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Perforation is used in multilayer tissue products, such as toilet and kitchen papers, as part of the converting process. Perforation facilitates the detachment of consecutive sheets by the user. The compromise between the strength required to detach a perforated sheet and the strength required to break a sheet affects the perforation efficiency. In this work, the mechanical behaviors of 15 commercial papers from different European producers were studied. A morphological analysis of the materials was performed, followed by the determination of their perforation efficiency (through tensile tests). A qualitative analysis of the cuts quality, along with a quantitative analysis of the same cuts dimensions was performed through an optical system. Finally, the stress concentration in the holes and the influence of the cuts distance were analyzed using a finite element model implemented in Abaqus/Standard finite element software. The results showed that a cut distance of 2.0 mm should not be used in these types of papers, and the perforation efficiency increased with the cut distance, regardless of the number of plies in the toilet paper. The stress concentration factor was also determined to have a limit value of 0.11. Papers above this limit value tear at the perforation line, as desired.

In present investigation, an attempt was made to optimise the peak stress for paper laminate composite using FRANC2D software. It was observed that the laminate having the triangular geometry supposed to be most appropriate as it has the lowest value of peak stress contour compared to other models like parallel strip, up-down tapered and down-up tapered. The minimum peak stress was observed for the samples having triangular geometry while the maximum was observed for down-up tapered samples. Therefore, the hypothesis adopted to use in-built materials with variables reinforcement area and strip geometry and length in the FRANC2D software to optimize the sample geometry and then apply it to the paper laminate by considering its mechanical properties might be use to optimize the peak stress of paper laminate composite in tensile loading conditions. It was also observed a length of one-quarter of the length of the plane strip, might be the optimum length of the paper laminate samples. However, it feels that, the above model can be further modified considering a more significant mechanical properties as well as different sample geometries.

The threat of increased industrial accidents and extreme explosive activities demands protection of structure against blast loading. The pressure-impulse (P-I) diagrams also called iso-damage diagrams indicates damage level in a structure. In the present investigation, P-I diagrams for sandwich panel with steel face and back-sheets and paper honeycomb core are developed. The numerical approach is used to get series of pressure and impulse points for particular damage level. The damage criteria considered in present study is maximum back sheet deflection. However, core crushing is limited to 5 mm in this investigation for the uniformity of the analysis. Sandwich panel with paper honeycomb core is modelled in ABAQUS/Explicit® and blast load is applied for range of loading i.e. impulsive, dynamic and quasi-static using CONWEP formulation. Based on the analysis performed, P-I diagrams are developed for damage levels of 1%, 1.5%, 2%, 2.5% and 3%.

Condenser bushings are considered the Achilles’ heel of power transformers because most of the explosions of transformers relate to their bushings’ failure. Typical bushings monitoring methods measure the tan delta, power factor, and bushings’ capacitance in line frequency. In contrast, the dielectric frequency response (DFR) or the frequency domain spectroscopy (FDS) measures these parameters over a wide frequency range. Some studies have revealed that the FDS curves have distinguished data that help detect bushing failures in their onset. However, there has not been a standard FDS interpretation method. Human experts’ opinions play a considerable role in the interpretation process. In this paper, a finite element method model of a 96 kV oil-impregnated paper bushing is built with different OIP moisture content. The FDS test is simulated under these moisture levels. Seven two-array and six one-array statistical indices are introduced to interpret the FDS results. The results have shown that all six one-array statistical indices, apart from average deviation (AVEDEV) and standard deviation (SD), can be perfect indicators of moisture levels of the OIP. Moreover, they can be used to assess the moisture content of the OIP bushings, and human errors are eliminated using this method.

The frequency domain spectroscopy (FDS) of the transformer oil-paper insulation can be simulated by using the finite element method (FEM). However, the effect of nonuniform aging on calculation results has not been included in previous simulation models. Given this issue, a novel simulation model including non-uniform aging is reported. In the present work, the oil-paper samples with various aging degrees are prepared to develop the composite structure of the oil-paper system. Then, the simulation models are constructed based on FEM. The comparison of measured FDS and simulated FDS is used to verify the feasibility of the proposed model. Present findings prove that the proposed model could predict the FDS of the transformer oil-paper insulation under non-uniform aging, which might be utilized to analyze its dielectric response property under non-uniform aging conditions.

