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Artykuły w czasopismach na temat "Honeycomb sandwiched beam"
1
Sharif, Umer, Bei Bei Sun, Peng Zhao, Dauda Sh Ibrahim, Orelaja Oluseyi Adewale i Aleena Zafar. "Dynamic Behavior Analysis of the Sandwich Beam Structure with Magnetorheological Honeycomb Core under Different Magnetic Intensities: A Numerical Approach". Materials Science Forum 1047 (18.10.2021): 31–38. http://dx.doi.org/10.4028/www.scientific.net/msf.1047.31.
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In this article a sandwich beam structure with honeycomb core filled of MRE (magnetorheological elastomer) with different ratios of Elastomer and iron particles is proposed. Modal response for structures with Nylon and Resin8000 honeycomb core filled with MRE and sandwiched between aluminum face sheets were analyzed and compared for two different ratios of MRE by placing magnets at free end and center of the structure. The force generated by magnets on the sandwich beam structure was calculated using ANSYS EDT and the modal response of the structure was then observed under generated magnetic force using ANSYS Workbench. The results showed that the resonance frequency of the structure decreased as the magnetic intensity was increased for all the cases specially for the first mode. Secondly structure with Nylon honeycomb core showed lower frequency drop and higher deformation than the structure with Resin8000 honeycomb core.
2
Atli-Veltin, B., i F. Gandhi. "Energy absorption of sandwiched honeycombs with facesheets under in-plane crushing". Aeronautical Journal 117, nr 1193 (lipiec 2013): 687–708. http://dx.doi.org/10.1017/s000192400000837x.
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AbstractThe in-plane crushing and energy absorption of sandwiched honeycomb cores with facesheets are examined through finite element simulations. Assuming no debonding between the facesheet and honeycomb core (which would be the case if manufacturing techniques such as brazing are used to produce very strong bonds between the facesheeet and the core), intracellular buckling mode for thin facesheets, and wrinkling mode for thick facesheets are observed. In the dimpling mode, deformation is governed by the core, honeycomb vertical cell walls do not deform, and the inclined wall deformation does not vary through the cell depth. In the wrinkling mode, deformation is governed by the facesheet, the vertical cell walls deform significantly, and the inclined cell wall deformation varies through the cell depth. Increasing cell angle increased Specific Energy Absorption (SEA) for honeycombs with thin facesheets. Decreasing vertical cell wall length increased SEA for honeycombs with thick facesheets. Increasing wall thickness and decreasing core depth increased SEA for honeycombs with thin and thick facesheets. With geometric changes, SEA increased ~3 times over the baseline configurations. For a given keel beam dimensions, using fewer rows of larger cells reduces the effective non-dimensional core-depth, thereby increasing the effect of the facesheet and the SEA significantly. The SEA of sandwiched honeycombs with facesheets in in-plane crushing appears to be competitive with, or better than, SEA honeycombs in out-of-plane crushing.
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Liu, Weidong, Honglin Li, Jiong Zhang i Hongda Li. "Theoretical analysis on the elasticity of a novel accordion cellular honeycomb core with in-plane curved beams". Journal of Sandwich Structures & Materials 22, nr 3 (11.04.2018): 702–27. http://dx.doi.org/10.1177/1099636218768174.
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Flexible skin is an essential component for morphing wind turbine blade to maintain a smooth profile and bear aerodynamic loads during morphing. Cellular honeycomb cores with low in-plane and high out-of-plane stiffness are potential candidates for support structures of flexible skin. Honeycomb structure also requires zero Poisson’s ratio to avoid unnecessary stress and strain during one-dimensional morphing. A novel accordion cellular honeycomb core of close-to-zero Poisson’s ratio with in-plane corrugated U-type beams was proposed as a solution for these problems. The elastic properties of the structure are illustrated through a combination of theoretical analysis and finite element analysis. Results show that better in-plane morphing and out-of-plane load-bearing capabilities can be obtained with parameters of larger height-to-length ratio, spacing-to-length ratio and vertical beam to U-type beam thickness ratio as well as smaller thickness-to-length ratio. Results of comparisons on properties of the proposed honeycomb with two existing accordion honeycombs reveal that the in-plane elastic modulus of the proposed structure is as low as about 56% of that of the accordion honeycomb with V-type beams and 79% of that of the accordion honeycomb with cosine beams, showing better in-plane property but weaker out-of-plane load-bearing capability. Nevertheless, the out-of-plane load-bearing capability can be reinforced by increasing the vertical beam to U-type beam thickness ratio. Smaller driving force and less energy consumption are required by the proposed honeycomb core than conventional structures during morphing. The methods and results could be used for predictions of elasticity in design of sandwich morphing skin with similar cellular honeycomb cores.
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Zhu, Dalei, Xiaoxin Wang, Shuang Yao, Jianfeng Zhang i Mengmeng Jiao. "Analytical and experimental study on honeycomb sandwich plates reinforced by ring beam of satellites". Journal of Physics: Conference Series 2472, nr 1 (1.05.2023): 012007. http://dx.doi.org/10.1088/1742-6596/2472/1/012007.
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Abstract The equivalent parameters of hexagon aluminum honeycombs are work out with the theories of sandwich plates in this paper. The honeycomb sandwich plate reinforced by ring beam applied with static load is simulated by the finite element model of honeycomb sandwich plates, which is validated by static test. The research results show that the numerical calculation error of the honeycomb sandwich plate is less than 10% compared with test results, which is acceptable for an engineering project, and the mechanical behavior of the honeycomb sandwich plate can be described in detail. Thus, the method of equivalent honeycomb parameter is proved to be effective for the design and analysis of honeycomb sandwich plates. The influence of equivalent elasticity modulus and equivalent shear modulus to honeycomb sandwich plates can be reflected exactly from the results which are figured out with the equivalent theories of sandwich plates. The assembly clearance and assembly accuracy have a significant influence to the test results of honeycomb sandwich plates, which is obvious especially at a lower load level.
