Abstract: The Charpy V notch specimens of X70 pipeline steel with different notch orientation are
tested under the static and dynamic conditions at different temperatures. By analyzing the load versus
displacement curves and fracture appearances of specimens the relation of fracture behavior and
loading rate is investigated. The maximum load increases and the displacement corresponding to
maximum load reduces with test temperature decreasing. Both under the static conditions are larger
than that under the dynamic conditions. The fracture sections of all test specimens are reduced in the
thickness direction and quantity reduced depends on the load rate, notch orientation and test
temperature. At the higher temperature, delamination cracks are found on the fracture surface both
under the static and dynamic conditions, which are perpendicular to the thickness direction in T-L
specimen and perpendicular to the main crack propagation direction in T-S specimen. Influence of
loading rate on the delamination crack size and amount is obvious. The fracture initiation energy and
total fracture energy increase with test temperature increasing. Influence of loading rate on the total
fracture energy is unobvious at the higher temperature, but is obvious at the lower temperature. So the
loading rate effects on total fracture energy are relevant to test temperature and notch orientation.
Abstract: In the recent years three-dimensional (3D) elastic-plastic analyses have been conducted
extensively for the opening mode (mode I) fracture and the constraint effects are discussed in detail.
However less work is focused on other modes as sliding mode (mode II), tearing mode (mode III)
or the mixed mode fracture in three-dimensional. In this paper the thickness effect on pure mode II
case is discussed by the finite element method (FEM). Modified Boundary Layer (MBL) model is
used, which has the ability to take into account the combined effects of the in-plane constraint
(T-stress) and the out-of-plane constraint (finite thickness). The result demonstrates the weak
thickness dependence on the near tip stress and strain fields under mode II loading. And the size of
the 3D zone at mode II loading is determined to range from 1.0 to 1.2 times the thickness. Two
fracture parameters of J integral and crack tip sliding displacement (CTSD) are discussed, which are
almost same at different thickness planes except those very near the surface. It is interesting to find
that the relations between J and CTSD keep linear at different thickness planes. T-stress is
symmetry on stress and strain distributions along the crack plane. However its effects indicate weak
thickness dependent on the CTSD and J integral fracture parameter.
Abstract: The present study deals with the problem of interfacial cracks of antiplane sliding mode
between a usual elastic material and a one-dimensional hexagonal quasicrystal. Based on the physical
facts that balance of the phason stress field is foreign to the real force in or out of quasicrystal in
physical space, and the quasicrystal is bonded to a usual elastic material without both phason
displacement and stress fields, the problem is described by analytic functions and attributed to find
solutions of the Riemann-Hilbert problem. It is found that the stress intensity factor is not related to
phason strain field, and the phason stress field does not exist. The discontinuity of phonon
displacement field across crack is related to the phason displacement field because of the coupling of
phonon and phason strain fields. Although there is not the phason displacement on the bonded portion
of interface, it exists on the crack’s surface. The energy release rate obtained from interfacial crack’s
propagating is different from that of an interfacial crack between two different pure elastic materials.
Abstract: An adaptive finite element method for analyzing two-dimensional and axisymmetric
nonlinear elastic fracture mechanics problems with cracks is presented. The J-integral is used as a
parameter to characterize the severity of stresses and deformation near a crack tip. The domain
integral technique is utilized as the J-integral solution scheme with the 9-node degenerated crack tip
elements. The solution accuracy is further improved by incorporating an error estimation procedure
to a remeshing algorithm with a solution mapping scheme to resume the analysis at a particular load
level after the adaptive remeshing technique has been applied. Two benchmark problems are
analyzed to evaluate the efficiency of the combined procedure.
Abstract: By controlled rolling and cooling process, a Mn-Ti high strength steel with yield
strength on the order of 700MPa had been developed successfully. The microstructure consists of
fine lath shaped bainite and ferrite. The strengthening factors of this steel are attributed to the tiny
interlocked distribution of bainite lath and titanium carbide precipitation. When the amount of
bainite is more than 70%, the yield strength of steel is higher than 700MPa, and good mechanical
performances are obtained. As a result of presence of finely dispersed bainite slabs the plasticity
of steel is improved, with the steel’s elongation being about 19%. Many tiny TiC precipitates are
observed under transmission electron micrograph, and these particles result in precipitation
Abstract: There are many problems in the common baiting methods, such as bad cross-section
quality, low efficiency and so on. In order to overcome these disadvantages, a new bar cutting
technology based on high speed and restrained state is put forward in the paper. The cutting process
and cutting mechanics were analyzed. The stressing intensity factor and fracture toughness were
introduced to analyze the influence of loading velocity on the cutting surface quality. By means of
the dislocation theory, the influence of loading velocity on the fracture process was researched.
Numerical simulation and experiments were carried out, and the results were conformed well with
the theoretical ones.
Abstract: Fracture properties of softwood under mode I loading perpendicular to the grain are studied
in this paper. The stress intensity factor KIC in the R and L directions is measured by the compact
tension test using small several specimens. The shape and size of plastic zone in crack tip is
determined by numerical simulations based on von Hill yield criterion. The results show that
anisotropic material constants do not affect the length of plastic zone along crack direction and it only
operates on the plastic zone with θcr≠ 0. Strength ratios α1, α2 and toughness ratios r1, r2, influencing
on the plastic zone, are discussed. Comparative analysis shows that r1 and r2 work markedly on the
shape and size of plastic zone, whereas α1, α2 do less.
Abstract: In this investigation, we evaluated diagnoses of a defect concerning coating of land-base
gas turbine using infrared thermography camera. In this camera method has a strong point which is
able to save time and costs compared with former method. Because it can be long field acquire
temperature distribution by using non-contact method. But it has a week point that method applies
thermal load about inspection sample. Presently, Method used widely in detection of crack is
ultrasonic inspection. But this method, There is problem in application in place that uneven surface.
In order to check cracks on a blade coating of a gas turbine, a part with cracks in a waste blade
disposed after having been used in the field was extracted to produce a sample. So we apply the
method by a infrared thermography camera to the produced sample, the sample was heated by means
of a halogen lamp. In this paper, we want to describe production of land-base turbine sample, a
method of applying thermal load at produced sample, infrared thermography camera technique, an
analysis technique of thermography, a defect analysis of coating of land-base gas turbine blades.
Abstract: Pitting corrosion is a great concern when the integrity of ship's hull structures is considered.
Corrosion pits with a conical shape are typically observed on coated hold frames in way of cargo
holds of bulk carriers which exclusively carry coal and iron ore. Therefore, it is important to
investigate the effect of pitting corrosion on local strength of hold frames of bulk carriers. In the
present study, a series of 3-point bend tests with structural models which consist of web, shell and
face plates has been conducted. In these tests, a concentrated load has been vertically applied at the
center of simply supported models so that shear load would act on the web plate with artificial pits. In
this testing condition, load increased even after shear buckling occurred. When there is artificial
pitting, fracture of web plates occurs due to strain concentration at the pits. It has been revealed that
the empirical formula, which was developed based on non-linear FE-analyses, overestimates the
equivalent thickness for the shear ultimate strength obtained in the present experiment, because the
effect of web fracture is not taken into account in the analyses.