Rigid Line Research Articles

Theoretical Review of Weight Functions for Rigid Line Inclusions: Implications for Stress Singularities and Crack Propagation

A comprehensive theoretical analysis of weight functions for rigid line inclusions in elastic materials is presented. Classical fracture mechanics approaches were extended to accurately predict stress intensity factors (SIFs) at the tips of these inclusions, which are crucial for understanding material failure. The analysis covered both static and dynamic loading conditions, including transient Mode-III problems. Weight functions for various deformation modes were derived, and the impact of rigid line inclusions on stress singularities and crack propagation was explored. These insights are valuable for the design and analysis of composite structures and materials subjected to dynamic loading.

Transient mode-III problem of the elastic matrix with a line inclusion

The method of pull-out test has been used to identify the mechanical performance of hybrid and fiber-reinforced composite materials. This paper investigates the elastic phase preceding the pull-out of a rigid line inclusion from the polymer matrix with fixed top and bottom surfaces. The mode-III problem is investigated such that the pull-out force is applied from the out-of-plane direction and it can be either transient or static. By applying the singular integral equation technique, the semi-analytical elastic field expressions are obtained. Under the static pull-out force, the stress intensity factor (SIF) near the inclusion tip shows a monotonic increase as the length and height of the matrix increase, whereas for the transient pull-out force, the SIF displays an initial increasing and followed by a decline. The maximum SIF is obtained for (1) the matrix length is 2 to 2.5 times of the inclusion length, and (2) the matrix height is 1 to 2 times of the inclusion length. Moreover, this paper provides a solution approach that incorporates the elasticity of the inclusion, showing that there is an optimal shear stiffness that minimizes the stress singularity of system. The conclusions of this study hold significance for the design and performance evaluation of fiber-reinforced composite materials.

Exploring the meaning in parametricism: a semiotic approach

ABSTRACT Parametricism appeals and promises a communicative meaning that is distinguished from Modernism in the way that the encoding process starts with the articulation of the formal composition and structural morphology. This study draws on interpretative semiotics to address how Parametricism communicates its users and context. An analytical semiotic framework is developed from the literature review of semiotics and the parametric design paradigm. The present study identifies three interaction dimensions (building – user, building – context, and building – architect) that Parametricism establishes to communicate with its users and environment. These dimensions are described and analysed using Eco’s semiotics conviction of denotation and connotation dimensions. Designed by Zaha Hadid Architects (ZHA), the Heydar Aliyev Cultural Centre in Baku is chosen as a case study. It concludes that Parametricism encompasses not only the organisation level, but also includes phenomenological articulation and semiological signification. Parametricism communicates with its context as a “field” rather than an “object”, thus blurring the rigid line between architecture and urban, inside and outside, ground and volume, cladding and flooring.

Influence of main operating conditions on contact wire wear of rigid catenary lines

A validated overhead conductor rail and a well-known wear model have been programmed to perform closer-to-reality simulations. Reliable wear rate estimates for two configurations of overhead conductor rails and three models of pantographs at different speeds and supply currents have been obtained. Results show that wear decreases with increasing speed at high currents and when the distances between supports are uniform. In addition, the use of different types of pantographs in the same facility has a positive effect in terms of wear reduction. Consequently, an adequate selection of the operating conditions contributes to reducing the wear rate.

Безопасность возведения эксплуатируемых кровельных покрытий с системами озеленения с использованием современных систем обеспечения безопасности работ на высоте

The relevance of the study relies on the fact that works at height are classified as highly dangerous. The number of injuries caused by falls from heights is threatening, compared with other factors of injuries. According to the statistics, the share of injuries caused by falls from heights is 28 %. According to the legislation, construction works are classified as works at height if there is a risk of fall for an employee from a height of 1.8 m and higher. At the same time, an employer must ensure the implementation of measures to minimize the existing level of injury rate at the construction site following the effective legislation. The basic measures of protection of employees working at heights can include personal and collective protection equipment and the use of protective fencing. In addition, the measures of protection include stationary anchoring devices mounted on the roofs of buildings. There are several versions of construction of anchoring lines; e.g., for concrete, metal, or green roofs. The structure of the anchoring device changes depending on the type of roof; e.g., a flexible anchoring line can be used in locations where the architectural appearance of the building must be preserved; due to its low visibility it is used for pitched roofs. A rigid line is more visible, and it is more appropriate to use it in locations where its impact on the architectural appearance of the building will be minimized. According to the conducted analysis, the existing safety systems used for roof works, to a certain extent, depend on the greening systems of the roof in use.

