Plate Segments Research Articles

Closed-form analytical solution for local buckling of omega-stringer-stiffened composite panels under compression

The use of stiffened thin-walled lightweight structures in e.g. aircraft fuselages requires efficient calculation methods to describe the stability behavior. In this work, a closed-form model for the local buckling analysis of orthotropic composite plates braced by omega-stringers is developed. The problem can be reduced to a plate simply supported at all edges subjected to uniaxial compression with eccentrically attached stringer feet, while the stringer itself is modeled as restraint stiffnesses along the longitudinal edges. The discontinuities in the stiffnesses introduced by the stringer feet result in discontinuities in the curvature behavior and the shear distortion of the structure. In order to map this influence on the local buckling behavior, the reduced model is divided into plate segments of corresponding stiffnesses, for which Ritz-based approach functions for the deformations are defined. Finally, an explicit formulation of the buckling load is derived using the energy method. To validate the model, the Lévy solution is obtained and a finite element analysis is conducted. The results of the parameter studies demonstrate excellent agreement within the design space of the aviation application area.

Development of High-Silica Adakitic Intrusions in the Northern Appalachians of New Brunswick (Canada), and Their Correlation with Slab Break-Off: Insights into the Formation of Fertile Cu-Au-Mo Porphyry Systems

High-silica adakites exhibit specific compositions, as follows: SiO2 ≥ 56 wt.%, Al2O3 ≥ 15 wt.%, Y ≤ 18 ppm, Yb ≤ 1.9 ppm, K2O/Na2O ≥ 1, MgO < 3 wt.%, high Sr/Y (≥10), and La/Yb (>10). Devonian I-type adakitic granitoids in the northern Appalachians of New Brunswick (NB, Canada) share geochemical signatures of adakites elsewhere, i.e., SiO2 ≥ 66.46 wt.%, Al2O3 > 15.47 wt.%, Y ≤ 22 ppm, Yb ≤ 2 ppm, K2O/Na2O > 1, MgO < 3 wt.%, Sr/Y ≥ 33 to 50, and La/Yb > 10. Remarkably, adakitic intrusions in NB, including the Blue Mountain Granodiorite Suite, Nicholas Denys, Sugar Loaf, Squaw Cap, North Dungarvan River, Magaguadavic Granite, Hampstead Granite, Tower Hill, Watson Brook Granodiorite, Rivière-Verte Porphyry, Eagle Lake Granite, Evandale Granodiorite, North Pole Stream Suite, and the McKenzie Gulch porphyry dykes all have associated Cu mineralization, similar to the Middle Devonian Cu porphyry intrusions in Mines Gaspé, Québec. Trace element data support the connection between adakite formation and slab break-off, a mechanism influencing fertility and generation of porphyry Cu systems. These adakitic rocks in NB are oxidized, and are relatively enriched in large ion lithophile elements, like Cs, Rb, Ba, and Pb, and depleted in some high field strength elements, like Y, Nb, Ta, P, and Ti; they also have Sr/Y ≥ 33 to 50, Nb/Y > 0.4, Ta/Yb > 0.3, La/Yb > 10, Ta/Yb > 0.3, Sm/Yb > 2.5, Gd/Yb > 2.0, Nb + Y < 60 ppm, and Ta + Yb < 6 ppm. These geochemical indicators point to failure of a subducting oceanic slab (slab rollback to slab break-off) in the terminal stages of subduction, as the generator of post-collisional granitoid magmatism. The break-off and separation of a dense subducted oceanic plate segment leads to upwelling asthenosphere, heat advection, and selective partial melting of the descending oceanic slab (adakite) and (or) suprasubduction zone lithospheric mantle. The resulting silica-rich adakitic magmas ascend through thickened mantle lithosphere, with minimal affect from the asthenosphere. The critical roles of transpression and transtension are highlighted in facilitating the ascent and emplacement of these fertile adakitic magmas in postsubduction zone settings.

