Early Detection of Rotor Cracks?Monitoring & Methodology
This paper describes a diagnostic method for the early detection of shaft cracks on rotating machines. The method is based on interpretation of the lateral synchronous (1x) and twice per...
The Cougar Project?Turbine Runner Replacement
The Cougar turbine runners have been subjected to a substantial amount of cavitation damage which has required repair by welding. The continued welding repair has subsequently resulted...
A Lesson in Repairing Cracked Kaplan Blades
Each of the three units that failed at Bonneville Lock and Dam started with a fatigue break and ended in a brittle fracture. Consequently, a comprehensive in-house weld procedure was developed...
Saco Dam?South America's First RCC Dam
Because of cost and a lack of suitable embankment materials, Saco Dam at Nova Olinda in Paraiba, Brazil, was redesigned and built with lean roller compacted concrete (RCC). The structure...
A Stochastic Model for Low-Cycle Elastic-Plastic Fatigue Crack Growth
In this paper a stochastic process approach is considered to represent the random nature of the low-cycle (elastic-plastic) fatigue crack growth process. A semi-Markov renewal model is...
Recent Thoughts on Probabilistic Fatigue Crack Growth
We briefly review recent results of analysis of fatigue crack growth data. Implications of this analysis are presented, and reasons are advanced in favor of increasing the dimension of...
Modeling Fatigue Crack Growth Resistance, dN/da
In the fracture mechanics approach to fatigue, da/dN is correlated with the cyclic range of the stress intensity factor, ?K; the resulting relation, da/dN=f (?K), is commonly called the...
Stochastic Modeling of Fatigue Crack Growth
A new lognormal fatigue crack propagation model has been presented in which a two-dimensional state vector has been employed to introduce experimentally observed history dependence of...
Probabilistic Prediction of Mixed Mode Fracture Initiation and Trajectory Under Random Stresses
Methods are developed for estimating crack trajectory and the probability of crack initiation in mixed mode fracture. The analysis is based on a computer program for deterministic fracture...
Probabilistic Fatigue Crack Growth Analysis with Reliability Updating
A randomized fatigue crack growth model based on the Paris and Erdogan crack growth equation is used to estimate the reliability of fatigue sensitive details in steel bridges. This model...
Fracture Control for Arctic Vessels and Structures
Materials used for construction of Arctic structures and vessels are exposed to low ambient temperatures, high local ice loads and intermediate to high loading rates. All these factors...
Fatigue Reliability and Inspection in Redundant Structural Systems
The reliability of redundant structural systems under fatigue including updating by inspection is studied using two different formulations, i.e., the stress intensity space and the crack...
Reliability Based Analysis of Contact Problems
The S.B. Batdorf model is modified to include the reduction in shear due to the effect of compressive stresses on the crack face. This new formulation was used to obtain the probability...
Reliability of Cracked, Prestressed Girders
For prestressed concrete structures in non-aggressive environments or where corrosion-protected prestressing strands are used, it may be possible to allow flexural cracking into the precompressed...
Structure of the Expert FRAMEX System on Fracture Mechanics
The FRAMEX expert system gathers, through independent modules, knowledge analysis techniques to be used by an expert for developing a fracture problem diagnosis. The system includes three...
Time Variant Reliability Analysis Using Bivariate Diffusive Crack Growth Models
This paper is concerned with the development of a time-dependent reliability concept. The time variant load carrying capacity, i.e., resistance, of a structure caused by fatigue is expressed...
Markov Approximation to Fatigue Crack Propagation
The distribution of the time required by a crack to reach a specified length and the distribution of the crack size itself are determined. To this end, the fatigue crack propagation growth...
Diffusion Models of Crack Growth Due to Random Overloads
Stochastic diffusion models of crack growth are developed, reflecting uncertainty in applied loading and residual stresses near the crack tip. Applications are shown to (1) random vibration...
A Multilayered Model for Analysis of Composite Pipes
A multilayered model is developed to analyze the behavior of composite pipes, such as prestressed concrete pipe, to the combined effects of internal pressure and applied loads. The pipe...
Estimation of Uplift Pressure in Cracks in Concrete Gravity Dams
This paper presents an analytical solution to predict uplift pressures in cracks in concrete gravity dams. It is shown that drainage systems are effective in reducing such pressures....
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