Product and production design - Rethinking views on flexibility

The recent years have shown that long global supply chains are vulnerable considering volatile markets. As a result, efforts to achieve supply chain resilience are increasing. Achieving resilience requires flexibility, incorporated in product development, which can be implemented by the production system. Flexibility also offers the advantage in the context of sustainability that production facilities remain in use longer than rigid production lines because they can be better retrofitted. Furthermore, volatile markets challenge companies with a higher frequency of changes of requirements and decreasing forecast quality. Accompanied by a decreasing time-to-market and higher complexity of products companies need to increase their overall flexibility. A particular challenge is that routing flexibility is not used in production, for example, because the control effort is too time-consuming and complex. The use of AI and cyber-physical systems provides support to manage the control effort and thus enable flexibility in production. This paper discusses the role of flexibility in product development and production planning. The characteristics of products and production systems are analysed to identify important design aspects for flexibility. Comparing different systems shows for instance that non-linear structures with flexible links offer strategic advantages.

STUDENTS OF CHUVASHIA HIGHER EDUCATIONAL INSTITUTIONS ABOUT PATRIOTISM: GENDER ANALYSIS

The relevance of the study determines the increasing importance of patriotism in education, primarily that of young people, including students. It is important both practically and theoretically to comprehend the role and the place of patriotism in the conditions of increasing confrontation with Western countries and ideologies. At this, it is important to take into account the multidimensional nature of this phenomenon, including the peculiarities of its gender perception.
 
 The purpose of the work is to analyze the opinions of Chuvashia students about patriotism, to identify the distinguishing characteristics of the responses given by boys and girls.
 
 Materials and methods. The analysis is based on data from a survey involving over 500 university students of Chuvashia, among whom 60% were girls, the remaining 40% were young people. The basis for the analysis seems to be quite representative. The obtained indicators will have not only theoretical, but also applied significance, since they will enable to choose more effective work strands with students, taking into account their gender characteristics. The processing of materials within the framework of the SPSS Statistics program makes it possible to take into account such aspects of the study.
 
 Study results. According to the respondents, the most distinctive feature of patriotism is love for one’s country. Conscious love for the Motherland, devotion to it – act as the basis of this political principle and social feeling. Further, the frequency of choice is followed by such answers as pride for the history of the country and readiness to defend it. In both cases, girls chose these options more often, especially in the first case. The elements of patriotic choice with a certain degree of conditionality can be divided into cognitive, emotional and active. Undoubtedly, they intersect, in each of them all three components are reflected, but the basic characteristics prevail.
 
 Conclusions. It follows from the data obtained that girls perceive to a greater extent such components of patriotism that are cognitive and emotional in nature, and young men – its effective component. At the same time, it is not necessary to draw rigid dividing lines between them, since some phenomena are perceived from different points of view, which we have tried to show in this article.

Design and Analysis of Internal–External Composite Meshing Hy-Vo Chain

The internal–external composite meshing mechanism should be the best way to improve the transmission performance of a silent chain drive, but there is no internal–external composite meshing Hy-Vo chain under the classical design approach. In this research, by building the Hy-Vo chain meshing system, the difference between the meshing of the chain–sprocket and the meshing of the rack–gear is deeply analyzed. By rigidifying the external meshing Hy-Vo chain as a rack, the fluctuation range of the pitch line of the external meshing Hy-Vo chain is analyzed. Based on the relations between the actual chain pitch line and the rigid chain pitch line, the design method for the internal meshing profile of the internal–external composite meshing Hy-Vo chain is deduced, the necessary conditions are obtained, and the meshing characteristics are analyzed. By conducting comparative multi-body dynamics experiments, the results prove that the design method of the internal–external composite meshing Hy-Vo chain proposed in this study is effective and feasible. The results also show that the description of the internal–external composite meshing in the classical meshing theory is not completely correct. In fact, the internal–external composite meshing mechanism cannot reduce the meshing impact of the Hy-Vo chain system and can only improve the system polygon action, the meshing performance, and the transmission stability.