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Li, Chong, Hui-Shen Shen i Hai Wang. "Nonlinear Vibration of Sandwich Beams with Functionally Graded Negative Poisson’s Ratio Honeycomb Core". International Journal of Structural Stability and Dynamics 19, nr 03 (marzec 2019): 1950034. http://dx.doi.org/10.1142/s0219455419500342.
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This paper investigates the nonlinear flexural vibration of sandwich beams with functionally graded (FG) negative Poisson’s ratio (NPR) honeycomb core in thermal environments. The novel constructions of sandwich beams with three FG configurations of re-entrant honeycomb cores through the beam thickness direction are proposed. The temperature-dependent material properties of both face sheets and core of the sandwich beams are considered. 3D full-scale finite element analyses are conducted to investigate the nonlinear vibration, and the variation of effective Poisson’s ratio (EPR) of the sandwich beams in the large deflection region. Numerical simulations are carried out for the sandwich beam with FG-NPR honeycomb core in different thermal environmental conditions, from which results for the same sandwich beam with uniform distributed NPR honeycomb core are obtained as a basis for comparison. The effects of FG configurations, temperature changes, boundary conditions, and facesheet-to-core thickness ratios on the nonlinear vibration ratio curves and EPR–deflection curves of sandwich beams are discussed in detail.
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Zhu, Xiujie, Chao Xiong, Junhui Yin, Dejun Yin i Huiyong Deng. "Bending Experiment and Mechanical Properties Analysis of Composite Sandwich Laminated Box Beams". Materials 12, nr 18 (12.09.2019): 2959. http://dx.doi.org/10.3390/ma12182959.
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The failure modes, ultimate load, stiffness performance, and their influencing factors of a composite sandwich laminated box beam under three-point bending load are studied by an experiment, finite element model, and analytical method. The three-point bending experiment was carried out on three different core composite sandwich laminated box beams, and the failure modes and bearing capacity were studied. With the use of composite progressive damage analysis and the core elastoplastic constitutive model, the finite element model of the composite sandwich laminated box beam was established, and the three-point bending failure process and failure modes were analyzed. The analytical model was established based on the Timoshenko beam theory. The overall bending stiffness and shear stiffness of the composite sandwich laminated box beam were calculated by the internal force–displacement relationship. The results show that the composite sandwich laminated box beam mainly suffers from local crushing failure, and the errors between the finite element simulation and the experiment result were within 7%. The analytical model of the composite sandwich laminated box beam can approximately predict the overall stiffness parameters, while the maximum error between theoretic results and experimental values was 5.2%. For composite aluminum honeycomb sandwich laminated box beams with a ratio of span to height less than 10, the additional deflection caused by shear deformation has an error of more than 25%. With the ratio of circumferential layers to longitudinal layers increasing, the three-point bending ultimate load of the composite sandwich laminated box beam increases, but the ratio of the overall stiffness to mass reduces. The use of low-density aluminum foam and smaller-wall-thickness cell aluminum honeycombs allows for the more obvious benefits of light weight.
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ZHU, KAIGE, i DAINING FANG. "CALCULATION OF DISPERSION CURVES FOR ARBITRARY WAVEGUIDES USING FINITE ELEMENT METHOD". International Journal of Applied Mechanics 06, nr 05 (październik 2014): 1450059. http://dx.doi.org/10.1142/s1758825114500598.
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Dispersion curves for waveguide structures are an important prerequisite for the implementation of guided wave-based nondestructive evaluation (NDE) approach. Although many methods exist, each method is only applicable to a certain type of structures, and also requires complex programming. A Bloch theorem-based finite element method (FEM) is proposed to obtain dispersion curves for arbitrary waveguides using commercial finite element software in this paper Dispersion curves can be obtained for a variety of structures, such as homogeneous plates, multilayered structures, finite cross section rods and honeycomb sandwiches. The propagation of guided waves in honeycomb sandwich plates and beams are discussed in detail. Then, dispersion curves for honeycomb sandwich beams are verified by experiments.
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Sharif, Umer, Lin Chen, Beibei Sun, Dauda Sh Ibrahim, Orelaja Oluseyi Adewale i Noman Tariq. "An experimental study on dynamic behaviour of a sandwich beam with 3D printed hexagonal honeycomb core filled with magnetorheological elastomer (MRE)". Smart Materials and Structures 31, nr 5 (18.03.2022): 055004. http://dx.doi.org/10.1088/1361-665x/ac5c8a.
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Abstract Sandwich beams with an aluminium face sheet and a magnetorheological elastomer (MRE) of varying proportions of elastomer and magnetic particles (weight to weight)% filled in a honeycomb core of Nylon and Resin8000 are manufactured and experimentally analysed in this study. To evaluate the dynamic properties of sandwich beams, manufactured structures subjected to sine sweep and classic shock tests and assessed both with and without magnetic field of varying intensities applied on the free end of the beam. The experimental results demonstrated good performance in vibration level attenuation, particularly in the structure’s primary vibration mode under consideration. The magnetic field applied was capable of lowering the first natural frequency of the proposed sandwich beam structures. Experiment results showed that an increase in an induced magnetic field shifted the natural frequencies, vibration amplitude, and damping ratio of sandwich panels with MRE honeycomb core.
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Gdoutos, E. E., i M. S. Konsta-Gdoutos. "Load and Geometry Effect on Failure Mode Initiation of Composite Sandwich Beams". Applied Mechanics and Materials 3-4 (sierpień 2006): 173–78. http://dx.doi.org/10.4028/www.scientific.net/amm.3-4.173.
