Plane Xz Research Articles

Increasing the Interlayer Fracture Toughness of Polymer Fabric Composites Using Local 3D-Reinforcement (Felting)

Introduction. One of the reasons for undesirable delamination of polymer composites with fabric reinforcement is low transverse shear properties. It is known that the reinforcement of polymer fabric composites in the Z direction reduces the sensitivity to delamination and increases the viscosity of interlayer fracture. Various methods of three-dimensional reinforcement of polymer fabric composites are proposed in the literature. However, they complicate the manufacturing process of the structure. The problem is solved by the method of three-dimensional reinforcement proposed in this article — felting. This is a local reinforcement of the composite in the Z direction with minimal production changes. The degree of Z-reinforcement is determined by the felting density, i.e., the number of needle punches per 1 cm2 of the fabric package. The work is aimed at evaluating the effect of felting on the interlayer crack resistance of a composite material.Materials and Methods. The interlayer fracture toughness GIIc was determined on a cross-woven fiberglass with felting of 10 cm-2. The material was impregnated with Etal-370 resin and Etal-45 hardener. Experiments according to ASTM D7905M–14 and GOST 33685–2015 standards were carried out on an Instron 5900R test machine. The stress state at the crack tip was analyzed with regard to the nonlocal strength theory in the ANSYS Workbench program (option “static strength analysis”). The finite element method (FEM) was used.Results. The “load — displacement” curves were considered for the samples. Values GIIc were calculated. The results of ENF tests for felting density of 0 cm–2 and 10 cm–2 were summarized. Control samples and felting samples were compared. In the latter case, GIIс turned out to be ~33% higher. The stress state at the crack tip was calculated under DCB and ENF loading. The dependences of maximum normal and shear stresses, as well as displacements, were visualized in the form of graphs and color charts. To get the calculated “load — displacement” dependences using FEM, the reverse method of obtaining transverse shear constants was used. DCB loading showed that felting provided increasing the rupture strength in the Z direction to ~18%, by 39 to 46 MPa, and in the planes XZ— to ~16%, by 77 to 89 MPa.Discussion and Conclusion. Felting as a method of local three-dimensional reinforcement enhances the interlayer crack resistance of polymer fabric composites. It provides reducing the area of stratifications after local impacts during the operation of structures. Flexible felting technology makes it possible to create zones with an arbitrary impact density, increasing fracture toughness only in the required places of structures. The FEM analysis of the stress state at the crack tip within the framework of the nonlocal strength theory has shown that in strength calculations, the stratification crack can be considered as a stress concentrator.

Zero velocity surface in the general three-body-problem

The zero-velocity surfaces of the general planar three-body problem are constructed in the form space, the factor-space of the configuration space by transfer and rotation. Such a space is the space of congruent triangles, and the sphere in this space is similar triangles. The integral of energy in the form space gives the equation of the zero velocity surface. These surfaces can also be obtained based on the Sundman inequality. Such surfaces separate areas of possible movement from areas where movement is impossible. Without loss of generality, we can assume that the constant energy is −1/2 and the sought for surfaces depend only on the magnitude of the angular momentum of the problem, J. Depending on this value, five topologically different types of surfaces can be distinguished. For small J, the surface consists of two separate surfaces, internal and external ones, the motion is possible only between them. With J increasing the inner surface increases, the outer surface decreases, the surfaces first have a common point at some value of J, with a further increasing of J, their topological type changes and finally the zero-velocity surface splits into three disjoint surfaces, the motion is possible only inside them. Examples of the corresponding surfaces are given for each of these types, their sections in the plane xy and in the plane xz and the surfaces themselves are constructed, their properties are studied.

Assessing ring‐shaped subsurface irrigation system through a conventional subsurface emitter

AbstractA ring‐shaped emitter is a cheap subsurface irrigation system recommended for small‐scale farms. This study compared the performance of a ring‐shaped emitter with conventional subsurface drip irrigation (SDI) under the same conditions. HYDRUS, which is a useful software that can thoroughly and adequately simulate water movement in the soil under different irrigation systems, was used to study the performance of the aforementioned irrigation systems. We used field data to calibrate and verify the numerical model. The water distribution around the irrigation systems studied was modelled as 2D in‐plane strain for ordinary SDI (vertical plane XZ) and axisymmetric geometrical states for the ring‐shaped emitter. This study mainly evaluated ring‐shaped emitters and compared them with SDI to verify whether these emitters could be a recommended alternative irrigation method in small‐scale farms. The simulation results showed that water availability in the exact coordinates in both emitters was approximately identical, except near the waterfront. Water movement in the ring‐shaped emitter was faster than that in SDI, and therefore, the waterfront in the ring‐shaped emitter was further away at all times. Finally, the water entrance to the second layer under this emitter met with less resistance.