Thermal vibration analysis of bi-directionally stepped porous functionally graded plates with segment-specific material property variation supported by Kerr foundation

This paper presents a comprehensive analysis of the nonlinear dynamic response of stepped rectangular plates made of functionally graded porous material (FGPM), supported by the Kerr foundation, in a thermal environment. A novel analytical framework is developed to explore geometric and material variations. The study investigates structural variations in plate thickness with abrupt changes in uni- or bi-directional orientations, examining both single and double stepped thickness profiles. Material properties vary with thickness, featuring distinct horizontal discontinuities across plate segments. Porosity distributions, both even and uneven, are addressed using modified mixture rules. Nonlinear kinematic relationships are established using Reddy’s third-order shear deformation plate theory and von Kármán’s nonlinear geometric assumptions, with equations of motion solved via Galerkin’s technique. This improved model effectively addresses non-continuous thickness variation through integral calculus, enhancing computational efficiency. Validation is achieved by comparing outcomes with published literature and Finite Element Analysis (FEA). The study investigates the influence of material properties, elastic foundation, boundary conditions, and geometric parameters on the free vibration and nonlinear behaviors of the plates. Some of the key findings include: increasing the thickness of the stepped segment significantly heightens the fundamental frequency while reducing vibrational amplitudes; optimizing the location of the stepped segment directly impacts the plate’s fundamental frequency and vibrational amplitudes; and as the load factor increases, the difference between linear and nonlinear deflection becomes evident. Therefore, accurate FGPM stepped plate design requires incorporating nonlinear terms in the strain–displacement relationships. Suggestions for future model modifications are also discussed, contributing to advancements in structural design and analysis.

Natural frequencies and modal shapes of folded sandwich plates made of porous core and FG-CNTRC coating layers resting on two parameters elastic foundation

Folded structures hold significant importance in aerospace technology due to their distinct design, effectively reconciling strength with a lightweight framework. Within aerospace applications, these structures fulfill diverse roles, serving as pivotal elements in aircraft wings, fuselage sections, and essential components of spacecraft and satellites. This study delves into the free vibration behavior of folded sandwich plates composed of a porous core and functionally graded carbon nanotube-reinforced composite (FG-CNTRC) coatings, resting on a two-parameter elastic foundation. Leveraging first-order shear deformation plate theory (FSDT), elasto-dynamic equations are established for each individual plate segment. Utilizing the two-dimensional generalized differential quadrature method (2D-GDQM), these equations are discretized. Subsequently, by applying boundary conditions to all six edges, including traditional clamped, simply supported, and free configurations, and incorporating continuity conditions for displacements, forces, and moments at the joint borders, natural frequencies and modal shapes are extracted for the folded plate structure. The validity of the proposed formulation and results is demonstrated by comparing them with numerical examples for both composite flat and folded plates. This comparison provides strong support for the accuracy and reliability of the present study. The study comprehensively examines the influence of various parameters on natural frequencies, including modal shape visualizations under different boundary configurations, plate thickness, crank angle, porosity parameter, core thickness, foundation stiffness, and CNTs distribution type.

Amino acid‐specific nitrogen stable isotope analysis reveals the trophic behavior of Icelandic fin whales in winter and suggests variable feeding strategies

AbstractFin whales (Balaenoptera physalus) aggregate west of Iceland during summer, where they feed mostly on krill, but their winter distribution is poorly known. This study investigates the winter behavior of fin whales that summer off Iceland by analyzing amino acid‐specific nitrogen isotope ratios in the baleen plates. This technique is increasingly used in large marine vertebrates to discriminate between changes in trophic position and changes in isotopic baseline levels, while ruling out the effect of fasting on these patterns. Analyses were conducted on samples extracted from two baleen plate segments: one corresponding to winter, another to summer. The trophic position was higher and slightly more variable in winter (3.6 ± 0.7) than in summer (3.0 ± 0.4), which indicates that during winter fin whales tend to feed on fish and are more generalist in feeding habits. Interestingly, the δ15NPhe values were not lower in winter than in summer (winter: 5.2‰ ± 2.4‰; summer: 4.0‰ ± 2.1‰). This was unexpected because baseline δ15N values (e.g., zooplankton) tend to be lower at low latitudes, where fin whales are believed to spend the winter. Fin whales may remain in relatively high latitudes during winter or visit low‐latitude areas with locally higher than average δ15N values, such as upwelling areas.

Analysis and design of a novel segmented energy absorbing steel plate shear wall system

A steel plate shear wall (SPSW) system capable of providing strength and stiffness under normal load conditions and dissipating energy under extreme load conditions is proposed. The infill plate of this proposed Segmented Energy Absorbing SPSW (SEA-SPSW) system consists of two trapezoidal plate segments. For each plate segment, one edge is connected to the beam while the opposite edge is joined together by steel strips. The steel strips are held together using high strength bolts with long-slotted holes. Under normal load conditions, the SEA-SPSW behaves like a conventional SPSW. However, under extreme load conditions, the plate segments will slide between the steel strips and dissipate energy through friction. Because the proposed system does not rely on yielding or buckling to dissipate energy, it can be reset and reused after a severe load event. The behavior of this SEA-SPSW is studied using finite element and compared to an all steel conventional SPSW system. It is found that the proposed system not only helps reduce inter-story displacement, it also offers a desirable equivalent viscous damping ratio as well as a rather favorable energy dissipation to mass ratio.