The finite element model for paper honeycomb was constructed, and the finite element method of out-of-plane compression for the paper honeycomb was studied. Then four kinds of paper honeycomb with different structural parameters were simulated and analyzed using finite element software ABAQUS. Moreover, the results obtained from finite element method were verified based on the existing theoretical research results and experimental results, respectively. The results show that stress–strain curves obtained from finite element method clearly show the four deformation stages of the paper honeycomb under out-of-plane compression, which is basically consistent with the trend of the typical curve. The values of initial peak stress, plateau stress and densification strain are close to the theoretical results. The stress–strain curves and deformation contours coincide with experiments well. The differences of initial peak stress σpk, plateau stress σpl and densification strain εD between theoretical, finite element method and experimental results are less than 15%. Therefore, the finite element method can be used to analyze the stress–strain curves and deformation characteristics of paper honeycomb. In addition, the results also show that the thickness of specimen has little effect on the stress and strain. However, people often prefer to use the thicker paper honeycomb to get better cushioning effect in practical applications, which was explained.

As a basic mechanical component, the sealing ring is widely used in industrial, aerospatial, and other fields. In this study, an elastic metal C-shaped sealing ring with a wave structure was taken as an example, and its performance was analyzed theoretically and measured experimentally. First, an experimental study was performed on the C-ring seal. The proposed method for experimental measurement of the contact stress of the C-ring seal involved innovative use of a universal electronic testing machine and pressure sensitive paper, in conjunction with the hue&ndash, saturation&ndash, brightness (HSB) method. Based on the discoloration of the pressure sensitive paper after contact stress, computer software was used for analysis, the discoloration was digitized, and the contact stress was established. Second, a theoretical calculation model of the C-ring seal was established using ANSYS software, and a finite element theoretical calculation of the mechanical properties of the sealing ring was established. Finally, the contact stress results were compared with the model calculation results of the C-ring seal. The error between the two was small (4.8%), which proved the validity of the calculation model and the scientificity of the experimental method.

To explore the application of environmental protection material-paper straw board in cold-formed thin-walled steel (CFS) structures and further develop the sheathing system, an innovative CFS framing wall sheathed by paper straw board (CFSSB) is proposed. Eight CFSSB composite wall specimens and one CFS frame without sheathing were tested under monotonic and reversed cyclic horizontal loads to study the shear performance of the CFSSB composite wall. Also, the shear performance of the wall specimens can be obtained. The key parameters include the value of the vertical load and the form of the CFS frame in this experimental program. By analyzing the specimen’s failure forms and failure process, the characteristic values of the bearing capacity, lateral stiffness, ductility coefficient and energy dissipation coefficient are obtained. The results show that the existence of paper straw board and adding diagonal braces to the CFS frame can significantly improve the shear capacity of CFSSB composite walls. The favorable seismic performance of the CFSSB composite wall was demonstrated in the experiment. In addition, a finite element model for CFSSB composite wall is developed using the software package ANSYS. The finite element analysis (FEA) results show a good agreement with the experiment results in terms of failure modes and skeleton curves, which verify the feasibility of the FEA model. Furthermore, extensive parametric analysis was carried out to analyze the factors affecting the shear capacity of the CFSSB composite wall. The FEA results show that the spacing of studs and self-tapping screws greatly influences the shear capacity of walls. Moreover, based on the failure of the screw connections, a formula for calculating the shear capacity of the CFSSB composite wall is proposed. The results of the formula calculation show good agreement with the experiment and FEA results, and it can provide a reference for engineering design.

An anisotropic elasto-plastic constitutive model of paper material is presented. It is formulated in a spatial setting in which anisotropic properties are accounted for by use of structural variables. A multiplicative split of the deformation gradient is employed to introduce plasticity. A similar approach is used to model the plastic deformation of the substructure. The yield surface adopted is based on the Tsai–Wu failure criterion, used previously to model failure of paper material. A non-associated plasticity theory is employed to calibrate the model to experimental data. It turns out that a multi-axial loading situation is needed to calibrate the model and here a biaxial tension test is audited. The model was implemented into a finite element environment and the creasing process of a corrugated board panel is investigated.