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Facing compressive failure, facing wrinkling and core shear failure are the most commonly encountered failure modes in sandwich beams with facings made of composite materials. The occurrence and sequence of these failure modes depends on the geometrical dimensions, the form of loading and type of support of the beam. In this paper the above three failure modes in sandwich beams with facings made of carbon/epoxy composites and cores made of aluminum honeycomb and two types of foam have been investigated. Two types of beams, the simply supported and the cantilever have been considered. Loading included concentrated and uniform. It was found that in beams with foam core facing wrinkling and core shear failure occur, whereas in beams with honeycomb core facing compressive failure and core shear crimping take place. Results were obtained for the dependence of failure mode on the geometry of the beam and the type of loading. The critical beam spans for failure mode transition from core shear to wrinkling failure were established. It was found that initiation of a particular failure mode depends on the properties of the facing and core materials, the geometrical configuration and loading of composite sandwich beams.
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Meng, Li Qing, Shi Zhe Chen, Yan Wu i Xue Feng Shu. "Projectile Impact Behaviour of Sandwich Material with Nomex Honeycomb and Metallic Skins". Advanced Materials Research 204-210 (luty 2011): 632–35. http://dx.doi.org/10.4028/www.scientific.net/amr.204-210.632.
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Projectile impact test is carried out to investigate damage and failure behaviour under different impact velocity from 90m/s to 160m/s. Strain-time history curve on the control points are analysed in this paper. Sandwich beam dynamic response and the degree of structural degeneration under impact loading both depends on the thickness of metallic skins. The projectile impact test demonstrate difference damage characteristics between the sandwich beams with different thickness skins. The peak stress value are estimated approximately to determine the skin deformation and sandwich beam global damage degree.
Rozprawy doktorskie na temat "Honeycomb sandwiched beam"
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Petras, Achilles. "Design of sandwich structures". Thesis, University of Cambridge, 1999. https://www.repository.cam.ac.uk/handle/1810/236995.
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Failure modes for sandwich beams of GFRP laminate skins and Nomex honeycomb core are investigated. Theoretical models using honeycomb mechanics and classical beam theory are described. A failure mode map for loading under 3-point bending, is constructed, showing the dependence of failure mode and load on the ratio of skin thickness to span length and honeycomb relative density. Beam specimens are tested in 3-point bending. The effect of honeycomb direction is also examined. The experimental data agree satisfactorily with the theoretical predictions. The results reveal the important role of core shear in a sandwich beam's bending behaviour and the need for a better understanding of indentation failure mechanism. High order sandwich beam theory (HOSBT) is implemented to extract useful information about the way that sandwich beams respond to localised loads under 3-point bending. 'High-order' or localised effects relate to the non-linear patterns of the in-plane and vertical displacements fields of the core through its height resulting from the unequal deformations in the loaded and unloaded skins. The localised effects are examined experimentally by Surface Displacement Analysis of video images recorded during 3-point bending tests. A new parameter based on the intrinsic material and geometric properties of a sandwich beam is introduced to characterise its susceptibility to localised effects. Skin flexural rigidity is shown to play a key role in determining the way that the top skin allows the external load to pass over the core. Furthermore, the contact stress distribution in the interface between the central roller and the top skin, and its importance to an indentation stress analysis, are investigated. To better model the failure in the core under the vicinity of localised loads, an Arcan- type test rig is used to test honeycomb cores under simultaneous compression and shear loading. The experimental measurements show a linear relationship between the out-of-plane compression and shear in honeycomb cores. This is used to derive a failure criterion for applied shear and compression, which is combined with the high order sandwich beam theory to predict failure caused by localised loads in sandwich beams made of GFRP laminate skins and Nomex honeycomb under 3-point bending loading. Short beam tests with three different indenter's size are performed on appropriately prepared specimens. Experiments validate the theoretical approach and reveal the nature of pre- and post-failure behaviour of these sandwich beams. HOSBT is used as a compact computational tool to reconstruct failure mode maps for sandwich panels. Superposition of weight and stiffness contours on these failure maps provide carpet plots for design optimisation procedures.
2
Maheri, M. R. "Vibration damping in composite/honeycomb sandwich beams". Thesis, University of Bristol, 1991. http://hdl.handle.net/1983/d96ba3e9-edb0-4a07-ac6e-69328ed22678.
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Ahmad, Nazeer. "Vibration mitigation in spacecraft components using Stewart platform and particle impact damping". Thesis, 2020. https://etd.iisc.ac.in/handle/2005/4856.
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A spacecraft encounters two regimes of vibrations: launch loads and on-orbit loads. Both these loads propagate through the spacecraft structure, which is primarily made up of honeycomb sandwich. The launch loads that are high amplitude and low frequency are critical to subsystems mounted on honeycomb sandwich panels that further amplify it owing to low inherent damping and local resonance. The damping behavior of the panels can be improved, and amplification at resonances can be reduced by inserting damping particles in the empty cells of the honeycomb core. Another way of reducing the vibration is to use a multi-axis isolator between source and target. This scenario is particularly useful for on-board extremely low amplitude vibrations called micro-vibration. In this work, both approaches have been addressed. First, a multi-axis vibration isolator design based on a Stewart-Gough platform (SGP) and a modified Stewart-Gough Platform (MSGP) is considered.
