نتایج جستجو برای: crack propagation
تعداد نتایج: 127162 فیلتر نتایج به سال:
در این رساله به بررسی مساله شروع و گسترش ترک های هیدرولیکی قرار گرفته در عرض یک گمانه درحالت کرنش مسطح در محیط سنگی هموژن و الاستیک نفوذناپذیر می پردازیم. ترک ها توسط سیال نیوتنی تراکم پذیر که با نرخ حجمی ثابت به داخل گمانه تزریق می شوند هدایت می شوند. تغییر شکل مصالح مطابق با معادله الاستیسیته خطی و جریان سیال ویسکوز داخل ترک با استفاده از تئوری روانسازی مدل می شود. اثر شعاع محدود گمانه با کرن...
Using molecular dynamics with an accurate many-body potential for metallic Tantalum, we studied crack propagation in a pre-notched nano-slab under uniaxial strain in a [100] direction. We study dislocation emission from the crack tip for various strain rate and temperatures, focusing on the influence of the local temperature at the crack tip on the propagation of the crack. We find a close conn...
The fundamentals associated with acoustic emission monitoring of fatigue crack initiation and propagation of Ti-6AI-4V were studied. Acoustic emission can detect and locate incipient fatigue crack extensions of approximately 1 0 gm. The technique therefore can serve as a sensitive warning to material failure. There are three distinct stages during which acoustic emission is generated. These sta...
Cracking and fracture of electrodes under diffusion during lithiation and delithiation is one of the main factors responsible for short life span of lithium based batteries employing high capacity electrodes. Coupling effects among lithium diffusion, stress evolution and crack propagation have a significant effect on dynamic processes of electrodes during cycling. In this paper, a phase field m...
Prognostics and health management techniques have drawn widespread attention due to their ability to facilitate maintenance activities based on need. On-line prognosis of fatigue crack propagation can offer information for optimizing operation and maintenance strategies in real-time. This paper proposes a Lamb wave-particle filter (LW-PF)-based method for on-line prognosis of fatigue crack prop...
Ultrasonic methods have been implemented for in situ sizing of fatigue cracks near fastener holes. These techniques, however, only provide an estimate at the time of the measurement and cannot predict the remaining life of the structure. In contrast, statistical crack propagation approaches model the expected fatigue life based on worst-case fatigue process assumptions. The authors have recentl...
We develop a model for the propagation of a fluid-filled crack in a porous medium. The problem is motivated by the mechanism whereby drainage networks may form in partially molten rock below the Earth‘s lithosphere. Other applications include the propagation of hydraulic fractures in jointed rocks and in oil drilling operations, and the formation of dessication cracks in soils. Motivated by the...
We study a lattice model for mode III crack propagation in brittle materials in a stripe geometry at constant applied stretching. Stiffening of the material at large deformation produces supersonic crack propagation. For large stretching the propagation is guided by well-developed soliton waves. For low stretching, the crack-tip velocity has a universal dependence on stretching that can be obta...
An analysis is presented for transient response of a mode-III interfacial crack propagating between two dissimilar piezoelectric half spaces. The dynamic fracture toughness of a piezoelectric interface is examined, which is a central issue related to the interface strength of multi-layered sensors and ferroelectric thin film devices. For the mode-III crack propagation in piezoelectric materials...
Crack propagation during the indentation test of a ferroelectric single crystal is simulated using a phase-field model. This model is based on variational formulations of brittle crack propagation and domain evolution in ferroelectric materials. Due to the high compressive stresses near the indenter contact faces, a modified regularized formulation of the variational brittle fracture is coupled...
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