Kink Behavior Research Articles

Weak interface-induced repeated kinking of a central crack in a brittle multilayered plate under remote shear loading

Understanding the repeated kinking pattern of cracks is essential for controlling the complex fracture trajectories in multilayered composites. While previous studies have explored many aspects of fractures in layered materials, the conditions governing the repeated kinking behavior under basic loading modes remain largely unrevealed. This research elucidates the continual kinking condition for a central crack in a brittle, multilayered plate with closely-parallel weak interfaces under remote shear stresses. Using the strain energy release rate (SERR) ratio criterion, we analytically derived a closed-form solution to the condition through the equivalent crack concept. The solution specifies a value domain for the intersection angle and fracture toughness ratio of weak interfaces, where the load-guided direction competes closely with the weak interface-guided direction to shape the crack trajectory into a repeated kinking pattern. Our theoretical results, validated by a series of finite element (FE) simulations, clarify how closely-parallel weak interfaces induce repeated crack kinking in multilayered materials under remote shear loading. This research paves the way for the deeper understanding of intricate crack trajectories under mixed loads in various practical applications.

Trajectories of Solitons Movement in the Potential Field of pPF1 Plasmid with Non-Zero Initial Velocity

Nonlinear conformational distortions, such as, for example, locally unwound regions of the DNA double helix, named open states, are considered in this work as solitons moving in the potential field of this molecule. It is believed that open states play an important role in the processes of transcription, replication, denaturation, as well as in the transmission of structural changes and information along the DNA molecule. This work examines the problem of the movement of kink-like solitons (kinks) in the potential field of the pPF1 plasmid, the sequence of which includes the genes of the fluorescent proteins Egfp and mCherry, separated by a small intermediate region. The results of calculations of energy profiles of the main and complementary sequences of the plasmid, as well as 2D and 3D trajectories of kinks with a non-zero initial velocity are presented. It has been shown that two types of kinks can be activated in the pPF1 plasmid, which can be considered as two types of quasiparticles that have their own energy, mass, velocity and move in the potential field of the plasmid. It was found that the lowest energy required to form these kinks is observed in the intermediate region located between the fluorescent protein genes. It was shown that the nature of the motion of kinks does not depend on the value of their initial velocity. It was shown that there are threshold values of the torsion field, upon reaching which the behavior of kinks changes sharply: from damped oscillations within the intermediate region to forward motion and penetration into neighboring regions. These values have been calculated. It turned out that for the first kink moving in the main sequence potential field, the threshold value is 4.95×10–22 J, and for the second kink – 4.20 × 10–22 J.

Long-period stacking ordered phase kinking, twinning behavior and dynamic recrystallization of Mg-Gd-Y-Zn-Zr alloy under severe shear deformation

A novel severe shear specimen with a maximum shear strain of 3 was designed to further clarify kinking and fragment behavior of long period stacking ordered (LPSO) phases, as well as their interaction with twinning behavior and dynamic recrystallization (DRX) behavior under severe shear deformation (SSD). The results indicate that promoted kinking and fragment behavior for LPSO phases is obseved for hihger activation of basal <a> dislocations induced by shear deformation. Besides the known crack causd by LPSO kinking, a new fragment process without kink bands formation is found for block-shaped LPSO phases under SSD, which follows three stages of micro-crack at the interface of LPSO/α-Mg matrix, crack and crush. Moreover, the actvition of tension twinning detected at kinked boundaries is reveled to be controlled by the combined effect of LPSO kinking and shear stress state. Specifically, crystal rotation related to LPSO kinking reorient grains to be possbile for twinning, and then high effective Schmid factor (ESF) under shear stress furter prioritise the twining acivaiton. Additionally, orientation dependence of DRX behaviors was weakened due to the particle-stimulated nucleation (PSN) mechanism caused by interdendritic block-shaped LPSO phases, which can accelerate the formation of low angle grain boundaries and DRX grains by activated pyramidal <c+a> slip systems even at basal grains.

