The Effect of Interface Delays in Substructuring Experiments

2011 ◽  
Author(s):  
Maria Rosaria Marsico ◽  
David J. Wagg ◽  
Simon A. Neild
Keyword(s):  
Real Time ◽  
Physical Model ◽  
Test Piece ◽  
Full Scale ◽  
Alternative Solution ◽  
Hybrid Testing ◽  
Physical Test ◽  
Time Dynamic ◽  
Control Techniques ◽  
Dynamic Substructuring

Normally, for feasibility reasons, tests must be conducted on scaled structures, although scaling can introduce other issues. An alternative solution is to experimentally test the part of the structure that is of particular interest, at full or closer to full scale, while numerically modeling the remainder of the structure. This method is termed real-time dynamic substructuring or hybrid testing. To complete the substructure interaction the forces required to impose the displacements on the physical model are measured and applied to the model in real-time. One of the key challenges is to compensate for the dynamics associated with the actuators that are imposing the displacements on the physical test-piece. Ideally these actuators would act instantaneously however even with sophisticated control techniques interface errors are inevitable. We used an example system to study the effects of interface error modeled as a delay, on the accuracy of the overall substructuring technique.

scholarly journals Substructurability: the effect of interface location on a real-time dynamic substructuring test

2016 ◽  
Vol 472 (2192) ◽  
pp. 20160433 ◽  
Author(s):  
N. Terkovics ◽  
S. A. Neild ◽  
M. Lowenberg ◽  
R. Szalai ◽  
B. Krauskopf
Keyword(s):  
Real Time ◽  
Control Strategies ◽  
A Priori ◽  
Major Effect ◽  
Physical Test ◽  
Actuator Dynamics ◽  
Time Dynamic ◽  
Main Challenge ◽  
Dynamic Substructuring ◽  
Interface Location

A full-scale experimental test for large and complex structures is not always achievable. This can be due to many reasons, the most prominent one being the size limitations of the test. Real-time dynamic substructuring is a hybrid testing method where part of the system is modelled numerically and the rest of the system is kept as the physical test specimen. The numerical–physical parts are connected via actuators and sensors and the interface is controlled by advanced algorithms to ensure that the tested structure replicates the emulated system with sufficient accuracy. The main challenge in such a test is to overcome the dynamic effects of the actuator and associated controller, that inevitably introduce delay into the substructured system which, in turn, can destabilize the experiment. To date, most research concentrates on developing control strategies for stable recreation of the full system when the interface location is given a priori . Therefore, substructurability is mostly studied in terms of control. Here, we consider the interface location as a parameter and study its effect on the stability of the system in the presence of delay due to actuator dynamics and define substructurability as the system’s tolerance to delay in terms of the different interface locations. It is shown that the interface location has a major effect on the tolerable delays in an experiment and, therefore, careful selection of it is necessary.

scholarly journals Seismic energy response analysis of equipment-structure system via real-time dynamic substructuring shaking table testing

2019 ◽  
Vol 23 (1) ◽  
pp. 37-50 ◽  
Author(s):  
Jihong Bi ◽  
Lanfang Luo ◽  
Nan Jiang
Keyword(s):  
Real Time ◽  
Shaking Table Test ◽  
Seismic Energy ◽  
Shaking Table ◽  
Energy Calculation ◽  
Test Results ◽  
Structure System ◽  
Time Dynamic ◽  
Dynamic Substructuring ◽  
Shaking Table Testing

Dynamic equations are presented that have been deduced for a real-time dynamic substructuring shaking table test of an equipment-structure system, based on the branch mode substructure method. The equipment is adopted as the experimental substructure, which is loaded by the shaking table, while the structure is adopted as the numerical substructure. Real-time data communication occurs between the two substructures during the test. A real-time seismic energy calculation method was proposed for the calculation of energy responses, both in the experimental substructure and the numerical substructure. Taking a representative four-story steel frame/equipment model, real-time dynamic substructuring shaking table tests and overall model tests were executed. The proposed real-time dynamic substructuring shaking table testing method was verified by comparing the test results with shaking table test results for the overall model. The energy responses of each component in the equipment-structure system, using different connection types, also were studied. Changes in the connection types can lead to changes in the energy responses of the equipment-structure system, especially with respect to the equipment. The choice of the connection for the equipment-structure coupled system should take into account the operational performance objective of the equipment.