Full Field Solution for Remotely Loaded One Side Completely Debonded Short Rigid Line Inclusion Embedded in Soft Matrix: Two-Dimensional Analytical and Experimental Insights

Abstract The problem of a completely debonded short fiber (rigid line inclusion/anticrack) embedded in a 2D isotropic elastic soft matrix subjected to the remote loading condition is of fundamental interest. The current work investigates completely debonded anticrack embedded in a soft (isotropic) matrix using Kolosov Muskhelisvili's complex potential framework. Here two configurations are studied: debonded inclusion oriented (i) parallel and (ii) perpendicular to the loading direction. In particular, the potentials take the form of a non-homogeneous Riemann—Hilbert equation for the given problem. Upon solving analytical forms of potentials, the stress fields were obtained. The stress field for the fully debonded anticrack exhibited oscillatory singular behavior between r−3/4 and r−1/4 with the dependence on the oscillatory index ε and material constants. The correctness of the analytical solution was validated using numerical simulation and experiments based on the digital photoelasticity technique. The analytical results were in good agreement with the experimental and numerically obtained stress fields confirming the accuracy of it. The magnitude of singularity is quantified by defining a complex stress intensity factor at the tip of the discontinuity and compared with the experimentally estimated value. So far in the literature, no full-field analytical solution exists for the completely debonded rigid inclusion embedded in an isotropic soft matrix. The solution obtained in the present work is of fundamental importance in developing the constitutive properties of short fiber reinforced thermoplastic (SFRT) composites.

Anti-plane pull-out of a rigid line inclusion from an elastic medium

Anti-plane pull-out of a rigid line inclusion from an elastic medium

Текстовые средства распространения реформационных идей в обществе Англии середины XVI века

The death of Henry VIII in January 1547 entailed a departure from a rather rigid line in religious policy, which, in turn, led to a freer dissemination of ideas in the field of religion. This spread was characterized not only by the increased number of published texts, but also by the boldness of the authors' statements, the brightness of the images they used. The article is devoted to the study of textual means of spreading of reformation ideas in the society of England in the middle of the 16th century. The object of the study is genrediverse works: the sermon “About the plow”, written by Hugh Latimer, one of the leaders of the promotion of religious transformations in England, and the satirical work “Doctor Double Ale”, published by the London doctor Luke Shepherd. Sermons and satirical works of the middle of the 16th century, given the rather large literacy of the population of the foggy Albion, should have found a warm response from those to whom the writings were addressed. However, despite the fact that these works were created in line with the official policy of religious transformations, it is quite difficult to talk about the degree of their direct influence on its implementation.

