utilization of a pressure transducer for each cylinder. The transducers are used to perform the instantaneous measurement of the in-cylinder pressure, in order to derive its corresponding burned mass fraction and the actual value of MFB50. It essentially consists of a closed-loop approach, which is based on a cycle-by-cycle and cylinder-to-cylinder correction of the start of injection of the main pulse (SOImain), in order to achieve the desired target of MFB50 for each cylinder. The model-based technique, instead, requires the adoption of a heat release predictive model to simulate MFB50; this model is based on an improved version of the accumulated fuel mass approach, which requires the injection rate as input. This control technique is essentially based on the inversion of the heat release model, in order to identify the optimal value of SOImain that allows the desired MFB50 target to be achieved cycle-by-cycle. The approach is therefore of the open-loop type. Both control techniques were developed and assessed by means of Model-in-the-Loop (MiL) and Hardware-in-the-Loop (HiL) techniques, and then tested on the engine using a rapid prototyping device. The experimental tests were performed on a highly dynamic test bench at the Politecnico di Torino. These techniques have shown a good potential for MFB50 control, compared to the standard methodology implemented in the Engine Control Unit (ECU).

Test and assessment method of Automotive Safety Systems (SSB) particularly to monitor traffic incidents

The rapid development of telematics, particularly mobile telephony (GSM), wireless data transmission (GPRS) and satellite positioning (GPS) noticeable in the last decade, resulted in an almost unlimited growth of the possibilities for monitoring of mobile objects. These solutions are already widely used in the so-called “Intelligent Transport Systems” - ITS and affect a significant increase for road safety. The article describes a method of testing and evaluation of Car Safety Systems (Polish abbreviation - SSB) especially for monitoring traffic incidents, such as collisions and accidents. The algorithm of SSB testing process is also presented. Tests are performed on the dynamic test bench, part of which is movable platform with car security system mounted on it. Crash tests with a rigid obstacle are carried out instead of destructive attempts to crash test of the entire vehicle which is expensive. The tested system, depending on the simulated traffic conditions, is mounted in such a position and with the use of components, indicated by the manufacturer for the automotive safety system installation in a vehicle, for which it is intended. Then, the tests and assessments are carried out.

Calibration of a precision SINS IMU and construction of IMU-bound orthogonal frame

The paper focuses on construction of reference orthogonal frame bound with inertial measurement system of a strapdown inertial navigation system. Main points of the algorithm refining the FOG IMU calibration parameters in dynamic test bench conditions using the Kalman filter and relying upon the system navigation solution are detailed. Time lags in FOG gyros and accelerometers’ measurement channels are estimated to the accuracy allowing construction of a 0.001 deg/h class navigation system.

Experimental study on the performance of a ZEBRA battery based propulsion system for urban commercial vehicles

Fleets of commercial vehicles for delivery services in urban areas constitute road transportation means which are required to run relatively short distances and to respect anti-pollution laws commonly imposed by many municipalities. For this kind of commercial applications, high efficiency and eco-friendly electric propulsion systems offer an interesting alternative to thermal engines. This paper is focused on the analysis of such solution, by presenting experimental results obtained with a ZEBRA battery based propulsion system, designed to power a specific urban unit within the category of electric commercial vehicles. A novel contribution is added to the relevant literature concerning battery based electric powertrains for road vehicles. The main novelty consists in a wide range of experimental results and performance analysis carried out with reference to the real behavior of both the whole propulsion system and each main component, when powering the commercial vehicle, on the urban part of the NEDC (New European Driving Cycle) standard driving cycle, at different slopes. The experimental results, expressed through electrical and mechanical parameters, are initially evaluated by means of a quasi-static numerical model of the electric powertrain and then experimentally verified with the support of a 1:1 scale laboratory dynamic test bench. The procedure followed and presented in this paper definitely demonstrates the good design and performance, obtained for the evaluated propulsion system, in satisfying the real energy and power requirements, specific of an urban use for delivery commercial vehicles, in terms of daily autonomy and slopes. The collections of experimental results, analyzed in the paper, represent in addition a useful set of data for simulation in order to build, verify and improve models in their outputs.

Experimental assessment of a phase change material storage tank

This paper describes the experimental study carried out to assess the performance of a Phase Change Material (PCM) storage tank in various operating conditions in a dynamic test bench. The studied horizontal PCM tank contains stacks of slab-like PCM capsules between which heat transfer fluid can circulate. The commercially available capsules were instrumented so the PCM behaviour could be measured in addition to that of the PCM tank as a whole. Numerous melting and solidification cycles were completed with different inlet fluid temperatures, flowrates and load profiles for which at least three repetitions were made. Analysis of test results shows significant variations in the PCM behaviour under the same tests conditions including varying degree of supercooling and differing phase change temperature. The outlet fluid temperature from the tank can however be predicted accurately from operating conditions and the initial state of the PCM. Interrupting phase change processes before the PCM is completely melted or solidified affects the temperature at which the PCM changes phase as well as the degree of supercooling measured. Results from this investigation will be especially useful for researchers developing and validating numerical models for use in various building energy systems as the complete experimental data set is made available as an online companion to this paper.

Fast estimation of combustion metrics in DI diesel engines for control-oriented applications

The present work has been focused on the development of low-throughput semi-empirical models to predict the peak firing pressure, indicated mean effective pressure and brake mean effective pressure in direct injection diesel engines. The models have been calibrated and assessed on a 1.6L GM Euro 6 diesel engine, on the basis of the results of experimental tests conducted at a dynamic test bench at GMPT-E (General Motors Powertrain-Europe). Model validation was carried out over “New European Driving Cycle” and “Worldwide Harmonized Light vehicle Test Procedure” missions. The performance of the semi-empirical models has been compared, in terms of prediction accuracy, robustness, inversion efficiency and computational expense, with that of a previously developed real-time physical combustion model. The thus developed semi-empirical models are characterized by a very low computational effort, and are therefore suitable for the development of innovative feed-forward control algorithms in the Engine Control Unit.