We propose a design where the first six modal frequencies are close to each other for a predefined payload, thus enabling effective vibration isolation for all six primary modes. The equations of dynamics of the 6-6 semi-regular SGP was obtained in terms of five geometric variable and position of the mass center of the combined top platform and the payload. A gradient-based optimization was used to obtain the dimensions of an SGP such that the first six modal frequencies are close to each other – the ratio of the maximum to the minimum natural frequency (also termed as dynamic isotropy index) was obtained as 1.70 and 1.31 when the torsional mode was excluded, respectively. A detailed analysis, including the effects of a typical payload and leg inertia, was performed. Based on the obtained design, a prototype Stewart-Gough vibration isolator was fabricated. The experiments with the prototype show that the observed ratio of the maximum to the minimum natural frequency, excluding the torsional mode, was 1.50. To obtain a better dynamic isotropy index, a modified version of the semi-regular SGP is considered. The main modification considered is that the attachment points on each platform are not in a circle but two circles. This modification leads to a configuration where all six frequencies are the same even after incorporating a cross-blade flexural joint and metallic bellow to provide the required stiffness to legs. The detailed finite element model used for modal analysis and steady-state dynamic analysis is performed. The transfer functions show the isolation of 33dB/oct is achievable. A numerical study to assess the performance of a fully isotropic MSGP with the top platform made up of honeycomb embedded with damping particles is also carried out.
In the second approach to improve the damping characteristics of the honeycomb panel, damping particles (DPs) are filled in the core of the honeycomb sandwich at strategically selected locations. The locations are chosen based on the targeted frequency band and mode shapes of the host structure. We present a mathematical model governing the motion of the cell-walls, DPs, and honeycomb plate/beam. The coupled dynamics of damping particle and honeycomb plate/beam is modeled using the discrete element method (DEM) combined with the finite element method (FEM). The DEM used to model the dynamics of the DPs is based on Newton's Laws, and the particle-particle and particle-cell walls interaction are modeled using modified nonlinear dissipative Hertz contact theory in conjunction with Coulomb friction. The coupled equations of motion of DPs, cell-walls, and host structure were solved using a numerical method. The interactions of damping particles with the walls of the cells and its overall effect on the frequency response function (FRF) and the damping of the structure were obtained. In two cases: a beam and a plate are considered for numerical and experimental studies.
In the honeycomb cantilever beam, contiguous blocks of cells near the tip of the cantilever beam were filled with the damping particles, and the beam was excited with a random signal near the fixed end. The damping and transfer functions were obtained and compared with the mathematical model, and they were found to match very well. Further, the model was used to study the effect of fill fraction, mass ratio, and excitation signal level on the transfer function. Significant reduction of vibration level was observed with respect to mass ratio and fill fraction. In another study, a honeycomb plate was partially filled at selected locations with damping particles. All the four edges were excited by a swept sine signal. The damping ratios and resonance peaks of the lower four modes of the HC plate, excited up to 1000 Hz, were obtained experimentally from the FRF measurements and numerically from the DEM model. They also compare very well. The damping ratios, response at resonances, and the FRF profiles are also similar. Significant improvement in damping ratios and attenuation of vibration level has been observed in the experiments.ISRO
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Lin, Yue Chung, i 林雲志. "Fracture Mechanics Analysis for Adhesive Delamination in Honeycomb Sandwich Beam". Thesis, 2004. http://ndltd.ncl.edu.tw/handle/47037375801862987593.
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碩士國立中正大學
機械系
92
The honeycomb sandwich plate have the advantage of high strength and low specific weight, so were popularly applied in main and minor structure of aircraft. The honeycomb core is bond by variable adhesives and faces, so the interface between adhesives and core are easy to be debonded (or called delamination) while undertaking external force. Hence the defects always appear in manufacturing, which makes the structure strength lower and unsafe. To provide a convenient design, safety examining and fixing principle for sandwich, it is essential to build up a method for calculating energy release rate. Analyzes and investigating the adhesive-core interface delamination problem, the present paper considers that（1）the foundation modulus of facing plate, adhesive layer and core under the crack plane is provided；（2）the flexural rigidity of the facing plate and adhesive layer is provided (3) the analytical solution of compliance and energy release rate of the composite beam is solved on condition that the crack zone pivot will subject to shear and rotate, where is then comparied with the result of FEM. The result of energy release rate of this study is compared with that of Hwang, Lee﹝19﹞. The result of comparison reveals that the effect of adhesive layer could not be ignored.
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Murthy, MVVS. "Wave Transmission Characteristics in Honeycomb Sandwich Structures using the Spectral Finite Element Method". Thesis, 2014. http://etd.iisc.ac.in/handle/2005/2901.
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Wave propagation is a phenomenon resulting from high transient loadings where the duration of the load is in µ seconds range. In aerospace and space craft industries it is important to gain knowledge about the high frequency characteristics as it aids in structural health monitoring, wave transmission/attenuation for vibration and noise level reduction.
The wave propagation problem can be approached by the conventional Finite Element Method(FEM); but at higher frequencies, the wavelengths being small, the size of the finite element is reduced to capture the response behavior accurately and thus increasing the number of equations to be solved, leading to high computational costs. On the other hand such problems are handled in the frequency domain using Fourier transforms and one such method is the Spectral Finite Element Method(SFEM). This method is introduced first by Doyle ,for isotropic case and later popularized in developing specific purpose elements for structural diagnostics for inhomogeneous materials, by Gopalakrishnan. The general approach in this method is that the partial differential wave equations are reduced to a set of ordinary differential equations(ODEs) by transforming these equations to another space(transformed domain, say Fourier domain). The reduced ODEs are usually solved exactly, the solution of which gives the dynamic shape functions. The interpolating functions used here are exact solution of the governing differential equations and hence, the exact elemental dynamic stiffness matrix is derived. Thus, in the absence of any discontinuities, one element is sufficient to model 1-D waveguide of any length. This elemental stiffness matrix can be assembled to obtain the global matrix as in FEM, but in the transformed space. Thus after obtaining the solution, the original domain responses are obtained using the inverse transform. Both the above mentioned manuscripts present the Fourier transform based spectral finite element (FSFE), which has the inherent aliasing problem that is persistent in the application of the Fourier series/Fourier transforms. This is alleviated by using an additional throw-off element and/or introducing slight damping in to the system. More recently wave let transform based spectral finite element(WSFE) has been formulated which alleviated the aliasing problem; but has a limitation in obtaining the frequency characteristics, like the group speeds are accurate only up-to certain fraction of the Nyquist(central frequency). Currently in this thesis Laplace transform based spectral finite elements(LSFE) are developed for sandwich members. The advantages and limitations of the use of different transforms in the spectral finite element framework is presented in detail in Chapter-1.
