General-purpose Simulation Software Research Articles

Thermal Parameter and State Estimation for Digital Twins of E-Powertrain Components

The performance of powertrain components in electric vehicles is tightly intertwined with their thermal behavior. In practical applications, their temperature must be monitored and kept below certain thresholds to avoid performance drops and failure. Sensors, however, cannot always be placed at critical locations. Instead, it is possible to use numerical models to estimate relevant magnitudes during system operation. Thermal effects in electric and electronic components can be represented in a compact way using lumped-parameter equivalent circuits. These can be combined with sensor readings from the device under study to develop digital twins and use them to monitor temperatures during test and operation. In this paper, we put forward a method to generate thermal digital twins of e-powertrain elements such as power inverters. The thermal equivalent circuit equations are obtained from a general-purpose simulation software tool and optimized to enable real-time execution. Kalman filters are then used to fuse the simulation results from this model and sensor measurements of component temperatures. The proposed method provides a way to estimate the inputs and parameters of the thermal circuit and can be used to avoid the drift of the simulation away from actual component behavior. The performance of this approach is demonstrated with a simple benchmark example and the thermal equivalent circuit of a three-phase inverter.

Double-panel active noise reducing casing with noise source enclosed inside – Modelling and simulation study

The main purpose of the article is to provide a theoretical study of a double-panel active casing by developing a mathematical model for such a dynamical system. The aim of the active casing is to reduce device noise generated to the acoustic environment by controlling vibration of wall panels of the device casing. The article concerns mathematical modeling and simulation of an active casing comprising six double–panel walls mounted to a rigid frame. The casing is considered as a complex coupled vibro-acoustic system, where the wall panels are excited by the acoustic fields inside the casing and by actuators bonded to the wall panels and used for active control. The acoustic field inside the casing is, in turn, produced by the noise originating from the device itself, and the secondary sound generated by all vibrating walls panels. In the first part of the paper a theoretical analysis is performed to derive mathematical model for the system under consideration. The Kirchhoff-Love equations are used to describe walls panels dynamics and the acoustic wave equations are applied to describe acoustic fields in appropriate media. The mathematical model represented as a system of coupled partial differential equations, subject to appropriate boundary conditions, is derived. The fluid–structure interactions of vibroacoustic and acoustic-vibration character, are also incorporated into the model. The model describes also imperfect fastening of the walls panels edges to the rigid frame. All assumptions applied to derive the model are chosen to relate the model to the realities of the utility. In the second part of the paper in order to prove the correctness of the derived model and give a better physical insight into the system, simulations are performed by means of a general-purpose simulation software COMSOL Multiphysics®. Responses to noise generated by a primary source of noise located in the interior of the active casing are investigated there. Simulations conditions are chosen in such a way to demonstrate the model behaves properly in the context of all incorporated vibro-acoustic interactions that can be observed in a real system.

Implementing railway vehicle dynamics simulation in general-purpose multibody simulation software packages

In terms of simulation efficiency, modelling and visualization, general-purpose multibody simulation (GPMBS) software packages have a lot of inherent advantages compared with specialized railway vehicle dynamics simulation software packages. However, their application is limited due to the absence of specialized force elements and contact models, and thus cannot be directly employed for railway vehicle dynamics simulation. To deal with this issue, this paper proposes a novel framework to use GPMBS software packages to simulate the dynamic behavior of the railway vehicle. This framework contains a loose coupling method, a sub-mechanism feature and a top-down modelling method and allows users to take full advantage of the advanced functionalities of the GPMBS software packages to improve the efficiency of railway vehicle dynamics simulation. The feasibility of this framework is verified by integrating extensions for two representative GPMBS software packages. In addition, the two comparisons between the self-developed extensions (for LMS Virtual.Lab Motion and Unity3D) and the widely used specialized railway vehicle dynamics simulation software (Simpack and Universal Mechanism), further confirm the validity of the framework.

