Non-deterministic Calibration
171
(much more accurately than conventional EBSD), and stress via Hooke’s law (if
the elastic parameters of the material are well-known). By looking at the curl of the
deformation gradient, HREBSD measurements may even be used to calculate Nye’s
tensor, a continuum representation of geometrically necessary dislocation density
[34].
2.2.3 Combining DIC and HREBSD
Recently, a new measurement method has been developed which allows for the
simultaneous acquisition of DIC and HREBSD on a specimen surface. The integration of these two, previously mutually exclusive, experimental methods is made
possible by the application of an amorphous DIC-pattern material, such as urethane
rubber [35], that provides good contrast for DIC in a SEM at low acceleration
voltage (at about 5 keV) using secondary electron imaging, but has negligible
interference with the primary electrons that form diffraction patterns at highaccelerating voltage (20 keV). An example of this stamp, imaged in two different
modes, is shown in Fig. 2. This combination of methods enables decomposition
of deformation within the same surface domain during loading. In other words,
DIC can be used to quantify the total deformation, while HREBSD can be used
to quantify the elastic part of that total deformation, allowing for a decomposition
of the elastic and plastic parts. Note that the current feature size of the stamp
is approximately 1 micron and the spatial resolution of the patterning technique
is expected to improve with further development. The implications of this new
measurement method on calibration methods are provided in Sect. 6.3.
3 Crystal Plasticity
As motivated in Sect. 1 of this chapter, CP models are becoming increasingly used
when microstructure dependence in engineering use cases is observed. There are at
least two driving factors for that increased adoption. First, CP models are reaching
maturity where even complex micromechanism multiphysics simulations can be
completed in a reasonable amount of time and with well-supported computational
toolsets. Second, in many engineering applications, component size reduction
is common. Examples of such applications are microelectromechanical systems,
electronic devices, and thinning of structural components in aerospace vehicle
components. Furthermore, material processing of Ni- and Al-based metals in
aerospace applications, e.g., turbine blades and pressure vessels, can result in grain
growth resulting in grain sizes approaching the structural scale. In these cases, and
others like them, the micromechanics plays a governing role in the behavior, size
effect, and variability in component performance and reliability and, hence, must be
considered during design and certification.
171
(much more accurately than conventional EBSD), and stress via Hooke’s law (if
the elastic parameters of the material are well-known). By looking at the curl of the
deformation gradient, HREBSD measurements may even be used to calculate Nye’s
tensor, a continuum representation of geometrically necessary dislocation density
[34].
2.2.3 Combining DIC and HREBSD
Recently, a new measurement method has been developed which allows for the
simultaneous acquisition of DIC and HREBSD on a specimen surface. The integration of these two, previously mutually exclusive, experimental methods is made
possible by the application of an amorphous DIC-pattern material, such as urethane
rubber [35], that provides good contrast for DIC in a SEM at low acceleration
voltage (at about 5 keV) using secondary electron imaging, but has negligible
interference with the primary electrons that form diffraction patterns at highaccelerating voltage (20 keV). An example of this stamp, imaged in two different
modes, is shown in Fig. 2. This combination of methods enables decomposition
of deformation within the same surface domain during loading. In other words,
DIC can be used to quantify the total deformation, while HREBSD can be used
to quantify the elastic part of that total deformation, allowing for a decomposition
of the elastic and plastic parts. Note that the current feature size of the stamp
is approximately 1 micron and the spatial resolution of the patterning technique
is expected to improve with further development. The implications of this new
measurement method on calibration methods are provided in Sect. 6.3.
3 Crystal Plasticity
As motivated in Sect. 1 of this chapter, CP models are becoming increasingly used
when microstructure dependence in engineering use cases is observed. There are at
least two driving factors for that increased adoption. First, CP models are reaching
maturity where even complex micromechanism multiphysics simulations can be
completed in a reasonable amount of time and with well-supported computational
toolsets. Second, in many engineering applications, component size reduction
is common. Examples of such applications are microelectromechanical systems,
electronic devices, and thinning of structural components in aerospace vehicle
components. Furthermore, material processing of Ni- and Al-based metals in
aerospace applications, e.g., turbine blades and pressure vessels, can result in grain
growth resulting in grain sizes approaching the structural scale. In these cases, and
others like them, the micromechanics plays a governing role in the behavior, size
effect, and variability in component performance and reliability and, hence, must be
considered during design and certification.