Sandwich structures are used in the space craft industry due to higher stiffness to weight ratio. Many issues considered in the design and analysis of sandwich structures are discussed in the well known books(by Zenkert, Beitzer). Typically the main load bearing structures are modeled as beam sand plates. Plate structures with kh<1 is analysed based on the Kirch off plate theory/Classical Plate Theory(CPT) and when the bending wavelength is small compared to the plate thickness, the effect of shear deformation and rotary inertia needs to be included where, k is the wave number and h is the thickness of the plate. Many works regarding the wave propagation in sandwich structures has been published in the past literature for wave propagation in infinite sandwich structure and giving the complete description of dispersion relation with no restriction on frequency and wavelength. More recently exact analytical solution or simply supported sandwich plate has been derived. Also it is seen by comparison of dispersion curves obtained with exact (3D formulation of theory of elasticity) and simplified theories (2D formulation as generalization of Timoshenko theory) made on infinite domain and concluded that the simplified theory can be reliably used to assess the waveguide properties of sandwich plate in the frequency range of interest. In order to approach the problems with finite domain and their implementation in the use of general purpose code; finite degrees of freedom is enforced. The concept of displacement based theories provides the flexibility in assuming different kinematic deformations to approach these problems. Many of the displacement based theories incorporate the Equivalent Single Layer(ESL) approach and these can capture the global behavior with relative ease. Chapter-2 presents the Laplace spectral finite element for thick beams based on the First order Shear Deformation Theory (FSDT). Here the effect of different choices of the real part of the Laplace variable is demonstrated. It is shown that the real part of the Laplace variable acts as a numerical damping factor. The spectrum and dispersion relations are obtained and the use of these relations are demonstrated by an example. Here, for sandwich members based on FSDT, an appropriate choice of the correction factor ,which arises due to the inconsistency between the kinematic hypothesis and the desired accuracy is presented. Finally the response obtained by the use of the element is validated with experimental results.
For high shock loading cases, the core flexibility induces local effects which are very predominant and this can lead to debonding of face sheets. The ESL theories mentioned above cannot capture these effects due to the computation of equivalent through the thickness section properties. Thus, higher order theories such as the layer-wise theories are required to capture the local behaviour. One such theory for sandwich panels is the Higher order Sandwich Plate theory (HSaPT). Here, the in-plane stress in the core has been neglected; but gives a good approximation for sandwich construction with soft cores. Including the axial inertial terms of the core will not yield constant shear stress distribution through the height of the core and hence more recently the Extended Higher order Sandwich Plate theory (EHSaPT) is proposed. The LSFE based on this theory has been formulated and is presented in Chapter-4. Detailed 3D orthotropic properties of typical sandwich construction is considered and the core compressibility effect of local behavior due to high shock loading is clearly brought out. As detailed local behavior is sought the degrees of freedom per element is high and the specific need for such theory as compared with the ESL theories is discussed.
Chapter-4 presents the spectral finite element for plates based on FSDT. Here, multi-transform method is used to solve the partial differential equations of the plate. The effect of shear deformation is brought out in the spectrum and dispersion relations plots. Response results obtained by the formulated element is compared and validated with many different experimental results.
Generally structures are built-up by connecting many different sub-structures. These connecting members, called joints play a very important role in the wave transmission/attenuation. Usually these joints are modeled as rigid joints; but in reality these are flexible and exhibits non-linear characteristics and offer high damping to the energy flow in the connected structures. Chapter-5 presents the attenuation and transmission of wave energy using the power flow approach for rigid joints for different configurations. Later, flexible spectral joint model is developed and the transmission/attenuation across the flexible joints is studied.
The thesis ends with conclusion and highlighting futures cope based on the developments reported in this thesis.
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Murthy, MVVS. "Wave Transmission Characteristics in Honeycomb Sandwich Structures using the Spectral Finite Element Method". Thesis, 2014. http://hdl.handle.net/2005/2901.
Pełny tekst źródłaStreszczenie:
Wave propagation is a phenomenon resulting from high transient loadings where the duration of the load is in µ seconds range. In aerospace and space craft industries it is important to gain knowledge about the high frequency characteristics as it aids in structural health monitoring, wave transmission/attenuation for vibration and noise level reduction.
