Core Constructions Research Articles

Investigation of the feasibility of using aluminum honeycomb cores in the design of the fin of the aircraft

The issues related to the use of a honeycomb cores in the design, the weight ratio of the empennage units are considered on the example of the fin of an aircraft. The article provides a comparative qualitative assessment of the weight efficiency, manufacturability of the design and design features of the fin with the use of honeycomb panels, compared with the classical frame construction of fin units. In addition, the article discusses the problems associated with the operation and repair of honeycomb core constructions. In the article the calculations of mass determination of honeycomb panel and transverse set for cases the thickness of the profile C=13%, C=8%, C=4% were carried out. Using he method of sequential calculations of each structural part of the honeycomb panel or the frame construction, the resulting masses of units were obtained. Based on the results, we can conclude that the use of three-layer panels in the construction of the fin with a given area and construction height is not justified, since the difference in weight is negligible, and honeycomb panels have several disadvantages.

Family Violence: Transformation of Developmental Trauma through Personal Construct Psychotherapy

The experience of family violence is one of harm that is traumatic and cumulative, leaving children with trauma-related negative core beliefs that have long-lasting effects on their brains and bodies. These core constructs determined by the impact of the violator, while adaptive at the time in organizing the children’s development around survival, are developmentally unhelpful understandings of their experience. Developmental trauma changes core constructions about people, the world, safety, relationships, and the future. It is proposed that personal construct psychology has a role in psychotherapy for child survivors of family violence. The paper will acknowledge two personal construct models for treating trauma. Through the presentation of a therapeutic case study of an eleven-year-old survivor of family violence, the account will attempt to demonstrate the usefulness of these models in treating family violence. This approach is one of credulously exploring the children’s reactive responses to traumatic distress, with the focus of the psychotherapy on understanding the core constructions of self-versus-other, of self-other permanency, and of self-other constancy which are central to a constructivist conceptualization of trauma (Leitner, Faidley, & Celentana, 2000). Meanings are changed by elaborating the traumatic experiences, and reconstructing core constructs through sociality.

Physical Activity Engagement outside of College Physical Education: Application of the Transtheoretical Model.

Objective: In this study, we examined physical activity (PA) engagement outside of college physical education (PE) classes using the Transtheoretical Model (TTM). Methods: Overall, 414 university students enrolled in PE classes voluntarily participated in this study. Participants were asked to complete a survey packet to measure 4 core constructs of TTM and their PA level performed outside of PE classes. Among the participants, 150 randomly selected students were asked to wear a triaxial accelerometer for 7 consecutive days to identify their PA level. Descriptive statistics and multivariate analyses of variance were used to determine the association between stages of motivational readiness and other strategic core constructions. Results: We categorized 77% of respondents into either the "action" stage or the "maintenance" stage for engaging in additional PA outside of the classes. Behavioral processes of change showed a graded and significant association with the stages. Both self-efficacy and decisional balance were significantly higher in students at higher stages. Conclusion: Our findings showed that most students enrolled in college PE classes had additional PA outside of the class participation. In addition, behavioral processes may be effective strategies for this specific target group to promote PA.

Glocalization as the dominant trend in the development of socio-political being: conflict models and constructs

Being a complex dialectical interaction process for differently directed social centrifugal and centripetal movements, glocalization leads to a significant transformation of political being and consciousness (Chumakov, 2016). Being a natural reaction to the developing unification narrative, the localization and differentiation tendencies, on the other hand, become a causal basis of the struggle for overcoming differences. Both trends symbolize, within their frameworks, the basic values of each narrative and create their political mythologies, each of which has an impact on the collective stratum of consciousness and, as a consequence, on a certain model of socio-political behavior of individuals. Political "myths of global unity" lead the core constructions of political and social being - the nation and the state - to a decrease in their authority and legitimacy level; at the same time, the "mythology of difference", while preserving the dominant political values, reorients them to local manifestations, also losing their connection with the central elements of the political matter. Thus, special conflictual forms of development are formed in contemporary society and are conditioned by both real objective preconditions and artificially generated constructs. Socio-political being, therefore, is in a state of dialectical equilibrium and develops within the conflict paradigm.

Creative design for sandwich structures: A review

Sandwich structures are important innovative multifunctional structures with the advantages of low density and high performance. Creative design for sandwich structures is a design process based on sandwich core structure evolution mechanisms, material design method, and panel (including core structure and facing sheets) performance prediction model. The review outlines recent research efforts on creative design for sandwich structures with different core constructions such as corrugated core, honeycomb core, foam core, truss core, and folded cores. The topics discussed in this review article include aspects of sandwich core structure design, material design, and mechanical properties, and panel performance and damage. In addition, examples of engineering applications of sandwich structures are discussed. Further research directions and potential applications are summarized.

Organocatalyzed Synthesis of Functionalized Quinolines.

As one of the most widely investigated compound skeleton, quinolines possess important medicinal and biological activities. As such, a great number of literatures, including reviews, have reported various methodologies to construct quinolines. Recently, organocatalyzed reactions have attracted the attention of organic chemists due to its being "green" because the reactions avoid the use of toxic metals. In this review, various distinctive contributions are surveyed with specific emphasis on organocatalyzed reactions for quinoline core constructions.

