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J. Hochhalter et al.
This chapter first covers the common methods for acquiring and processing
experimental data, when calibrating CP model parameters. The methods are organized into global and local approaches. Subsequently, a brief introduction to CP
is given, mainly to provide sufficient understanding of the CP parameters to be
calibrated and how they are involved in the model. Common numerical methods
for CP model parameter calibration are then discussed in context of the global
and local data that can be acquired and processed. The fundamental concepts
of uncertainty quantification, with focus on the context of CP model parameter
calibration, are then provided. Lastly, each of the discussed methods for calibration
is evaluated on a simulated experiment with known CP parameters. This provides a
clear quantification of the practical issues of uniqueness of the identified parameters.
2 Acquiring and Processing Experiment Data
The experimental measurements that must be made and post-processing methods
to prepare the acquired data are overviewed here. There are two general categories,
global and local, by which the acquiring and processing methods can be binned.
The fundamental definitions for each of these types of acquired data are given
here because they are important for understanding of the subsequently described
calibration methods.
2.1 Global Data
Global data here is defined by any measurement or post-processing method that
quantifies the bulk behavior of a mechanical test coupon. An example of a directly
measured global data set would be the applied or reaction force provided by a load
cell during testing. Similarly, this data could then be post-processed to produce
either the engineering or true stress by considering the initial or current cross-section
area, respectively. While displacements can similarly be obtained from the stroke of
the test stand during testing, typically a displacement or strain gauge is attached to
the test coupon for this data. Using gauges in this way means that any test-stand
compliance is inherently filtered out of the displacement or strain data. Because
these gauges homogenize underlying coupon deformation over their length, they
are also considered global data.
2.2 Local Data
Local data here is defined as any measurement or post-processing method that
extracts data as a field across the coupon surface or volume. An example of a directly
J. Hochhalter et al.
This chapter first covers the common methods for acquiring and processing
experimental data, when calibrating CP model parameters. The methods are organized into global and local approaches. Subsequently, a brief introduction to CP
is given, mainly to provide sufficient understanding of the CP parameters to be
calibrated and how they are involved in the model. Common numerical methods
for CP model parameter calibration are then discussed in context of the global
and local data that can be acquired and processed. The fundamental concepts
of uncertainty quantification, with focus on the context of CP model parameter
calibration, are then provided. Lastly, each of the discussed methods for calibration
is evaluated on a simulated experiment with known CP parameters. This provides a
clear quantification of the practical issues of uniqueness of the identified parameters.
2 Acquiring and Processing Experiment Data
The experimental measurements that must be made and post-processing methods
to prepare the acquired data are overviewed here. There are two general categories,
global and local, by which the acquiring and processing methods can be binned.
The fundamental definitions for each of these types of acquired data are given
here because they are important for understanding of the subsequently described
calibration methods.
2.1 Global Data
Global data here is defined by any measurement or post-processing method that
quantifies the bulk behavior of a mechanical test coupon. An example of a directly
measured global data set would be the applied or reaction force provided by a load
cell during testing. Similarly, this data could then be post-processed to produce
either the engineering or true stress by considering the initial or current cross-section
area, respectively. While displacements can similarly be obtained from the stroke of
the test stand during testing, typically a displacement or strain gauge is attached to
the test coupon for this data. Using gauges in this way means that any test-stand
compliance is inherently filtered out of the displacement or strain data. Because
these gauges homogenize underlying coupon deformation over their length, they
are also considered global data.
2.2 Local Data
Local data here is defined as any measurement or post-processing method that
extracts data as a field across the coupon surface or volume. An example of a directly