The Experts below are selected from a list of 321 Experts worldwide ranked by ideXlab platform
Gang Liu - One of the best experts on this subject based on the ideXlab platform.
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Crystal Period Vectors under External Stress in Statistical Physics
2020Co-Authors: Gang LiuAbstract:For crystal periodic structure prediction, a new and concise approach based on the principles of statistical physics was employed to derive a new form of the equation to determine their period vectors (cell edge vectors), under general External Stress. Then the new form is applicable to both classical physics and quantum physics. It also turned out to be the equation of state and the mechanical equilibrium condition for crystals under External Stress and temperature. It should be helpful in piezoelectric and piezomagnetic studies, as the period vectors were changed by the External Stress. For linear elastic crystals, it is actually also the microscopic but temperature-dependent form of the generalized Hooke's law, then can be used to calculate the corresponding elastic constants of the law, for given temperatures.
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Crystal Period Vectors under External Stress in Statistical Physics
2020Co-Authors: Gang LiuAbstract:For crystal periodic structure prediction, a new and concise approach based on the principles of statistical physics was employed to derive a new form of the equation to determine their period vectors (cell edge vectors), under general External Stress. Then the new form is applicable to both classical physics and quantum physics. It also turned out to be the equation of state and the specific explicit equilibrium condition for crystals under External Stress and temperature. It should be helpful in piezoelectric and piezomagnetic studies, as the period vectors were changed by the External Stress. For linear elastic crystals, it is actually also the microscopic but temperature-dependent form of the generalized Hooke's law, then can be used to calculate the corresponding elastic constants of the law, for given temperatures.
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Crystal Period Vectors under External Stress in Statistical Physics
2020Co-Authors: Gang LiuAbstract:In crystal periodic structure prediction, a basic and general equation is needed to determine their period vectors (cell edge vectors), especially under arbitrary External Stress. It was derived in Newtonian dynamics years ago, which can be combined with quantum physics by further modeling. Here a new and concise approach based on the principles of statistical physics was employed to derive it into a new form, then applicable to both classical physics and quantum physics by its own. The new form also turned out to be the specific explicit equilibrium condition and the equation of state for crystals under External Stress and temperature. This work was also compared with the elasticity theory.
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Crystal Period Vectors under External Stress in Statistical Physics
2020Co-Authors: Gang LiuAbstract:In crystal periodic structure prediction, a basic and general equation is needed to determine their period vectors (cell edge vectors), especially under arbitrary External Stress. It was derived in Newtonian dynamics years ago, which can be combined with quantum physics by further modeling. Here a new and concise approach based on the principles of statistical physics was employed to derive it into a new form, then applicable to both classical physics and quantum physics by its own. The new form also turned out to be the specific explicit equilibrium condition and the equation of state for crystals under External Stress and temperature. Contrary to a general belief, the new form also concluded that harmonic oscillators can cause crystal thermal expansion.
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Crystal Period Vectors under External Stress in Statistical Physics
2019Co-Authors: Gang LiuAbstract:In crystal periodic structure prediction, a general equation is needed to determine the period vectors (cell edge vectors), especially when crystals are under arbitrary External Stress. It has been derived in Newtonian dynamics years ago, which can be combined with quantum mechanics by further modeling. Here we derived such an equation in statistical physics, applicable to both classical physics and quantum physics by itself.
Xudong Chen - One of the best experts on this subject based on the ideXlab platform.
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dynamic reversible bonds enable External Stress free two way shape memory effect of a polymer network and the interrelated intrinsic self healability of wider crack and recyclability
Journal of Materials Chemistry, 2018Co-Authors: Long Fei Fan, Min Zhi Rong, Ming Qiu Zhang, Xudong ChenAbstract:In this paper, we propose a new method to prepare an External Stress free two-way shape memory polymer. The core advance lies in the introduction of alkoxyamine moieties into the main chains of crystalline polycaprolactone (PCL) based crosslinked polyurethanes (PUs). By using the synchronous bond fission/radical recombination habit of C–ON bonds in alkoxyamine in a controlled manner, the stretched PU network undergoes uneven partial Stress relaxation depending on the triggering status of C–ON bonds in the specific sites. Accordingly, the greatly relaxed portions tend to maintain the extended status, while the nearly unrelaxed portions tend to recover to their original undeformed shape. These two opposite tendencies successfully create an internal tensional force, which cooperates with the bidirectional deformation induced by melting/recrystallization of the crystalline phase and leads to two-way shape memory effect. Additionally, the dynamic reversibility of C–ON bonds further enables interrelated reprogramming, intrinsic self-healing of wider crack and recycling of the crosslinked PU. Such a diversity of smart stimuli-responsive properties is not available in the case of irreversible polymers.
Long Fei Fan - One of the best experts on this subject based on the ideXlab platform.
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External Stress-Free Reversible Multiple Shape Memory Polymers
ACS Applied Materials & Interfaces, 2019Co-Authors: Ya Nan Huang, Long Fei Fan, Min Zhi Rong, Ming Qiu Zhang, Yu Ming GaoAbstract:The present work is focused on developing External Stress-free two-way triple shape memory polymers (SMPs). Accordingly, a series of innovative approaches are proposed for the material design and preparation. Polyurethane prepolymers carrying crystalline polytetrahydrofuran (PTMEG) and poly(e-caprolactone) (PCL) as the switching phases are respectively synthesized in advance and then cross-linked to produce the target material. The stepwise method is believed to be conducive to manipulation of the relative contribution of PCL and PTMEG. Moreover, the chain extender, 2-amino-5-(2-hydroxyethyl)-6-methylpyrimidin-4-ol (UPy), is incorporated to establish hydrogen bonds among the macromolecules. By straightforward stretching treatment at different temperatures, the hydrogen bond networks are successfully converted into an internal Stress provider, which overcomes the challenge of Stress relaxation of the melted low melting temperature polymer (i.e., PTMEG) and increases the efficiency of Stress transfer. Meanw...
