Large Inclination Angle Research Articles

Remarks on the black hole shadows in Kerr-de Sitter space times

This work is geared towards analysis of shadows cast by Kerr-de Sitter (KdS) and Kerr-de Sitter Revisited (RKdS) black holes. Considering observers in the vicinity of the static radius, we derive the impact parameters defining the apparent positions of the shadows. Such observers are of interest to our work because embedding diagrams have shown that de Sitter space-time is analogous to an asymptotically flat one in the vicinity of the static radius. We also perform a comparative analysis between our result with that in Ref. [1]. Furthermore, we numerically obtain the radii of curvature, vertical diameters and horizontal diameters of the shadows. We find that for Lambda =1.11times 10^{-52} ,, m^{-2}, M87* observations cannot distinguish a RKdS black hole shadow from that of a Kerr black hole. Additionally, for the same value of Lambda , KdS and RKdS black hole shadows are, in practise, indistinguishable. Previously, it has also been shown that when Lambda =1.11times 10^{-52} ,, {text {m}}^{-2}, KdS and Kerr black hole shadows are indistinguishable. Utilizing the 2017 EHT observations of M87* on the allowed range of the characteristic radius of the shadow, we obtain constraints on both black holes. When, a/M>0.812311, we observe that large angles of inclination (theta >30.5107^{circ }) do not pass the constraints for both KdS and RKdS black holes.

Investigating the Disk–Jet Structure in M87 through Flux Separation in the Linear and Circular Polarization Images

For testing different electron temperature (T e) prescriptions in general relativistic magnetohydrodynamics (GRMHD) simulations through observations, we propose to utilize linear polarization (LP) and circular polarization (CP) images. We calculate the polarization images based on a semi-magnetically arrested disk GRMHD model for various T e parameters, bearing M87 in mind. We find an LP–CP separation in the images of the low-T e disk cases at 230GHz; namely, the LP flux mainly originates from downstream of the jet, and the CP flux comes from the counter-side jet, while the total intensity is maximum at the jet base. This can be understood as follows: although the LP flux is generated through synchrotron emission widely around the black hole, most of the LP flux from the jet base does not reach the observer, since it undergoes Faraday rotation () when passing through the outer cold disk and is thus depolarized. Hence, only the LP flux from the downstream (not passing the cold dense plasmas) can survive. Meanwhile, the CP flux is generated from the LP flux by Faraday conversion ( ∝ T e) in the inner hot region. Stronger CP flux is thus observed from the counter-side jet. Moreover, the LP–CP separation is more enhanced at a lower frequency, such as 86 GHz, but is rather weak at 43 GHz, since the media in the latter case is optically thick for synchrotron self-absorption so that all of the fluxes should come from the photosphere. The same is true for cases with higher mass accretion rates and/or larger inclination angles.

Effect of inclination angle on fire hazard of melting dust layers

Combustible dusts deposited on ground or surfaces present a fire hazard to process industries. It was found that flame spread on an upwardly inclined surface was significantly faster than on a horizontal surface. However, hazard during downward inclined fire spread has been underestimated for dust layers having melting capability. In this paper, the effects of melting fluidity, sample inclination angle, and layer thickness on the fire hazard of four melting dusts were investigated. For sulfur with its excellent melting fluidity, dust layer inclination at a small angle can significantly increase downward flame spread velocity (FSV). For anthraquinone having a moderate melting fluidity, upward or downward dust layer inclination significantly increased FSV. For polystyrene and magnesium having weak melting fluidity, dust layer inclination angle had relatively little effect on flame propagation. Increasing thickness of dust layers significantly enhanced the promotion effect of the inclination angle on the flow of molten material, which in turn affected FSV. As a result, melting fluidity coupled with a large inclination angle and high layer thickness would significantly enhance dust layer fire hazard. These findings should be taken into consideration wherever powders having melting capability are encountered in process industries or in certain public activities.