Sound transmission loss of sandwich panel with closed octahedral core

In this paper, an ultralightweight sandwich panel with closed octahedral core is proposed, which demonstrates excellent acoustic property of sound transmission loss as well as great mechanical performance. Simulation models are established with considerations of acoustic-structure interactions. The validity of simulation calculations is checked against experimental measurements with the tested specimens provided by additive manufacturing. Numerical discussions are conducted to demonstrate the effects of incident angles, topological parameters, and so on which should be helpful for practical design. This novel class of sandwich structure with closed octahedral core constructions shows promising engineering applications.

Sandwich Structures with Prismatic and Foam Cores: A Review

This article provides a comprehensive review of recent research efforts on the development and characterization of sandwich structures with corrugated, honeycomb, and foam cores. The topics discussed in this review article include aspects of core‐face bonding and reinforcement, enhancement of core mechanical properties and panel performance (including the role of structural hierarchy), and multifunctional advantages offered by different core constructions. In addition, the review discusses potential applications, including in morphing wing design, impact resistance, and ultralightweight applications. Future research directions are discussed.

Modelling of a Hall Effect-Based Current Sensor with an Open Core Magnetic Concentrator.

The present paper deals with the modelling of a Hall effect current sensor with open core magnetic concentrator. 3D magnetic field modelling is carried out using the finite element method (FEM) and Comsol Multiphysics software. Two rectangular core constructions are considered. Different geometric parameters of the magnetic concentrator are varied and their influence on the sensor characteristic is studied, with the aim of reducing the dependence on the output signal on the distance to the conductor. Of the studied parameters, core window length leads to the most significant change in the sensor characteristic. Future work can include the optimization of the sensor construction.

Enhanced Transformer Model for Low- and Mid-Frequency Transients—Part II: Validation and Simulation Results

The transformer model developed in Part I is validated based on the zero-sequence test data, a ferroresonance event, and the geomagnetically induced current (GIC) measurements. Various transformer core constructions, including single phase, three limb, five limb, conventional shell type, and seven-limb shell type are represented, based on the proposed transformer model. The simulation results show high accuracy of the proposed transformer model in representing the studied cases. The study reveals that the saturation of the transformers at a given GIC level is more severe than that predicted by the existing transformer models. Furthermore, the proposed transformer model clearly explains the reasons for the previously reported discrepancies between the GIC experimental and simulation results. The study also concludes that for an accurate transformer model, particularly for the three-limb core type, the detailed representation of the zero-sequence characteristic is an essential requirement. Such a characteristic can be obtained based on either the proposed approach of the paper or a zero-sequence dc excitation test in addition to the test data at the power frequency.

Metallic sandwich panels subjected to multiple intense shocks

The mechanical response and fracture of metal sandwich panels subjected to multiple impulsive pressure loads (shocks) were investigated for panels with honeycomb and folded plate core constructions. The structural performance of panels with specific core configurations under multiple impulsive pressure loads is quantified by the maximum transverse deflection of the face sheets and the core crushing strain at mid-span of the panels. A limited set of simulations was carried out to find the optimum core density of a square honeycomb core sandwich panels under two shocks. The panels with a relative core density of 4%–5% are shown to have minimum face sheet deflection for the loading conditions considered here. This was consistent with the findings related to the sandwich panel response subjected to a single intense shock. Comparison of these results showed that optimized sandwich panels outperform solid plates under shock loading. An empirical method for prediction of the deflection and fracture of sandwich panels under two consecutive shocks – based on finding an effective peak over-pressure – was provided. Moreover, a limited number of simulations related to response and fracture of sandwich panels under multiple shocks with different material properties were performed to highlight the role of metal strength and ductility. In this set of simulations, square honeycomb sandwich panels made of four steels representing a relatively wide range of strength, strain hardening and ductility values were studied. For panels clamped at their edge, the observed failure mechanisms are core failure, top face failure and tearing at or close to the clamped edge. Failure diagrams for sandwich panels were constructed which reveal the fracture and failure mechanisms under various shock intensities for panels subjected to up to three consecutive shocks. The results complement previous studies on the behavior and fracture of these panels under high intensity dynamic loading and further highlights the potential of these panels for development of threat-resistant structural systems.

Mechanical behavior of carbon fiber composite lattice core sandwich panels fabricated by laser cutting

This paper presents a novel method for rapid fabrication and prototyping of low-density carbon fiber sandwich panel cores based on laser beam cutting (LBC). Using LCB, sandwich panels with lattice core constructions with oblique and vertical strut morphologies were fabricated from two fiber-orientation architectures. Scanning electron microscopy images illustrate the relatively small extent of damage from laser cutting. The shear strength of the lattice cores was improved by eliminating core-to-face sheet bond failures. Crushing and shear responses of fabricated truss cores were measured, and analytical models are presented to predict the stiffness, strength and dominant failure modes under each loading condition. The sandwich-panel cores investigated appear to be promising candidates for lightweight systems and multifunctional applications.

