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1

Breaking the Testing Pyramid with Virtual Testing and Hybrid Simulation

You Shawn, Gao Shawn, Nelson Arlin

Fatigue of Aircraft Structures

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2019

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Iss. 11

1--10

EN

Virtual testing and hybrid simulation have become an important trend in airplane design and validation. The traditional Testing Pyramid (or Building Block) approaches that emphasis on uniaxial coupon test and full structure certification test are being challenged. Researchers are trying to use advanced testing and simulation methods to replace the Testing Pyramid approach. Before physical testing, virtual testing can be conducted to simulate the physical test. Virtual model of the full testing system including controller, actuators, and fixtures can be constructed and validated. In this work, an example has been developed and validated to show the potentials of the virtual testing process. Hybrid simulation is an approach of analyzing an analysis model and physical structure integrated system under realistic loading conditions. Hybrid simulation combines the lab testing with numerical analysis to explore the benefits of both methodologies. In this study, a hybrid simulation for a simplified airplane wing was conducted to demonstrate the process. Virtual testing and hybrid simulation are alternative methods of Testing Pyramid approach. Full scale tests are still required for certification but the more that is known about the test article, the greater chances of success in the full-scale certification testing.

2

An improvement in stable Pade approximation using constrained minimization

Bandyopadhyay B., Singare P. S.

Systems Science

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2006

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Vol. 32, no 2

5-17

EN

In this paper, an improvement in Pade approximation is proposed to reduce the order of a linear-time-invariant higher order stable system, using the Hermite-Biehler stability theorem. Two free parameters are introduced in the denominator polynomial of the reduced model. It will be shown that for any positive values of these two parameters, the resulting reduced model will be stable. The numerator polynomial and these two parameters are obtained by matching time moments. In this proposed algorithm, the reduced model matches (r + 2) time moments exactly while (r + 3)-th moment is matched approximately. The proposed method is illustrated by two numerical examples.

3

Design of output feedback compensator for smart structure model via reduced order model

Umapathy M., Bandyopadhyay B., Unbehauen H.

Systems Science

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2002

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Vol. 28, nr 4

61-84

EN

A method of designing an output feedback compensator for vibration control of a flexible smart cantilever beam based on its reduced order model is presented. By retaining the first two vibration modes the state space model is obtained from a smart structure Finite Element Model (FEM). A reduced order model is obtained by retaining the first vibration mode. It has been shown that an output feedback compensator can be obtained for the smart structure model from the state feedback gains designed from its reduced order model. It has also been shown that if the compensator is placed in the closed loop with the higher order system, it guarantees the closed loop stability. As the states are not needed for feedback, the method is simple and can be easily implemented.

4

Mathematical model of sequentially controlled activated sludge processes

Metzger M.

Archives of Control Sciences

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1999

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Vol. 9, no. 3/4

111-133

EN

Reduced order model of the activated sludge process dynamics, presented in the paper, can be treated as a compromise between simplicity (needed for control purposes) and complexity (needed for process behaviour description). Proper calibration of reduced order models is a very difficult task. A new strategy of the model calibration for two different-type sequentially controlled processes (sequentially operated continuous process and sequencing batch reactor) is presented. The proposed method accepts typical values of the model parameters and is based on the fitting of the measured process responses by manipulation of only two model parameters: the initial values of heterotrophic and autotrophic biomass concentrations. Discussion of the response fitting possibilities by changes of XBH and XBA in bio-acceptable limits, as well as validation results for experimental data from two pilot plants, show very promising application of the method.