Research on Mechanical Properties of V-Type Folded Core Sandwich Structures

A folded core is a three-dimensional configuration formed by folding a flat sheet of paper. Similar to foam and honeycomb, folded cores are widely used in aerospace as the cores for sandwich structures due to their excellent mechanical properties and light structural weight. In general, the core’s configuration is heterogeneous and anisotropic, while from a macroscopic point of view it is considered homogeneous. Analytical solutions of equivalent mechanical properties are generally obtained by equivalent methods and modified by numerical simulations due to the complexity of the configuration. We can find the best combination of a core’s parameters by using analytical solutions. The faceted regular folded configuration (RFC), consisting of repetitive identical cells, can be expanded to a plane. According to the principle of equivalent load-deformation, this article investigates the equivalent mechanical properties of the V-type folded core (VFC). The analytical solutions of Ez—equivalent elastic modulus in Direction z, equivalent shear modulus in Plane xz—Gxz, and equivalent shear modulus in Plane yz—Gyz have been obtained and verified by numerical simulations. In addition, the reliability of the equivalent mechanical properties is further demonstrated by the case study. By applying the analytical solutions, the optimization process of VFC can be simplified and sped up, which is of great engineering significance to the aircraft design process.

Effect of ellipticity of optical eigenwaves on the enhancement of efficiency of acousto-optic Bragg diffraction. A case of optically active Pb5Ge3O11 crystals

We show that the existence of optical activity in an optical material can lead to essential enhancement of acousto-optic (AO) figure of merit. The reason is that the ellipticity of interacting optical eigenwaves approaches unity near the optical axis and so additional elasto-optic (EO) tensor components become involved in the effective EO coefficient. We demonstrate on lead germanate crystals that the increase in the efficiency of AO diffraction manifests itself for all types of AO interactions whenever the incident optical wave propagates close to the optical axis. In the particular case of diffraction in the interaction plane XZ of Pb5Ge3O11 crystals, the maximal enhancement of the AO figure of merit takes place under conditions of the isotropic diffraction of ordinary and extraordinary optical waves with a pure transverse acoustic wave (AW) polarized parallel to the Y axis (a so-called AW PT2), with the AO figure of merit increasing from zero to 7.5 × 10−17 s3/kg, and the types of anisotropic diffraction on the AWs QT1 and PT2 when the AO figure of merit increases twice (e.g., from 7.6 × 10−17 to 1.5 × 10−16 s3/kg). The maximal AO efficiency in the interaction plane XZ is reached at types I and II of the isotropic AO interactions of ordinary and extraordinary optical waves with a quasi-longitudinal AW; in these cases, the AO figure of merit increases from 6.8 × 10−15 to 12.4 × 10−15 s3/kg and from 5.6 × 10−15 to 12.4 × 10−15 s3/kg, respectively.

Stability and free vibration analyses of orthotropic 3d beam–columns with singly symmetric section including shear effects

A complete beam–column classification and the corresponding characteristic equations for the stability and undamped natural frequencies of 3D orthotropic Timoshenko beam–columns with singly symmetric closed section and with elastic end connections subjected to an eccentric end axial load are presented and derived using three different approaches. The first two approaches are those by Engesser and Haringx that include the shear component of the applied axial force proportional to the slope (du/dx and dv/dx in planes xz and yz, respectively) and to the angle of rotation of the cross-section (θx and θy in planes yz and xz, respectively) along the span of the member, respectively. The third approach is a simplified formulation based on the classical Euler theory that includes the effects of shear deformations but neglects the induced shear component of the applied axial force along the member. The proposed methods and characteristic equations are capable of determining the critical axial loads and undamped natural frequencies of beam–columns with elastic end connections. Four comprehensive examples are included that show the effectiveness and simplicity of the proposed method and the results obtained are compared with experimental results available in the technical literature. It is shown that: (1) the natural frequencies and critical axial loads of beam–columns increase as the shear stiffness GAs, the degrees of fixity and lateral bracings at the ends of the member increase; (2) the natural frequencies calculated using the three approaches are identical to each other when the applied axial load is zero; (3) the critical axial load in compression using the Engesser approach is lower than the one obtained using the Haringx approach; (4) the critical axial loads in compression are highly affected by the degree of flexural fixity at the supports, but those in tension are not affected much; and (5) the Haringx approach is the only one among the three approaches capable of capturing the phenomena of tension buckling observed in seismic isolators.