On the Computation of the Dispersion Diagram of Symmetric One-Dimensionally Periodic Structures

A critical discussion on the computation of the dispersion diagram of electromagnetic guiding/radiating structures with one-dimensional periodicity using general-purpose electromagnetic simulation software is presented in this work. In these methods, full-wave simulations of finite sections of the periodic structure are combined with appropriate simplifying network models. In particular, we analyze the advantages and limitations of two different combined methods, with emphasis on the determination of their range of validity. Our discussion is complemented with several selected numerical examples in order to show the most relevant aspects that a potential user of these methods should be aware of. Special attention is paid to the relevant role played by the high-order coupling between adjacent unit cells and between the two halves of unit cells exhibiting reflection, inversion, and glide symmetries.

Study of inter-operational breaks impact on materials flow in flexible manufacturing system

Present development of advanced technologies in production and logistics, orientation for a customer needs and global, competitive market determines a creation of flexible manufacturing systems. Each FMS consisting of the automated and robotized subsystems of production, assembly, inter-operational transport and storage should be treated as a complete logistics system in which the efficient flow of materials is realized, at every stage of processing. The efficiency of the system is based on possibility of quick, automated retooling and reprogramming for the manufacturing of new products, especially in the production for individual order. Except that, according to modern concepts of enterprise management, one of the factors to improve material flow is to minimize unnecessary inter-operative interruptions. The inter-operational breaks include many factors: handling and transport, waiting for a technological operation and assembly, quality control, unpredictable failures. While technological times are almost impossible to shorten, all issues related with logistics are possible to improve. The inter-operational breaks don’t create added value, they’re only waste. They often remain outside the research sphere or are treated marginally as a loss included in the manufacturing process. The article describes study on an effective method of searching for negative inter-operational breaks in advanced manufacturing processes and eliminating them. Advanced software for off-line programming of machine tools, robots, automated transport and warehouse systems and general-purpose simulation software for production and logistics gives possibility to conduct research on limiting the impact of inter-operational breaks on FMS.

A Simulation App based on reduced order modeling for manufacturing optimization of composite outlet guide vanes

Composites manufacturing processes usually involve multiscale models in both space and time, highly non-linear and anisotropic behaviors, strongly coupled multiphysics and complex geometries. In this framework, the use of simulation for real-time decision making directly in the manufacturing facility is still precluded nowadays, in spite of the impressive progresses reached in numerical analysis and computer science during the last decade. In this paper, a process-specific simulation tool based on reduced order modeling is introduced, the Simulation App. This concept is presented through a practical case involving a multi-physics and coupled problem describing the manufacturing process of a composite outlet guide vane. We show that several manufacturing settings can be simulated in few seconds with the Simulation App, thus enabling fast process optimization. Finally, the advantages over general-purpose simulation software, in the context of process simulation, are discussed.

Accounting for sliding motion in fast numerical simulations of abdominal HIFU applications for targets under respiratory motion

Non-invasive ablation and hyperthermia treatments of abdominal organs using High Intensity Focused Ultrasound (HIFU) still impose severe challenges. Especially for liver and kidney treatments, the target motion and accessibility over the entire respiratory cycle make the application of HIFU difficult. To allow for a safe, effective, and efficient treatment, detailed planning and monitoring of the intervention is needed. Current general-purpose physics simulation software cannot fulfill the real-time requirements of the therapy-monitoring application. Our goal is to improve this by numerical simulation to allow for fast and accurate treatment planning and real-time detection of motion-induced risks during HIFU-therapy.

Robust static analysis using general-purpose multibody dynamics

This work discusses the implementation of a pseudo-arc-length algorithm in general-purpose multibody formulations. Such algorithm and implementation support the analysis of static problems subjected to bifurcations and turning points, expanding the applicability of such formulations. Its application to existing free general-purpose simulation software made the analysis of nontrivial static structural problems possible. Several examples of applications are presented and compared with existing solutions obtained from state-of-the-art formulations.