Improved calculation of winding losses in gapped inductors

Field patterns in gapped inductors are more complicated than the fields in transformers, thus the winding losses in inductors are given with higher complexity. An improved presentation of winding losses in inductors is reported, using a correction loss factor. The full expression of that correction loss factor, called kF, is tuned using FEM calculations. An approximation of kF as a function of a parameter κ is provided. The parameter is depending on the sum of the distance coil–air gap and 1∕3 winding thickness, divided by the window width. The features of the approach are the fast and straight winding loss calculation combined with sufficient accuracy and wide application for gapped inductors with different frequencies, wire diameters, conductor fittings, and core and air gap constructions.

Stomatal frequency responses in hardwood‐swamp vegetation from Florida during a 60‐year continuous CO2 increase

In a stomatal frequency analysis of leaf remains of Quercus nigra, Acer rubrum, Myrica cerifera, Ilex cassine, and Osmunda regalis that were preserved in precisely dated peat deposits of north-central Florida, the stomatal index decreased as a response to an atmospheric CO(2) increase from 310 ppmv to 370 ppmv over the past 60 years. The observations indicate that CO(2) responsiveness may occur in different canopy levels of hardwood-swamp vegetation. Apart from common woody plants, long-lived ferns of the undergrowth appear to be affected by CO(2) changes. Response rates are most pronounced in M. cerifera, I. cassine, and O. regalis. The potential of these species for quantifying past atmospheric CO(2) levels is assessed by a combined analysis of the well-dated buried leaf record and herbarium material collected during the past century. Leaf remains of the widely occurring species M. cerifera and I. cassine are concluded to be highly suitable for CO(2) reconstructions, by which the application range of the stomatal frequency proxy is extended into the warm-temperate to subtropical realm of North America.

Cast post and core foundation for the badly broken down molar tooth.

This article addresses the difficult clinical problem of restoration of endodontically treated posterior teeth, where there is nothing left of the clinical crown. A step by step procedure, including instrumentation and materials and a new impression technique, is described in detail, with clinical photographs. This technique results in the fabrication of a robust and extremely retentive post and core on which to place fixed prosthodontic restorations. The author has placed over 600 restorations of this type over a five year period, without any reported failures. With the 'greying' of the population there are increased demands on dentists to restore structurally compromised teeth, and increasing expectations of the performance of these restorations. This technique is offered as a superior alternative to conventional post and core constructions methods.

A Study on Flexural Properties of Sandwich Injection Moldings

Abstract In recent years composite materials have been widely used, largely because of their superior mechanical properties. Sandwich constructions can be suitably tailored to make use of each material's properties in the moldings, effectively (for example in honeycomb core constructions) in order to improve the mechanical properties of the moldings. In the injection molding process, however, it is quite difficult to fabricate sandwich constructions. A sandwich injection molding process in which the sandwich injection moldings are performed using two melt sources and one nozzle has been developed. At the present, there have been few investigations with respect to the mechanical properties of the sandwich structures produced by the injection moldings. In this study, we tried to examine the sandwich construction made by the injection molding process. Three kinds of materials including polyamide resin, the short and the longer fiber reinforced polyamides were used as layer structural materials for the sandwich injection moldings. The flexural properties for the sandwich injection moldings were measured and their fracture surfaces observed to clarify the mechanical behaviors. Furthermore, the flexural moduli for the sandwich injection moldings composed of the polyamides reinforced with the different fiber lengths were predicted based on two-layer orientation model.

Arrangement of Thin Film Cores for Planar Coil Inductor

Miniaturized thin film inductors with various shaped magnetic cores are described. The dimensions of these inductors are about 2 mm × 2 mm. Since they are used at frequencies above 100 MHz, the effective utilization of the magnetic core must be considered. We measured the inductance of inductors with magnetic cores of various shapes, and investigated the flux density distribution. The inductors were based on from 100 to 240 core pieces, each piece with from one to three coil turns. The conductor of these inductors was confined to a single plane to prevent connection defects. According to measured results, the inductor with the highest inductance per unit area employed two-turn magnetic core pieces. There was no significant difference in the inductance of closed-loop and open-loop core constructions.

A 3-year postoperative clinical evaluation of posts and cores beneath existing crowns

Fabrication of posts and cores for fixed partial denture (FPD) and removable partial denture (RPD) abutment restorations is common in dentistry. The biocompatibility of various post and core techniques with the restorations was clinically evaluated according to location and function. In this study, 154 post and core constructions for 150 patients were observed for a 3-year period to determine if the function of the original restorations remained unsatisfactory. The following techniques were included: (1) screw post and light-curing composite resins, (2) cemented post with parallel sides and light-curing composite resins, and (3) a cast and core technique. Seventeen of the 154 restorations failed; four failures were attributed to root fractures, three to radicular caries, and five to crown dislodgment, while five failures were from detachment of the post and core from the root. The statistical analysis revealed that only the factor “type of abutment” (RPDs and FPDs) had some effect on the failure of the restorations.