A SIMPLE DEVICE FOR MONITORING CRACKS FROM PHOTOGRAPHS

Abstract. The article presents a simple technological solution PMC (PhotoMicrometer Contrast) for monitoring cracks and deformation joints in buildings and structures. The solution is based on the methods of image processing and photogrammetry. The monitoring equipment includes a special marker, a digital camera and specialized processing software. The marker consists of two thin plastic plates where Aruco marks and special measuring areas are printed. There are two types of markers – for monitoring in one or two directions of crack development. While monitoring is performed, two plates are fixed on both sides of the crack or deformation joint. Then the plates are photographed with a digital camera as often as the observation cycle requires. Any conventional modern digital camera is suitable for photographing after successfully passing the distortion effect test described in the article. Image processing in the software includes automatic identification of the marker in the image, binarization of the image, determination of its scale and dimensions of measuring areas in the current observation cycle. For processing images made at large angles of inclination and rotation, a preliminary solution of the resection in space and the images rectification to the found angles is provided. The dynamics of crack development is determined by the results of several cycles of observations collected over period. Our technology ensures the accuracy of the determination of coordinates and deformations at the level of 0.05 mm and higher for photographing distances from 0.3 to 50 m.

アルペンスキー選手のターン動作の定量評価及びスキーブーツの調整に関する検討

Research Center for Winter Sports Science of Kitami Institute of Technology was established in 2016. Curling and alpine skiing are researched at this center located in a snowy and heavy cold area. In research on alpine skiing, we are conducting experiments to adjust the ski boots and improve their skills of Japanese skiers. Previous experimental studies have shown that the large inclination angle and a fast inclination angular velocity during turns have a great influence on the improvement of downhill speed in alpine skiing (2) ~ (5). Furthermore, it has been found that attaching parts to the underside of the footbed inside the ski boot changes the inclination angle and inclination angular velocity. In this study, we used the ski simulator "SkyTech" at this center and "the real-time experimental data collection system" with a pressure sensor and the inclination angle measuring devices, and performed an experiment to adjustment of depression angle. And we calculated the parameters for evaluating the athletes’ turn movements from the obtained experimental data, and investigated the quantitative evaluation of alpine skiers’ skill of turning motion.

Effect of inclination angle on the startup of a frozen sodium heat pipe

Screen-wick sodium heat pipes are highly effective passive devices for heat transport, which are mainly used in a horizontal orientation. For practical applications, the sodium heat pipe may operate at an inclination. Previous studies have mainly focused on large inclination angles where gravity dominates. By contrast, fewer experiments were conducted at a near-horizontal inclination, where neither the capillary nor gravity dominate. The coupling effects may significantly change heat pipes’ startup and operation characteristics. This work experimentally investigated the temperature variations during a sodium heat pipe frozen startup at near-horizontal inclination angles, focusing on the effects of inclination angle (−15°, −10°, 0°, 5°, 10°, 15°, 30°, 45°) with a heating power of 0–1.4 kW. Various startup power regimes are identified for the various conditions. Critical startup power transits at 15° due to the competing effects of the capillary and gravitational forces. During the transient startup, the outer wall temperatures oscillated at positive inclination angles when the evaporator bottom temperature is over 580 ℃, with the oscillations suddenly stopping at 780 ℃. The inclination angle significantly affects the oscillation periods and amplitudes, which first increased and then decreased with increasing inclination angle, with peaks at 15°.

Method of calibration mems accelerometer and magnetometer for increasing the accuracy determination angular orientation of satellite antenna reflector

The paper is devoted to the measurement errors investigation that arise due to the influence of MEMS accelerometers' nonlinear characteristics. They appear at large inclination angles of the antenna system support-rotary platform, as well as in the presence of a magnetic inclination, which is due to the peculiarity of the Earth's magnetic field for the magnetometer. The study was conducted to assess the possibility of using such devices to increase the accuracy of a satellite antenna control with a classic rotary platform. The experimental setup for researching the parameters of MEMS sensors allows comparison of measurement results with data obtained from precision optical encoder. The experimental results show the main sources of MEMS sensors errors. An accuracy increasing method of antenna system angular position determining using a triaxial accelerometer and a magnetometer is proposed. The main advantage of the proposed estimation vector determining approach using the least squares method is the possibility of carrying out the calibration procedure without reference to the coordinate system. The method makes it possible to get rid of the zero offset error, as well as compensate for the non-unit scale of the sensor axes and the error of the magnetometer angular orientation. This method can be used for many applications including robotics, design of unmanned aerial vehicles and many other technical systems. The proposed method makes it possible to increase the reliability and reduce the cost of such systems.