The mechanical response of three different structural core sandwich panels in out-of-plane compression and shear has been analyzed. Specific core shapes examined are arc-tangent, wavy trapezoidal and hemispherical. Unit cells consisting of representative elements of the core attached to face sheets were selected for analysis. Both face sheets and core were assumed made from paper. Finite element analysis employing large deformation and rotations and orthotropic elastic–plastic behavior was used. The results show that the arc-tangent and trapezoidal cores are prone to collapse by extensive bending and buckling, whereas the hemispherical core behaved more stably in compression and shear. Core sheets with a hemispherical shape were prepared from copy paper sheets in a specially designed forming machine. Sandwich test specimens were prepared from this core and tested in out-of-plane compression, and the load-displacement response was compared to predictions from finite element simulations. The experimental and finite element results were consistent.

Stiffness based sorting of mixed paper waste at high speed is desirable for sorting board, cardstock, and paper from each other for efficient recycling. We propose a quick, non-contact method for measuring the relative stiffness of paper samples moving on a conveyor at high speeds. The method consists of impinging an air jet on a moving paper sample while it is crossing a gap during transfer from one conveyor belt to another. The deflection caused by the impinging air jet can be measured and used to categorize different grades of paper. In this paper, we report results from a simulation of the proposed method using a finite element model. Influence of conveyor speed, sample orientation and nozzle pressure is studied using the model. Results indicate that the stiffness estimation has sufficient resolution to distinguish between board and paper grades at high conveyor speeds.

Paper pulper machines a capacity of 83 litres/process must have a low-cost material, robust and safe to operate. Paper pulper machine components analysed are tubes, frames, helical screw shaft and the shaft holder. The method uses a static structural analysis to obtain von mises stress and displacement. Static structural analysis uses finite element analysis with the help of CATIA® Software. The safe component size and lowest cost (safety factor more than 2.5) were selected in this study. Calculation of costs by multiplying the size of the material needs by material prices. Tube components use SUS 304 with thickness variations of 0.5, 0.6, 0.8, 1, 1.5, and 2mm. Frame and shaft holder using L shape ASTM A36 size 40x40mm and 50 x50 mm with thickness variations of 3, 4, and 5 mm respectively. Variations in material size are determined based on standard material sizes available on the market. The simulation result of each component shows the thicker the material, the lower the von mises stress, the lower the displacement and the higher safety factor. Tubes with a thickness of 0.5mm have a von mises stress of 4.43 MPa, a displacement of 4.7 x 104 mm with SF 56.4 is safe and were chosen because of the lowest material costs (IDR 360,009). The frame size was chosen 40x40x3 mm based on the SF frame value (26) with the lowest material cost (IDR 197,800). The shaft holder is also chosen for the size of 40x40x3mm where the SF value (3834) and the lowest material cost (IDR 14,400). Helical screw shaft size is chosen at 0.5mm thickness where SF is 304 and material costs IDR 100,968. The overall results of the static structural analysis on various sizes of the paper pulper machine components showed ovon under Oyield, small displacement, and SF is safe.

A finite element procedure, developed in order to account for the effect of high anisotropy at folding of coated papers, is presented. The anisotropic behaviour (with very low stiffness in the thic ...

In this review paper structural damage identification work in cantilever beam is done by using the Artificial Neural Network as diagnostic parameter. The study is based on the concept that natural frequency is inversely proportional to the mass of the structure. Thus to regulate the proper condition of structure, periodical frequency measurement is necessary. But in dynamic conditions and in complicated structures frequency measurement is difficult, for the same we reviewed various papers to identify the structural damage using various methods. The factors which affects on the damage of structural parts like crack depth, crack location etc. is also discussed in this work. Natural frequency is measured with the help of fast fourier transform by various authors and artificial neural network is also used for identification of the damage in many papers. So in this review work we studied methods of structural damage identification such as vibrations, finite element analysis and artificial neural network.

In this paper, a method using neural network for optimizing the grading ring of ±1100kV ultra-high voltage direct current (UHVDC) wall bushing is presented. Firstly, the finite element method (FEM) is applied to calculate the electric field distribution along hollow insulator surface with various pipe diameter, ring diameter and installation position of the grading ring and the optimal goal is set according to the FEM numerical results. Then the neural network model is built and trained with L- M algorithm using 300 sets of data calculated by the method of parametric scanning. Finally, the parameters of grading ring are optimized according to the neural network fitting results. The optimized grading ring uniforms the electric field distribution along the hollow insulator surface. This paper can provide a reference on structural design of UHVDC wall bushing.

