The fracture behaviour of three fiber reinforced and regular HPC （high performance concretes） is presented in this paper. Two mixes are based on optimization of HPC whereas the third mix was a commercial mix develop...The fracture behaviour of three fiber reinforced and regular HPC （high performance concretes） is presented in this paper. Two mixes are based on optimization of HPC whereas the third mix was a commercial mix developed by CONTEC ApS （Denmark）. The wedge splitting test setup with 48 cubical specimens was used experimentally and the cracked non-linear hinge model based on the fictitious crack model was applied for the interpretation of the results. The stress-crack opening relationships were extracted by using inverse analysis algorithm for various multi-linear softening curves. This showed that the refinement of the softening curves reflects in improved accuracy of the WST （wedge splitting test） simulation in comparison with bi-linear softening curves with acceptable increase of computational time. Furthermore, the fracture mechanics parameters such as COD （crack opening displacement）, fracture energy and characteristic length were experimentally determined. Experiments were performed at 1, 3, 7 and 28 days. Fracture energy, Gf, was found to increase with age, while the characteristic length, Lch, was found to decrease.展开更多
Magnetic properties and magnetocaloric effects （MCEs） of the HoPdA1 compounds with the hexagonal ZrNiAl-type and the orthorhombic TiNiSi-type structures are investigated. Both the compounds are found to be antiferro...Magnetic properties and magnetocaloric effects （MCEs） of the HoPdA1 compounds with the hexagonal ZrNiAl-type and the orthorhombic TiNiSi-type structures are investigated. Both the compounds are found to be antiferromagnet with the Nrel tem- perature TN=12 and 10 K, respectively. A field-induced metamagnetic transition from antiferromagnetic （AFM） state to ferro- magnetic （FM） state is observed below TN. For the hexagonal HoPdA1, a small magnetic field can induce an FM-like state due to a weak AFM coupling, which leads to a high saturation magnetization and gives rise to a large MCE around TN. The maxi- mal value of magnetic entropy change （ASM） is -20.6 J/kg K with a refrigerant capacity （RC） value of 386 J/kg for a field change of 0-5 T. For the orthorhombic HoPdA1, the critical field required for metamagnetic transition is estimated to be about 1.5 T, showing a strong AFM coupling. However, the maximal ASM value is still -13.7 J/kg K around TN for a field change of 0-5 T. The large reversible ASM and considerable RC suggest that HoPdA1 may be an appropriate candidate for magnetic re- frigerant in a low temperature range.展开更多
文摘The fracture behaviour of three fiber reinforced and regular HPC （high performance concretes） is presented in this paper. Two mixes are based on optimization of HPC whereas the third mix was a commercial mix developed by CONTEC ApS （Denmark）. The wedge splitting test setup with 48 cubical specimens was used experimentally and the cracked non-linear hinge model based on the fictitious crack model was applied for the interpretation of the results. The stress-crack opening relationships were extracted by using inverse analysis algorithm for various multi-linear softening curves. This showed that the refinement of the softening curves reflects in improved accuracy of the WST （wedge splitting test） simulation in comparison with bi-linear softening curves with acceptable increase of computational time. Furthermore, the fracture mechanics parameters such as COD （crack opening displacement）, fracture energy and characteristic length were experimentally determined. Experiments were performed at 1, 3, 7 and 28 days. Fracture energy, Gf, was found to increase with age, while the characteristic length, Lch, was found to decrease.
基金supported by the National Natural Science Foundation of China (Grant Nos. 50731007 and 51021061)the Knowledge Innovation Project of the Chinese Academy of Sciencesthe High-Technology Research and Development Program of China
文摘Magnetic properties and magnetocaloric effects （MCEs） of the HoPdA1 compounds with the hexagonal ZrNiAl-type and the orthorhombic TiNiSi-type structures are investigated. Both the compounds are found to be antiferromagnet with the Nrel tem- perature TN=12 and 10 K, respectively. A field-induced metamagnetic transition from antiferromagnetic （AFM） state to ferro- magnetic （FM） state is observed below TN. For the hexagonal HoPdA1, a small magnetic field can induce an FM-like state due to a weak AFM coupling, which leads to a high saturation magnetization and gives rise to a large MCE around TN. The maxi- mal value of magnetic entropy change （ASM） is -20.6 J/kg K with a refrigerant capacity （RC） value of 386 J/kg for a field change of 0-5 T. For the orthorhombic HoPdA1, the critical field required for metamagnetic transition is estimated to be about 1.5 T, showing a strong AFM coupling. However, the maximal ASM value is still -13.7 J/kg K around TN for a field change of 0-5 T. The large reversible ASM and considerable RC suggest that HoPdA1 may be an appropriate candidate for magnetic re- frigerant in a low temperature range.
