Papers by Keyword: Failure Process

Abstract: The special advantages of Soundless Crack method are safety and environmental protection. Soundless Crack is widely used in stone exploitation, partly crack of brittleness materials such as rock and concrete, and backout of building in city. In these engineering, we must drill many holes for loading Soundless Cracking Agents, but the drilling cost is expensive including human cost and materials cost, at the same time need much time to drill these holes. So we hope to gain the best crack results at the minimum drillhole numbers. This paper used RFPA software to set up some models with different drillhole numbers, gained different failure process of models. Adopted different drilling plan will occur different results. We should drill more holes if we need partly crack smoothly. We can plan the number of drillholes based on our need if we can use RFPA to simulate the failure process before beginning.

Abstract: Identification of failure mechanisms of thermal spray coatings by means of traditional fractography of failed parts is often troublesome. Reason for this is a highly inhomogeneous character of the coating microstructure and harsh in-service conditions which may hinder evidentiary fractographic marks. In this study, failure evolution of advanced thermal barrier coating (TBC) prepared by plasma spraying was studied in-situ at high magnification in a scanning electron microscope under well-defined laboratory conditions of three-point bending (3PB).

Abstract: This paper uses 2D DDA program to simulate the failure process of highly jointed rock slope with a fault. In addition, seismic forces, as a most common triggered factor of landslide, are also simplified simulated by applying an initial velocity to the slope. Based on the simulation results, the weakest discontinuity, fault, determines the slide path of rock blocks; the accumulation of blocks' displacements leads to the overall failure of slope; and the existence of highly developed joints provide the possibility of the accumulation of displacements.

Abstract: Rubber-sleeved headed stud shear connector is flexible shear connector used in steel-concrete composite structures. In this work, nonlinear finite element model has been developed to simulate the failure process of the shear connector under shear loading. The stress distribution, deformation, crack propagation and failure mode were analyzed. The material nonlinearities of rubber, headed stud, concrete were considered in the material model. The rubber was assumed as a perfect material with no defect, and a modified reduced polynomial form of strain energy including an energy limiter and a new constant was introduced into the user material subroutine VUANISOHYPER-INV of ABAQUS software. Damaged plasticity model was used to model the concrete material. A tri-linear elastic-plastic curve was used in stud material model. Comparing the results obtained from the finite element analysis with those from push-out test, good agreement is highlighted in the capacity, ductility and failure mode of rubber-sleeved headed stud shear connector.

Abstract: Mine ventilation system is a repairable system, with the characters of time-varied and randomness. It made us encounter some difficulties when we discussed the system failure evolution process and its operational reliability, as well as when we sought the system reliability parameters developing trends following with ventilation system operation time variation and air adjustment. Firstly, according to the reliability theory, the failure process characteristic values, which affect the ventilation system, were defined. And then, by mean of the analysis of the failure process deterioration of mine ventilation system, the deterioration and its amelioration discriminants are given basing on two parameters’ Weibull process. Finally, on the basis of adaptive neural network technology, the ventilation system failure processes were simulated, the failure process characteristic parameters were determined, and the failure curves were drawn accordingly. The results show that the failure process of the experiment mine ventilation system is a Non-homogeneous Poisson Process; the mean time between failures of the ventilation system is between 160h and 170h; the failure ratio curves present the trends of concave or convex variation when the system failure process deterioration or amelioration.

Abstract: The meso-element equivalent method (MEEM), is developed in the study to investigate the damage process and the macro-mechanical properties of concrete. The Monte Carlo method is adopted to generate the random aggregate structure (RAS) firstly, and then the characteristic element size is applied to divide the RAS into many identical units. Each unit obtained is processed equivalently to be a homogeneous and isotropic unit by the homogenization theory. Some concrete specimens in 2-D and 3-D are undertaken to verify the feasibility and accuracy of the proposed approach. The results indicate the high efficiency and accuracy of the present methodology.

Abstract: As the main geohazard triggered by Wenchuan earthquake, landslide is widely distributed. It caused many people lost their lives and incipient fault. This paper analyzes the genesis of these landslides from the aspects of geomorphy, geological structure of slope body, rock characters, earthquake motion, stable condition of slope, weathering effect and stream action. Strong earthquake motion near the fracture zone and geological structure of slope body are the main reasons caused the slope failure. Take Wangjiayan landslide as the typical example, the genesis of earthquake-induced landslide is analyzed. Strong earthquake motion near the fracture zone and the extroversion structural surfaces are the main reasons caused the slide, and great slope and instable state of slope can also promote the slop failure. Failure process of slope is also analyzed.

Abstract: Based on the RCC（roller compacted concrete） gravity dam, considering the multiphase, heterogeneity and microscopic structure characteristics of RCC, we use the RFPA analysis system to analyze the whole destruction process of the RCC weak level under the action of the pure water pressure in this paper. By simulation, we obtained the distribution of the stress, elastic modulus, water pressure on the whole failure process of RCC weak level and several parameters, such as the up crack load, instability load and critical crack propagation length. By calculation, we got the double K fracture toughness of RCC under the different of water pressure, and the results show that the up crack toughness and instability toughness change regularly with the increasing of water pressure initial value in the mass.

Abstract: Arch dam’s failure is a super nonlinear irreversible process. The research on process of it would give quite important information for safety evaluation. In this paper, it analyses overload of the highest RCC arch dam of the world with explicit FEM and shows the process of dam’s failure from normal operation, local deformation to overall failure by water-level overcharge method. It gives a more direct and precise safety factor. This method is also can be used in other structures.

Abstract: Arch dam’s failure is a super nonlinear irreversible process. The failure process of it is quite important for safety evaluation. It analyses overload of the highest RCC arch dam of the world with explicit FEM and shows the process of dam’s failure from normal operation, local deformation to overall failure by water specific gravity overcharge method. It gives a more direct and precisely safety factor. This method is also can be used in other structures.