Showing papers on "Flexural rigidity published in 2010"
TL;DR: In this paper, the experimental and finite element analysis results of a proposed steel buckling-restrained brace (BRB) have been presented, which has two components: a steel core plate that carries all axial forces during tension and compression, and two identical restraining members that sandwich the core plate with fully tensioned high-strength A490 bolts to prevent core buckling.
255 citations
TL;DR: The overall understanding of the capacity of composite analogue bone models mimic the structural properties of average healthy adult human bones is advanced and the failure modes of these composite models were close to published findings for human bones.
Abstract: Composite analogue bone models provide consistent geometric and structural properties that represent a valuable asset in a range of biomechanical analyses and testing procedures. The objective of this study was to evaluate the diaphyseal structural properties of the large-size Fourth-Generation composite analogue femur and tibia models concentrated on mechanical behaviors under axial compression, bending and torsion. Thirty of each large-size composite analogue models (femora and tibiae) were tested under medial-lateral four-point bending, anterior-posterior four-point bending, axial compression and external rotational torque to evaluate flexural rigidity, axial stiffness, torsional rigidity and ultimate failure strength. The composite femur was tested under torsion at both the femoral neck and the mid-diaphyseal areas. Large-size Fourth-Generation composite replicate bones exhibited intra-specimen variations under 10% for all cases and was also found to perform within the biological range of healthy adult bones (age: <80 years old) range with respect to flexural rigidity (<8%) and torsional rigidity (<12%). The failure modes of these composite models were close to published findings for human bones (four-point bending: butterfly fragment fracture; torsional: spiral fracture; and compression: transverse fracture). The large-size composite analogue femur and tibia are close to ideal replicas for standardization in biomechanical analyses. One advantage of these analogue models is that their variability is significantly lower than that of cadaveric specimens for all loading regimens. Published results vary widely in cadaveric studies, which is likely due to the high anatomic variability among cadaveric specimens. This study evaluated and advanced our overall understanding of the capacity of composite analogue bone models mimic the structural properties of average healthy adult human bones.
187 citations
TL;DR: In this paper, the authors used the plastic stress method to predict the stiffness and resistance of CFT components under combined axial and flexural loading and determined the best models for predicting the stiffness.
Abstract: Concrete-filled tubes (CFTs) are composite structural members that consist of a steel tube and concrete infill. CFTs optimize the contributions of both components by improving their geometric efficiency and fully using their inherent strengths. The concrete infill is confined by the steel tube, resulting in a triaxial state of compression that increases the strength and strain capacity of the concrete. The perimeter steel is at its optimal location, and the concrete infill delays local and global buckling of the tube. CFTs are easily and rapidly constructed and provide significant compression, bending, and shear resistance. They may be used for bridge piers and building columns. However, current design specifications for CFTs vary significantly, thereby limiting the current understanding and use of these components. This study addresses combined axial and flexural loading and determines the best models for predicting the stiffness and resistance of circular CFT. A database of 122 test specimens was compiled and evaluated. The results indicate that the plastic stress method is a simple yet effective method to predict the resistance of circular CFT components under combined loading. These data show that current specifications provide inaccurate predictions of the flexural stiffness, and a new stiffness expression is proposed. The proposed models permit simple yet accurate predictions of stiffness and resistance and allow engineers to use CFT components routinely in structural design.
143 citations
TL;DR: In this paper, the shape of the outer rise for plate ages ranging from 0 to 50 Ma is predicted by using an elastic plate model with variable elastic thickness Te(x) as a function of the distance measured from the trench axis.
Abstract: SUMMARY The Chilean subduction zone presents a unique opportunity to study trench outer rise deformation of the subducting oceanic lithosphere at different thermal ages. The shape of the outer rise for plate ages ranging from 0 to 50 Ma is predicted by using an elastic plate model with variable elastic thickness Te(x) as a function of the distance measured from the trench axis. In addition, the uncertainties of our results are estimated by performing a Monte Carlo-type analysis and we considered explicitly the sediment loading effect on the lithospheric flexure in regions where the trench is heavily sedimented. The results show a systematic reduction in Te of up to 50 per cent (or reduction in the flexural rigidity D of up to ∼90 per cent) from the peak of the outer rise to the trench axis. The reduction in Te and D observed in most of the bathymetric profiles is coincident with (i) high plate curvatures (>5 × 10 −7 m −1 ), (ii) strong bending moments (>10 16 N m), (iii) pervasive fracturing and faulting of the oceanic basement (as imaged by high-resolution bathymetry data) and (iv) reduction in crustal and mantle seismic velocities. The reduction in flexural rigidity towards the trench suggests a weakening of the oceanic lithosphere and is interpreted to be caused partially by fracturing and a likely increase in fluid-pore pressure. In general, our estimates do not show consistent increases in elastic thickness as a function of plate age. This result suggests that either Te is independent of plate age or Te depends strongly on other factors. These factors could include lithospheric weakening due to hydro-fracturing and the loading history of the plate prior to subduction.
