Effect Of Defect Location Research Articles

A Study on The Effect Of Defect Location On Stress In Bending Pipe

In this study, the stress that generated when the first or second root of a corrugated pipe is defective is analyzed. The model is analyzed using F.E.M. code. The boundary conditions of deflection or torsion on the opposite side of the defect in the corrugated pipe are changed. The effect of the defect is evaluated using the change of the stress magnitude and the stress concentration factor(K) according to those conditions. As a result of comparing the stress magnitude, K around the flaw at the secondary root is larger than K around the flaw at the first root. Based on the position of the defect, the stress difference in the 1st root increases depending on the boundary condition of bending deflection. However, when the 2nd root is defective, the stress magnitude is similar in both cases regardless of the bending deflection. The magnitude of the stress generated in the corrugated pipe is the highest when the second root is defective. And the stress magnitude is the lowest when there is no defect. In the absence of defects, the stress gradually increases after the stress reaches the minimum value as the amount of deformation increases. However, if there is a defect, stress continues to increase, and when it passes through the plastic zone, the stress gradually increases.

Effect of defect location and size on the degradation of torsional fatigue properties of EBM titanium alloy

Effect of defect location and size on the degradation of torsional fatigue properties of EBM titanium alloy

Effect of defect location on the swimming speed of a microscopic artificial swimmer: A numerical study

The main objective of this work is to explore the effect of defect location on the swimming speed of a microscopic artificial swimmer. The swimmer consists of an artificial filament composed of super-paramagnetic beads connected by elastic linkers and is modeled with a worm-like-chain configuration. To simulate the swimming motion of the filament, a load particle is attached at one end of the filament. The Rotne-Prager approximation is used to evaluate the hydrodynamic interactions between the filament and the fluid. To validate the numerical code, we first simulated the swimming motion of the filament without defect (‘without defect’ means the bending stiffness of the filament is uniform along its length). Next, we simulated the swimming motion of defective filament by setting zero for the bending stiffness value at a particular bead location. We observed that when the location of defect is on the load side of the filament, the swimming velocity is less than that of the defect-less filament, and vice versa. The effect of defect is more significant when it is located on the load side of the filament (The difference between the swimming velocity of defective and defect-less filament amounts to 38%) than when it is on the free end side (The difference is only 7% ). We also observed that at a certain sperm number the swimming direction is reversed when the defect is located very close to the load particle.

The effect of the defect location on the finite element modelling of defect MFL fields

Magnetic flux leakage (MFL) measurement is one of the most widely used non-destructive testing techniques for in-service inspection of oil & gas pipelines. Numerical computation techniques, such as the finite element method (FEM), have been successfully employed for the study of flux leakage fields. FEM has special advantages when predicting the field profiles of simulated corrosion defects because it can model complex boundary geometries and non-linear material characteristics. According to the traditional FEM modelling method, the defect should be placed at different locations along the pipe to simulate the movement of the MFL inspection tool inside the pipe. In this paper, the effect of defect location within the finite element model is discussed and a simplified FEM modelling method is introduced. The simulation results obtained from the new method are compared to those of the traditional method. It is found that the new method can significantly shorten the solution times without compromising the accuracy of the FEM model of MFL inspection.

The effect of defect location on coating fragmentation patterns under biaxial tension

Fragmentation of a coating possessing orthogonal preferential crack propagation directions is modeled for equibiaxial tensile loading. Two plausible cracking scenarios are compared, caused by flaws randomly distributed over the area of the coating or along the coating fragment edges. The two fragmentation scenarios considered are shown to yield qualitatively different fragment patterns.