TY  - JOUR
A1  - Buljak, Vladimir
A1  - Bruno, Giovanni
T1  - Numerical modeling of thermally induced microcracking in porous ceramics
BT  - an approach using cohesive elements
JF  - Journal of the European Ceramic Society
N2  - A numerical framework is developed to study the hysteresis of elastic properties of porous ceramics as a function of temperature. The developed numerical model is capable of employing experimentally measured crystallographic orientation distribution and coefficient of thermal expansion values. For realistic modeling of the microstructure, Voronoi polygons are used to generate polycrystalline grains. Some grains are considered as voids, to simulate the material porosity. To model intercrystalline cracking, cohesive elements are inserted along grain boundaries. Crack healing (recovery of the initial properties) upon closure is taken into account with special cohesive elements implemented in the commercial code ABAQUS. The numerical model can be used to estimate fracture properties governing the cohesive behavior through inverse analysis procedure. The model is applied to a porous cordierite ceramic. The obtained fracture properties are further used to successfully simulate general non-linear macroscopic stress-strain curves of cordierite, thereby validating the model.
KW  - analysis
KW  - Cohesive finite elements
KW  - Interfacial strength
Y1  - 2018
U6  - https://doi.org/10.1016/j.jeurceramsoc.2018.03.041
SN  - 0955-2219
SN  - 1873-619X
VL  - 38
IS  - 11
SP  - 4099
EP  - 4108
PB  - Elsevier
CY  - Oxford
ER  - 
TY  - JOUR
A1  - Bürger, Gerd
T1  - A counterexample to decomposing climate shifts and trends by weather types
JF  - International Journal of Climatology
N2  - The literature contains a sizable number of publications where weather types are used to decompose climate shifts or trends into contributions of frequency and mean of those types. They are all based on the product rule, that is, a transformation of a product of sums into a sum of products, the latter providing the decomposition. While there is nothing to argue about the transformation itself, its interpretation as a climate shift or trend decomposition is bound to fail. While the case of a climate shift may be viewed as an incomplete description of a more complex behaviour, trend decomposition indeed produces bogus trends, as demonstrated by a synthetic counterexample with well-defined trends in type frequency and mean. Consequently, decompositions based on that transformation, be it for climate shifts or trends, must not be used.
KW  - analysis
KW  - climate
KW  - statistical methods
Y1  - 2018
U6  - https://doi.org/10.1002/joc.5519
SN  - 0899-8418
SN  - 1097-0088
VL  - 38
IS  - 9
SP  - 3732
EP  - 3735
PB  - Wiley
CY  - Hoboken
ER  -