Modal Test Optimization Using VETO (Virtual Environment for Test Optimization)

摘要

We present a software environment integrating analysis and test based models to support optimal modal test design through a Virtual Environment for Test Optimization (VETO). A goal in developing this software tool is to provide test and analysis organizations with a capability of mathematically simulating the complete test environment within a computer. Derived models of test equipment, instrumentation and hardware can be combined within the VETO to provide the user with a unique analysis and visualization ca ability to evaluate new and existing test methods. The VET 8 assists analysis and test engineers in maximizing the value of each modal test. It is particularly advantageous for structural dynamics model reconciliation applications. The VETO enables an engineer to interact with a finite element model of a test object to optimally place sensors and exciters and to investigate the selection of data acquisition parameters needed to conduct a complete modal survey. Additionally, the user can evaluate the use of different types of instrumentation such as filters, amplifiers and transducers for which models are available in the VETO. The dynamic response of most of the virtual instruments (including the device under test) are modeled in the state space domain. Design of modal excitation levels and impropriate test instrumentation are facilitated by the VETO'S ability to simulate such features as unmeasured external inputs. A/D quantization effects, and electronic noise. Measures of the duality of the experimental design, including the Modal Assurance Criterion, and the Normal Mode indicator Function are available[1]. The VETO also integrates tools such as Effective Independence[2] and minamac[1] to assist in selection of optimal sensor locations. The software is designed about three distinct modules: 1.a main controller and GUI written in C++, 2.a visualization model, taken from FEAVR[3], running, under AVS, and 3.a state space model and time integration module, built in SIMULINK. These modules are designed to run as separate processes on interconnected machines. MATLAB's external interface library is used to provide transparent, bidirectional communication between the controlling program and the computational engine where all the time integration is performed. Date from the finite element model is downloaded to the MATLAB engine where the SIMULINK model is automatically created and executed. MATLAB GUI elements are used to simulate the data acquisition environment including response traces, over-range indicators, and full scale voltage ranges.