Number Plate Detection in an Image

Automatic Vehicle license plate detection and recognition is a key technique in most of traffic related applications and is an active research topic in the image processing domain. Different methods, techniques and algorithms have been developed for license plate detection and recognitions. Due to the varying characteristics of the license plate like numbering system, colors, style and sizes of license plate, When detection and recognition are two separate jobs, which also results in a huge number of factors, there is an issue with identification. So,further research is still needed in this area. We propose a unified convolutional neural network (CNN) and the F1 score as metrics in a deep learning project for picture categorization which can localize license plates and recognize the letters. We work on license plate recognition and segments characters in the license plate firstly, and then recognizes each segmented character using Optical Character Recognition(OCR)techniques. Extensive experiments show the effectiveness and the efficiency of our proposed approach.

Late Ordovician to Early Devonian tectono-magmatic prequel to the Acadian Orogeny in northeastern North America and the British Isles

Geochemical data from Katian to earliest Emsian (∼453–405 Ma) igneous rocks in northeastern North America and the British Isles were compiled to identify tectono-magmatic events related to ocean closure and the formation of the Appalachian–Caledonian Belt. These rocks all have geochemical affinities with plate-margin settings, but only a few can be attributed to arc magmatism, whereas the others have slab-failure signatures or affinities with anhydrous, extensional plate-margin (A2-type) settings. Based on these setting attributions as well as constraints from the palaeomagnetic, palaeontologic, structural, stratigraphic and sedimentologic records, a model for Iapetus and Rheic ocean closure is proposed, which also involves three subordinate ocean plate segments: the Tornquist Sea, Acadian Seaway and Tetagouche–Exploits oceanic back-arc basin. The model includes several new perspectives, such as (1) an early Silurian rather than late Silurian closure of the Tetagouche–Exploits back-arc basin; (2) Acadian Seaway slab failure at the Ludlow–Pridoli boundary due to its interaction at depth with the overlying and slowly-sinking Tetagouche–Exploits slab, which generated profuse, extensional, A2-type volcanism; and (3) an Early Devonian reactivation of Acadian Seaway slab subduction, possibly due to Rheic Ocean closure and the convergence of a Gondwanan promontory against Avalonia, which was attached to oceanic lithosphere of the Acadian Seaway. Furthermore, age constraints allowed to identify chronological trends in the geochemical signatures of the igneous rocks under study, which suggest that development of a new tectono-magmatic signature was gradual due to compositional inheritance from the previous setting. These trends also suggest that, although the transition from active subduction to slab failure generates an increase in Nb/Y and light over heavy rare earth elements, these ratios tend to decrease with time due to a fading contribution of the sinking slab at the source, whereas high-field-strength element contents tend to increase due to a lack of new water input from subduction.

Analytic Solution for Free Vibrations of Folded Plate Structures

In this work, a new high accuracy solution for vibrations of structures made of plate segments is presented. Each plate segment is deforming both in and out of its plane, and the edges common to two plate segments must have compatible displacements, rotations, shear forces, and moments. It is obtained by using carefully chosen series that solve the combined partial differential equations of motion, for in-plane and out-of-plane deformations for all possible combinations of edge conditions. The number of terms in the series is taken such that convergence is ensured to the number of digits as shown. Examples of the new solutions are given and compared with available solutions for the same cases.

