Multiphysics Design Research Articles

Thermo-mechanical model of rubber network with transient non-bonded interaction concept for multi-physics design

We propose a new concept on theoretical explanation of the relationship between transient non-bonded interaction and thermo-mechanical behavior on rubber-like materials. The theoretical equation can describe the extension ratio dependence of stress and temperature simultaneously. The approach found important evidence on the presence of the uncertainty relation between non-bonded interaction and angular momentum of molecular chain. We applied this concept to analysis for thermal molecular motion of Joule's experiments on thermo-dynamic properties of the vulcanized rubber. Our theoretical approaches, at least, provide the important parameters; the number of non-bonded interaction, the fluctuation energy, the attractive energy, the radius of rotation, the finite extensibility effect and the effective molar mass. These parameters can be used as a rule of thumb guide for multi-physics design in the future work to bridge the atomic behavior and the thermo-mechanical behavior which is associated with various rubber properties such as energy loss, damping, flexibility, friction, heat build-up, fatigue and fracture.

An Analytical Temperature-Dependent Design Model for Contour-Mode MEMS Resonators and Oscillators Verified by Measurements.

The importance of micro-electromechanical systems (MEMS) for radio-frequency (RF) applications is rapidly growing. In RF mobile-communication systems, MEMS-based circuits enable a compact implementation, low power consumption and high RF performance, e.g., bulk-acoustic wave filters with low insertion loss and low noise or fast and reliable MEMS switches. However, the cross-hierarchical modelling of micro-electronic and micro-electromechanical constituents together in one multi-physical design process is still not as established as the design of integrated micro-electronic circuits, such as operational amplifiers. To close the gap between micro-electronics and micro-electromechanics, this paper presents an analytical approach towards the linear top-down design of MEMS resonators, based on their electrical specification, by the solution of the mechanical wave equation. In view of the central importance of thermal effects for the performance and stability of MEMS-based RF circuits, the temperature dependence was included in the model; the aim was to study the variations of the RF parameters of the resonators and to enable a temperature dependent MEMS oscillator simulation. The variations of the resonator parameters with respect to the ambient temperature were then verified by RF measurements in a vacuum chamber at temperatures between −35 C and 85 C. The systematic body of data revealed temperature coefficients of the resonant frequency between −26 ppm/K and −20 ppm/K, which are in good agreement with other data from the literature. Based on the MEMS resonator model derived, a MEMS oscillator was designed, simulated, and measured in a vacuum chamber yielding a measured temperature coefficient of the oscillation frequency of −26.3 ppm/K. The difference of the temperature coefficients of frequency of oscillator and resonator turned out to be mainly influenced by the limited Q-factor of the MEMS device. In both studies, the analytical model and the measurement showed very good agreement in terms of temperature dependence and the prediction of fabrication results of the resonators designed. This analytical modelling approach serves therefore as an important step towards the design and simulation of micro-electronics and micro-electromechanics in one uniform design process. Furthermore, temperature dependences of MEMS oscillators can now be studied by simulations instead of time-consuming and complex measurements.

Enhancing interior noise of electric vehicles by design analyses and refinements of traction motors

Without thorough acoustic consideration, traction motorsâ–”the core of electric powertrainsâ–”may emit annoying whining noise during operation and deteriorate the interior noise of electric vehicles (EVs). To minimize such whining noise from traction motors, this article presents the interior noise developments of EVs which include the overview of acoustic sources, noise benchmark, noise paths investigation, multi-physics coupled analyses, design refinement and acoustic validation. Based on a developing EV, this study investigated on crucial mechatronic design of the traction motor in detail. By benchmarking, general interior noise levels of EVs were obtained and the target for acoustic refinement of the EV studied was defined. Noise and vibration measurements of the original EV and its associated traction motor identified the harmonics of electromagnetic forces from original traction motor were the root cause of whining noise concern. Noise paths assessment further identified the right mount of original traction motor being a critical structureborne path. Through refining the motor structure, simulated natural frequencies of the modified motor were 16â–“33% higher than those of original motor for the first four modes, and the vibration of modified motor was reduced accordingly. The mechatronic analysis further concluded the inappropriate pole and slot combination of original traction motor caused high electromagnetic forces. By optimizing mechatronic design for the modified traction motor, the interior noise level of modified EV was reduced dramatically with a maximum noise reduction of 16 dB. In addition, the modified EV achieved a 9.6 dB legislative pass-by noise reduction against that of original EV. By providing the comprehensive interior noise developments of EVs and illustrating the details of the acoustic design analyses and refinements of traction motors, this article can serve as a reference of acoustic design and development for other EVs and electric powertrains.

