MAPOD based reliability assessment of ultrasonic features for bonding quality ev

  • MAPOD based reliability assessment of ultrasonic features for bonding quality ev

    Posted by arsal on 27/11/2021 at 2:28 pm

    Thank you for the presentation in MAPOD! I hereby have some questions to your presentation slides:
    1. Page 8 (Validate numerical simulation with exp. results): You compare the A-scan amplitudes between simulation and experimental results. I wonder on what base are your comparing these two approaches? In experiments I know that you can specify the input wave energy and get a response in percentage of screen height. Did you also specify this input value in your simulations so that you can compare the resulted amplitude? Or did you normalize the amplitude from each approach?
    2. Build variation model with metamodels: Could you please explain how did you determine the number of calculation/simulation points of 1054 in each of your cases? What kind of design of experiment (DOE) sequence did you use to generate these amount of calculation points? You also mentioned meta-model somewhere. As I understand, meta-model is the model of a model, and it is formulated based on modelling your results, i.e., when you have results from your simulations, you kind of using these simulations as a trainning base to “train” a faster model to emulate your original model, so that you can rapidly do lots of virtual simulations, whose results are close to your original model but less time-consuming (hopefully I clarify myself in a understandable way :). So did you go through this process or?
    Thank you again for your presentation and interesting work! Looking forward to hearing your answers!

    lucas replied 5 months, 3 weeks ago 2 Members · 1 Reply
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    lucas

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    27/11/2021 at 10:45 pm
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    Thank you for your interest and insightful comments. Here are some explanations:

    1. Page 8: When we compare A-scan amplitudes of experimental and numerical results we followed two steps:
    a) For experimental results, as you mentioned, we have converted the ultrasonic response energy to percentage.
    b) For numerical results, the A-scan responses are not normalized, however, calibrated. The numerical software used in this study is CIVA (CEA, Fr) is based on semi-analytical finite element model calculations. As a result, we obtain “CIVA points” for each calculation and these points are converted into percentages.
    The calibration value for all work is selected as the maximum amplitude observed from the defect center of 5 mm debonding. In order to match the response for each case, results are not normalized however numerical model parameters have been adjusted.

    2. Variation model with metamodels: As you described, metamodels are models of models, or response surfaces, that are mathematical approximations that are used to reduce the computation time of specific points. In this work, we have calculated 1054 real models to build, or ‘train’, our metamodel based on the number and the range of selected uncertain parameters. While in theory, it is possible to build a metamodel with a lower amount of calculations, in our case, it would have increased the error caused by mathematical approximation.
    Each MAPOD curve we have obtained is based on the calculated metamodel, as a result, the confidence bound and calculated PoD values are quite similar.

    I hope this explains your questions, however, in case it is not clear, please feel free to continue the discussion.