Grzegorz Wszołek

A nonlinear, data-driven model applied in the design process of disc-spring valve systems used in hydraulic dampers

This paper proposes an analytical tool that supports the design process of a disc-spring valve system used in hydraulic dampers. Such a valve is representative of a broader family of valve systems used in many industrial applications. The tool will speed up the valve-system design process. The paper considers a valve system that combines a number of circular metal plates, referred to further in the paper as ‘a stack of plates’. The proposed analytical tool obtains a key design characteristic of a valve, the flow rate, and the corresponding maximum stress level in the stack of plates as a function of pressure load. The stress level enables the ranking of valve settings in terms of durability. The calculation process is based on the response of a nonlinear, data-driven model that approximates the a priori simulated cases to cover the complete range of input design parameters, namely the number of plates, their thickness and their diameter. The cases are produced by a first-principle model using a Finite Element (FE) approach. The model was calibrated based on experimental results to provide accurate results in the entire range of input parameters. The advantage of the analytical tool is its ability to immediately provide the pressure-stress-flow characteristic of a valve instead of repeating time-consuming calculations for each new setting of input parameters. The objectives of the paper are as follows: to (a) adapt the model to a three-plate stack by applying large strain theory, (b) select and rank the Artificial Neural Networks used in order to approximate simulation data, and (c) demonstrate validation and application results obtained with the Approximation Tool.

Development of an optimization method for minimizing vibrations of a hydraulic damper

The aim of this paper is to provide a mathematical method for minimizing the vibrations produced by hydraulic dampers, while maintaining the same damping force characteristics. The vibration level depends on the force–pressure characteristics of valve systems, which determine the damping force and high-frequency acceleration characteristic of a damper, and which need to be optimally tuned to lower the noise level. The paper considers a model-based approach to obtain the optimal pressure–flow characteristic via simulations conducted with the use of coupled models, including the damper and the servo-hydraulic tester model. The objectives of this work were as follows: (i) develop or adapt a double-tube damper model including pressure–flow valve characteristics; (ii) define key parameters of the valve characteristics influencing the high-frequency piston-rod acceleration, which is considered as a measure of vibration level; (iii) identify the parameter values (trends) minimizing the piston-rod acceleration using two alternative methods, namely a quick-and-dirty method based on a design of experiment (DOE) plan and a nonlinear programming method; (iv) obtain the optimal pressure–flow characteristic minimizing the vibration level by means of simulation; and (v) perform an experimental study comparing the high-frequency content of acceleration produced by the damper assembled with the original and optimized valve system using a laboratory setup.

The Systematized Data Structures Oriented Towards Diagnosis and Prediction

The structured notation using an identification of relations between key process data and functional characteristics of distributed systems has been presented in the paper. Such approach allows obtaining optimal form mapping the structures stored in a PLC‘s memory and also forming reciprocal relationships between hardware devices. Described notation is used at the stage connected with elaboration of diagnostic and prognostic functions. The authors have proposed an universal notation in a domain of sets, which can be used in identification of operational data indispensable in phase connected with a definition of program structures. A particular attention was given to stages connected with optimization necessity of number of main parameters (especially an isolation of a minimal data set required at control and diagnosis stages in case of distributed drives). Revised data sets combine both quantitative and qualitative features, allowing simultaneously for a reconstruction of the structural relationships between real components of distributed systems (a minimization of technical documentation).

Approximation methods applied in assessment of valve system fatigue failure

This paper proposes an analytical tool that supports the design process of a disc spring valve system used in hydraulic dampers. The proposed analytical tool obtains a key design characteristic of a valve, which is the flow rate and the corresponding maximum stress level in the stack of plates. The tool is prepared based on the cases produced by a first-principle model using a finite element approach. The finite element model was calibrated based on experimental results to provide accurate results in the entire range of input parameters.