Comparison Between Single-Model and Multimodel Optimization Methods for Multiphysical Design of Electrical Machines

The purpose of this paper is to compare two optimization approaches, used for the research of optimal configurations of electrical machines. The first one uses a single multiphysical model, called “reference model,” directly used by a classical optimization routine. The second approach proposes the use of a second surrogate model in association with the previous reference model. This second configuration corresponds to the space mapping (SM) methodology. In both cases, models involved are multiphysical descriptions of the main phenomena occurring in electrical machines. They consider electrical, magnetic, thermal, and mechanical aspects. They use different modeling techniques (analytical relations, lumped parameter networks, and finite-element analyses), depending on the physics to be described. Appropriate coupling strategies between these different submodels are chosen to get the best results in the framework of the SM methods. This paper evaluates both approaches by a comparison of the corresponding computation costs, evaluated by the number of evaluations of the fine (reference) model. The paper shows that SM-like methods allow faster optimization processes and require a smaller number of evaluations (of the reference model) and lead to similar final machine designs. The use and the comparison of these two approaches is illustrated through the optimal sizing of an automotive electrical machine.

Elliptical superconducting RF cavities for FRIB energy upgrade

The multi-physics design of a five cell, βG=0.61, 644 MHz superconducting elliptical cavity being developed for an energy upgrade in the Facility for Rare Isotope Beams (FRIB) is presented. The FRIB energy upgrade from 200 MeV/u to 400 MeV/u for heaviest uranium ions will increase the intensities of rare isotope beams by nearly an order of magnitude. After studying three different frequencies, 1288 MHz, 805 MHz, and 644 MHz, the 644 MHz cavity was shown to provide the highest energy gain per cavity for both uranium and protons. The FRIB upgrade will include 11 cryomodules containing 5 cavities each and installed in 80-meter available space in the tunnel. The cavity development included extensive multi-physics optimization, mechanical and engineering analysis. The development of a niobium cavity is complete and two cavities are being fabricated in industry. The detailed design of the cavity sub-systems such as fundamental power coupler and dynamic tuner are currently being pursued. In the overall design of the cavity and its sub-systems we extensively applied experience gained during the development of 650 MHz low-beta cavities at Fermi National Accelerator Laboratory (FNAL) for the Proton Improvement Plan (PIP) II.

Multiphysics design optimization of RF-MEMS switch using response surface methodology

This paper presents the multi-objective geometric design exploration and optimization of an electrostatic Symmetric Toggle RF-MEMS switch (STS), considering both the electromechanical and RF characteristics simultaneously. The output responses considered for the STS switch optimization are pull-in voltage, switching time, insertion loss in the on-state and isolation in the off-state. Metamodels for the output responses, with respect to geometric design parameters, are developed using Design of Experiments (DOE) based Response Surface Methodology (RSM) and Finite Element Method (FEM) simulations. A single optimization objective function, considering all the four output responses and microfabrication process constraints, is defined and optimized for the design factors using combined desirability function and heuristic search algorithm approach. The predicted values of the output responses are verified through both the electromechanical and electromagnetic FEM simulations. The effect of residual stress, developed in the RF-MEMS switch during the sacrificial layer removal step of the microfabrication process, on both the electromechanical and RF characteristics of the final optimized switch geometry is analyzed using coupled structural-thermal-electric FEM simulations. The proposed DOE and RSM based design optimization technique can be implemented for the design space exploration and optimization of complex MEMS devices which involve coupled multiphysics interactions.