The differential analysis for temperature distribution diagnostics of arc current-carrying region in sheet slanting tungsten electrode inert gas welding with the electrostatic probe

Abstract An electrostatic probe differential analysis method is used to diagnose the arc current-carrying region of the sheet slanting tungsten electrode. Based on the local thermal equilibrium condition and energy transition model with charged particles collision, the temperature distribution in the current-carrying region of different welding process parameters is solved by saturated ion current. The results show that the temperature distribution range in the width direction of sheet slanting tungsten electrode expands, the arc high-temperature region shifts integrally, and the temperature in the thickness direction of sheet slanting tungsten electrode would be symmetrical. The guide effect of the hypotenuse of sheet slanting tungsten electrode for arc current and the inertia drag effect of arc would mainly change the temperature distribution. The variation of the inclination angle of the hypotenuse of sheet slanting tungsten electrode will aggravate the shift of the arc high-temperature region. The larger inclination angle will enhance the guiding effect, and then the inertia drag effect would be in a dominant position with a smaller inclination angle. With the increase of welding current, both the arc stiffness and the guiding effect would be intensified, the latter should make the arc high-temperature zone shift to the position with a small discharge gap.

Numerical analysis of wave\u2013structure interaction of regular waves with surface-piercing inclined plates

The Mocean wave energy converter consists of two sections, hinged at a central location, allowing the device to convert energy from the relative pitching motion of the sections. In a simplified form, the scattering problem for the device can be modelled as monochromatic waves incident upon a thin, inclined, surface-piercing plate of length L' in a finite depth d' of water. In this paper, the flow past such a plate is solved using a Boundary Element Method (BEM) and Computational Fluid Dynamics (CFD). While the BEM solution is based on linear potential flow theory, CFD directly solves the Navier–Stokes equations. Problems of this type are known to exhibit near-perfect reflection (indicated by a reflection coefficient |R|approx 1) of waves at specific wavenumbers k'. In this paper, we show that the resonant motion of the fluid induces large hydrodynamic forces on the plate. Furthermore, we argue that this low-frequency resonance resembles Helmholtz resonance, and that Mocean’s device being able to tune to these low frequencies does not act like an attenuator. For the case where the water is deep (d'>lambda '/2, where lambda '=2pi /k'), we find excellent agreement between our simulations and previous semi-analytical studies on the value of the resonant wave periods in deep water. We also find excellent agreement between the excitation forces on the plate computed using the BEM model, analytical results, and CFD for large inclination angles (alpha > 45^circ ). For alpha le 15^circ , both methods show the same trend, but the CFD predicts a significantly smaller peak in the excitation force compared with BEM, which we attribute to non-linear effects such as the non-linear Froude–Krylov force

Experimental study on the migration and expansion of liquid nitrogen in loose media with different dip angles

ABSTRACT The goaf is the main disaster area for natural fires in mines, and liquid nitrogen has become an essential medium for fire prevention in goafs due to its excellent cooling and inerting properties.At present, there is no in-depth research on the transport and vaporization of liquid nitrogen after injection into the goaf, and it is impossible to quantitatively evaluate the cooling inerting effect after liquid nitrogen injection. To address the above problems, this project proposes to carry out the following research: to study the effects of different inclination angles on the transport and vaporization of liquid nitrogen and temperature distribution in the loose medium in confined space by monitoring the temperature field changes during the pressure injection of liquid nitrogen in the loose medium in confined space.The results show that the temperature field distribution is very uneven after liquid nitrogen is injected into the loose medium in the restricted space.It is found that the vaporization rate of liquid nitrogen decreases with the increase of diffusion time and diffusion area, and the instantaneous vaporization rate of liquid nitrogen decreases with the larger inclination angle under the same injection position. Compared with the horizontal state, the maximum vaporization rate decreased 84.79% when the maximum inclination angle was 15°, which indicates that the vaporization rate was greatly affected by the inclination angle of the surface. In the vertical direction of the experimental box, the cooling area of liquid nitrogen in the experimental box is mainly concentrated within 0.05 m height from the bottom of the experimental box, and the changes of the “cooling restricted zone” after liquid nitrogen injection into the goaf are further explained during the experiment.It is found that the “cooling restricted zone” mainly exists in the upper part of the goaf, under the inclined condition, and the area increases with the increase of the inclination angle, so the increase of the angle is not conducive to the effective cooling effect of liquid nitrogen.The research results of the project will help to improve the theory of liquid nitrogen fire prevention in mines and provide theoretical support for the fire prevention technology of liquid nitrogen direct injection in goafs.