Optimization of a Hydraulic Damper Performance with the Use of Fluid-Structure Simulation

The aim of this paper is to develop a method for optimizing the design of a spring valve system by reducing the aeration and cavitation effect which negatively influences the performance of a shock absorber. A fluid-structure interaction (FSI) model is used in order to modify the geometry of the valve interior and, in turn, to achieve better performance in shock absorbers. The paper analyzes the pressure distribution along the flow paths inside the valve cavity to reduce the risk of aeration and cavitation, while other important engineering aspects are omitted, e.g. durability of disc-spring valve systems as discussed in [1]. The objective of this work is to show key steps of the simulation process focusing on interactions between fluid and structure domain and to review relevant simulation results.

The Analysis of the Registration Accuracy of Distributed Drives Parameters

The article includes a description of the validation used for an assessment of accuracy of measured symptoms in case of distributed drives connected via the ProfiBus DP network. Particular attention has been given to acquiring the diagnostic data especially in case of currents intensities in the start-up and braking phases. The authors also raise a problem of the usefulness and precision of measured data obtained with usage of recording methods by means of dedicated system in comparison with the solutions delivered by the manufacturer of examined drives. Presented results of practical measurements contain values based on the registration of output currents of frequency converters and the measured values of current intensities in the motor windings. The described parameters are significant for the evaluation of electrical damages, caused by various factors (including excessive loads, improper selection, etc.).

Simulation of the behavior of disc-spring valve systems with the fuzzy inference systems and artificial neural networks

This paper proposes an analytical tool that supports the design process of a hydraulic damper valve system. The analytical tool combines Artificial Neural Networks (ANNs) and Fuzzy Inference Systems (FIS) into one tool called, in the paper, the Approximation Tool. The proposed Approximation Tool obtains a key design characteristic of a valve, which is the flow rate, and the corresponding maximum stress level in the valve components, as a function of a pressure load. The cases required to prepare the Approximation Tool were produced by a first-principle model using a finite element approach. The model was calibrated based on experimental results to provide accurate results in the entire range of input parameters. The paper describes the proposal, implementation, validation and an example of applying the Approximation Tool that allows the replacement of complex high- fidelity Finite Element analyses. As an approximator the Feed Forward Neural Network and FIS were taken.

The Application of a First-Principle Damper Model for Tracking the Variation of Eigenvalues under Non-stationary Road Excitation

The paper presents a method for analyzing and understanding the dynamics of prototype designs of hydraulic damper under non-stationary load conditions. In the method proposed in this paper, a high-frequency first-principle model of a damper is linearized around a series of operating points which are obtained from a preceding numerical simulation of the model. As a result of multiple repetitions of an elementary linearization, a series of linearized models and their respective eigenvalues are collected over a certain period of operation time, corresponding to the duration of a non-stationary excitation signal.

Application of a Nonlinear Data-Driven Model to Rapid Design of Disc-Spring Valve Systems

This paper proposes an analytical tool that supports the design process of a disc spring valve system used in car dampers. The proposed analytical tool obtains a key design characteristic of a valve, which is the flow rate and the corresponding maximum stress level in the stack of plates, as a function of a pressure load. The tool is prepared based on the cases produced by a first-principle model using a finite element approach. The finite element model was calibrated based on experimental results to provide accurate results in the entire range of input parameters.

Optimization of a Shock Absorber Design Using Model-Based Approach

The aim of this paper is to demonstrate a possibility to optimize a shock absorber design to minimize level of vibrations with the use of model-based approach. The paper introduces a proposal of an optimization method that allows to choose the optimal values of the design parameters using a shock absorber model to minimize the level of vibrations. A model-based approach is considered to obtain the optimal pressure-flow characteristic by simulations conducted with the use of coupled models, including the damper and the servo-hydraulic tester model. The presence of the tester model is required due to high non-linear coupling of the tested object (damper) and the tester itself to be used for noise evaluation. This kind of evaluation is used in the automotive industry to investigate dampers, as an alternative to vehicle-level tests. The paper provides numerical experimental case studies to show application scope of the proposed method