The wave propagation problem can be approached by the conventional Finite Element Method(FEM); but at higher frequencies, the wavelengths being small, the size of the finite element is reduced to capture the response behavior accurately and thus increasing the number of equations to be solved, leading to high computational costs. On the other hand such problems are handled in the frequency domain using Fourier transforms and one such method is the Spectral Finite Element Method(SFEM). This method is introduced first by Doyle ,for isotropic case and later popularized in developing specific purpose elements for structural diagnostics for inhomogeneous materials, by Gopalakrishnan. The general approach in this method is that the partial differential wave equations are reduced to a set of ordinary differential equations(ODEs) by transforming these equations to another space(transformed domain, say Fourier domain). The reduced ODEs are usually solved exactly, the solution of which gives the dynamic shape functions. The interpolating functions used here are exact solution of the governing differential equations and hence, the exact elemental dynamic stiffness matrix is derived. Thus, in the absence of any discontinuities, one element is sufficient to model 1-D waveguide of any length. This elemental stiffness matrix can be assembled to obtain the global matrix as in FEM, but in the transformed space. Thus after obtaining the solution, the original domain responses are obtained using the inverse transform. Both the above mentioned manuscripts present the Fourier transform based spectral finite element (FSFE), which has the inherent aliasing problem that is persistent in the application of the Fourier series/Fourier transforms. This is alleviated by using an additional throw-off element and/or introducing slight damping in to the system. More recently wave let transform based spectral finite element(WSFE) has been formulated which alleviated the aliasing problem; but has a limitation in obtaining the frequency characteristics, like the group speeds are accurate only up-to certain fraction of the Nyquist(central frequency). Currently in this thesis Laplace transform based spectral finite elements(LSFE) are developed for sandwich members. The advantages and limitations of the use of different transforms in the spectral finite element framework is presented in detail in Chapter-1.
Sandwich structures are used in the space craft industry due to higher stiffness to weight ratio. Many issues considered in the design and analysis of sandwich structures are discussed in the well known books(by Zenkert, Beitzer). Typically the main load bearing structures are modeled as beam sand plates. Plate structures with kh<1 is analysed based on the Kirch off plate theory/Classical Plate Theory(CPT) and when the bending wavelength is small compared to the plate thickness, the effect of shear deformation and rotary inertia needs to be included where, k is the wave number and h is the thickness of the plate. Many works regarding the wave propagation in sandwich structures has been published in the past literature for wave propagation in infinite sandwich structure and giving the complete description of dispersion relation with no restriction on frequency and wavelength. More recently exact analytical solution or simply supported sandwich plate has been derived. Also it is seen by comparison of dispersion curves obtained with exact (3D formulation of theory of elasticity) and simplified theories (2D formulation as generalization of Timoshenko theory) made on infinite domain and concluded that the simplified theory can be reliably used to assess the waveguide properties of sandwich plate in the frequency range of interest. In order to approach the problems with finite domain and their implementation in the use of general purpose code; finite degrees of freedom is enforced. The concept of displacement based theories provides the flexibility in assuming different kinematic deformations to approach these problems. Many of the displacement based theories incorporate the Equivalent Single Layer(ESL) approach and these can capture the global behavior with relative ease. Chapter-2 presents the Laplace spectral finite element for thick beams based on the First order Shear Deformation Theory (FSDT). Here the effect of different choices of the real part of the Laplace variable is demonstrated. It is shown that the real part of the Laplace variable acts as a numerical damping factor. The spectrum and dispersion relations are obtained and the use of these relations are demonstrated by an example. Here, for sandwich members based on FSDT, an appropriate choice of the correction factor ,which arises due to the inconsistency between the kinematic hypothesis and the desired accuracy is presented. Finally the response obtained by the use of the element is validated with experimental results.
For high shock loading cases, the core flexibility induces local effects which are very predominant and this can lead to debonding of face sheets. The ESL theories mentioned above cannot capture these effects due to the computation of equivalent through the thickness section properties. Thus, higher order theories such as the layer-wise theories are required to capture the local behaviour. One such theory for sandwich panels is the Higher order Sandwich Plate theory (HSaPT). Here, the in-plane stress in the core has been neglected; but gives a good approximation for sandwich construction with soft cores. Including the axial inertial terms of the core will not yield constant shear stress distribution through the height of the core and hence more recently the Extended Higher order Sandwich Plate theory (EHSaPT) is proposed. The LSFE based on this theory has been formulated and is presented in Chapter-4. Detailed 3D orthotropic properties of typical sandwich construction is considered and the core compressibility effect of local behavior due to high shock loading is clearly brought out. As detailed local behavior is sought the degrees of freedom per element is high and the specific need for such theory as compared with the ESL theories is discussed.
Chapter-4 presents the spectral finite element for plates based on FSDT. Here, multi-transform method is used to solve the partial differential equations of the plate. The effect of shear deformation is brought out in the spectrum and dispersion relations plots. Response results obtained by the formulated element is compared and validated with many different experimental results.
Generally structures are built-up by connecting many different sub-structures. These connecting members, called joints play a very important role in the wave transmission/attenuation. Usually these joints are modeled as rigid joints; but in reality these are flexible and exhibits non-linear characteristics and offer high damping to the energy flow in the connected structures. Chapter-5 presents the attenuation and transmission of wave energy using the power flow approach for rigid joints for different configurations. Later, flexible spectral joint model is developed and the transmission/attenuation across the flexible joints is studied.
The thesis ends with conclusion and highlighting futures cope based on the developments reported in this thesis.
Części książek na temat "Honeycomb sandwiched beam"
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Zghal, Souhir, i Rachid Nasri. "Experimental Investigation for Forced Vibration of Honeycomb Sandwich Beams". W Applied Condition Monitoring, 223–33. Cham: Springer International Publishing, 2016. http://dx.doi.org/10.1007/978-3-319-41459-1_22.
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Lajili, Ramzi, Khaoula Chikhaoui i Mohamed Lamjed Bouazizi. "Statistical Investigations of Uncertainty Impact on Experiment-Based Identification of a Honeycomb Sandwich Beam". W Applied Condition Monitoring, 176–85. Cham: Springer International Publishing, 2018. http://dx.doi.org/10.1007/978-3-319-94616-0_18.
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Kassab, R., i P. Sadeghian. "Three-Point Bending of Sandwich Beams with FRP Facing and PP Honeycomb Core". W Lecture Notes in Civil Engineering, 353–59. Singapore: Springer Nature Singapore, 2022. http://dx.doi.org/10.1007/978-981-19-0503-2_29.