Considering the slight deformation of the paper honeycomb sandwich plate in the vibration, the stiffness coefficient of the paper honeycomb sandwich plate was equivalent to the elasticity. The analytical model of natural frequency related to the structural and material parameters of the paper honeycomb sandwich plate and mass of block was derived. Subsequently, 5 different paper honeycomb sandwich plates and 3 different blocks were chosen to modify the analytical model by finite element method and verify it by experiment. The results show that the modifying factorl is 0.606 and the error between analytical and experimental results is less than 10%. In the future, the analytical model can be used to predict the natural frequency of paper honeycomb sandwich plate with different structural parameters under different blocks. Therefore, it provides the necessary theoretical reference for the optimization design of paper honeycomb sandwich plate.

Thin-walled tubular Crash box are extensively used as energy absorbers in numerous automotive and aerospace applications as a result of their higher energy absorption capacity. In past lot of research has been done on crash tubes. Crash box of various cross section/shape and materials have been analyzed. Some researchers have done quasi-static analysis whereas some have gone for dynamic analysis. Just in case of energy absorption through dynamic impact, Speed of impact & momentum of impact are influential factors. The dimensions viz. lengths, width, wall thickness, material, and loading conditions were also varied. Crash box with metallic/structural foam filling, multi-cell or tapered crash boxes have also been studied for axial or oblique loading conditions. Some researchers have used finite element based software's for their study while others used experimental method. Review of all the above factors & their effect on energy absorption capability of tubes is taken into account during this paper, based on which the parameters will be selected for further research.

Oil-paper insulation has been widely used in power equipments such as bushing, high voltage cable and power transformer. As a result, effective methods to diagnose equipment's insulation condition that in high reliability are urgently needed. In recent year, with advantages of accurate results and strong anti-interference ability, frequency domain spectroscopy(FDS) has been widely used for insulation condition diagnosis of oil-paper insulating equipment all over the world. In this paper, a new modeling method using lumped element circuit was introduced to study the effect of temperature factor on the overall broadband frequency domain spectroscopy curves of transformer, and results from XY model, finite element model (FEM) and lumped element circuit (LEC) were compared to discuss their different characteristics and the application scope. Results show that there are peaks and valleys at about 105Hz of the FDS curves got from lumped element circuit, and temperature mainly affects the amplitude of peaks and valleys. Data got from XY model and finite element model have a high consistency, but are still different in certain frequency bands. The curves of dielectric loss tangent got from lumped element circuit are quite different with the former two models. Lumped element circuit should be firstly considered when the insulation condition of transformers are assessed from multiple perspectives or with broadband curves.

This paper presents analysis of a 3-dimensional engineered structural panel (3DESP) having a tri-axial core structure made from phenolic impregnated laminated-paper composites with and without high-strength composite carbon-fiber fabric laminated to the outside of both faces. Both I-beam equations and finite element method were used to analyze four-point bending of the panels. Comparisons were made with experimental panels. In this study, four experimental panels were fabricated and analyzed to determine the influence of the carbon-fiber on bending performance. The materials properties for finite element analyses (FEA) and I-beam equations were obtained from either the manufacturer or in-house material tensile tests. The results of the FEA and I-beam equations were used to compare with the experimental 3DESP four-point bending tests. The maximum load, face stresses, shear stresses, and apparent modulus of elasticity were determined. For the I-beam equations, failure was based on maximum stress values. For FEA, the Tsai-Wu strength failure criterion was used to determine structural materials failure. The I-beam equations underestimated the performance of the experimental panels. The FEA-estimated load values were generally higher than the experimental panels exhibiting slightly higher panel properties and load capacity. The addition of carbon-fiber fabric to the face of the panels influenced the failure mechanism from face buckling to panel shear at the face–rib interface. FEA provided the best comparison with the experimental bending results for 3DESP.