88 citations
TL;DR: In this paper, the thermal buckling behavior of composite laminated plates was studied by making the use of finite element method and the results indicated that the high E1/E2 and α2/α1 ratios of AS4/3501-6 and T 300/5208 laminates produce higher bending rigidity along the fiber direction and higher in-plane compressive force in a direction perpendicular to the fibre direction.
80 citations
TL;DR: In this paper, the effects of hollow glass microsphere fillers and the addition of short fibre reinforcements on the mechanical behaviour of epoxy binding matrix composites were studied, and the results showed that flexural and compressive stiffness, maximum compressive stresses, fracture toughness and impact absorbed energy decrease significantly with increasing filler content.
Abstract: This paper presents the results of an investigation into the effects of hollow glass microsphere fillers and of the addition of short fibre reinforcements on the mechanical behaviour of epoxy binding matrix composites. Properties like flexural stiffness, compressive strength, fracture toughness and absorbed impact energy, were studied. The specimens were cut from plates produced by vacuum resin transfer moulding having a microsphere contents of up to 50% and with fibre reinforcement up to 1.2% by volume. The tests performed with unreinforced composites show that flexural and compressive stiffness, maximum compressive stresses, fracture toughness and impact absorbed energy decrease significantly with increasing filler content. However, in terms of specific values, both flexural and compressive stiffness and impact absorbed energy increase with microsphere content. The addition of glass fibre produces only a slight improvement in the flexure stiffness and fracture toughness, while increasing significantly the absorbed impact energy. In contrast, the addition of a small percentage of carbon fibres produces an important improvement in both fracture toughness and flexure stiffness, when hybrid composites with 0.9% carbon fibre are compared to unreinforced foam, but did not improved absorbed impact energy.
67 citations
TL;DR: In this article, the authors reported that the bending rigidity of graphene sheets is dependent on the size and shape of the graphene sheets, and the dependence of the rigidity on the deflection is found.
57 citations
TL;DR: In this paper, the effect of torsional loads on the damage introduced by lateral impacts on cylindrical T300-carbon/epoxy specimens was investigated, and the impact damage initiation was studied in detail by various FEM analyses.
52 citations
TL;DR: This work analyzes the elastic response of single-walled CNT forests, attached to the bottom wall of a channel, to the aerodynamic loading exerted by both laminar and turbulent flows to determine flexural rigidity of CNTs in wind-tunnel experiments.
Abstract: The ability to determine static and (hydro)dynamic properties of carbon nanotubes (CNTs) is crucial for many applications. While their static properties (e.g., solubility and wettability) are fairly well understood, their mechanical responses (e.g., deflection under shear) to ambient fluid flow are to a large extent unknown. We analyze the elastic response of single-walled CNT forests, attached to the bottom wall of a channel, to the aerodynamic loading exerted by both laminar and turbulent flows. Our analysis yields analytical expressions for velocity distributions, the drag coefficient, and bending profiles of individual CNTs. This enables us to determine flexural rigidity of CNTs in wind-tunnel experiments. The model predictions agree with laboratory experiments for a large range of channel velocities.
49 citations
TL;DR: In this paper, a new type of reduced beam section (RBS) connection, called the Accordion Web RBS (AW-RBS), is presented, where the flat web is replaced by corrugated plates (L-shape folded plates, used here) at the expected location of the beam's hinge.
47 citations
TL;DR: In this article, static experimental tests on four half-scale models of steel and concrete composite girders with different shear connectors such as studs and Perfo-Bond Strips (PBLs) under hogging moments are cautiously conducted in order to investigate the reduction of flexural stiffness and the inelastic behaviour after cracking.
TL;DR: The results underscore that porcine-derived heterograft biomaterials are very sensitive to flexural fatigue, with delamination of the tissue layers the primary underlying mechanism, in contrast to pericardial BHV, wherein high tensile stresses are considered to be the major cause of structural failure.