Broadband THz Absorber for Large Inclination Angle TE and TM Waves

Terahertz (THz) electromagnetic wave absorbers are finding new applications both in military and civilian sectors. This is the reason why constant efforts have been made worldwide to enhance the working performance of these absorbers. One downside of the available absorbers is their response to Transverse Electric (TE) and Transverse Magnetic (TM) waves at different frequency bands. Specific strategic applications require response of an absorber in same frequency band for TE and TM electromagnetic waves, for large inclination and polarization angle of the incoming signal. In this work, we present a metasurface based THz absorber with improved functionality. The fractional bandwidth is 91.64% w.r.t the center frequency of 1.97 THz, that shows an absorptivity of more than 90%. Due to the fourfold symmetry, the absorber is polarization insensitive. It shows more than 80% absorptivity for incoming wave inclinations upto <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">$60^{\circ }$</tex-math></inline-formula> . The thickness of the absorber is <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">$\sim$</tex-math></inline-formula> <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">$\lambda$</tex-math></inline-formula> /11. The good point is that the absorber shows all these improved performance for both TE and TM incoming signals in the same frequency range. Overall, the designed absorber is a much improved version of its peers available in the literature.

Grid filtering method for shale reservoir 3-D property modeling using horizontal well data

Wells drilled in the core area of shale reservoir are predominantly horizontal compared to vertical wells in conventional reservoirs. Due to the different features of data in horizontal and vertical wells, the 3-D property modeling of shale reservoirs is distinct from the conventional reservoirs. Lateral drilling usually leads to the repeated sampling in the specific vertical intervals and the missing sampling in the bottom part of the shale reservoir. This biased sampling distorts the distribution characteristics in well data from the real reservoir properties. Moreover, because of the large inclination angle in the laterals, it is so common to penetrate only the upper or lower part of the grid. Given that the same method is utilized to assign well values to these partially penetrated girds and fully penetrated grids, the assigned value in these partially penetrated grids fail to represent the reservoir property in the associated grid layer. Therefore, we developed a grid filtering method to solve the issues arised from the biased sampling and the partially penetrated grids. It includes five parts: (1) divide wellbore into multiple well segments using formation top data; (2) recognize the type of well segments and well-penetrated grids to generate a grid filter; (3) process the log-format data of each complete sampling segment using the grid filter; (4) generate one dataset for analyzing distribution features and another dataset as the control points of geostatistic simulation algorithms; (5) build the 3-D property models using the analyzed distribution features and the control points as the input. By generating two independent datasets, we achieved the maximum utilization of log-format data in horizontal wells and eliminated the biased sampling effect. The total organic carbon content and shale lithofacies in the JY-1 district, Jiaoshiba Area, Eastern Sichuan Basin, were used to demonstrate our method.

Shale Reservoir 3D Structural Modeling Using Horizontal Well Data: Main Issues and an Improved Method

Shale oil and gas fields usually contain many horizontal wells. The key of 3D structural modeling for shale reservoirs is to effectively utilize all structure-associated data (e.g., formation tops) in these horizontal wells. The inclination angle of horizontal wells is usually large, especially in the lateral section. As a result, formation tops in a horizontal well are located at the distinct lateral positions, while formation tops in a vertical well are usually stacked in the same or similar lateral position. It becomes very challenging to estimate shale layer thickness and structural map of multiple formation surfaces using formation tops in horizontal wells. Meanwhile, the large inclination angle of horizontal wells indicates a complicated spatial relation with shale formation surfaces. The 3D structural modeling using horizontal well data is much more difficult than that using vertical well data. To overcome these new challenges in 3D structural modeling using horizontal well data, we developed a method for 3D structural modeling using horizontal well data. The main process included 1) adding pseudo vertical wells at formation tops to convert the uncoupled formation tops to coupled formation tops as in vertical wells, 2) estimating shale thickness by balancing the shale thickness and dip angle change of a key surface, and 3) detecting horizontal well segments landing in the wrong formations and adding pseudo vertical wells to fix them. We used our improved method to successfully construct two structural models of Longmaxi–Wufeng shale reservoirs at a well pad scale and a shale oil/gas field scale. Our research demonstrated that 3D structural modeling could be improved by maximizing the utilization of horizontal well data, thus optimizing the quality of the structural model of shale reservoirs.