[formula omitted] wave teleseismic tomography of the subducted Chile rise

We investigate the crustal and upper mantle structure of the Aysén region of Chile from 44° to 49° S, a place where the diverging oceanic Nazca and Antarctic plates subduct beneath the South American continent. The Seismic Experiment in the Aysén Region of Chile (SEARCH) project operated a network of up to 60 land-based seismometers in this region between 2004 and 2006, centered over a 6 Myr old subducted spreading center. The data are used to examine the P wave velocity structure beneath the region using relative-arrival teleseismic travel time tomography, using 2534 P wave residuals from 173 teleseismic earthquakes. It is possible to image the velocity structure beneath the seismic network from ∼30 down to ∼300 km depth. The model can resolve structures at a spatial scale between ∼60 and ∼200 km and shows a large difference between the northern and southern parts of the region. To the north, a ∼100 km thick fast anomaly exists which dips away from the subduction trench; likely to be related to the subducting Nazca plate. Going to the south, as the age of this plate at the subduction trench decreases and arc volcanism shuts off, the fast anomaly migrates further from the trench, suggesting that the Nazca plate subducts at a reduced angle over a larger distance before the subduction angle steepens. The distinct sections of the fast anomaly suggest that slab tears exist across the fracture zones between subducted plate segments. Where the 6 Myr old subducted ridge segment is predicted to lie, there is a region of low velocity between ∼100 and ∼300 km depth, and no fast region associated with a subducting slab is present, indicating the presence of an asthenospheric window between the subducted Nazca and Antarctic plates.

Free vibration analysis of uniform thickness and stepped P-FGM plates: A FSDT-based dynamic stiffness approach

In this article, the dynamic stiffness method (DSM) is implemented to analyze the out-of-plane free vibration behavior of uniform thickness and stepped functionally graded plates with power-law material property variation (P-FGM) along the thickness direction. The P-FGM plate is discretized suitably in a number of segments, and for each segment the dynamic stiffness (DS) matrix is formulated. The displacement field is defined with respect to the physical neutral surface of the plate based on the first-order shear deformation theory (FSDT). Assuming Levy-type plate boundary conditions, the governing differential equations are solved exactly to obtain the DS matrix pertaining to a plate segment. Finally, the eigenvalues and eigenvectors of the assembled global DS matrix are computed using the Wittrick–Williams algorithm to obtain the natural frequencies and mode shapes of various P-FGM plate configurations. It is shown that the frequency results obtained using DSM are very accurate as the method utilizes the exact solution of the governing differential equations. It is emphasized that FSDT-based frequency results for stepped P-FGM plates are reported, for the first time, in this article, and these results can be used as benchmark solutions for comparison purposes.

Numerical study on bottom-hinged plate wave energy converter geometry design

This study focuses on the fluence on the power harvest performance exerted by plate geometry, damping setting and number of plates. Linear potential fluid theory is applied to calculate the hydrodynamic coefficients of the plate in frequency domain, and motion of bottom-hinged plate with different damping coefficients in time domain. The power capture performance is carried out based on the character of the plate motion. The performance of the device in different wave periods is studied and the adaption of the device is evaluated. The parameterized study is conducted to research the width, thickness, and the cross section of the plate. It is found that a two-dimensional plate model cannot fully reveal the hydrodynamic characteristic of the bottom-hinged plate, the width of the plate is an important factor and should take into consideration. The thickness of the plate is not a sensitive factor. The cross section of the plate has a distinct influence on plate performance. The number of the plate segment with a fixed whole width is studied. It is found that dividing plate cannot improve the performance of the plate, and dividing the plate cannot improve the performance of the plate while facing non-front-inducing waves either.

Hindu Kush intermediate-depth seismicity: A possible explanation for the preferential asymmetry displayed by river catchments within the corresponding epicentral area

Some conceptual models proposed for explaining the Hindu Kush intermediate-depth seismicity assumed that a subhorizontal fracture was migrating laterally, from east toward west, along the strike of a subducted tectonic plate. The present study has identified a distinct cluster of earthquake hypocenters, likely corresponding to the advancing tip of the subhorizontal fracture. Those hypocenters belonged to a set of fairly moderate earthquakes (5.6 ≤ M ≤ 6.5), which had not been, so far, explicitly addressed in the Hindu Kush seismo-tectonic interpretations, and which were proven to be virtually the only events displaying a failure regime characteristic to a laterally propagating breakoff – namely, reverse-fault focal mechanisms with subhorizontal compression axes parallel to the slab strike. A separate, upper-positioned hypocenter cluster was noticed to include all the Mw ≥ 7 intermediate-depth earthquakes: it was conjectured, relying on a previously published numerical model, that those strong events could be triggered by upward transfer of the viscoelastic stress induced by the slab pull increase caused by an episode of lateral breakoff advance. At the same time, as the inferred breakoff fracture enables the deeper segment of the plate to detach from the shallower segment, the plate region situated above the severed region is relieved of the gravitational pull that was imposed by the deeper, and currently detached, plate segment. In response to the resulting crustal rebound, the surface topography is expected to exhibit down-tilting to the west. Such an anticipation seems to be confirmed by the catchments of several streams which flow roughly perpendicular to the intermediate-depth earthquakes epicentral domain: relevant geomorphic indices (the swath profile average and maximum elevation curves; the transverse hypsometric integral – THi; the transverse topographic symmetry factor – T-vector) computed for the concerned valleys consistently suggested larger uplift rates in the east, as compared to those manifest further to the west.