Abstract: Although bioprosthetic heart valves (BHV) remain the primary treatment modality for adult heart valve replacement, continued problems with durability remain. Several studies have implicated flexure as a major damage mode in porcine-derived heterograft biomaterials used in BHV fabrication. Although conventional accelerated wear testing can provide valuable insights into BHV damage phenomena, the constituent tissues are subjected to complex, time-varying deformation modes (i.e., tension and flexure) that do not allow for the control of the amount, direction, and location of flexure. Thus, in this study, customized fatigue testing devices were developed to subject circumferentially oriented porcine BHV tissue strips to controlled cyclic flexural loading. By using this approach, we were able to study layer-specific structural damage induced by cyclic flexural tensile and compressive stresses alone. Cycle levels of 10 x 10(6), 25 x 10(6), and 50 x 10(6) were used, with resulting changes in flexural stiffness and collagen structure assessed. Results indicated that flexural rigidity was markedly reduced after only 10 x 10(6) cycles, and progressively decayed at a lower rate with cycle number thereafter. Moreover, the against-curvature fatigue direction induced the most damage, suggesting that the ventricularis and fibrosa layers have low resistance to cyclic flexural compressive and tensile loads, respectively. The histological analyses indicated progressive collagen fiber delamination as early as 10 x 10(6) cycles but otherwise no change in gross collagen orientation. Our results underscore that porcine-derived heterograft biomaterials are very sensitive to flexural fatigue, with delamination of the tissue layers the primary underlying mechanism. This appears to be in contrast to pericardial BHV, wherein high tensile stresses are considered to be the major cause of structural failure. These findings point toward the need for the development of chemical fixation technologies that minimize flexure-induced damage to extend porcine heterograft biomaterial durability. (c) 2010 Wiley Periodicals, Inc. J Biomed Mater Res, 2010.
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TL;DR: The results recommend that the parabolic shear deformation-beam theory offers a unified simple 1D model, which can capture the length dependence of flexural rigidity and be applied to various static and dynamic problems of microtubule mechanics.
TL;DR: In this article, the effect of surface effects on the elastic properties of a linear elastic rectilinear rod has been analyzed and a complex model combining both the presence of surface stresses and the surface layer with the properties that differ from those of the matrix has been proposed.
Abstract: 279 Many nanomaterials have abnormal physical prop� erties, which differ considerably from the properties of bulk materials. One of the explanations for these dif� ferences consists in the presence of surface effects, the role of which can be extremely large for nanodimen� sional structures in comparison with those in classical mechanics [1]. The purpose of this work is analysis of the influence of surface effects on the elastic characteristics of nan� oporous materials. Two models are considered. The first one is based on taking into account the surface stresses [1–4]. The surface stresses τ are the generali� zation of the surface tension known in the theory of capillarity for the case of solids. As is shown in [1, 5], taking into account surface stresses results in increas� ing stiffness of nanoporous materials. This phenome� non is similar to increasing flexural stiffness of nano� plates in comparison with the plates of macroscopic sizes [6, 7]. The second model uses the approach of the theory of composite materials [8–10]. In this approach, the surface effects are taken into account due to the surface layer of finite thickness with elastic moduli differing from those of the basic material (the matrix). Here the increase or decrease in the rod stiff� ness depends on the relation between the elastic mod� uli of the surface layer and the matrix. The effective stiffness can both decrease and increase with decreas� ing pore radius. On the basis of these two approaches, we proposed a complex model combining both the presence of surface stresses and the surface layer with the properties that differ from those of the matrix. PROBLEM FORMULATION We consider the problem on the tension–compres� sion of a linear elastic rectilinear rod. Let the rod have a circular cross section of radius R. We consider that n cylindrical pores with identical radii r (Fig. 1) are located in parallel to the rod axis. We designate the area occupied with pores in the rod cross section as S = πnr 2 . We assume also that the rod cross section is symmetric so that it is not subjected to bending under tension. A regularly distributed load, which is stati� cally equivalent to forces P, acts on the rod end faces. We designate the Young’s modulus of the rod mate� rial as E. For a large number (n � 1) of pores, the rod can be considered as a homogeneous cylinder made of transversally isotropic material. We designate the cor� responding effective longitudinal Young’s modulus
01 Feb 2010
TL;DR: In this article, the tensile stresses developed in cracked concrete beams are analyzed using a finite element (FE) model that takes into account the non-linear biaxial behaviour of the concrete and the nonlinear bond stress-slip behavior of the steel reinforcement-concrete interface.