Development of a bioresorbable self-expanding microstent for interventional applications - an innovative approach for stent-assisted coiling.

Objectives Stent-assisted coiling prevents coil migration in broad-based intracranial aneurysms. So far, only permanent metal stents are approved for intracranial use. Bioresorbable stents allow a new therapeutic approach that may prevent the need for lifelong anticoagulation. We developed a neurovascular bioresorbable microstent (NBRS) and compared it in vitro to the commercial Neuroform EZ stent. Materials and Methods The self-expanding NBRS design is oriented on the Neuroform EZ stent. Poly L-lactic acid (PLLA) was used to manufacture semi-finished products in a dipping process. For the compensation of the inferior material properties of PLLA, design adjustments were made. The NBRS were cut by means of femtosecond (fs) laser and were morphologically and mechanically compared in vitro to the Neuroform EZ stent. In vitro implantation of an NBRS was performed using a complex patient-specific 3D-printed aneurysm model. In addition, an in vitro coiling procedure to assess the stent’s ability to support a coil package was conducted. Results The NBRS could be reproducibly manufactured and had high quality regarding surface morphology. The radial force at the indicated vessel diameter of 3.0 mm was slightly higher for the Neuroform EZ stent compared to the NBRS. The self-expansion ability of the NBRS could be proven. The kink behavior of the NBRS was comparable to that of the Neuroform EZ stent, so no vessel lumen size reduction is expected. The stents showed identical deformation under local compression of 25 % based on the initial diameter, resulting in maximum forces of 24 ± 5 mN (Neuroform EZ) and 8 ± 2 mN (NBRS). The implanted NBRS expanded uniformly, and proper vessel wall adaptation was observed. The NBRS has the ability to retain a coil package. Conclusion This study reported a reproducible manufacturing process for the developed NBRS as well as mechanical and morphological in vitro tests. Furthermore, successful NBRS implantation into a complex patient-specific vessel model was presented as proof of concept. The promising results of this study, also considering the commercial Neuroform EZ stent, support the idea of fully biodegradable microstents for intracranial aneurysm treatment. Key Points

Diffusion in Metallic Glass-Forming Systems: A Description of the Kink Behavior Observed in the Temperature Dependence

The temperature dependence of the diffusion coefficient in metallic glass-forming systems do not follow the Arrhenius behavior over a wide temperature range. Instead, it exhibits a kink behavior at around the glass transition temperature. Some researchers associate this behavior to the difference in the diffusion mechanism operating in the glassy and the supercooled liquid state, whereas others do not support this view. In addition, usually, the temperature dependence of the diffusion coefficient is analyzed by splitting the temperature range into two regions, above and below the glass transition temperature. In the present study, we developed an analytical theory that describes the continuous variation of the diffusion coefficient across a temperature where the kink behavior is observed. According to the theory, the kink behavior arises from the freezing of free volume available for diffusion by lowering the temperature. A connection to the vacancy mechanism of diffusion has been also pointed out.

Dynamical analysis and new solitary wave patterns of coupled nonlinear Schrödinger model arising in birefringent fibers

Coupled nonlinear Schrödinger type equation is used to represent the transmission of optical signals in birefringent fibers. These types of equations are significant models for a vast range of disciplines, including fluids, nonlinear optics, the theory of deep ocean waves etc. In this manuscript, coupled nonlinear Schrödinger type equation is investigated by using two techniques namely, the G′/(bG′+G+a)-expansion method and the modified Jacobi elliptic expansion schemes. Furthermore, modulation instability analysis is performed on our model. The extracted solutions show dark, Kink and singular solitons behaviors, which are depicted graphically by using surface and line plots. The obtained solutions are unique and novel. The employed integration techniques are widely used to examine exact solutions of various partial differential equations.

