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21.
The existence and uniqueness of the weak solution to the model for the dynamics of a viscoelastic rod which is in adhesive contact with an obstacle is established. The model consists of a hyperbolic equation for the vibrations of the rod coupled with a nonlinear ordinary differential equation (ODE) for the evolution of the bonding function. The model allows for failure, i.e., complete debonding, in finite time. The existence of the weak solution is established by using an existence result for ODEs and the Schauder fixed-point theorem. The limit of an elastic rod when the viscosity vanishes is studied, too. 相似文献
22.
C. Gonilho Pereira R. Fangueiro S. Jalali M. Araujo P. Marques 《Mechanics of Composite Materials》2008,44(3):221-230
This paper reports on the development of braided reinforced composite rods as a substitute for the steel reinforcement in
concrete. The research work aims at understanding the mechanical behaviour of core-reinforced braided fabrics and braided
reinforced composite rods, namely concerning the influence of the braiding angle, the type of core reinforcement fibre, and
preloading and postloading conditions. The core-reinforced braided fabrics were made from polyester fibres for producing braided
structures, and E-glass, carbon, HT polyethylene, and sisal fibres were used for the core reinforcement. The braided reinforced
composite rods were obtained by impregnating the core-reinforced braided fabric with a vinyl ester resin. The preloading of
the core-reinforced braided fabrics and the postloading of the braided reinforced composite rods were performed in three and
two stages, respectively. The results of tensile tests carried out on different samples of core-reinforced braided fabrics
are presented and discussed. The tensile and bending properties of the braided reinforced composite rods have been evaluated,
and the results obtained are presented, discussed, and compared with those of conventional materials, such as steel.
Russian translation published in Mekhanika Kompozitnykh Materialov, Vol. 44, No. 4, pp. 327–338, May–June, 2008. 相似文献
23.
在高斯光束传输理论的基础上,利用矩阵光学原理和高斯光束耦合理论,得出光学相干层析系统中参考反射镜的空间位置对系统耦合效率影响的表达式,并用计算机模拟系统的耦合效率与参考反射镜和棒透镜间的距离及参考反射镜偏转角度的关系曲线。实验结果和理论分析相符合。 相似文献
24.
One of the most well-known situations in which nonlinear effects must be taken into account to obtain realistic results is
the rotating beam problem. This problem has been extensively studied in the literature and has even become a benchmark problem
for the validation of nonlinear formulations. Among other approaches, the substructuring technique was proven to be a valid
strategy to account for this problem. Later, the similarities between the absolute nodal coordinate formulation and the substructuring
technique were demonstrated. At the same time, it was found the existence of a critical angular velocity, beyond which the
system becomes unstable that was dependent on the number of substructures. Since the dependence of the critical velocity was
not so far clear, this paper tries to shed some light on it. Moreover, previous studies were focused on a constant angular
velocity analysis where the effects of Coriolis forces were neglected. In this paper, the influence of the Coriolis force
term is not neglected. The influence of the reference conditions of the element frame are also investigated in this paper. 相似文献
25.
Three formulations for the problem of an elastica adhering to a rigid surface are discussed and compared. These include stationary principles, the surface integral of Eshelby’s energy-momentum tensor, and the material (configurational) force balance. The configuration at static equilibrium is predicted in closed form for a pair of structures that arise in nano- and microscale applications. 相似文献
26.
针对飞机起落架活塞杆在外场使用过程中裂纹失效问题,利用扫描电子显微镜对其断裂面微观形貌进行观察,研究其断裂机理.结果表明:该活塞杆断裂性质为服役过程中循环应力作用下的疲劳断裂.应力使活塞杆件表面出现微裂纹,在其内部形成微孔.随着应力循环次数增加,微孔的数量和大小都不断增加,最终导致了钢的疲劳断裂.通过优化其热处理工艺,使活塞杆获得良好的强韧配比,提高了抗疲劳性能. 相似文献
27.
This paper analyses perturbations of Noether symmetry, Lie symmetry, and form invariance for super-long elastic slender rod systems. Criterion and structure equations of the symmetries after disturbance are proposed. Considering perturbation of all infinitesimal generators, three types of adiabatic invariants induced by perturbation of symmetries for the system are obtained. 相似文献
28.
29.
Katsuhiro Inomata Yoichi Sasaki Takuhei Nose 《Journal of Polymer Science.Polymer Physics》2002,40(17):1904-1912
We have investigated the morphology and packing manner of graft copolymers consisting of rigid‐rod‐like poly(γ‐benzyl L ‐glutamate) (PBLG) main chains and grafted diblock copolymers of amorphous poly(propylene glycol) (PPG) and crystalline poly(ethylene glycol) (PEG). The results of differential scanning calorimetry and wide‐angle X‐ray scattering measurements for graft copolymers with higher side‐chain volume fractions suggest that the rodlike main chains and crystallized PEG chains exist in segregated domains. Small‐angle X‐ray scattering profiles for these samples show diffraction intensity maxima accompanied by higher order peaks, the positions of which suggest the formation of an ordered layered structure. From these observations, the graft copolymers are estimated to form repeated layered structure consisting of segregated PBLG, PPG, and PEG layers. A proposed model for molecular packing of the graft copolymers is consistent with the experimental observation that the repeating distance for the layered structure decreases with an increase in the volume fraction of side chains. © 2002 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 40: 1904–1912, 2002 相似文献
30.
Yeong‐Deuk Shin Sang‐Ho Han Shashadhar Samal Jae‐Suk Lee 《Journal of polymer science. Part A, Polymer chemistry》2005,43(3):607-615
A well‐defined amphiphilic coil‐rod block copolymer, poly(2‐vinyl pyridine)‐b‐poly(n‐hexyl isocyanate) (P2VP‐b‐PHIC), was synthesized with quantitative yields by anionic polymerization. A low reactive one‐directional initiator, potassium diphenyl methane (DPM‐K), was very effective in polymerizing 2‐vinyl pyridine (2VP) without side reactions, leading to perfect control over molecular weight and molecular weight distribution over a broad range of initiator and monomer concentration. Copolymerization of 2VP with n‐hexyl isocyanate (HIC) was carried out in the presence of sodium tetraphenyl borate (NaBPh4) to prevent backbiting reactions during isocyanate polymerization. Terminating the living end with a suitable end‐capping agent resulted in a P2VP‐b‐PHIC coil‐rod block copolymer with controlled molecular weight and narrow molecular weight distribution. Cast film from a chloroform solution of P2VP‐b‐PHIC displayed microphase separation, characteristic of coil‐rod block copolymers. © 2004 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 43: 607–615, 2005 相似文献