Numerical Analysis of Welding Phenomena in High-Frequency Electric Resistance Welding

High-frequency electric resistance welded pipes are used for high-grade line pipes. To address the significant need for weld seam reliability, it is important to clarify the associated welding phenomena. In this study, a numerical analysis model is developed to clarify the behaviours of the molten steel and oxide in HFW pipes. The temperature distribution of the HFW is calculated using electromagnetic and heat conductive finite element analysis methods. The molten metal and oxide flows are analysed by modelling heat conductive and plastic flows. The movement behaviour of the oxides in the molten steel is successfully analysed with this technique. The material properties as a function of the temperature of the steel pipe are calculated using general-purpose simulation software. With pressurisation by the welding rolls, the molten steel moves to the upper part, and the oxide, which exists in the internal parts, rapidly decreases such that almost all of the oxide transitions to the excess metal part. The internal oxide content rate after pressurisation at 0.08 m/s is less than 0.01. To decrease the oxide content, the pressurisation rate must increase such that the molten steel and an oxide pressurised at high temperatures transition to the excess metal part.

Synthetic Data for Hybrid Prognosis

Using condition-based maintenance (CBM) to assess machinery health is a popular technique in many industries, especially those using rotating machines. CBM is relevant in environments where the prediction of a failure and the prevention and mitigation of its consequences increase both profit and safety. Prognosis is the most critical part of this process and the estimation of Remaining Useful Life (RUL) is essential once failure is identified. This paper presents a method of synthetic data generation for hybrid model-based prognosis. In this approach, physical and data-driven models are combined to relate process features to damage accumulation in time-varying service equipment. It uses parametric models and observer-based approaches to Fault Detection and Identification (FDI). A nominal set of parameters is chosen for the simulated system, and a sensitivity analysis is performed using a general-purpose simulation package. Synthetic data sets are then generated to compensate for information missing in the acquired data sets. Information fusion techniques are proposed to merge real and synthetic data to create training data sets which reproduce all identified failure modes, even those that do not occur in the asset, such as Reliability Centered Maintenance (RCM), Failure Mode and Effect Analysis (FMEA). This new technology can lead to better prediction of remaining useful life of rotating machinery and minimizing and mitigating the costly effects of unplanned maintenance actions.

Inverse dynamics of serial and parallel underactuated multibody systems using a DAE optimal control approach

The inverse dynamics analysis of underactuated multibody systems aims at determining the control inputs in order to track a prescribed trajectory. This paper studies the inverse dynamics of non-minimum phase underactuated multibody systems with serial and parallel planar topology, e.g. for end-effector control of flexible manipulators or manipulators with passive joints. Unlike for minimum phase systems, the inverse dynamics of non-minimum phase systems cannot be solved by adding trajectory constraints (servo-constraints) to the equations of motion and applying a forward time integration. Indeed, the inverse dynamics of a non-minimum phase system is known to be non-causal, which means that the control forces and torques should start before the beginning of the trajectory (pre-actuation phase) and continue after the end-point is reached (post-actuation phase). The existing stable inversion method proposed for general nonlinear non-minimum phase systems requires to derive explicitly the equations of the internal dynamics and to solve a boundary value problem. This paper proposes an alternative solution strategy which is based on an optimal control approach using a direct transcription method. The method is illustrated for the inverse dynamics of an underactuated serial manipulator with rigid links and four degrees-of-freedom and an underactuated parallel machine. An important advantage of the proposed approach is that it can be applied directly to the standard equations of motion of multibody systems either in ODE or in DAE form. Therefore, it is easier to implement this method in a general purpose simulation software.

RF cavity simulations for superconducting cyclotron C400

Compact superconducting isochronous cyclotron C400 [1] has been designed at IBA (Belgium) in collaboration with the JINR (Dubna). This cyclotron will be the first cyclotron in the world capable of delivering protons, carbon and helium ions for therapeutic use. 12C6+ and 4He2+ ions will be accelerated to 400 MeV/u energy and extracted by electrostatic deflector, H2+ ions will be accelerated to the energy of 265 MeV/u and extracted by stripping. It is planned to use two normal conducting RF cavities for ion beam acceleration in the cyclotron C400. Computer model of the double gap delta RF cavity with 4 stems was developed in the general-purpose simulation software CST STUDIO SUITE. Necessary resonant frequency and increase of the voltage along the gaps were achieved. Optimization of the RF cavity parameters leads us to the cavity with quality factor about 14000, RF power dissipation is equal to about 50 kW per cavity.