Quasi in-situ investigation on kinking behavior of Fe-Cr-Al alloy during thermal compression

As a rare plastic deformation mechanism, kinking has attracted substantial attention because of its additional softening effect on the matrix and its heterogeneous refinement on the original grains. However, the details of kinking deformation and the influence of crystal orientation on itself have not been sufficiently elucidated yet, thereby resulting in inadequate microstructure optimization associated with kinking. In this work, the kinking formation process in Fe-Cr-Al alloy during thermal compression deformation has been investigated by using quasi in-situ electron backscatter diffraction (EBSD). By employing the average Schmid factor (Average-SF) model, the influence of crystal orientation on kinking behavior is predicted accurately. The results suggest that the softening effect of kinking on the matrix can be attributed to the fact that the nucleation of pre kink bands (pre-KBs, misorientation <15°) leads to a pronounced reduction in geometrically necessary dislocations (GNDs) density within them. Besides, the ripening behavior of pre-KBs is closely associated with the variation of GNDs density and the overall slip activation capability of the matrix, and is essentially dependent on crystal orientation. The harder the crystal orientation, the smaller the Average-SF, the higher the increment rate of GNDs density, the larger the ripening rate pre-KBs. Under equivalent strain, orientations close to 〈111〉// compression direction (CD) have the highest probability of forming mature KBs with high angle grain boundaries (HAGBs, >15°), whereas KBs in those close to 〈001〉//CD almost always remain as pre-KBs with low angle grain boundaries (LAGBs).

An exploration of marks/injuries related to BDSM sexual experiences.

Despite its growing prevalence, BDSM practice (bondage, discipline, dominance, submission, and sadomasochism) is still stigmatized, and little is known about the physical marks and injuries that individuals sustain from consensual BDSM-related activities. In this exploratory study, we examined BDSM sexual experiences and the physical marks and injuries resulting from these experiences in a convenience sample of 513US adults. We examined the extent to which individuals at various stages of BDSM exploration engage with different types of BDSM and kink behaviors, along with the frequency with which they communicate about, inflict, and receive physical marks from these activities. Our main outcome measures were intentional and unintentional marks sustained from BDSM-related activities, BDSM experiences, and the use of safe words. Results revealed that BDSM marks and injuries are common and quite varied (from small scratches to very large bruises) and unintentional and intentional marks differ in terms of typical size, place on body, and severity of injury. Additionally, BDSM experience is positively associated with the use of safe words and marking behaviors. Disclosure of marks and injuries, intentional and unintentional, may be improved if health care providers are aware of, and make efforts to reduce stigma surrounding, BDSM and rough sex activity. The findings of this study must be interpreted with acknowledgment of the limitations that it was a survey study with a convenience sample. However, as one of the few studies exploring the marks and injuries sustained from BDSM activities, the exploration of intentional and unintentional marks sustained provides a critical starting point for future examination of BDSM consequences that intersect with health care and the law. Marks and injuries from BDSM-related activities are common, and despite the greater use of safe words, practitioners with more BDSM experience inflict more marks than those with less BDSM experience.

Comparative study on charge radii and their kinks at magic numbers

Isotope dependences of charge radii, i.e., isotope shifts, calculated by the Skyrme Hartree-Fock, the relativistic mean-field, and the relativistic Hartree-Fock calculations are compared against the experimental data of magic and semimagic nuclei. It is found that the tensor interaction plays a role in reproducing the ``kink'' behavior, irregularity of isotope shifts at the neutron magic number, in the relativistic Hartree-Fock approach. With several Skyrme models, it is found that the kink behavior can be reproduced with the spin-orbit interaction having nonzero isovector channel. The single-particle orbitals near the Fermi energy are crucial to determine the kink size. The effects of the symmetry energy and the pairing interaction are also discussed in relation to the kink behavior.