Abstract: Although after cracking, concrete has negligible tension capacity, the intact concrete between cracks within the tension zone of a reinforced concrete beam can still develop significant tensile stresses to contribute to the flexural stiffness of the concrete beam. Such a tension stiffening effect in a flexural member is not quite the same as that in an axial member because the tensile stresses in a cracked flexural member are induced not only by the steel reinforcement–concrete bond but also by the curvature of the flexural member. In this study, the tensile stresses developed in cracked concrete beams are analysed using a finite-element (FE) model that takes into account the non-linear biaxial behaviour of the concrete and the non-linear bond stress–slip behaviour of the steel reinforcement–concrete interface. Based on the numerical results so obtained, a tensile stress block is proposed for section analysis of the moment–curvature curves of reinforced concrete beams at both the uncracked and cracked sta...
01 Aug 2010
TL;DR: In this paper, a model for the stiffness of inclined screws used as shear connectors in timber and concrete composite floors is presented, which assumes that the screw behaves as a beam on a two-dimensional elastic foundation and models the timber as orthogonal springs with differing stiffnesses in the grain and transverse directions.
Abstract: This paper presents a model for the stiffness of inclined screws used as shear connectors in timber and concrete composite floors Screws inclined in the direction of slip have been shown to provide a higher stiffness (slip modulus) than vertically placed screws An increased slip modulus per screw enhances the effective flexural stiffness of a partially composite timber and concrete beam, or, alternatively, allows the same flexural stiffness to be achieved with fewer screws The model assumes that the screw behaves as a beam on a two-dimensional elastic foundation: it takes account of the inclination of the screw and models the timber as orthogonal springs with differing stiffnesses in the grain and transverse directions The model also considers axial deformation, and hence shear lag, of the screw Optimum inclination angle and embedment length of screw can be predicted Preliminary validation of the model is provided by comparison with some experimental results
TL;DR: In this article, the first layer failure strength of an Al/Mg/Al composite with a trilaminate structure was investigated and the tensile and bending properties of the laminates were calculated based on the classical Laminate Theory.
Abstract: An Al/Mg/Al composite with a trilaminate structure was fabricated by hot rolling and its mechanical properties at quasi-static rates of strain were investigated. The bonding strength of the trilaminated composite is about 40 MPa, mainly attributing to the mechanical bond at the interfaces. The first layer failure strength of the laminated composite increases from 305 to 372 MPa when the relative thickness of aluminium alloy layer increases from 0.235 to 0.265. The tensile and bending properties of the laminates were calculated based on the Classical Laminate Theory (CLT). The calculations of first layer failure strength based on CLT agree with the experimental data in the error of 2.9–18%. Thus, the first layer failure strength of the Al/Mg/Al trilaminated composite fabricated by hot rolling can be calculated by CLT with the maximum stress criteria. The calculations also show that the tensile modulus, the tensile rigidity, the specific tensile rigidity and the first layer failure strength of the laminated composite increase almost linearly with the relative thickness of the aluminium alloy component. The bending rigidity of the laminated composite increases with the relative thickness of aluminium alloy, and approximates to a fixed value after the relative thickness over 0.3. The specific bending rigidity increases with the relative thickness of aluminium alloy and reaches a maximum value when the relative thickness is 0.25.
TL;DR: In this article, two joint types soldered by mechanical controlled jointing with uniform pressure application have been adopted, and critical currents of the jointed tapes have been measured at 77 K and self field.
Abstract: Although long-length superconducting wires are now being developed and manufactured, there is still a need for jointing in coil manufacturing and power cables for power distribution which requires miles in length. Therefore, it is important to develop an easy and practical jointing that has an acceptable electrical and mechanical integrity. Depending upon the applications, jointed coated conductor (CC) tapes will experience different stresses and strains during manufacturing and operation that could affect its transport property. Bending strain characterization is necessary since CC tapes are being wound into coils for magnet applications and other electrical devices. In this study, two joint types soldered by mechanical controlled jointing with uniform pressure application have been adopted. Critical currents of the jointed tapes have been measured at 77 K and self field. In the case of easy bending test, a new test procedure has been adopted considering the non-uniform flexural stiffness between jointed and unjointed parts of the sample. Relationship between the critical current and bending strain in easy bending mode has been investigated.