Development and Validation of a Real-Time Model for the Simulation of the Heat Release Rate, In-Cylinder Pressure and Pollutant Emissions in Diesel Engines

A real-time mean-value engine model for the simulation of the HRR (heat release rate), in-cylinder pressure, brake torque and pollutant emissions, including NOx and soot, has been developed, calibrated and assessed at both and transient conditions for a Euro 6 1.6L GM diesel engine. The chemical energy release has been simulated using an improved version of a previously developed model that is based on the accumulated fuel mass approach. The in-cylinder pressure has been evaluated on the basis of the inversion of a single-zone model, using the net energy release as input. The latter quantity was derived starting from the simulated chemical energy release, and evaluating the heat transfer of the charge with the walls. NOx and soot emissions were simulated on the basis of semiempirical correlations that take into account the in-cylinder thermodynamic properties, the chemical energy release and the main engine parameters. The model is also referred to as steady-state as the main thermodynamic properties in the intake and exhaust manifolds, as well as the inducted mass flow rate, have been evaluated by means of cor relations that were calibrated under conditions. This has allowed a very low computational time to be obtained, so that the approach is suitable for implementation in an ECU for real-time applications. The model has been calibrated over several experimental tests carried out at a dynamic test bench at GMPT-E (General Motors powertrain-Europe). The tests include a complete engine map as well as several full-factorial variation lists of the main engine parameters, which have been conducted for seven representative operating conditions of the NEDC (New European Driving Cycle). The validation has been carried out under transient conditions over NEDC and WLTP missions, which were simulated at the dynamic test bench for a C-class vehicle.

Dynamic calibration uncertainty of three-axis low frequency accelerometers

In this paper a methodology concerning the static and dynamic calibration of three-axis low-cost accelerometers in the (0 to 10) Hz frequency range is described, to be used for evaluation of existing civil infrastructures. <br /> Main and cross sensitivities of the accelerometers have been experimentally estimated by means of the matrix sensitivity concept. <br />The standard deviation of accelerations obtained along all three axes using different calibration data sets in repeatability conditions has been calculated and intended as dynamic calibration uncertainty. <br />The method has been validated by using reference accelerations accurately realized, in order to evaluate the residual bias error. <br />Static and dynamic calibration test benches have been used to realize reference accelerations. In order to create a three-axis acceleration field, a mechanical arm is used in static calibration; a rotary device is used in order to test the accelerometers in dynamic conditions. <br />According to the procedure described in this paper, a great improvement of the low cost accelerometers' metrological characterization could be achieved, especially in dynamic working conditions.

Numerical and Experimental Analysis of the Intake and Exhaust Valves of a Rotary Expansion Device for Micro generation

The use of ORCs is growing in importance the last years, because this type of cycles permits to exploit energy sources which are characterized by low enthalpies (waste heat, low temperature geothermal, low concentration solar plants, etc.) and low installed power sizes (up to 50-100kW). In this size range, volumetric machines are very attractive devices because they show better efficiencies than turbines. Volumetric expansion devices flow rate is not continuous as in turbines but on the contrary has a pulsating behavior and the effective flow area of the intake and exhaust ports plays an important role in determining the efficiency of such devices.In this paper an analysis regarding the influence of the intake and exhaust valves features on the performances of a rotary expansion device for micro generation derived from a Wankel engine is presented. The analysis which is presented in this paper was carried out by means of both numerical and experimental techniques. CFD simulations of two different types of valves were performed to obtain the values of discharge coefficient and, subsequently, the results were validated at the fluid dynamic test bench. These solutions were also evaluated by testing the prototype using compressed air as working fluid under various operating conditions (pressure ratio, rotating speed). The delivered torque, the air mass flow rate and the indicated cycle were taken into account for the evaluation of the influence of the valves shape and timing on the device performances.

Experimental and numerical assessment of methods to reduce warm up time of engine lubricant oil

Carbon dioxide emission reduction is the most important challenge concerning on the road transportation. Stringent quantitative commitments have been set, both for automotive and for light and heavy duty vehicles. Future engine (and vehicle) technologies will consider a portfolio of new components, engine layouts, control strategies, integrated functions which will match also new comfort standards and fun to drive options, and complying fuel consumption savings.Engine thermal management is an area of intervention aimed at reducing the warm up time: in most part of the homologation cycle, both in passenger cars and in light duty vehicles, engines do not reach a stabilized thermal state. This produces a significant pollutants and fuel consumption increase. Engine thermal management can match also more effective cabin heating requirements, improving comfort, which is an important market advantage.Basic idea of engine thermal management is to reduce or make nil the cooling fluid circulation inside the engine.In this paper, the oil warm up is considered as the main focus: a faster temperature grow up decreases oil viscosity and improves mechanical efficiency and organic efficiency, during engine cold state. An experimental activity has been conducted on a dynamic test bench, testing the cooling fluid and oil dynamics of a widely known commercial engine, in fixed engine points and during the New European Driving Cycle (NEDC).A comprehensive mathematical model reproducing both the integrated circuits has been developed and validated: this required an overall engine and vehicle modeling whose input data was determined by the vehicle mission profile. By means of such model, three new technologies have been proposed and verified in terms of warm up time. They are: (a) by pass of the oil cooling, (b) oil heating using exhaust gases, and (c) a partial reduction of the oil quantity inside the sump.All of them were applied during transients, which revealed they are able to reduce warm up time of about 65–70% with a significant benefit in terms of CO2 reduction.