Plastic contribution via DRX induced by kink and twin in a hot compressed Mg-Gd-Zn-Mn alloy with 14H LPSO

The plastic deformation behavior in Mg alloy with long period stacking ordered phases (LPSO) has not fully understood yet. To understand the interaction between twins, kink and dynamic recrystallization in a Mg alloy with long period stacking ordered phases, the plastic forming behavior under compression at elevated temperatures of the Mg-4Gd-1Zn-0.5Mn alloys containing lamellar long period stacking order phases were investigated. The lamellar long period stacking ordered phases hindered the occurrence of grain boundary migration, thus delaying dynamic recrystallization. The dominated deformation mechanisms of the compressed alloy were slip and discontinuous dynamic recrystallization accompanied by the occurrence of kink bands at low deformation rates. The twinning was the domination deformation mechanisms of the alloy at high deformation rates, a few recrystallized grains distributed along the boundaries of the twins and it was an obvious twin-induced dynamic recrystallization mechanism. The dissolving of long period stacking ordered phases reduced the grain boundary migration resistance of dynamic recrystallization and thus promoted the nucleation of the recrystallized grains at 500 °C. The broken small-sized lamellar long period stacking ordered phases became effective heterogeneous nucleation sites and thus promoted DRX. The parallel and beak-like kink bands are clearly observed in the microstructures of the deformed alloys. The severe kink behavior improves the plastic formability of the alloy.

Lie symmetry classification for the 1+1 and 1+2 generalized Zoomeron equations

We present a complete algebraic classification of the Lie symmetries for generalized Zoomeron equations. For the generalized [Formula: see text] and [Formula: see text] Zoomeron equations we solve the Lie symmetry conditions in order to constrain the free functions of the equations. We find that the differential equations of our consideration admit the same number of Lie symmetries with the non-generalized equations. The admitted Lie symmetries form the Lie algebras [Formula: see text], [Formula: see text] for the [Formula: see text] generalized Zoomeron equation, and the [Formula: see text], [Formula: see text] in the case of the [Formula: see text] generalized Zoomeron equation. The one-dimensional optimal system is constructed for the two equations and similarity solutions are derived. The similarity transformation led to the derivation of kink solutions. Indeed, the similarity exact solutions determined in this work are asymptotic solutions near the singular behavior of the kink behavior.

Analysis of Kink Behaviour of KdV-mKdV Equation under Caputo Fractional Operator with Non-Singular Kernel

The KdV equation has many applications in mechanics and wave dynamics. Therefore, researchers are carrying out work to develop and analyze modified and generalized forms of the standard KdV equation. In this paper, we inspect the KdV-mKdV equation, which is a modified and generalized form of the ordinary KdV equation. We use the fractional operator in the Caputo sense to analyze the equation. We examine some theoretical results concerned with the solution’s existence, uniqueness, and stability. We employ a modified Laplace method to extract the numerical results of the considered equation. We use MATLAB-2020 to simulate the results in a few fractional orders. We report the effects of the fractional order on the wave dynamics of the proposed equation.

Second-order phase transition of silicon from a band insulator to metal induced by strong magnetic fields

We present the second-order phase transition from a band insulator to metal that is induced by a strong magnetic field. The magnetic-field dependences of the magnetization and energy band gap of a crystalline silicon immersed in a magnetic field are investigated by means of the nonperturbative magnetic-field-containing relativistic tight-binding approximation method (2018 Phys. Rev. B 97 195135). It is shown that the energy band gap disappears at the critical magnetic field of 2.22 × 104 (T). At the critical magnetic field, the magnetic-field dependence of the magnetization exhibits a kink behavior, which means that this phenomenon is the second-order phase transition from a band insulator to metal. It is found that in strong magnetic fields above the critical magnetic field, namely in the metallic phase, the oscillation of the magnetization appears. It is shown that this magnetic oscillation comes from the magnetic energy bands in the magnetic Brillouin zone that change from the occupied states to unoccupied states or vice vasa.

