TY - GEN
T1 - Variability in mixed-mode delamination toughness with implications for research and practical applications
AU - Teller, Sean S.
AU - Davidson, Barry D.
PY - 2006
Y1 - 2006
N2 - Results are presented from a study examining the batch-to-batch and panel-to-panel variability in delamination toughness data and its implications in research settings as well as in practical structural applications. Toughness data from various sets of double cantilevered beam, single leg bending, and end-notched flexure tests are statistically compared. These data sets contain results from different batches of material, different panels within a batch, different test geometries and different operators used for manufacture and testing. For research, the focus is on the use of delamination toughness data to develop and validate delamination growth prediction methodologies. The issue examined here is the balance of creating a large data set versus maintaining accuracy due to the variability in results. To this end, the t-test, analysis of variance for means test, and the k-sample Anderson Darling test are used to examine under what conditions the various data sets could be considered as belonging to the same population. It is found that the delamination toughness of new batches of material will not necessarily pool with existing test data. Thus, for research applications, it is concluded that new toughness values must be determined for each batch of material considered. For practical applications, it is assumed that B-basis values will be used for design, and the test data is examined for two different situations: when delamination toughness is used as an acceptance criterion, and when it is not. In the former case, three different criteria for determining whether or not new batches can be accepted are evaluated, and in the latter case, physical and statistical tests are suggested to ensure that B-basis design allowables reflect the variability of those batches used in production.
AB - Results are presented from a study examining the batch-to-batch and panel-to-panel variability in delamination toughness data and its implications in research settings as well as in practical structural applications. Toughness data from various sets of double cantilevered beam, single leg bending, and end-notched flexure tests are statistically compared. These data sets contain results from different batches of material, different panels within a batch, different test geometries and different operators used for manufacture and testing. For research, the focus is on the use of delamination toughness data to develop and validate delamination growth prediction methodologies. The issue examined here is the balance of creating a large data set versus maintaining accuracy due to the variability in results. To this end, the t-test, analysis of variance for means test, and the k-sample Anderson Darling test are used to examine under what conditions the various data sets could be considered as belonging to the same population. It is found that the delamination toughness of new batches of material will not necessarily pool with existing test data. Thus, for research applications, it is concluded that new toughness values must be determined for each batch of material considered. For practical applications, it is assumed that B-basis values will be used for design, and the test data is examined for two different situations: when delamination toughness is used as an acceptance criterion, and when it is not. In the former case, three different criteria for determining whether or not new batches can be accepted are evaluated, and in the latter case, physical and statistical tests are suggested to ensure that B-basis design allowables reflect the variability of those batches used in production.
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M3 - Conference contribution
AN - SCOPUS:34247166681
SN - 1563478080
SN - 9781563478086
T3 - Collection of Technical Papers - AIAA/ASME/ASCE/AHS/ASC Structures, Structural Dynamics and Materials Conference
SP - 898
EP - 911
BT - Collection of Technical Papers - 47th AIAA/ASME/ASCE/AHS/ASC Structures, Structural Dynamics and Materials Conference
T2 - 47th AIAA/ASME/ASCE/AHS/ASC Structures, Structural Dynamics and Materials Conference
Y2 - 1 May 2006 through 4 May 2006
ER -