Multiphysics Design Optimization of a Permanent Magnet Synchronous Generator

This paper presents the multiphysics design optimization of a permanent magnet synchronous generator (PMSG). A medium-power wind turbine (55 kW) is taken as the basis for the design optimization, whereas reducing its cost is the optimization goal. The design comprises the multiphysics generator model and the cost and losses models of the grid connection static power converters (SPC). The power converter command strategy is analyzed as it influences the system cost. Papers that dealt with the optimal design of the PMSGs usually did not consider the SPC cost and losses in the total system cost. The analysis of three power converter command strategies, implemented in the multidisciplinary design optimization, aims to define the phase angle of the generator current that leads to the lowest cost of the system composed by the generator and power converter.

Design and Optimization for Vehicle Driving Cycle of Rare-Earth-Free SynRM Based on Coupled Lumped Thermal and Magnetic Networks

This study presents a range optimization of a synchronous reluctance motor and a permanent-magnet-assisted synchronous reluctance motor according to a standard driving cycle, and the solutions obtained are compared. The proposed approach avoids the use of a finite-element analysis during the optimization process, thus greatly reducing the time required to obtain the optimal solution. This paper validates the optimal motors obtained in different domains, since the methodology takes into account a multiphysics design. Using two coupled reluctance and thermal networks, all possible working points in the torque–speed plane are obtained taking into account thermal effects, magnetic saturation, iron losses, as well as voltage and current constraints imposed by the inverter. The proposed approach allows a fast comparison of the solutions attained. The design and optimization methodology presented in this study can be applied to any driving cycle.

State of the art of thermal characterization of electronic components using computational fluid dynamic tools

PurposeLatest Computational Fluid Dynamics (CFDs) tools allow modeling more finely the conjugate thermo-fluidic behavior of a single electronic component mounted on a Printed Wiring Board (PWB). A realistic three-dimensional representation of a large set of electric copper traces of its composite structure is henceforth achievable. The purpose of this study is to confront the predictions of the fully detailed numerical model of an electronic board to a set of experiment results to assess their relevance.Design/methodology/approachThe present study focuses on the case of a Ball Grid Array (BGA) package of 208 solder balls that connect the component electronic chip to the Printed Wiring Board. Its complete geometrical definition has to be coupled with a realistic board layers layout and a fine description of their numerous copper traces to appropriately predict the way the heat is spread throughout that multi-layer composite structure. The numerical model computations were conducted on four CFD software then compare to experiment results. The component thermal metrics for single-chip packages are based on the standard promoted by the Joint Electron Device Engineering Council (JEDEC), named JESD-51. The agreement of the numerical predictions and measurements has been done for free and forced convection.FindingsThe present work shows that the numerical model error is lower than 2 per cent for various convective boundary conditions. Moreover, the establishment of realistic numerical models of electronic components permits to properly apprehend multi-physics design issues, such as joule heating effect in copper traces. Moreover, the practical modeling assumptions, such as effective thermal conductivity calculation, used since decades, for characterizing the thermal performances of an electronic component were tested and appeared to be tricky. A new approach based on an effective thermal conductivity matrix is investigated to reduce computation time. The obtained numerical results highlight a good agreement with experimental data.Research limitations/implicationsThe study highlights that the board three-dimensional modeling is mandatory to properly match the set of experiment results. The conventional approach based on a single homogenous layer using effective thermal conductivity calculation has to be banned.Practical implicationsThe thermal design of complex electronic components is henceforth under increasing control. For instance, the impact of gold wire-bonds can now be investigated. The three-dimensional geometry of sophisticated packages, such as in BGA family, can be imported with all its internal details as well as those of its associated test board to build a realistic numerical model. The establishment of behavioral models such as DELPHI Compact Thermal Models can be performed on a consistent three-dimensional representation with the aim to minimize computation time.Originality/valueThe study highlights that multi-layer copper trace plane discretization could be used to strongly reduce computation time while conserving a high accuracy level.

Heavy ion linear accelerator for radiation damage studies of materials.