Lamellar kinking in primary hot working of titanium alloy: Cross-scale behavior and mechanism

Lamellar kinking, a complex and significant cross-scale heterogeneous deformation behavior during primary hot working of titanium alloys, affects the microstructure evolution, mechanical response as well as optimization of product performance. However, the essence, development processes, formation condition, and contribution of kinking are still controversial. To address these issues, a two-scale crystal plasticity model is developed to analyze the intra-colony strain partitioning and inter-colony interaction. In-situ laser confocal microscope experiments with detailed microstructure characterization enable to track the origin and evolution of lamellar kinking. Kinking is re-recognized as deformation banding rather than the conventionally claimed instability resulting from elastic or plastic buckling or macro plastic flow. Strain partitioning plays a pivotal role in the driving force of kinking by stimulating the continuous orientation softening and leading to a decrease of strain energy. The dependence of kinking’s formation condition on geometrical orientation can be rationalized by the orientation sensitivity of strain partitioning. The formation of kinking contributes to reducing the deformation resistance of colony with initially “hard” orientation and further improve the deformation compatibility among colonies. This work provides new insight into the cross-scale mechanisms of lamellar kinking, which can be utilized to control microstructure homogeneity during hot deformation of titanium alloys aiming at optimizing the performance of forging pieces.

Effect of shear stress and compressive stress deformation on LPSO phase kink behavior of Mg-Gd-Y-Zn-Zr alloy

Using torsion and compression experiments, the kink behavior of the long period stacking ordered (LPSO) phase under different stress deformation of the Mg-13Gd-4Y-2Zn-0.5Zr alloy were studied. The results show that different stress states have different effects on the kink of LPSO phase. The grain deformation of the shear stress deformed (SSD) alloy is relatively weak, where LPSO phases are mostly C-shaped or S-shaped kinks. The kink forms can be divided into parallel kinks and angular kinks. The grains of compressive stress deformed (CSD) alloy are significantly elongated and perpendicular to the compression direction, in which occur more Z-shaped zigzag kinks. The kink angle and kink times of the shear stress deformed alloy are small, while the relative kink width is larger. There are large number kink bands during compressive stress deformation, almost all of which are distributed in perpendicular to the compression direction. The difference in the kink behavior is due to the non-basal slip of SSD is easy to active, while in the CSD alloy, the non-basal slip is relatively difficult to active, resulting in more dislocation pile-up. Different forms of kinks can release stress concentration, and all of kinks make the grains deflect in the direction with higher non-basal slip schmid factor.

Rates of Injury and Healthcare Utilization for Kink-Identified Patients

BackgroundKink-involved people engage in atypical erotic activities such as bondage, rough sex, and other fetish activities that might risk injury or medical complication. To date, however, no one has examined the rate of injury or healthcare utilization for people who engage in these activities. AimTo describe the type and rate of injuries from kink activities, and the use of healthcare by kink-involved people, including how many people disclose their involvement in kink when seeking care. MethodsA survey of 1,398 kink-involved or kink-identified people, using a convenience sampling method. OutcomesThe study is the first to report on rates of injury and disclosure of kink involvement to care providers using a large community sample of kink-involved people. ResultsA high number of participants did not disclose their kink behavior to their physical healthcare clinician (58.3%) or to their mental healthcare clinician (49.6%). Past experiences of kink-related injuries were relatively common (13.5%), as was the number of people who reported delaying or avoiding healthcare because of anticipated or perceived stigma for kink involvement (19.0%). Clinical TranslationThe findings of the current study point to the need for clinicians to address barriers to culturally competent care for kink-involved people. Anticipated stigma leads to non-disclosure of kink involvement and delay in seeking care, thereby creating barriers to health and well-being. Strengths & LimitationsStrengths include a sample size large enough to examine regression models to predict disclosure to care providers, and lifetime rates of injury from kink activities overall. Limitations include the use of a convenience sampling method and self-report survey design, which affect the generalizability of the results. ConclusionThe patterns of anticipated stigma, delay or avoidance of care, and concealment of kink and/or BDSM involvement fit the Minority Stress Model, and we argue that kink-identified people should be considered a sexual minority for the purposes of healthcare.Sprott RA, Randall A, Smith K et al. Rates of Injury and Healthcare Utilization for Kink-Identified Patients. J Sex Med 2021;18:1721–1734.

