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Título:
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Set‐up of a split hopkinson pressure bar. Calibration and wave dispersion correction
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Autor/a:
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Jiménez Garcia, Àlex
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Otros autores:
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Hughes, Kevin |
Abstract:
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The mechanical properties of materials change depending upon the strain rate that
they are subject to. Robust models that capture the materials response at different
strain rates are important. High strain rates from 100s‐1 to 10000s‐1 are undergone in
impact applications. The most widely used method to characterise materials at high
strain rates is the Split Hopkinson Pressure Bar (SHPB).
This project deals with the set‐up and calibration of a Split Hopkinson Pressure Bar for
the dynamic testing of metallic materials at high strain rates. The features of the
equipment needed are discussed, as well as the instrumentation and the connections
between the different components. A calibration routine is also presented in this text.
A finite element analysis of a SHPB calibration test has been performed with LS‐DYNA.
The model consists of two bars put together and does not include a specimen. The
time dependent strain and stress pulses obtained are very well correlated to the
theory. The results from a calibration test in the laboratory at Cranfield University are
also presented. It is observed that the level of accuracy of the finite element model is
better than that of the experimental calibration test.
A complete analysis of a SHPB with a metallic specimen is also performed with finite
elements in LS‐DYNA. The results achieved are extremely close to those predicted by
some hand calculations. The creation and application of a routine with Matlab that
corrects the dispersion effect in the model is a key point to increase the accuracy of
the results. The dispersion correction routine consists of a technique that enables to
filter out the high frequency components of the sampled signal; therefore, part of the
noise is removed. This is performed after the time domain data is converted into the
frequency domain, after using the Fast Fourier Transform. This routine has also been
applied to the experimental results obtained through the calibration test. |
Abstract:
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Outgoing |
Materia(s):
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-Àrees temàtiques de la UPC::Enginyeria dels materials::Assaig de materials::Assaigs mecànics -Àrees temàtiques de la UPC::Enginyeria dels materials::Metal·lúrgia::Metal·lografia -Metals -- Mechanical properties -Strains and stresses -Metalls –- Propietats mecàniques -Deformacions i tensions |
Derechos:
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Tipo de documento:
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Trabajo/Proyecto fin de carrera |
Editor:
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Universitat Politècnica de Catalunya
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