Modulating flow and mixing characteristics of an inclined jet in crossflow at a large backward inclination angle by acoustic excitation

Previous investigations revealed that the backward-inclined jet in crossflow exhibits seemingly lower transverse velocity and turbulence intensity at inclination angles higher than a critical value about 25°, thus resulting in significantly low jet fluid dispersion properties. In this article, the acoustic excitations were applied to a backward-inclined jet in crossflow at an inclination angle higher than the critical value to examine experimentally whether the flow and dispersion characteristics could be improved or not. The flow in the test section of an open-loop wind tunnel was used as the crossflow. A profiled nozzle assembly with a loudspeaker installed in the lower part of it was used to generate the pulsating jet. The instantaneous and time-averaged smoke flow patterns were obtained by the laser-light-sheet assisted flow visualization method. The binary edge detection method was employed to the long-exposure smoke flow images to measure the jet spread width. The turbulence intensities, as well as the Lagrangian integral turbulence time and length scales, were obtained using a hotwire anemometer. The jet-fluid dispersion characteristics were examined using the tracer-gas detection technique. The results revealed that in the domain of jet pulsation intensity and excitation Strouhal number, the pulsed backward-inclined jet in crossflow presented three characteristic flow modes: synchronized oscillating jet, transition, and synchronized shear-layer vortices. The synchronized oscillating jet exhibited violent transverse oscillations due to the high axial jet pulsations induced by the acoustic excitation. The transverse jet width and jet penetration height were enlarged. The turbulence intensities were significantly increased, and the turbulence time and length scales were decreased, therefore led to a significant enhancement in the jet-fluid dispersions and mixing capabilities.

Radio absorption in high-mass gamma-ray binaries

High-mass γ-ray binaries consist of a presumptive pulsar in orbit with a massive star. The intense outflows from the star can absorb radio emission from the pulsar, making the detection of pulsation difficult. In this work, we present the basic geometry and formulae that describe the absorption process of a pulsar in binary with an O/B star and apply our model to two typical and well-studied binaries: PSR B1259−63/LS 2883 and LS 5039. We investigate the influences of the equatorial disc of LS 2883 with different orientations on the dispersion measure and free-free absorption of the radio pulsation from PSR B1259−63. The observed data are consistent with the disc inserted on the orbital plane with a relatively large inclination angle. For LS 5039, due to its tight orbit, it was believed that the strong wind absorption makes detecting radio emissions from the putative pulsar unlikely. However, considering the wind interaction and orbital motion, a bow shock cavity and a Coriolis shock would be formed, thereby allowing the pulsations to partially avoid stellar outflow absorption. We investigate the dependence of the radio optical depth on the observing frequencies, the orbital inclination angle, and the wind parameters. We suppose that the presumptive pulsar in LS 5039 is similar to PSR B1259−63 with pulsed emission extending to several tens of gigahertz. In that case, there could be a transparent window for radio pulsations when the pulsar is moving around the inferior conjunction. The following deep monitoring of LS 5039 and other systems by radio telescopes at high radio frequencies might reveal the nature of compact objects in the future. Alternatively, even a null detection could still provide further constraints on the properties of the putative pulsar and stellar outflows.

The geometric phase and the dry friction of sleeping tops on inclined planes

We report on the motion of a spinning sleeping top on an inclined plane. Below a critical inclination angle the sleeping tops are force free. The trajectory of a sleeping top on weakly inclined planes in the adiabatic limit is invariant of the angular frequency of the top and thus invariant under a rescaling of the time, however not invariant under time reversal. The stationary trajectory of the sleeping top is characterized by its Hannay type geometric angle to the in plane horizontal direction. At larger inclinations of the plane the stationary motion of the top becomes unstable and the top accelerates downhill. The behavior points towards a complex law of dry friction of the contact point between the top tip and the material of the inclined plane that depends on a slip parameter. We propose a phenomenological law of dry friction that can explain the relaxation of the top into the sleeping position, the geometric behavior of the top trajectories, and the instability of the stationary motion at larger inclination angles.

Experimental investigation on the melting and solidification performance enhancement of a fractal latent heat storage unit

This work designs a fractal latent heat storage (LHS) unit with tree-shaped fins for enhancing heat exchange efficiency. The melting/solidification processes inside a fractal LHS unit are experimentally studied by visualization observation, focusing on the role of inclination angles. Comparative studies on fractal LHS and traditional LHS units are conducted by assessing the temperature response, phase change behavior, liquid fraction variation, and thermal storage/release performance. The experimental results indicate that the inclination angle presents a more significant impact on melting processes than solidification processes, especially for thermal characteristics in the axial direction. Variations in the onset and duration of natural convection determine the main difference in the melting/solidification mechanism of fractal LHS units. Large inclination angle is not conducive to convection development, thus prolonging the late conduction-dominated stage and diminishing the overall thermal performance. Therefore, the thermal characteristics of fractal LHS units are less affected by orientations than traditional LHS units. Moreover, the overall thermal performance of fractal LHS units is more superior to traditional LHS units irrespective of orientations. Particularly, the vertical fractal LHS unit has a maximum reduction of 52.6% in the complete melting duration, and the heat storage/release rate of horizontal fractal LHS units augments by 94.7% and 101.5% when compared with traditional LHS units.