Experimental investigation of high frequency pulse loading on fatigue crack growth in 5052-H32 series aluminum

In the marine industry, designers utilize 5052-H32 marine grade series aluminum for its strength to weight ratio, and the ability of this series to resist marine corrosive environments. During the operating lifetime of a marine vessel, it experiences constant and variable amplitude loading conditions from the sea environment, plus overloads/underloads in the form of high frequency pulses. These high frequency pulses can influence the fatigue crack growth behavior of the aluminum structure. Foundational models like Wheeler and Willenborg have previously been used to predict effects of underloads/overloads on fatigue crack growth, but have proven to be inadequate for all high frequency pulse loading conditions. In this paper, we coupled observations of the crack growth path obtained using an optical microscope with detailed measurements of surface strain fields using Digital Image Correlation (DIC) to elucidate the effects resulting from these high frequency pulses. An experimental test matrix was developed for applying pulses of varying amplitude and frequency to gain fundamental understanding of the characteristics of the high frequency pulses on crack growth behavior. Experimental results indicated there is a novel crack kinking behavior which results in retardation of the fatigue crack growth. Using DIC, we identified changes in the plastic zone ahead of the crack tip that mimic a hard inclusion, affecting not only the crack path, but also the crack opening displacements and subsequent crack growth rates. This work provides a foundation for understanding effects of high frequency pulses on crack growth to enable future development of a model incorporating the effects of the plastic zone on the growth mechanisms.

Shear banding behavior of AA2099 Al-Li alloy in asymmetrical rolling and its effect on recrystallization in subsequent annealing

AA2099 Al-Cu-Li alloys were rolled by both asymmetrical and conventional rolling to a total thickness reduction of 80% at room temperature. Microstructure and texture evolution through thickness of rolling sheets were comprehensively investigated. Results show that large shear stress in ASR sample gave rise to a distortion of grain structure and a remarkable work hardening at region close to fast rolled surface. Shear banding behavior was largely promoted by ASR and various types of shear bands with higher density were observed. The shear bands triggered a kink of grain structure during rolling process. The kink behavior was related to the tilt angle and width of shear bands. The shear bands exhibited large tilt angle and width gave rise to a more significant kink of the grain structure nearby. Recrystallization during subsequent annealing was also promoted by ASR. Shear bands became favorable nucleation sites for rolled material. Growth advantage of some nuclei inside shear bands had a stronger influence on the recrystallized texture in AA2099 rolled sheets.

Generation of wave packets and breathers by oscillating kinks in the sine-Gordon system

Evolution of the nonequilibrium inhomogeneities and topological defects is studied in terms of complex kink solutions of the sine–Gordon equation. The weakly damped oscillation of the sine–Gordon kink, named as the kink quasimode, is described explicitly. It is shown that the oscillatory kink behavior and the wave packet generation depend significantly on the initial nonequilibrium kink profile. In order to specify conditions of the generation of wobbling kinks with a multibreather structure we reformulate the direct scattering problem associated with the sine-Gordon equation as the spectral problem of the Schrödinger operator. We obtain the dependence of the radiation energy, which is emitted during formation of the multi-frequency wobbling kink, on the effective dimension of its initial profile.

A new approach to investigate the nonlinear dynamics in a (3 + 1)-dimensional nonlinear evolution equation via Wronskian condition with a free function

This paper proposes a new approach to investigate the nonlinear dynamics in a (3 + 1)-dimensional nonlinear evolution equation via Wronskian condition with a free function. Firstly, a Wronskian condition involving a free function is introduced for the equation. Secondly, by solving the Wronskian condition, some exact solutions are presented. Thirdly, the dynamical behaviors are analyzed by choosing specific functions in the Wronskian condition. In addition, some exact solutions are graphically illustrated by using Mathematica symbolic computations. The dynamical behaviors include stationary y-breather, line-soliton resonance, line-soliton-like phenomenon, parabola–soliton interaction, cubic–parabola–soliton resonance, kink behavior, and singular waves. These results not only illustrate the merits of the proposed method in deriving new exact solutions but also novel dynamical behaviors in the (3 + 1)-dimensional nonlinear evolution equation.