TL;DR: In this article, a model of shear flow over a periodic array of cylindrical rods attached to a substrate is studied as a model for flow over carbon nanotubes, and the hydrodynamic traction and macroscopic slip velocity are computed by solving the equations of Stokes flow for a doubly periodic square or hexagonal arrangement.
TL;DR: In this article, the mass and stiffness variations along the wing of the blowfly Calliphora have been determined by measuring the bending stiffness at three locations, basal (near root), medial and distal (near tip) of the fly wing.
Abstract: Experiments are performed to determine the mass and stiffness variations along the wing of the blowfly Calliphora. The results are obtained for a pairs of wings of 10 male flies and fresh wings are used. The wing is divided into nine locations along the span and seven locations along the chord based on venation patterns. The length and mass of the sections is measured and the mass per unit length is calculated. The bending stiffness measurements are taken at three locations, basal (near root), medial and distal (near tip) of the fly wing. Torsional stiffness measurements are also made and the elastic axis of the wing is approximately located. The experimental data is then used for structural modeling of the wing as a stepped cantilever beam with nine spanwise sections of varying mass per unit lengths, flexural rigidity (EI) and torsional rigidity (GJ) values. Inertial values of nine sections are found to approximately vary according to an exponentially decreasing law over the nine sections from root to tip and it is used to calculate an approximate value of Young’s modulus of the wing biomaterial. Shear modulus is obtained assuming the wing biomaterial to be isotropic. Natural frequencies, both in bending and torsion, are obtained by solving the homogeneous part of the respective governing differential equations using the finite element method. The results provide a complete analysis of Calliphora wing structure and also provide guidelines for the biomimetic structural design of insect-scale flapping wings.
TL;DR: In this article, the lattice Boltzmann flexible particle method (LBFPM) is used to simulate fluid-structure interaction and motion of a flexible wing in a three-dimensional space.
Abstract: The lattice Boltzmann flexible particle method (LBFPM) is used to simulate fluid-structure interaction and motion of a flexible wing in a three-dimensional space. In the method, a beam with rectangular cross section has been discretized into a chain of rigid segments. The segments are connected through ball and socket joints at their ends and may be bent and twisted. Deformation of flexible structure is treated with a linear elasticity model through bending and twisting. It is demonstrated that the flexible particle method (FPM) can approximate the nonlinear Euler–Bernoulli beam equation without resorting to a nonlinear elasticity model. Simulations of plunge and pitch of flexible wing at Reynolds number Re=136 are conducted in hovering condition by using the LBFPM. It is found that both lift and drag forces increase first, then decrease dramatically as the bending rigidity in spanwise direction decreases and that the lift and drag forces are sensitive to rigidity in a certain range. It is shown that the ...
TL;DR: In this paper, the authors focus on multi-layered beams with controllable flexural stiffness and show that removing the cover layers from the base beam through softening of the polymer reduces axial strain in the cover layer significantly.
Abstract: Morphing aerospace structures could benefit from the ability of structural elements to transition from a stiff load-bearing state to a relatively compliant state that can undergo large deformation at low actuation cost. The present paper focuses on multi-layered beams with controllable flexural stiffness—comprising polymer layers affixed to the surfaces of a base beam and cover layers, in turn, affixed to the surfaces of the polymer layers. Heating the polymer through the glass transition reduces its shear modulus, decouples the cover layers from the base beam and reduces the overall flexural stiffness. Although the stiffness and actuation force required to bend the beam reduce, the energy required to heat the polymer layer must also be considered. Results show that for beams with low slenderness ratios, relatively thick polymer layers, and cover layers whose extensional stiffness is high, the decoupling of the cover layers through softening of the polymer layers can result in flexural stiffness reductions of over 95%. The energy savings are also highest for these configurations, and will increase as the deformation of the beam increases. The decoupling of the cover layers from the base beam through the softening of the polymer reduces the axial strains in the cover layers significantly; otherwise material failure would prevent large deformation. Results show that when the polymer layer is stiff, the cover layers are the dominant contributors to the total energy in the beam, and the energy in the polymer layers is predominantly axial strain energy. When the polymer layers are softened the energy in the cover layers is a small contributor to the total energy which is dominated by energy in the base beam and shear strain energy in the polymer layer.
TL;DR: In this article, the authors considered wave radiation (both heave and sway) by a sphere submerged in a two-layer ocean consisting of a layer of fresh water of finite depth with an ice cover and an infinite layer of salt water.
