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排序方式: 共有213条查询结果,搜索用时 31 毫秒
101.
Thermoplastic elastomers (TPEs) based on high-impact polystyrene (HIPS)/waste styrene–butadiene rubber powder (WSBRP) blends were prepared by melt-compounding; they were enhanced by incorporation of styrene–butadiene–styrene block copolymer (SBS) and aromatic oil (AO). The effects of SBS and AO dosage on the mechanical properties, Mullins effect and morphological properties of the blends were investigated. Experimental results showed that the incorporation of SBS and AO in the HIPS/WSBRP blends could improve the mechanical properties significantly. Compared with that of HIPS/WSBRP blends, the elongation at break had a maximum value with 9 phr SBS and 15 phr AO loading, being improved by about 220%. The Mullins effect results showed that a softening effect appeared obviously after the first loading–unloading cycle, while the residual deformation and internal friction loss of the HIPS/SBS/AO/WSBRP TPEs were much lower than those of the HIPS/WSBRP blends, indicating the improvement of elasticity. 相似文献
102.
在二维正方Heisenberg铁磁系统的基础上建立了磁振子-声子相互作用模型.利用Matsubara格林函数理论研究了系统的横向声频支声子激发,计算了布里渊区的主要对称点线上的横向声频支声子色散曲线,发现在第一布里渊区的Σ线上,小波矢区(Γ附近kxa<0.2)横向声频支声子有硬化现象,但是在软化区(0.25<kxa<0.7)有横向声频支声子有软化现象,在M附近(0.75<kxa)横向声频支声子有硬化现象.在Δ线上没有发生横向声频支声子有软化与硬化现象.在Z线上小波失区(X附近kxa<0.65)横向声频支声子有软化现象,但是在M附近横向声频支声子有硬化现象.并且又讨论了各项参数对横向声频支声子激发的影响,发现磁振子-声子耦合与自旋波劲度常数对横向声频支声子软化起很大的作用.
关键词:
磁振子-声子相互作用
横向声频支声子软化
Matsubara格林函数理论
铁磁系统 相似文献
103.
104.
Rusinko A 《Ultrasonics》2011,51(6):709-714
In the presented work, a modeling of ultrasonic hardening and softening has been carried out. The analytical model is constructed by the generalization of the synthetic theory of plastic deformation. A new term, ultrasonic defect intensity, is being introduced so that the phenomenon of both hardening and softening is described by the uniform system of constitutive equations. 相似文献
105.
Molecular dynamics simulations were performed to study void evolution subject to unidirectional self-bombardment and radiation-induced variation of mechanical properties in single crystalline vanadium. 3D simulation cells of perfect body-centered cubic (BCC) vanadium, as well as those with one, two, four, and six voids, were investigated. For the no void case, the maximum number of defects, maximum volumetric swelling, and the number of defects left in bulk after a sufficiently long recovery period increased with higher primary recoil energy. For the cases containing voids, a primary recoil energy was carefully assigned to an atom so as to initiate a dense collision spike in the voids center, where some self-interstitial atoms gained kinetic energy by secondary replacement collision sequence traveling along the ? 111? direction. It is found that the larger or the greater the number of voids contained initially in the box, the larger the normalized void volume, and the smaller the volumetric swelling after sufficient recovery of systems. In the single void case, the void became elongated along the bombarding direction; in the multiple void cases, the voids coalesced only when the intervoid ligament distance was short. After sufficient relaxation of the irradiated specimen, a hydrostatic tension was exerted on the box, where the voids were treated as dislocation sources. It is shown that with higher primary recoil energy, the yield stress dropped in cases with smaller or fewer voids but rose in those with larger or greater number of voids. This radiation-induced softening to hardening transition with increasing dislocation density can be attributed to the combined effects of the defect-induced dislocation nucleation and the resistance of defects to dislocation motion. Moreover, as the primary recoil energy increased, the ductility of vanadium in the no void case decreased, but was only slightly changed in the cases containing void. 相似文献
106.
Ye-Ning Wang Hui-Min Shen Lin-Hai Sun Xiao-Hua Chen Jin-Song Zhu Jin Wu 《Phase Transitions》2013,86(1-4):9-30
Two broad internal friction (attenuation as well) peaks in YBCO measured at around 120 K and 250 K are found to exhibit the characteristics of a first-order phase transition. X-ray diffraction indicates no symmetry change on cooling from room temperature but only a downward jump of the lattice parameters was observed. This is referred to as a phase-like transition (PLT) and further confirmed by stress-strain, specific heat and Debye-Waller factor measurements. There always occurs a phase-like transition at 10-30 K above T c in YBCO, BSCCO and TBCCO which disappears in the non-superconducting phases. Ultrasonic studies on single-crystal BSCCO reveal a pronounced elastic anisotropy in the c-plane and a velocity minimum associated with PLT. The overall trend of elastic stiffening below room temperature and some discrepancies and questions in elasticity measurements so far observed for high-T c oxides have been explained or clarified in terms of an abnormal fast change of lattice parameters. 相似文献
107.
《International Journal of Solids and Structures》2014,51(25-26):4357-4372
The motivating key for this work was the absence of a phenomenological model that can reasonably predict a variety of non-proportional experimental data on the anisotropic Mullins effect for different types of rubber-like materials. Hence, in this paper, we propose a purely phenomenological direction dependent orthotropic model that can describe the anisotropic Mullins behaviour with permanent set and, has orthotropic invariants that have a clear physical interpretation. The formulation is based on an orthotropic principal axis theory recently developed for nonlinear elastic problems. A damage function and a direction dependent damage parameter are introduced in the formulation to facilitate the analysis of anisotropic stress softening in rubber-like materials. A direction dependent free energy function, written explicitly in terms of principal stretches, is postulated. The proposed theory is able to predict and compares well with experimental data available in the literature for different types of rubberlike materials. 相似文献
108.
An evolution of the 3D Penrose tiling, which leads to a cubic primitive lattice on a side and to a f.c.c. vertices arrangement on the other side, is shown here. Physical implications are suggested. 相似文献
109.
110.