The ALBA high-stability monochromator for VUV and soft X-rays

LOREA is ALBA’s beamline devoted to the investigation of solids electronic structure by means of Angle Resolved Photo-Emission Spectroscopy (ARPES). The beamline operates in the photon energy range 10-1000 eV with tuneable linear and circular polarizations produced by an APPLE II helical undulator. Thanks to its energy range and the high photon flux, LOREA is suitable for high resolution VUV ARPES investigations in the 10-200 eV range, while it is feasible to extend ARPES measurements to the 200-600 eV energy range (soft X-ray ARPES). Core level photoemission, resonant photoemission and X-ray absorption spectroscopies will be accessible in the whole energy range. The energy selection is obtained by an Hettrick-Underwood monochromator without entrance slit. The optical arrangement, with 3 spherical mirrors (SM) and 4 plane varied line-spaced (VLS) gratings, is able to cover the entire energy range of the beamline. The monochromator includes the motions to select and do the fine adjustments of the mirrors (pitch and height), and to scan the energy and select among the different gratings (grating pitch and grating horizontal translation). The monochromator has been designed by the ALBA team of engineers, and has been fully assembled and commissioned at the facility. Besides the required range and resolution performances, it has been designed to achieve high stability and reproducibility, and optimal performance of the optical surfaces under different heat loads and conditions. The cooling circuits of mirrors and gratings are mechanically decoupled from the optical elements. In the case of the gratings, heat load is removed by flexible copper straps connected from optics to rigid water lines, through temperature controller devices based on Peltier elements. The use of Peltier element allows stabilizing the temperature of the gratings to room temperature also under quickly varying heat loads. The gradients within the grating are well below the one degree, and the thermal equilibrium with the surrounding mechanics contributes the long-term stability of the system. The water circuit and the Peltiers, rest in an independent platform inside the vacuum chamber, that allows them drift freely with no effect on the position of optical elements. In the case of the mirrors, the water tubes and cooling pads are not pressed against the mirrors, but just in contact through a 0.1 mm thick pellicle of eutectic InGa. This allows for a very efficient heat transfer using a minimum contact surface sufficient to evacuate up to 60 W, and without any deformation of the mirrors. The mechanics are also designed so that no flexible loops are required, which contributes to a better vibration stability of the system. Mirrors and gratings can be removed from the monochromator inside their holders and with the cooling scheme installed on it. This is a mandatory goal of design, as it is necessary for a careful installation and control of surface deformations at the optics laboratory. In this contribution we describe the main features of the monochromator that allow reaching the target performances, especially those concerning the cooling scheme. And also, we provide details about the positioning mechanics of the optical elements, the energy scanning mechanism and the vacuum system. The monochromator has been already mounted and installed and it is already in operation. The first results of the He photoionization spectra shows an energy resolution better than 10meV at 60eV, with a strong ionization signal and very low noise.

Nonlocal fields and effective properties of piezoelectric material with a rigid line inclusion perpendicular to the poling direction

Nonlocal fields and effective properties of piezoelectric material with a rigid line inclusion perpendicular to the poling direction

A theoretical model of fracture of biological composites considering complex structural arrangement of microstructures

Although it is known that biological materials have remarkable fracture strength and toughness, the underlying mechanisms have not been fully understood. A key question is what effects of the structural arrangement of the microstructure are in biological materials. To address this problem, we developed a fracture model based on the fundamental solutions of the crack and rigid line inclusions in matrix to consider the roles of the complex arrangement of the microstructure. Firstly, we obtained the analytical solutions of the SIFs of three basic problems with two inclusions. These solutions revealed several fundamental toughening mechanisms of biological composites via controlling the geometric arrangement of microstructures. Then, we analyzed the fracture problem of multiple rigid lines and cracks with one-level of hierarchy of composite structure. We found that the large aspect ratio of rigid lines produces significant stress shielding effect on the main crack, but it simultaneously creates high possibility of producing local microcracks therein. Interestingly, these microcracks can significantly reduce the SIFs of the rigid lines, while only slightly increases the SIF of the main crack. Finally, we studied the effect of the hierarchical structure on the fracture toughness of biological materials. Compared with the one-level structure, the two-level hierarchy can effectively reduce the SIF of the main crack, and at the same time it becomes less sensitive to the change of the geometric parameters of the microstructures at higher level. This study may provide guidelines for the structural design of advanced biomimetic materials.

Static and transient thermal conductions and associated thermal stresses in an elastic strip with a rigid line inclusion

The problem of a rigid inclusion in an elastic strip under steady or transient thermal loading is studied. The inclusion is assumed to be extremely thin and thermally insulated so that it does not disturb the heat conduction in the strip. The thermal strain and stress fields are obtained by using the singular integral equation technique. The inclusion tip strain and stress are found to be singular. The near tip stresses are expressed in terms of the thermal strain intensity factor. Case studies include the influence of temperature boundary condition, inclusion location and strip width on the thermal strain intensity factor. The highest and lowest values (upper and lower bounds) of the intensity of the thermal strain are identified.