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Essaadaoui, K., M. Ait El Fqih, M. Idiri i B. Boubeker. "Numerical Study of Damaged, Failure and Cracking of Concrete Beam Reinforced by Honeycomb Sandwich Panel Structures". W Communications in Computer and Information Science, 316–25. Cham: Springer International Publishing, 2020. http://dx.doi.org/10.1007/978-3-030-45183-7_24.
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Fu, Yuchen, i Pedram Sadeghian. "Flexural characteristics of bio-based sandwich beams made of paper honeycomb cores and flax FRP skins". W Current Perspectives and New Directions in Mechanics, Modelling and Design of Structural Systems, 1515–20. London: CRC Press, 2022. http://dx.doi.org/10.1201/9781003348443-247.
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Fu, Yuchen, i Pedram Sadeghian. "Flexural characteristics of bio-based sandwich beams made of paper honeycomb cores and flax FRP skins". W Current Perspectives and New Directions in Mechanics, Modelling and Design of Structural Systems, 525–26. London: CRC Press, 2022. http://dx.doi.org/10.1201/9781003348450-247.
Pełny tekst źródłaStreszczenia konferencji na temat "Honeycomb sandwiched beam"
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Ruzzene, M. "Vibration and Sound Radiation of Sandwich Beams With Honeycomb Truss Core". W ASME 2003 International Mechanical Engineering Congress and Exposition. ASMEDC, 2003. http://dx.doi.org/10.1115/imece2003-41552.
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The vibrations of and the sound radiation from sandwich beams with truss core are here analyzed. The structure of the core is composed of a sequence of identical unit cells repeating along the beam length and across the core thickness. Each cell is composed of beam elements assembled to form a frame structure. Layouts with honeycomb patterns arranged through the thickness of the core are considered. This design represents an alternative with respect to the traditional application of honeycombs in sandwich construction. The proposed configuration provides sandwich beams with interesting structural as well as acoustic characteristics. A spectral finite element model is developed to evaluate the structural and the acoustic behavior of the considered class of sandwich beams. The spectral model can be easily coupled with a Fourier Transform based analysis of the sound radiated by the fluidloaded structure. The model predicts the performance of beams with various core configurations. The comparison is carried out in terms of vibration and sound radiation in an unbounded acoustic half-plane. Hexagonal and re-entrant honeycomb configurations are considered to study the effects of core geometry on structural response and acoustic radiation.
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Sugimura, Yuki. "Design and Characterization of Small-Scale Sandwich Beams Fabricated by Photolithography and Electrodeposition". W ASME 2000 International Mechanical Engineering Congress and Exposition. American Society of Mechanical Engineers, 2000. http://dx.doi.org/10.1115/imece2000-1103.
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Abstract Small-scale sandwich beams with core structures having cell diameters and wall widths on the order of 500 μm and 100 μm, respectively, have been produced through fabrication methods that combine photolithography and electrodeposition. Two core configurations have been examined: 1) regular hexagonal honeycomb and 2) high-aspect ratio hexagonal shells having an open architecture. The bending response of the sandwich beams has been examined and compared with the beam theory predictions. Shear stiffness of the honeycomb core was considerably high and therefore the bending behavior was dominated by the face sheets. The bending of the sandwich specimens with the hexagonal shells, on the other hand, was largely dependent on the core. The sandwich beam dimensions investigated in this study have not been optimized for weight minimization and structural efficiency. Further advances in fabrication methods to produce micrometer-size features and high-aspect ratio cores will enable realization of structurally efficient, lightweight sandwich beams and panels that can be used as multifunctional components in small-scale devices.
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Wallace, Brian T., Bhavani V. Sankar i Peter G. Ifju. "Delamination Suppression in Sandwich Beams Using Translaminar Reinforcements". W ASME 1999 International Mechanical Engineering Congress and Exposition. American Society of Mechanical Engineers, 1999. http://dx.doi.org/10.1115/imece1999-0130.
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Abstract The present study is concerned with translaminar reinforcement in a sandwich beam for preventing buckling of a delaminated face-sheet under axial compression. Graphite/epoxy pins are used as reinforcement in the thickness direction of sandwich beams consisting of graphite/epoxy face-sheets and a Aramid honeycomb core. Compression tests are performed to understand the effects of the diameter of the reinforcing pins and reinforcement spacing on the ultimate compressive strength of the delaminated beams. A finite element analysis is performed to understand the effects of translaminar reinforcement on the critical buckling loads and post-buckling behavior of the sandwich beam under axial compression.
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Avery, John L., Manickam Narayanan i Bhavani V. Sankar. "Compressive Failure of Debonded Sandwich Beams". W ASME 1998 International Mechanical Engineering Congress and Exposition. American Society of Mechanical Engineers, 1998. http://dx.doi.org/10.1115/imece1998-0380.
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Abstract Compression tests were performed on debonded sandwich beams made of graphite/epoxy face-sheets and aramid fiber honeycomb core. The sandwich beams were manufactured using a vacuum bagging process. The face-sheet and the sandwich beam were co-cured, thus the excess resin from the graphite/epoxy prepregs was used to bond the face-sheet and the core. Delamination between one of the face sheets and the core was introduced by using a Teflon® layer during the curing process. Axial compression tests were performed to determine the ultimate load carrying capacity of the debonded beams. Double Cantilever Beam tests were performed to determine the fracture toughness of the face-sheet/core interface. It was concluded that linear buckling analysis was inadequate for predicting the ultimate loads. A post-buckling analysis was carried out using a nonlinear plane finite element model of the sandwich beam. The ultimate loads predicted by the finite element model were reasonably good for specimens with long delaminations.