Numerical modelling of opposing subduction in the Western Mediterranean

The geodynamic evolution of the Western Mediterranean related to the closure of the Ligurian-Tethys ocean is not yet fully resolved. We present a new 3D numerical model of double subduction with opposite polarities fostered by the inherited segmentation of the Ligurian-Tethys margins and rifting system between Iberia and NW Africa. The model is constrained by plate kinematic reconstructions and assumes that both Alboran-Tethys and Algerian-Tethys plate segments are separated by a NW-SE transform zone enabling that subduction polarity changes from SE-dipping in the Alboran-Tethys segment to NW-dipping in the Algerian-Tethys segment. The model starts about late Eocene times at 36.5 Ma and the temporal evolution of the simulation is tied to the geological evolution by comparing the rates of convergence and trench retreat, and the onset and end of opening in the Alboran Basin. Curvature of the Alboran-Tethys slab is imposed by the pinning of its western edge when reaching the end of the transform zone in the adjacent west-Africa continental block. The progressive curvature of the trench explains the observed regional stress reorientation changing from N-S to NW-SE and to E-W in the central and western regions of the Alboran Basin. The increase of the retreat rates from the Alboran-Tethys to the Algerian-Tethys slabs is compatible with the west-to-east transition from continental-to-magmatic-to-oceanic crustal nature and with the massive and partially synchronous calc-alkaline and alkaline magmatism.

Strength enhancements across various parts in intermediate and edge stiffened angle sections due to cold-forming

This study presents an experimental study on the strength characteristics of steel coupons extracted from various parts of Cold-Formed Steel (CFS) Intermediate and Edge Stiffened Angle Sections. The light gauge thin-walled CFS sections formed for specific design requisites are of different shapes, and often the profiles are stiffened by the employment of intermediate and edge stiffeners to resist elemental plate segment local buckling. As a result, these sections undergo modifications in their actual tensile strength characteristics across various regions, say the flat portions, corners and stiffened portions of the cross-section geometry due to the cold-forming from sheets into sections; hence is essential to know the stress-strain responses of the section before using them as structural members. Based on this study on various grades of stiffened angle sections, it is found that there is strength enhancement due to forming. Moreover, there is a notable increase in tensile capacities, say the maximum of 8% in the yield strength and a 5% increase in the ultimate strength in the corners and at the stiffened zones, with slightly less elongation capacity, in comparison with the tensile properties of flat parts. And also, there exists a marginal difference of 2–3% in the tensile properties between the partially stiffened and fully stiffened elemental parts of flat portions. These results can be effectively utilised while performing higher-order parametric studies by the Finite Element Analysis approach.

Seismicity of Turkey and Real-Time Seismology Applications in Determining Earthquake Hazard

Turkey is between three major tectonic plates, is the most active area of the Mediterranean region in terms of earthquake activity. Relative motions between the African, Arabian and Eurasian plates account for most of the tectonic activity in the region. As a result, the Anatolian plate has a high danger for seismicity. This consists of the North Anatolian Fault Zone (NAFZ), East Anatolian Fault Zone (EAFZ) and SE Anatolian Thrust Zone which form the borders of the Anatolian Plate and important active fault segments throughout Western Anatolia. All these active faults cause a short time intervals intensive damages in Turkey earthquakes. In order to investigate and to real-time monitor the seismic activity and seismotectonic of Turkey and its vicinity, The Kandilli Observatory and Earthquake Research Institute (KOERI) of Bogaziçi University and AFAD operates seismic stations countrywide. Observatory has been supplying mainly 3 kind of seismological data: phase readings, waveform and catalogue to the earth scientists in Turkey. Earth science studies have an important contribution to the emergence of earthquake hazard. The evaluation of the data receiving from the seismic stations contributes to the determination of earthquake hazard in detail, and to contribute to the minimization of the risks of the earthquake by developing earthquake catalogues. Also, all of the earthquake parameters after the earthquake, automatically distributed and mapped. After an important earthquake, KOERI and AFAD is quickly sent information from the smartphones to the society and the decision-making institutions carrying out disaster studies.

Effectiveness of laddered embossed structure in a locking compression plate for biodegradable orthopaedic implants.