A new eXtreme MATerial (XMAT) research facility is being proposed at Argonne National Laboratory to enable rapid in situ mesoscale bulk analysis of ion radiation damage in advanced materials and nuclear fuels. This facility combines a new heavy-ion accelerator with the existing high-energy X-ray analysis capability of the Argonne Advanced Photon Source. The heavy-ion accelerator and target complex will enable experimenters to emulate the environment of a nuclear reactor making possible the study of fission fragment damage in materials. Material scientists will be able to use the measured material parameters to validate computer simulation codes and extrapolate the response of the material in a nuclear reactor environment. Utilizing a new heavy-ion accelerator will provide the appropriate energies and intensities to study these effects with beam intensities which allow experiments to run over hours or days instead of years. The XMAT facility will use a CW heavy-ion accelerator capable of providing beams of any stable isotope with adjustable energy up to 1.2 MeV/u for 238U50+ and 1.7 MeV for protons. This energy is crucial to the design since it well mimics fission fragments that provide the major portion of the damage in nuclear fuels. The energy also allows damage to be created far from the surface of the material allowing bulk radiation damage effects to be investigated. The XMAT ion linac includes an electron cyclotron resonance ion source, a normal-conducting radio-frequency quadrupole and four normal-conducting multi-gap quarter-wave resonators operating at 60.625 MHz. This paper presents the 3D multi-physics design and analysis of the accelerating structures and beam dynamics studies of the linac.

Multi-layer Graph Theory Utilisation for Improving Traceability and Knowledge Management in Early Design Stages

Decision making processes in design often challenges designers to prioritise specifications and variables in order to develop solutions that are closer to the product's requirement goals. Concerning to support their decisions, different tools and methods are used by engineers and designers allowing to reduce uncertainty in design. Nevertheless, many of these decision support systems are focused in late design stages, such as detailed design and manufacturing design, even if the possibility to influence a new product is higher in early stages. The issues regarding to those situations are often associated to design processes related to multi-physics design, where the modification of geometric-related variables might affect the performance of the solution, and the analysis of tracking the influence of the modifications might generate reprocessing and loses of time, specially when those relations are tricky and are not easily identifiable by analysing equations and a manual analysis of requirements must be performed. This article is centred in proposing a traceability model for early design stages based in graph theory. The proposal supports the information generated in design, from the input requirements (linguistic field) up to mathematical modelling and variables definition (real numbers field). This information is arranged into different layers, allowing a multilevel approach in terms of information management. The model also features a novel solution for weighting vertex in graph model, featuring a model that balances the direction of improvement, the importance and flexibility of any specification and how its behaviour will affect the design variables associated to it. The goal of the proposed model is to offer to designers, since the conceptual design stage, a method that can show automatically the level of correlation between any pair variables and specifications by the use of information trees and featuring chains that can connect them whether there is or not a connection via equations.

Design of a 50.000-r/min Synchronous Reluctance Machine for an Aeronautic Diesel Engine Compressor

This paper describes the design procedure followed to realize a high-speed synchronous reluctance machine for aeronautical application. The attention is mainly focused on the rotor design that is the most critical part of any synchronous reluctance machine; in particular for high-speed applications. After a preliminary optimization of the rotor geometry, a multiphysical design that considered mechanical, thermal, and electromagnetic properties was developed. The main steps of the design procedure together with an extensive analysis of the final design are presented here. Two prototypes have been realized using different rotor lamination materials in order to validate the design procedure.

A Variational Art Algorithm for Image Generation

The authors propose a variational art algorithm: a virtual system-based optimization algorithm developed for generating images. Observing that the topology optimization method used for multiphysics system design can produce two- or three-dimensional layouts without baselines, the authors propose to expand it beyond engineering applications for generating images. They have devised a virtual physical system—a heat-path system—that “interprets” the optimization-based process of image generation as the simultaneous drawing of multiple strokes in a painting.