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Daniel, Isaac M., i R. A. Jandro Abot. "Fabrication, Testing and Analysis of Composite Sandwich Structures". W ASME 1998 International Mechanical Engineering Congress and Exposition. American Society of Mechanical Engineers, 1998. http://dx.doi.org/10.1115/imece1998-1206.
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Abstract The objective of this work was to study the behavior of composite sandwich structures and develop simple models to explain this behavior as a function of material, geometric and loading parameters. The scope of the study consists of mechanical characterization of the sandwich constituent materials, i. e., composite facings, honeycomb or foam cores, and adhesive layers; fabrication and testing of sandwich beams in pure bending; identification and recording of failure mechanisms by direct observation and nondestructive evaluation; and comparison of observed deformation and failure behavior with analytical predictions. Sandwich beams were fabricated by bonding carbon/epoxy (AS4/3501-6) facings to an aluminum honeycomb core with FM 73 film adhesive. Special techniques were developed to prevent premature failures under the loads and in the core and to insure failure in the test section under pure bending. Strains to failure in the facings were recorded with strain gages, and beam deflections and core strains were recorded with Moire techniques. The beam facings displayed characteristic nonlinearities for the composite material used, a softening nonlinearity on the compression side and a stiffening one on the tension side. These nonlinearities appear more pronounced than in the case of monotonic axial loadings of the composite material alone. The linear response of the beam is perfectly described by a simple bending model neglecting the contribution of the core, however, the more pronounced nonlinear behavior requires more accurate characterization of the core and adhesive materials separately, and more refined modeling.
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Vinson, Jack R., i Nihar R. Satapathy. "Analysis and Optimization of Foam Core Mid-Plane Asymmetric Sandwich Beams Under Lateral Loads". W ASME 2000 International Mechanical Engineering Congress and Exposition. American Society of Mechanical Engineers, 2000. http://dx.doi.org/10.1115/imece2000-2035.
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Abstract The equations with which to analyze, design and optimize honeycomb sandwich beams subjected to laterally distributed loads are presented. They apply to beams using composite materials and for isotropic materials. Specifically they account for mid-plane asymmetry in order to maximize the structural efficiency, thus providing for differing face materials, ply sequencing and/or thicknesses. Explicit solutions are given for the beam subjected to a uniform lateral load for several boundary conditions. To attain minimum weight, the means to select each face thickness, the core depth and the honeycomb core wall thickness and cell size are given. Localized face dimpling and face wrinkling, using and comparing the results of Heath equation and the Hoff-Mautner equation are included. The effects of transverse shear deformation are also shown. In order to choose the face material and core materials to achieve a minimum weight structure, Factors of Merit are defined for the faces and the core. Various face materials are then compared.
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Maley, Scott, i C. T. Sun. "Particulate Enhanced Damping in Sandwich Structures". W ASME 1999 International Mechanical Engineering Congress and Exposition. American Society of Mechanical Engineers, 1999. http://dx.doi.org/10.1115/imece1999-0134.
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Abstract This paper investigates the damping effect of loose particulate within the core of sandwich structures. Beam specimens fabricated from aluminum honeycomb core and IM7 carbon fiber face sheets with various amounts of loose particulate are experimentally examined. Both free vibration and forced vibration tests are performed. It is shown that a moderate amount of particulate can cause a large increase in damping. The effect of varying amounts of particulate is also investigated. Plate equations of motion with damping and inertia terms are derived to model the beam and compare with experimental results. Effective mass and effective viscous damping are generated by matching the theoretical model to the experimental data.
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Okabe, Yoji, Hiroshi Sugiyama i Toru Inayoshi. "Lightweight Actuator Structure With SMA Honeycomb Core and CFRP Skins". W ASME 2009 Conference on Smart Materials, Adaptive Structures and Intelligent Systems. ASMEDC, 2009. http://dx.doi.org/10.1115/smasis2009-1236.
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The authors proposed a sandwich structure that consists of a shape memory alloy (SMA) honeycomb core and carbon fiber reinforced plastic (CFRP) skins as a shape-controllable structure. This actuator structure can be bent by heating, even though it is lightweight and has a moderate bending stiffness. First, unidirectional CFRP skins were bonded to the SMA honeycomb core made of thin SMA foils and a pre-shear-strain was applied to the SMA core. Then the ends of the upper and lower skins were fixed together to other cores. The length of the sandwich beam specimen was 18cm, and the weight was only 9.2g. When the specimen was heated, the beam was bent upward taking the form of a sigmoid curve and generated the sufficient actuation force. Then, when the specimen was cooled to the room temperature, the beam returned to the initial straight shape. Hence the two-way actuation is possible. This method has the better ability to bend skins with high in-plane stiffness, because the recovery shear force has the out-of-plane stress component and is applied uniformly to the skins from the inner core. Also the microscopic mechanism of this bending deformation could be clarified by a numerical simulation with the finite element method. Furthermore, this actuator structure has a possibility to be used as a member to suppress the resonance, because the natural frequency of the beam can be controlled owing to the increase in the elastic moduli of SMA by heating.
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Sharif, Umer, Beibei Sun, Irfan Tariq, Dauda Sh Ibrahim, Orelaja Oluseyi Adewale i Aleena Zafar. "Static and Modal Analysis of Sandwich Beam Structure with Magnetorheological Honeycomb Core". W 2020 6th International Conference on Mechanical Engineering and Automation Science (ICMEAS). IEEE, 2020. http://dx.doi.org/10.1109/icmeas51739.2020.00011.
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Omer, A., i K. Ferhat. "Dynamic Behavior of FML/Aluminum Honeycomb Sandwich Structures Using Vibrating Beam Technique". W SAMPE neXus 2021. NA SAMPE, 2021. http://dx.doi.org/10.33599/nasampe/s.21.0430.
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