Real-time dynamic hybrid testing for soil–structure interaction analysis

2011 ◽  
Vol 31 (12) ◽  
pp. 1690-1702 ◽  
Author(s):  
Qiang Wang ◽  
Jin-Ting Wang ◽  
Feng Jin ◽  
Fu-Dong Chi ◽  
Chu-Han Zhang
Keyword(s):  
Real Time ◽  
Soil Structure ◽  
Interaction Analysis ◽  
Soil Structure Interaction ◽  
Hybrid Testing ◽  
Time Dynamic ◽  
Structure Interaction ◽  
Dynamic Hybrid

A Comparison of Runge Kutta and Novel L-Stable Methods for Real-Time Integration Methods for Dynamic Substructuring

2006 ◽  
Author(s):  
Alicia Gonzalez-Buelga ◽  
David Wagg ◽  
Simon Neild ◽  
Oreste S. Bursi
Keyword(s):  
Real Time ◽  
Experimental Testing ◽  
Time Integration ◽  
Delay Compensation ◽  
Real Time Control ◽  
Time Dynamic ◽  
Time Control ◽  
Dynamic Substructuring ◽  
Integration Algorithms ◽  
Runge Kutta

In this paper we compare the performance of Runge-Kutta and novel L-stable real-time (LSRT) integration algorithms for real-time dynamic substructuring testing. Substructuring is a hybrid numerical-experimental testing method which can be used to test critical components in a system experimentally while the remainder of the system is numerically modelled. The physical substructure and the numerical model must interact in real time in order to replicate the behavior of the whole (or emulated) system. The systems chosen for our study are mass-spring-dampers, which have well known dynamics and therefore we can benchmark the performance of the hybrid testing techniques and in particular the numerical integration part of the algorithm. The coupling between the numerical part and experimental part is provided by an electrically driven actuator and a load cell. The real-time control algorithm provides bi-directional coupling and delay compensation which couples together the two parts of the overall system. In this paper we consider the behavior of novel L-stable real-time (LSRT) integration algorithms, which are based on Rosenbrock's method. The new algorithms have considerable advantages over 4th order Runge-Kutta in that they are unconditionally stable, real-time compatible and less computationally intensive. They also offer the possibility of damping out unwanted high frequencies and integrating stiff problems. The paper presents comparisons between 4th order Runge-Kutta and the LSRT integration algorithms using three experimental configurations which demonstrate these properties.

Stability Switches in a Neutral Delay Differential Equation with Application to Real-Time Dynamic Substructuring

2006 ◽  
Vol 5-6 ◽  
pp. 79-84 ◽  
Author(s):  
Y.N. Kyrychko ◽  
K.B. Blyuss ◽  
A. Gonzalez-Buelga ◽  
S.J. Hogan ◽  
David J. Wagg
Keyword(s):  
Real Time ◽  
Closed Loop ◽  
Numerical Models ◽  
Closed Loop System ◽  
Neutral Delay ◽  
Time Dynamic ◽  
Dynamic Substructuring ◽  
Delay Differential ◽  
Mass Spring ◽  
Theoretical Results

In this paper delay differential equations approach is used to model a real-time dynamic substructuring experiment. Real-time dynamic substructuring involves dividing the structure under testing into two or more parts. One part is physically constructed in the lab- oratory and the remaining parts are being replaced by their numerical models. The numerical and physical parts are connected via an actuator. One of the main difficulties of this testing technique is the presence of delay in a closed loop system. We apply real-time dynamic sub- structuring to a nonlinear system consisting of a pendulum attached to a mass-spring-damper. We will show how a delay can have (de)stabilising effect on the behaviour of the whole system. Theoretical results agree very well with experimental data.

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