Numerical and experimental validation of multi-physics design models for axial flux permanent magnet wind generator

Numerical and experimental validation of multi-physics design models for axial flux permanent magnet wind generator

Active lubrication applied to radial gas journal bearings. Part 2: Modelling improvement and experimental validation

Actively-controlled lubrication techniques are applied to radial gas bearings aiming at enhancing one of their most critical drawbacks, their lack of damping. A model-based control design approach is presented using simple feedback control laws, i.e. proportional controllers. The design approach combines three main domains: tribology, dynamics and control. The Reynolds equation with radial injection, including piezoelectrically controlled jet, describes the non-linear interaction between bearing surface and rotating shaft. Dynamics of the flexible shaft and rotating parts are modelled aid by finite element method and the global model is used as control design tool. Active lubrication allows for significant increase in damping factor of the rotor-bearing system. Very good agreement between theory and experiment is obtained, supporting the multi-physic design tool developed.

Towards Multi-Domain and Multi-Physical Electronic Design

Electronic systems are increasingly fusing multiple technology solutions exchanging information both at electrical and at non-electrical levels, and in general both analog and digital operation coexists in multiple physical domains.

Multiphysics design of a spatial combiner predisposed for thermo-mechanically affected operation

This paper describes the design based on a Multiphysics simulation for a waveguide X-Band Fin Taper (FT) Spatial Power Combiner. The proposed device uses Fin Lines to microstrip transition (FLuS) to convert the energy from a rectangular waveguide (WG) TE10 fundamental mode to a microstrip (μS) transmission line (TL) quasi-TEM (q-TEM) mode, in order to be amplified by Solid-State Power Amplifiers. An alteration of the electromagnetic behavior can be produced by the temperature increase and the geometrical displacement induced by the thermal expansion of the structure due to the power dissipation of the MMIC amplifiers. A proper multiphysics model is proposed to select materials and shapes of the probes and their support (carrier), considering the thermo-mechanical operative condition. A virtual prototyping technique is proposed: electric field and S-parameters’ computation in such critical conditions are shown. The proposed study has allowed for the proper thermo-mechanical design for such amplifiers; hence, best materials and technologies have been chosen.

Multiphysics design and implementation of a microsystem for displacement-controlled tensile testing of nanomaterials

MEMS-based tensile testing devices are powerful tools for mechanical characterization of nanoscale materials. In a typical configuration, their design includes an actuator to deliver loads/displacements to a sample, and a sensing unit for load measurement. The sensing unit consists of a flexible structure, which deforms in response to the force imposed to the sample. Such deformation, while being necessary for the sensing function, may become a source of instability. When the sample experiences a load drop, as it may result from yield, necking or phase transitions, the elastic energy accumulated by the sensor can be released, thus leading to loss of the displacement-controlled condition and dynamic failure. Here, we report a newly-developed MEMS testing system where the sensor is designed to constantly keep its equilibrium position through an electrostatic feedback-control. We show design, implementation, and calibration of the system, as well as validation by tensile testing of silver nanowires. The implemented system allows capture of softening events and affords significant improvement on the resolution of stress–strain curves.

Multiphysics design methodology for photonic-based phased array antennas

This work proposes a multiphysics design methodology for photonic-based phased array antennas. It is based on the use of circuital and full wave electromagnetic solvers in conjunction with an optical numerical tool. To illustrate the proposed methodology, it is presented the design of a photonic beamformer for a phased array based on four patch antennas operating at 5.8 GHz. The array has been numerically evaluated using a 50-km radio over fiber system, responsible to transmit the RF signal from the Central Office to the Remote Antenna Site. It has been used the following pieces of software: VPI Transmission Maker for optical domain simulations, Designer and HFSS from ANSYS for electrical domain simulations. The last two are easily integrated, as the same company had produced them. Conversely, it was necessary to create an efficiency interface for enabling the integration between VPI Transmission Maker and them. This interface enables the integration between the optical domain at hundreds of THz and the electrical domain at some GHz. © 2014 Wiley Periodicals, Inc. Microwave Opt Technol Lett 56:838–843, 2014

Focus on software and data acquisition

Focus on software and data acquisition