Automated Material Parameter Calibration for an Electric Motor Stator

For accurate prediction of E-motor noise and vibration performance at the design stage, it is important to model the E-Motor stator structural behavior with high fidelity. Orthotropic material properties have been widely used in practice to simulate laminated steel in the stator. In these models, material constants are calibrated to match natural frequencies of critical modes such as oval/triangle/square modes. Typically, identifying accurate material properties is a manual, time-consuming process, involving lots of trial and error. This study presents an automated workflow to calibrate the material properties for the stator with Ansys Mechanical and optiSLang. The developed workflow can track natural frequencies and corresponding mode shapes of critical modes, and adjust material constants automatically to find best material parameters for the given frequencies. It can rotate the mode shapes and find the orientation that gives best match to the measurements based on modal assurance criteria (MAC). This workflow has shown a good correlation between simulation and test in terms of natural frequencies and corresponding mode shapes for the stator of a switched reluctance motor (SRM). Such an automated workflow enables the fast, efficient material calibration process, therefore accurate electric powertrain NVH simulations.

Viscoelastic Material Calibration Procedure for Rolling Resistance Calculation

ABSTRACT As tire engineers, the authors are interested in predicting rolling resistance using tools such as numerical simulation and tests. When a car is driven along, its tires are subjected to repeated deformation, leading to energy dissipation as heat. Each point of a loaded tire is deformed as it completes a revolution. Most energy dissipation comes from the cyclic loading of the tire, which causes the rolling resistance in addition to the friction force in the contact patch between the tire and road. Rolling resistance mainly depends on the viscoelastic energy dissipation of the rubber materials used to manufacture the tires. To obtain an accurate amount of dissipated energy, a good understanding of the material mathematical model and its behavior is mandatory. For this reason, a calibration procedure was developed. To obtain a good method for calculating rolling resistance, it is necessary to calibrate all rubber compounds of the tire at different temperatures and strain frequencies. Thus, to validate the calibration procedure, simulations were performed to evaluate the error between the tests and models at material sample and tire levels. For implementation of the calibration procedure in the finite element models of rolling tires, a procedure is briefly described that takes into account the change in properties caused by the temperature during the simulations. Linear viscoelasticity is used to model the properties of the materials and is found to be a suitable approach to tackle energy dissipation due to hysteresis for rolling resistance calculation.

The simple calibration procedure on the example of small town water supply system

The practical application of the model of water supply network realized in the program Epanet 2 requires the calibration of the model. The proposed simple calibration procedure, allows for taking into account the changes in resistance caused by the aging process, to be substituted by resistance coefficient K. In order to determine the substitute resistance coefficient K, the fire hydrant flow tests could be used, which allows to determine the aging for a given material. Calibration of the water supply network model is shown on the example of a small urban network in central Poland..

An Investigation of Calibration Phantoms for CT Scanners with Tube Voltage Modulation

The effects of calibration phantoms on the correction results of the empirical artifacts correction method (ECCU) for the case of tube modulation were investigated. To improve the validity of the ECCU method, the effect of the geometry parameter of a typical single-material calibration phantom (water calibration phantom) on the ECCU algorithm was investigated. Dual-material calibration phantoms (such as water-bone calibration phantom), geometry arrangement, and the area-ratio of dual-material calibration phantoms were also studied. Preliminary results implied that, to assure the effectiveness of the ECCU algorithm, the polychromatic projections of calibration phantoms must cover the polychromatic projection data of the scanning object. However, the projection range of a water calibration phantom is limited by the scan field of view (SFOV), thus leading to methodological limitations. A dual-material phantom of a proper size and material can overcome the limitations of a single-material phantom and achieve good correction effects.