Presentation of a virtual power plant environment and its application with combined first-principle and data-driven models intended for the diagnostics of a power plant – Part 2

This work aims to present and discuss the architecture and application aspects of the Virtual Power Plant (VPP) environment, a tool created for the purpose of the modeling, simulation, data management, and visualization of power plant systems. The VPP environment is based on a general-purpose simulation package that provides a framework for incorporating a broad variety of models, ranging from real-time models to detailed models that require off-line execution. The VPP, as a tool, opens up the possibility to develop, test, and validate the feasibility of new software and hardware components within simulated operational scenarios. An original approach to tuning a first-principle model using the example of a feedwater heater by means of a parameter estimation technique is presented, along with a case study of modeling a 225 MW coal-fired power unit. The objectives are as follows: (i) develop a tuning method for this model; (ii) propose key indicators of feedwater heater performance using a model-based approach; and finally (iii) automate the calculation process of the indicators.

Presentation of a virtual power plant environment and its application with combined first-principle and data-driven models intended for the diagnostics of a power plant – Part 1

This work aims to present and discuss the architecture and application aspects of the Virtual Power Plant (VPP) environment, a tool created for the purpose of modeling, simulation, data management, and visualization of power plant systems. The VPP environment is based on a general-purpose simulation package that provides a framework for incorporating a broad variety of models, ranging from real-time models to detailed models that require off-line execution. The VPP, as a tool, opens up the possibility to develop, test, and validate the feasibility of new software and hardware components within simulated operational scenarios. The first part of the work presents the architecture of the VPP and briefly describes its main components. The implementation, including necessary simplifications, encapsulation, and integration of sub-models is discussed and illustrated. A feedwater heater model is the main contributor to the performance of the entire simulation model of a power unit. In the first part of this work, the development process of such a model is presented, including necessary simplifications for improving its performance and functionality.

Exploit the Parallel Paradigm

Transmission line matrix (TLM) methods are powerful numerical procedures for modeling electromagnetic fields in the time domain. The theoretical foundations of various TLM methods are well described in the literature, but to develop general purpose simulation software based on the procedures is still a challenging task. The computational electromagnetics industry is by and large responsible for implementing the procedures in commercially available software. However, many open-source and free software packages have been written by researchers; some of these packages also come with a graphical user interface.The finite difference time domain (FDTD) technique and TLM methods are two similar time-domain numerical procedures for modelling electromagnetic fields. Instead of updating the electric and magnetic field quantities as is done in the FDTD procedure, TLM methods update the voltage quantities using a voltage scattering procedure. Electric and magnetic field quantities are not needed to carry out the scattering process; the field quantities of course can be obtained from the voltage quantities if needed.

Prediction of Shrinkage Pore Volume Fraction Using a Dimensionless Niyama Criterion

A method is presented to use a dimensionless form of the well-known Niyama criterion to directly predict the amount of shrinkage porosity that forms during solidification of metal alloy castings. The main advancement offered by this method is that it avoids the need to know the threshold Niyama value below which shrinkage porosity forms; such threshold values are generally unknown and alloy dependent. The dimensionless criterion accounts for both the local thermal conditions (as in the original Niyama criterion) and the properties and solidification characteristics of the alloy. Once a dimensionless Niyama criterion value is obtained from casting simulation results, the corresponding shrinkage pore volume fraction can be determined knowing only the solid fraction-temperature curve and the total solidification shrinkage of the alloy. Curves providing the shrinkage pore volume percentage as a function of the dimensionless Niyama criterion are given for WCB steel, aluminum alloy A356, and magnesium alloy AZ91D. The present method is used in a general-purpose casting simulation software package to predict shrinkage porosity in three-dimensional (3-D) castings. Comparisons between simulated and experimental shrinkage porosity results for a WCB steel plate casting demonstrate that this method can reasonably predict shrinkage. Additional simulations for magnesium alloy AZ91D illustrate that this method is applicable to a wide variety of alloys and casting conditions.

