Abstract Out of phase （OP） thermal mechanical fatigue （TMF） behavior of a directionally solid- ified （DS） superalloy DZI25 was experimentally and numerically studied. Two different tempera- ture conditions, whic...Abstract Out of phase （OP） thermal mechanical fatigue （TMF） behavior of a directionally solid- ified （DS） superalloy DZI25 was experimentally and numerically studied. Two different tempera- ture conditions, which are 500-1000 ℃ and 400-900℃, were considered in the present research. Stress and strain responses as well as fatigue life results were presented and discussed. Scanning elec- tron microscope （SEM） and metallographic analysis were used to study the damage mechanism. An oxidation assisted crack initiation and propagation phenomenon were found to explain the shorted life under TMF cycles. In order to characterize the stress and strain deformations under TMF load- ings, a modified Chaboche＇s constitutive model was applied. Additionally, the TMF life of the material was modeled and predicted by Neu-Sehitoglu damage law with high accuracy.展开更多
In this work, a test method was developed to determine the interfacial fracture toughness of the air plasma sprayed （APS） thermal barrier coatings （TBCs） over a wide range of mode mixities. For this mixed-mode tes...In this work, a test method was developed to determine the interfacial fracture toughness of the air plasma sprayed （APS） thermal barrier coatings （TBCs） over a wide range of mode mixities. For this mixed-mode test method, the analytical expres- sions for the energy release rate and stress intensity factors were derived based on the energy theory and the concept of ＂equi- valence＂. The fidelity of these expressions was affirmed by selected finite element analysis. The experimental results showed that the critical energy release rate increased with the increase of the positive mode mixity, which was mainly due to the increase in contact/friction effect and plastic work dissipation with increasing shear mode loading. Furthermore, an elliptical interfacial failure criterion in terms of the stress intensity factors was proposed. The agreement between the experimental results in the literature and those in our work indicated that our test method and the corresponding analytical solutions can well determine the interfaeial fracture toughness of the TBCs over a wide range of mode mixities.展开更多
基金financially supported by the National Basic Research Program of China(No.2015CB057400)
文摘Abstract Out of phase （OP） thermal mechanical fatigue （TMF） behavior of a directionally solid- ified （DS） superalloy DZI25 was experimentally and numerically studied. Two different tempera- ture conditions, which are 500-1000 ℃ and 400-900℃, were considered in the present research. Stress and strain responses as well as fatigue life results were presented and discussed. Scanning elec- tron microscope （SEM） and metallographic analysis were used to study the damage mechanism. An oxidation assisted crack initiation and propagation phenomenon were found to explain the shorted life under TMF cycles. In order to characterize the stress and strain deformations under TMF load- ings, a modified Chaboche＇s constitutive model was applied. Additionally, the TMF life of the material was modeled and predicted by Neu-Sehitoglu damage law with high accuracy.
基金supports from the National Natural Science Foundation of China(No. 10872105 and No. 51071094)
文摘In this work, a test method was developed to determine the interfacial fracture toughness of the air plasma sprayed （APS） thermal barrier coatings （TBCs） over a wide range of mode mixities. For this mixed-mode test method, the analytical expres- sions for the energy release rate and stress intensity factors were derived based on the energy theory and the concept of ＂equi- valence＂. The fidelity of these expressions was affirmed by selected finite element analysis. The experimental results showed that the critical energy release rate increased with the increase of the positive mode mixity, which was mainly due to the increase in contact/friction effect and plastic work dissipation with increasing shear mode loading. Furthermore, an elliptical interfacial failure criterion in terms of the stress intensity factors was proposed. The agreement between the experimental results in the literature and those in our work indicated that our test method and the corresponding analytical solutions can well determine the interfaeial fracture toughness of the TBCs over a wide range of mode mixities.