Depth-Aided Tracking Multiple Objects under Occlusion

In this paper, we have presented a novel tracking method aiming at detecting objects and maintaining their la-bel/identification over the time. The key factors of this method are to use depth information and different strategies to track objects under various occlusion scenarios. The foreground objects are detected and refined by background subtraction and shadow cancellation. The occlusion detection is based on information of foreground blobs in successive frames. The occlusion regions are projected to the projection plane XZ to analysis occlusion situation. According to the occlusion analysis results, different objects’ corresponding strategies are introduced to track objects under various occlusion scenarios including tracking occluded objects in similar depth layer and in different depth layers. The experimental results show that our proposed method can track the moving objects under the most typical and challenging occlusion scenarios.

ANÁLISE ESTRUTURAL E DEFORMACIONAL EM ZONAS DE CISALHAMENTO DE BAIXO MERGULHO E TRANSCORRENTES ASSOCIADAS A ZONA DE SUTURA ALTEROSA, NA REGIÃO DE CRISTINA E ITAJUBÁ - MG

The region or Cristina and Itajuba-MG, located south of Sao Francisco Craton, comprises paragneisses of the Piracaia Complex, granulites and ortogneisses of the Paraisopolis Complex which are overthrusted on metassediments of the Andrelândia Group and its basement (Amparo/Sao Goncalo do Sapucai Complex), metamorphosed in the amphibolite facies. Ductile fabrics record two main tectonic events. A thrusting event (Dn) generated the regional Sn, which shows foliation with NW-SE strike and low dips to SW, in association with down dip stretching lineations. Dn is attributed to the collision of the Sao Paulo Block (Socorro-Guaxupe Terrane) to ENE onto the Sao Francisco Plate during the Brasilia Orogeny (630-610 Ma), whose limit, the Alterosa Suture Zone (ASZ), is marked in that area by the Lourenco Velho SZ. Sn also shows a progressive sinistral inflection to a almost vertical NE-SW orientation along the Maria da Fe and Cristina strike slip shear zones. These amphibolite to granulite facies shear zones are consistent with the SW-NE compressive tectonic regime and are interpreted as lateral ramps of the Dn event. A Strike-slip/transpressive deformation (Dn + 1) formed, in lower amphibolite facies, the mylonitic foliation Sn + 1, that occur along NE-SW trending dextral shear zones within the transpressive Rio Paraiba do Sul Belt, with is related to the younger Ribeira collision (590-560 Ma). The strain analysis using Fry and Rf/phy methods revealed oblate strain elipsoids, with predominance of pure shear component of over simple shear. Simple shear predominates only in samples close to the SLSZ, where kinematic markers indicate top movement to NE and constitutes an important zone of mass transport . The obliquity between the largest axis of the strain e1lipse in relation to the foliation in planes XZ and YZ indicates non-coaxial deformation in both kinematic planes. The analyses of the strain ratio on these sections indicates that the quartz exerted strong rheologic importance for shear zone development, better accomodating the regional strains in relation to feldspars, that does not show substantial strain variation among samples with low and high deformation.

A study of basis set and electron correlation effects in the ab initio calculation of the electric dipole hyperpolarizability of ethene (H2C=CH2)

We report finite-field self-consistent field (SCF) and many-body perturbation theory calculations of the dipole polarizability and hyperpolarizability of ethene. Large Gaussian-type basis sets have been used to ensure the determination of reliable, near Hartree–Fock values for all the independent components of the dipole hyperpolarizability tensor γαβγδ. The calculated SCF values of γ display strong basis set dependence. Electron correlation changes drastically the SCF picture of γαβγδ. The most important effect is the increase by nearly 70% of the component parallel to the double bond, γzzzz (molecular plane xz). It is found that the contribution from the fourth-order triple substitutions T4, dominates the fourth-order correction to the SCF value for almost all components of γ. The best SCF values obtained in this work are (in atomic units), γxxxx=3466, γyyyy=11 080, γzzzz=3351, γxxyy=2390, γyyzz=2936, γzzxx=1660, and γ̄=6374e4a04Eh−3. The estimated electron correlation corrections (Δ corr) are 431±79, −870±421, 2318±87, −134±101, −67±133, 240±62, and 392±236e4a04Eh−3, respectively. Albeit electron correlation affects strongly the individual tensor components of γ, the overall effect on the mean hyperpolarizability γ̄ does not exceed a few percent. The final estimate of γ̄=(68 ± 2)×102 e4 a04 Eh−3 is in essential agreement with the experimental results of Ward and Elliott.

Creep strength of anisotropic plates taking account of transverse shear strains

Cylindrical creep buckling of an orthotropic glass-reinforced plastic plate is investigated with consideration of shear creep in the plane xz. In this case the rheology of buckling is not described by the Kirchhoff-Love model, therefore the investigation is carried out using the modified theory of plates [3]. The long-time and instantaneous critical forces are obtained.