An ideal homokinetic joint formulation for general-purpose multibody real-time simulation

This work presents a compact formulation of an ideal homokinetic joint, suitable for implementation in multibody simulation. This type of joint is widely used in machinery design, and significantly in the helicopter industry to alleviate the moments transmitted by the rotors to the airframe in modern tilting rotor aircraft designs. When simulating the dynamics of complex mechanical systems, the accurate description of the kinematics can be of paramount importance. General-purpose multibody simulation software usually allow enough generality to model arbitrary kinematics to the desired level of accuracy. However, in some cases, the kinematics of complex joints can only be obtained by combining a considerable number of basic building blocks, often resulting in unnecessarily large models. When minimizing the size of the model is mandatory, as in real-time simulation, dedicated kinematic components that synthesize complex joints without reducing the fidelity of the motion description may help. The advantages of the proposed formulation are shown by illustrating how it improved the capability to simulate the dynamics of a tiltrotor wind-tunnel model in real-time.

Value of Information in a Capacitated Supply Chain

The aim of this study is to understand the effect of end item demand variability, production flexibility, inventory characteristics, the number of retailers, and the impact of information sharing between channel members in a capacitated supply chain. Discrete event simulation is carried out to determine the impact of the above mentioned factors in a supply chain under different information sharing strategies. The simulation allows us to capturing the dynamic and stochastic complexity of the supply chain system. A two-level supply chain with one supplier having a capacity constraint and N identical retailers experiencing stationary and stochastic demand was built using a General Purpose Simulation Software. The optimum value of decision variables for various information scenarios is determined by multiple simulation runs and the response surface methodology technique.

A modeling approach for engine dynamics based on electrical analogy

In this paper, a multi-cylinder, internal combustion engine model is presented. The paper is focused on a simple modular, physically based and lumped parameter (zero dimensional) approach, leading to a complete and coherent model structure. The model is conceived to be used with general purpose simulation software, as MATLAB/Simulink. The mean value outputs of the model (pressure, temperature, mass flow, torque) are compared with experimental data, collected by a Fiat 1.8 liter engine, in order to perform a standard identification and validation procedure.

バーチャルヒューマンモデルと感性工学による溶接の作業性評価

The authors have carried out the human task simulation by a computer about the shipbuilding works in order to increase the productivity and safety so far, corresponding to the recent situation of the Japanese shipbuilding industry; decreasing of skilled workes and increasing of old workers. This report picked up the welding works for hull construction as a main job in shipbuilding. For the typical welding postures such as flat, horizontal, vertical, and overhead position, the human body analysis has been carried out, using general-purpose human simulation software “Jack”; static strength prediction of human body, lumbar force analysis, and energy consumption analysis. Moreover, the necessary rest time to recover the fatigue has been studied, and the optimal work cycle is examined. In addition, “Kansei Engineering” technique has been introduced for the evaluation of the results by the biomechanical analysis. SD (Semantic Differential) evaluation has been carried out concerning the body feeling of welding workers, and then principle factor analysis, one of multivariate analysis, has been executed, according to the process of “Kansei Engineering”. As the result, it can be concluded that the flat position to weld, widely applied posture, is most severe for static load on lower body as well as energy expenditure, and that the rule of “short breaks and often” is preferable from the viewpoint of recovery of the fatigue, especially for the works such that the consumption energy is large. Furthermore, it can be concluded that overhead position to weld is severe in the evaluation of “Kansei Engineering”, because of the fatigue on upper body, and that “the weariness of the hand” causes the working fatigue by the welding works.