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dynamic reversible bonds enable External Stress free two way shape memory effect of a polymer network and the interrelated intrinsic self healability of wider crack and recyclability
Journal of Materials Chemistry, 2018Co-Authors: Long Fei Fan, Min Zhi Rong, Ming Qiu Zhang, Xudong ChenAbstract:In this paper, we propose a new method to prepare an External Stress free two-way shape memory polymer. The core advance lies in the introduction of alkoxyamine moieties into the main chains of crystalline polycaprolactone (PCL) based crosslinked polyurethanes (PUs). By using the synchronous bond fission/radical recombination habit of C–ON bonds in alkoxyamine in a controlled manner, the stretched PU network undergoes uneven partial Stress relaxation depending on the triggering status of C–ON bonds in the specific sites. Accordingly, the greatly relaxed portions tend to maintain the extended status, while the nearly unrelaxed portions tend to recover to their original undeformed shape. These two opposite tendencies successfully create an internal tensional force, which cooperates with the bidirectional deformation induced by melting/recrystallization of the crystalline phase and leads to two-way shape memory effect. Additionally, the dynamic reversibility of C–ON bonds further enables interrelated reprogramming, intrinsic self-healing of wider crack and recycling of the crosslinked PU. Such a diversity of smart stimuli-responsive properties is not available in the case of irreversible polymers.
Dong-woo Suh - One of the best experts on this subject based on the ideXlab platform.
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a model for transformation plasticity during bainite transformation of steel under External Stress
Acta Materialia, 2003Co-Authors: Heung Nam Han, Dong-woo SuhAbstract:A model, which can calculate the transformation strain components when steel transforms to bainite under an External Stress, is suggested. In the model, the change of the nucleation rate for each variant due to the applied Stress during transformation is considered. To assess the difference of the nucleation rate for variants, the interaction energy between the lattice deformation of the variant and the Externally applied Stress is calculated on the basis of Kurdjumov-Sachs (KS) orientation relationship. From the model, both the volumetric and deviatoric strains caused by bainite transformation can be simultaneously obtained. The calculation results are compared with the experimental dilatometric measurements under various uniaxial compressive Stresses. Good agreement is found between the calculated and experimental values of transformation strain.
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Effect of External Stress on the orientation distribution of ferrite
Scripta Materialia, 2002Co-Authors: Joo-hee Kang, Dong-woo Suh, J.-y Cho, Hu-chul LeeAbstract:Abstract The effect of External Stress on the orientation distribution of ferrite during the transformation was examined. Two types of carbon steel were used to evaluate the deviation angle of ferrite from the Kurdjumov–Sachs (K–S) relationship using electron backscattered diffraction. The K–S relationship was weakened when an External Stress was applied during the transformation.
Katsushi Tanaka - One of the best experts on this subject based on the ideXlab platform.
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interpretation in elastic regime for rafting of ni base superalloy based on the External Stress free dimensional change due to internal Stress equilibration
Acta Materialia, 2005Co-Authors: Tetsu Ichitsubo, Katsushi TanakaAbstract:Abstract The directional coarsening, so-called rafting, phenomenon in Ni-base superalloys is reexamined in the elastic regime, focusing on the evaluation of the External-Stress-free macroscopic-shape change in the light of the Tien–Copley description [Metall Trans 1971:2;215]. The present parametric study using a simple but essential model explicitly demonstrates that creep dislocations are, in theory, not always required for the raft formation. The present result is consistent with the result of the Nabarro theory [Metall Mater Trans 1996:A27;513], and the two prior literature views are found to be equivalent. In the elastic framework, the trigger of rafting is the gain of the potential energy of an External load due to the dimensional change caused by the microstructural change. The argument based on the mechanical free energy indicates that the potential-energy change is much smaller than the strain energy released by the relaxation of the lattice mismatch, and the latter is found to be decisive for most of the rafting phenomena.
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rafting mechanism for ni base superalloy under External Stress elastic or elastic plastic phenomena
Acta Materialia, 2003Co-Authors: Tetsu Ichitsubo, Daisuke Koumoto, Masahiko Hirao, Katsushi Tanaka, Makoto Osawa, Tadaharu Yokokawa, Hiroshi HaradaAbstract:Abstract Rafting mechanism in Ni-base single-crystal superalloys has been discussed with the total mechanical energy calculated for typical microstructures. We found that the actual rafting phenomena cannot be explained within the coherent elastic regime. The present calculations reveal that (i) only the transverse rafted structure with laminates normal to the Stress direction can be realized, regardless of tensile or compressive Stresses, and (ii) the lattice misfit is not relevant to the choice of the rafted structures. However, when the eigenstrain of the spherical (dilatational) symmetry changes into that of the tetragonal symmetry with misfit dislocations on the γ/γ′ interfaces, the signs of lattice misfit and External Stress govern the choice of the transverse or longitudinal rafts. It is concluded that the rafting belongs to an elastic–plastic phenomenon.