Locking compression plate (LCP) has conventionally been the most extensively employed plate in internal fixation bone implants used in orthopaedic applications. LCP is usually made up of non-biodegradable materials that have a higher mechanical capability. Biodegradable materials, by and large, have less mechanical strength at the point of implantation and lose strength even more after a few months of continuous degradation in the physiological environment. To attain the adequate mechanical capability of a biodegradable bone implant plate, LCP has been modified by adding laddered - type semicircular filleted embossed structure. This improved design may be named as laddered embossed locking compression plate (LELCP). It is likely to provide additional mechanical strength with the most eligible biodegradable material, namely, Mg-alloy, even after continuous degradation that results in diminished thickness. For mechanical validation and comparison of LELCP made up of Mg-alloy, four-point bending test (4PBT) and axial compressive test (ACT) have been performed on LELCP, LCP and continuously degraded LELCP (CD-LELCP) with the aid of finite element method (FEM) for the assembly of bone segments, plate and screw segments. LELCP, when subjected to the above mentioned two tests, has been observed to provide 26% and 10.4% lower equivalent stress, respectively, than LCP without degradation. It is also observed mechanically safe and capable of up to 2 and 6 months of continuous degradation (uniform reduction in thickness) for 4PBT and ACT, respectively. These results have also been found reasonably accurate through real-time surgical simulations by approaching the most optimal mesh. According to these improved mechanical performance parameters, LELCP may be used or considered as a viable biodegradable implant plate option in the future after real life or in vivo validation.

Vivaldi Antennas for Contactless Sensing of Implant Deflections and Stiffness for Orthopaedic Applications.

The implementation of novel coaxial dipole antennas has been shown to be a satisfactory diagnostic platform for the prediction of orthopaedic bone fracture healing outcomes. These techniques require mechanical deflection of implanted metallic hardware (i.e., rods and plates), which, when loaded, produce measurable changes in the resonant frequency of the adjacent antenna. Despite promising initial results, the coiled coaxial antenna design is limited by large antenna sizes and nonlinearity in the resonant frequency data. The purpose of this study was to develop two Vivaldi antennas (a.k.a., “standard” and “miniaturized”) to address these challenges. Antenna behaviors were first computationally modeled prior to prototype fabrication. In subsequent benchtop tests, metallic plate segments were displaced from the prototype antennas via precision linear actuator while measuring resultant change in resonant frequency. Close agreement was observed between computational and benchtop results, where antennas were highly sensitive to small displacements of the metallic hardware, with sensitivity decreasing nonlinearly with increasing distance. Greater sensitivity was observed for the miniaturized design for both stainless steel and titanium implants. Additionally, these data demonstrated that by taking resonant frequency data during implant displacement and then again during antenna displacement from the same sample, via linear actuators, that “antenna calibration procedures” could be used to enable a clinically relevant quantification of fracture stiffness from the raw resonant frequency data. These improvements mitigate diagnostic challenges associated with nonlinear resonant frequency response seen in previous antenna designs.

Prediction of the in-plane vibration behavior of porous annular plate with porosity distributions in the thickness and radial directions

A semi-analytical model is proposed in this study to investigate the in-plane vibration behavior of porous annular plate with porosity distributions in the thickness and radial directions. A variational method combined with a multi-segment technique is employed to establish the theoretical model of elastic restrained porous annular plate. Admissible functions of each plate segment are expanded in the mixed series form, that is, the Jacobian orthogonal polynomial for radial variables and Fourier series for circumferential variables. The boundary penalty parameters are introduced to implement different boundary restrictions and the coupling penalty parameters are employed for ensuring the continuity conditions between segments. A series of numerical examples are given to discuss the convergence characteristics and numerical stability of the current model. The comparison between modal tests and numerical predictions shows that good prediction capabilities with acceptable errors are achieved by the proposed method. The influences of geometrical and material parameters on the in-plane vibration characteristics of porous annular plate are also discussed in detail.

Influence of the chemical composition on the hardness of defibrator plate segments

Influence of the chemical composition on the hardness of defibrator plate segments. The paper presents the results of the hardness measurements of the material of defibrator plate segments, in connection with their chemical composition. The investigations of the chemical composition were performed using Energy Dispersive X-ray Spectroscopy (EDS). The hardness was measured using the Rockwell method. The increased number of the alloy components leads to an increase in hardness by approx. 3%, in comparison with the normalized L210H21S cast steel. Changes of the chemical composition and increase in the number of alloy components are ineffective from the viewpoint of the alloy hardness.