Interaction of a rigid line inclusion with various discontinuities using experimental and numerical techniques

Using boundary element method (BEM) and photoelasticity, the interaction effects of a rigid line inclusion with various discontinuities embedded in a matrix are investigated. The interaction effect of discontinuities on a rigid line inclusion has not received much attention when compared to the studies on the interaction effect of discontinuities on a crack. The following discontinuities are considered: rigid circular inclusion, rigid elliptical inclusion, circular hole, elliptical hole, and crack when a tensile load is applied along the inclusion length. A circular hole approaching normal to the line inclusion strengthens the strain fields at the rigid line inclusion tip, whereas a hole along the line inclusion alleviates the strain level. However, in the case of rigid circular inclusion, the opposite trends are observed. The influence of the aspect ratio of the elliptical hole on the elastic fields of a rigid line inclusion is also brought out. The influence of a crack near the vicinity of a rigid line inclusion is also studied. The interaction effects of a circular inclusion, a circular hole, and a crack on the rigid line inclusion are further experimentally analyzed for the first time using the photoelastic technique towards validating the boundary element model. The magnitude of singularity at the inclusion tip is quantified using the strain intensity factor. Also, the magnitude of the stress intensity factor (SIF) at the crack tip is reported. Both the strain intensity factor for rigid line inclusion and the SIF for the crack tip are estimated using the domain integral method.

Singular elastic field induced by a rigid line adhering to a micro/nanoscale plate during bending

In this work, the elastic analysis of a micro/nanoscale plate with a stiffer ribbon adhering to it is studied. The stiffer ribbon is understood as a rigid line. The problem is solved by superposition and the singular elastic field induced by a rigid line is concerned when the plate is during bending. The singular elastic field of a micro/nanoscale elastic thin plate with surface elasticity is determined for a parabolic rigid line. The theoretical analysis is based on a mixed boundary value problem that is solved through the Fourier integral transform technique. According to the classical Kirchhoff thin plate theory incorporating surface elasticity, some basic equations are established. The mixed boundary value problem is reduced to a singular integral equation of the first kind with Cauchy kernel. Explicit expressions for the moments and effective shear forces as well as the surface and bulk stress components in any position of the whole nanoplate are obtained. The singularity coefficients of the moment and effective shear force at the tip of the rigid line are determined in closed form. From the obtained results, we find that the normal stress components for bulk and surface phases and bending moments at the rigid line tips have a usual inverse square-root singularity, but the effective shear forces behave like r−3/2, r being the distance from the tip of the rigid line or admit an r−3/2 singularity. The numerical results are displayed graphically and show that the singularity coefficients are heavily dependent on the surface and bulk material constants.

Multiple elastic or rigid line inclusions in a multilayered orthotropic solid

This paper studies the problem of multiple line inclusions in a non-homogeneous medium. The formulation and solutions for rigid line inclusions and homogeneous medium are special cases when the stiffness values of the inclusions are infinite and the non-homogeneity of the material vanishes. The model built in this study is capable of dealing with any material non-homogeneity (material properties vary continuously or in step-wise form), orthotropic mechanical properties, isotropic mechanical properties, and any number of parallel or collinear inclusions. More importantly, the inclusions are not limited to rigid (they can be elastic). Dependence of the inclusion tip fields on the strain intensity factor is given in closed form. Numerical results are given for the situations of mechanical load as well as thermal load applied in the medium.

A rigid line inclusion in a nonlocal elastic medium – Mode I deformation

In this paper, the problem of a rigid line inclusion in a nonlocal elastic medium is solved. Two special inclusion orientations are considered. These are (1) inclusion is parallel to the border of the medium, and (2) inclusion is perpendicular to the border of the medium. The two-dimensional stress and strain field and the effective mechanical property of the medium with inclusion are obtained. Because of the nonlocal effect, the stresses near the tips of the inclusion are significantly smaller than those based on the classic continuum mechanics framework. Essentially, under the nonlocal theory, there is no stress singularity at the tips of the inclusion. When the nonlocal effect vanishes, the results for the classic continuum theory of elasticity are recovered. In addition to the single inclusion, results for collinear inclusions are also presented.

An Interethnic Paradox: Chicago's Irish and Everyone Else

An Interethnic Paradox: Chicago's Irish and Everyone Else