To study discrete objects and relationships among them 2. Computer Engg. Goodaire, M. Kolman, R. Busby and S. Tremblay, R.

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Modeling and Numerical Simulation of Material Science, , 1, doi The received signal from the simulation is compared to that of an actual measurement in the time domain. The comparison of simulated, experimental data clearly shows that acoustic wave propaga- tion can be modeled. The feasibility has been demonstrated in an ultrasound transducer setup for material property investigations.

The results of simulation are compared to experimental measurements. Results ob- tained fit some much with those found in experiment and show the validity of the used model. The simula- tion tool therefore provides a way to predict the received signal before anything is built. Furthermore, the use of an ultrasonic simulation package allows for the development of the associated electronics to amplify and process the received ultrasonic signals.

Such a virtual design and testing procedure not only can save us time and money, but also provide better understanding on design failures and allow us to modify designs more efficiently and economically. Introduction Numerical simulations i. Numerical simulations permit one to solve problems that may be inaccessible to direct experimental study or too complex for theoretical analysis.

Computer simulations can bridge the gap between analysis and experiment. Numerical simulations analysis and experiment cover mutual weak- ness of both experiment and theory. These simulations will remain a third dimension in ultrasonic measurements, of equal status and importance to experiment and analy- sis.

It has taken a permanent place in all aspects of ultra- sonic measurements from basic research to engineering design. The computer experiment is a new and poten- tially powerful tool. By combining conventional theory, experiment and computer simulation, one can discover new and unsolved aspects of natural process.

These as- pects could often neither have been understood nor rev- eled by analysis or experiments alone. There might be many use of ultrasound but a common one is its application to non-destructive evaluation. Pulsed ultrasonic is finding an increasing number of applications in research and industrial nondestructive testing. In such evaluation, one tries to obtain information about the in- ner parts of an ensemble without dismantling it.

In an ultrasonic system, a transducer consists of a collection of material layers. The design and optimization of a multi- layered transducer is a complicated engineering task that involves knowledge of physical acoustics, analog elec- tronics, and the acoustical properties of the materials involved. This task is made even more difficult by the lack of available information about frequency and ther- mal dependencies of these materials characteristics.

The optimal combination of suitable materials can be found by trial and error, but not without considerable time and cost, both of which can be minimized through the use of simulations. The aim of this paper is to present a tool which provides a simulation of the received signal prior to construction. Of the different ways to model the elec- tro-acoustic system, a total electrical simulation tool is used for the following reasons.

This paper pre- sents a simulation solution to ease the selection process. The use of PSPICE provides an opportu- nity to simulate the complex set of excitation electronics, the ultrasonic transducer, the material under investigation, and the receiving electronics. Electrical analogies of one- dimensional acoustic phenomenons have studied over the years. Mason [23], modeled electromechanical transducers with a lumped equivalent circuit.

With the transmission line, one can represent the time delay nec- essary for a mechanical signal to travel from one side of the transducer to the other. In the case of a plate trans- ducer, the derivation of both models includes a negative capacitor. Krimholtz et al. Leach [22], used controlled current and voltage sources instead of transformers.

Puttmer et al. Benny et al. A comparison of experimental and simula- ted results for piezoelectric composite, piezoelectric po- lymer, and electrostatic transducers is then presented to demonstrate some quite different airborne ultrasonic beam-profile characteristics.

San Emeterio et al. Hirsekon et al. The current work applies the approach of Puttmer et al. In order to keep things at a manageable level, the following simplifications and assumptions are made. The acoustic propagation travels along one direction and consist of planner longitudinal waves, which are normal to the direction of propagation. The amplitudes are small enough to keep things in linear regions of the devices such that the principle of superposition is not violated.

Validation of the theory is achieved by comparing experimental data obtained from different liquids at fixed frequency and temperature. Modeling The piezoelectric phenomenon is modeled using con- trolled voltage and current sources [22] Figure 1.

The equivalent circuit consists of the static capacitance C0 capacitance between the electrodes , a transmission line representing the mechanical part of the piezoelectric transducer and two controlled sources for coupling be- tween the electrical and mechanical part of the circuit.

This pulse can be pictured as a disturbance to which the medium reacts to. In the case of longitudinal wave, the disturbance is a compression or rarefaction of matter, which the medium displaces to return to its equilibrium state. Their relationship to the speed of sound is: cvM.



Not open for further replies. One weekend is NOT GOING to teach them what they need to know, and the alternative, which seems to be asking the same old questions, over and over again on the ZED is certainly not a very satisfactory answer. Click to expand An even bigger problem is that a lot of people want instant answers but then immediately forget them after their short-term problem goes away, so they end up asking the same questions every time they run into the same problem. The old proverb about "give me a fish, I eat for today; teach me to fish, I eat for a lifetime" applies here. No argument on that one, Jim, but remember that it takes two to make the learning process work: one to impart the knowledge, and another to receive it.


CW power VS. SSB power






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