TL;DR: In this paper, the bending properties of carbon nanoribbons were investigated by combining continuum elasticity theory and tight-binding atomistic simulations, and a complete analysis of a given bended configuration through continuum mechanics was developed.
Abstract: We investigate the bending properties of carbon nanoribbons by combining continuum elasticity theory and tight-binding atomistic simulations. First, we develop a complete analysis of a given bended configuration through continuum mechanics. Then, we provide by tight-binding calculations the value of the bending rigidity in good agreement with recent literature. We discuss the emergence of a stretching field induced by the full atomic-scale relaxation of the nanoribbon architecture. We further prove that such an in-plane strain field can be decomposed into a first contribution due to the actual bending of the sheet and a second one due to edge effects.
TL;DR: In this paper, it is shown that a remarkably quantifiable hysteresis occurs in the slope of loading curves whenever the normal flexural stiffness of the cantilever is greater than that of the sample.
Abstract: It has long been recognized that the angular deflection of an atomic force microscope (AFM) cantilever under “normal” loading conditions can be profoundly influenced by the friction between the tip and the surface. It is shown here that a remarkably quantifiable hysteresis occurs in the slope of loading curves whenever the normal flexural stiffness of the AFM cantilever is greater than that of the sample. This situation arises naturally in cantilever-on-cantilever calibration, but also when trying to measure the stiffness of nanomechanical devices or test structures, or when probing any type of surface or structure that is much more compliant along the surface normal than in transverse directions. Expressions and techniques for evaluating the coefficient of sliding friction between the cantilever tip and sample from normal force curves, as well as relations for determining the stiffness of a mechanically compliant specimen are presented. The model is experimentally supported by the results of cantilever-o...
TL;DR: In this article, a box girder was fabricated using a pultruded hat-shape glass-fiber reinforced polymer (GFRP) trapezoidal section combined with a flat GFRP plate and a concrete slab cast above the plate.
TL;DR: The results indicate that the transition of microtubule's rigidity is associated with the tubulin conformation change from a GTP- bound state to a GDP-bound state in the α/β subunit.
TL;DR: In this paper, the homotopy perturbation method (HPM) is introduced for elastic stability analysis of tilt-buckled columns with variable flexural stiffness, and the authors determined the buckling loads and corresponding mode shapes.
Abstract: In this paper, the Homotopy Perturbation Method (HPM), is introduced for elastic stability analysis of tilt‐buckled columns with variable flexural stiffness. Buckling loads and corresponding mode shapes are determined considering different types of variations in flexural stiffness of columns. The proposed approach is an efficient technique for the elastic stability analysis of specified problems.
TL;DR: In this paper, a combination of continuum modeling, atomistic simulations, and numerical optimization is used to estimate the flexural rigidity of a graphene sheet, which is initially parallel to a rigid substrate and deflects in response to loading on a pair of opposite edges.
Abstract: Using a combination of continuum modeling, atomistic simulations, and numerical optimization, we estimate the flexural rigidity of a graphene sheet. We consider a rectangular sheet that is initially parallel to a rigid substrate. The sheet interacts with the substrate by van der Waals forces and deflects in response to loading on a pair of opposite edges. To estimate the flexural rigidity, we model the graphene sheet as a continuum and numerically solve an appropriate differential equation for the transverse deflection. This solution depends on the flexural rigidity. We then use an optimization procedure to find the value of the flexural rigidity that minimizes the difference between the numerical solutions and the deflections predicted by atomistic simulations. This procedure predicts a flexural rigidity of 0.26 nN nm=1.62 eV.
TL;DR: In this paper, the curvature and face/core debond influence on the vibration behavior of curved composite sandwich beams made up of carbon/epoxy laminate skins over a polyurethane foam core.
Abstract: The aim of this research was to investigate the curvature and face/core debond influence on the vibration behavior of curved composite sandwich beams made up of carbon/epoxy laminate skins over a polyurethane foam core. Flat and curved sandwich beams with debond were prepared by keeping the arc length of the sandwich beams equal to the length of the flat sandwich beams. Sandwich specimens with three different curvatures and debond between the top and bottom face/core were manufactured. Systematic vibration and static experiments were carried to determine the response and to study the effect of curvature and debond. Flexural stiffness and strength of the sandwich beams were determined by four-point bending tests. The natural frequencies and damping loss factors of the sandwich beams were determined using impulse frequency response technique under free—free boundary conditions. Four-point bending test results indicate that stiffness of the beams decrease with presence of debond. Vibration test results show ...