Eruption pattern of the maxillary canines: features of natural eruption seen in PTG at the late mixed stage\u2014Part I

AimTo describe the variation of eruption pattern of maxillary canines in the late mixed stage of dentition seen in PTG when eruption was later natural.MethodsMaterial for this longitudinal and retrospective register-based study consisted of 1454 PTGs of children living in Eastern Finland (mean age 9.3 years, SD 0.6). Natural eruption of a canine consisted of 744 PTGs (336 girls and 408 boys) including 1488 maxillary canines. The variables examined were treatment/natural eruption, overlapping, inclination, dental age, developmental stage of the canine and lateral incisor.ResultsOnly 2.0% of maxillary canines had clear overlapping and 56.2% no overlapping was detected at the age of 8.5–10.5 years. Large inclination angle (≥ 25°) was found for 5.5% of examined canines. Overlapping of canine with lateral incisor root decreased as the development of canine root exceeded 1/3. Larger inclinations occurred at earlier stages but decreased significantly as the root developed from 1/3 to 1/2. Mean inclination was significantly larger at children with normal dental age and/or incomplete lateral incisors when overlapping occurred. Regardless overlapping mean inclination was larger if dental age was delayed and/or lateral incisors incomplete.ConclusionSome overlapping and larger inclination in maxillary canine are features of normal eruption pattern at an earlier stage of canine development and while lateral incisor is incomplete in PTG (8.5–10.5 years). In addition to the overlapping and inclination, stages of canine and lateral incisor root as well as dental age should be observed radiologically when evaluating erupting maxillary canine in children of this age.

“Peel cutting” – A new cutting method for difficult-to-cut workpieces with hard oxide surfaces

A new cutting method named “peel cutting” is proposed in this research to suppress notch wear in machining of metals with hard oxide surfaces. In general, metals are produced by hot deformation processes like rolling, forging, and extrusion, which cause hard oxide surfaces called scales on their surfaces. These hard scales need to be removed first in machining of precision parts. However, the machining causes the severe notch wear at the depth-of-cut position, where the tool contacts the hard scale. To solve this problem, the proposed peel cutting avoids this direct contact between the tool and the scale by inclining the end cutting edge at an extremely large inclination (oblique) angle. This extremely oblique cutting changes the material flow and generates a “burr-like chip”. In the proposed cutting method, the tool contacts only soft non-oxide metal under the scale during cutting. Cutting of titanium alloy Ti–6Al–4V is conducted by modifying commercial tools to provide extremely large inclination angles, and it is clarified that an inclination angle of 70 deg or greater is required to realize the proposed cutting. Tool wear in the proposed cutting of the alloy with a hard scale is also observed in comparison with the ordinary cutting, and the result verifies that the notch wear can be suppressed successfully by the proposed peel cutting.

A discrimination model for crack propagation behavior at the interface of layered composite structures considering loading rate effect

It is difficult to accurately judge the crack propagation behavior at the interfaces of layered composite structures under impact loads. By mainly considering the influence of the loading rate on the interaction between a crack and an interface, this paper presents a new discrimination model to predict the crack propagation behavior. Based on the energy release rate criterion, which is used to judge the static crack propagation behavior at the interface of a composite structure, a discrimination model was established by introducing a general function related to the crack growth rate and combining the relationship between the loading rate and the energy release rate of the crack tip. The prediction results of the discrimination model were in good agreement with the experimental and numerical simulation results. Taking the mud–sandstone composite layer of Shihezi Formation in Linxing block as the research object, parameter sensitivity analysis was conducted using the control variable method. Parametric analysis results revealed that cracks are more likely to penetrate from high-shear-modulus, low-Poisson’s-ratio, and high-density materials into low-shear-modulus, high-Poisson’s-ratio, and low-density materials. A small interface inclination and large interface fracture energy are beneficial for crack penetration. In extreme layered composite structures, such as those with significant interlayer differences, large inclination angles, and small interface fracture energies, increasing the loading rate can make the deflection crack penetrate the interface.