Full metadata
Title
Characterization of the Dynamic Strength of Aluminium at Extreme Strain Rates and Pressures
Description
The study of response of various materials to intense dynamic loading events,
such as shock loading due to high-velocity impacts, is extremely important in a wide
variety of military and industrial applications. Shock loading triggers extreme states,
leading to high pressures and strain rates, and neglecting strength is a typical
approximation under such conditions. However, recent results have shown that strength
effects are larger than expected, so they must be taken into account. Recently,
hydrodynamic instabilities, the most common being the Rayleigh-Taylor (RTI) and
Richtmyer-Meshkov (RMI) instabilities, have been used to infer the dynamic strength of
materials at high pressure conditions. In our experiments and simulations, a novel RMI
approach is used, in which periodic surface perturbations are made on high purity
aluminium target, which was laser ablated to create a rippled shock front. Due to the
slow linear growth rate of RMI, the evolution of the perturbations on the back surface of
the sample as a result of the rippled shock can be measured via Transient Imaging
Displacement Interferometry (TIDI). The velocity history at the free surface was
recorded by spatially resolved laser velocimetry. These measurements were compared
with the results from the simulations, which were implemented using rate independent
and rate dependent material models, to characterize the dynamic strength of the
material. Simulations using the elastic-perfectly plastic model, which is rate
independent, failed to provide a value of dynamic yield strength that would match
experimental measurements of perturbation amplitudes. The Preston-Tonks-Wallace
(PTW) model, which is rate dependent model, worked well for aluminium. This model
was, in turn, used as a reference for calibrating the rate dependent Steinberg-Lund
model and the results from simulations using the calibration models were also compared
to experimental measurements.
such as shock loading due to high-velocity impacts, is extremely important in a wide
variety of military and industrial applications. Shock loading triggers extreme states,
leading to high pressures and strain rates, and neglecting strength is a typical
approximation under such conditions. However, recent results have shown that strength
effects are larger than expected, so they must be taken into account. Recently,
hydrodynamic instabilities, the most common being the Rayleigh-Taylor (RTI) and
Richtmyer-Meshkov (RMI) instabilities, have been used to infer the dynamic strength of
materials at high pressure conditions. In our experiments and simulations, a novel RMI
approach is used, in which periodic surface perturbations are made on high purity
aluminium target, which was laser ablated to create a rippled shock front. Due to the
slow linear growth rate of RMI, the evolution of the perturbations on the back surface of
the sample as a result of the rippled shock can be measured via Transient Imaging
Displacement Interferometry (TIDI). The velocity history at the free surface was
recorded by spatially resolved laser velocimetry. These measurements were compared
with the results from the simulations, which were implemented using rate independent
and rate dependent material models, to characterize the dynamic strength of the
material. Simulations using the elastic-perfectly plastic model, which is rate
independent, failed to provide a value of dynamic yield strength that would match
experimental measurements of perturbation amplitudes. The Preston-Tonks-Wallace
(PTW) model, which is rate dependent model, worked well for aluminium. This model
was, in turn, used as a reference for calibrating the rate dependent Steinberg-Lund
model and the results from simulations using the calibration models were also compared
to experimental measurements.
Date Created
2017
Contributors
- Gopalakrishnan, Ashish (Author)
- Peralta, Pedro (Thesis advisor)
- Rajagopalan, Jagannathan (Committee member)
- Solanki, Kiran (Committee member)
- Arizona State University (Publisher)
Topical Subject
Resource Type
Extent
153 pages
Language
Copyright Statement
In Copyright
Primary Member of
Peer-reviewed
No
Open Access
No
Handle
https://hdl.handle.net/2286/R.I.44143
Level of coding
minimal
Note
Masters Thesis Mechanical Engineering 2017
System Created
- 2017-06-01 01:52:23
System Modified
- 2021-08-26 09:47:01
- 2 years 8 months ago
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