The use of finite element models as research tools in biomechanics and orthopedics grew exponentially over the last two decades. However, the attention to mesh quality, model validation and appropriate energy balance methods and the reporting of these metrics has not kept pace with the general use of finite element modeling. Therefore, the purpose of this review was to develop the nonlinear filter and thermal buckling of an FGM panel under the combined effect of elevated temperature conditions and aerodynamic loading is investigated using a finite element model based on the thin plate theory and von Karman strain-displacement relations to account for moderately large deflection. It is found that the temperature increase has an adverse effect on the FGM panel flutter characteristics through decreasing the critical dynamic pressure. Decreasing the volume fraction enhances flutter characteristics, but this is limited by the structural integrity aspect. Structural finite element analysis has been employed to determine the FGM panel's adaptive response while under the influence of a uniaxial compressive load in excess of its critical buckling value. By increasing the applications of using composite materials inside aviation stages, it is visualized that the versatile FGM plate setup will broaden the operational execution over traditional materials and structures, especially when the structure is presented to a raised temperature. The vicinity of air motion facilitating stream brings about delaying the locking temperature and in stifling under loads, while the temperature build gives route for higher thermal-cycle abundance.

In this study, lightweight sandwich panels with different Kraft paper honeycomb core structures and wood composite skins were constructed. The influence of structural parameters, including core shape, cell size, core density, core and web thickness, and material properties of the core and skin layers on the mechanical behavior of these lightweight sandwich panels were studied by experimental testing and finite element modeling methods. The panels were subjected to compression and shear loadings. Test and simulation results indicated that core density and core shape mainly affected the panel stiffness under out-of-plane loading conditions (e.g. E z , G xz and G yz ). Material properties of the skin layer affected the panel stiffness both under in-plane and out-of-plane loadings if the skin layer was orthotropic.

In this paper a finite element model of a rotating paper machine roll for nip unit rolling contact analyses is discussed. This work presented here is based on the earlier work of the authors presented in [1] and [2]. The major motivations for developing a tailored FE-model including the large spin rotation are firstly to include the complex vibration phenomena as the shell vibrations of the roll structure in the analyses and secondly to reduce the computational costs of the numerical simulations due to the large number of degrees of freedom. The approach used is the use of the modal analysis i.e. to express the dynamics of the roll in terms of the lowest eigenmodes. The equations of motion are at first written in the rotating coordinates and then in addition to this the equations are expressed by using the modal coordinates. Numerical tests executed show that this modeling technique reduces computational costs significantly. Furthermore, use of the (semidefinite) eigenmode basis maintains the vibration characteristics of the roll structure. For verification purposes a test model was constructed and these simulation results were compared to the standard geometrically non-linear finite element analysis.

Variable head sizes of paper roll will influence the stability of paper feeding device and hence the printing quality. Therefore, it is necessary to improve the printing quality by improving the stability of paper feeding device based on dynamic analysis on the phenomenon of variable head sizes of paper roll. It is found through dynamic analysis that the effect of variable head sizes on the support force of bearings is nearly five times that of the case when such effect does not exist. Vibration performance analysis of paper feeding device using finite element analysis obtains the natural frequencies of the first 6 orders for paper carriage and their dominant vibrational modes. This provides theoretical basis for the improvement of paper feeding device.

Two equivalent models based on sandwich panel theory and equivalent panel theory were discussed in this paper. By analyzing the performance of fiber - paper honeycomb sandwich structure compound panel by bending load, the computational results are in accordance with test and Engineering software ANSYS. Therefore, it shows that the finite element equivalent models are reasonable and practical for the optimization design of fiber - paper honeycomb sandwich composites.

Thin-walled components have characteristics of high intensity and light mass and are used widely in aeronautical industry. NC milling is one of the most popular machining methods for the thin-walled components. Because of their poor rigidity, the deformation of the thin-walled workpieces caused by cutting force is a main factor that decreases the machining precision and increases aeronautical product cost. Based on the analyses of the machining deformation mechanism and basic machining deformation characteristics of the thin-walled workpieces, a NC milling deformation forecasting approach is presented based on CAD/CAM/FEA integration to forecast the machining deformation of the aeronautical thin-walled workpieces. Taking a typical workpiece for example, the proposed deformation forecast framework is validated by the analytic and experimental results. The straight side walls of aluminum LY12CZ workpieces are processed on a vertical machining center THA5656 and their errors are analyzed. Based on orthogonal tests, the deformation characters of the thin-walled workpieces are discussed under different cutting conditions. By the comparison of experimental results and FEA results, although there exist definite difference, their variation tendencies are similar on the whole. Thus, the FEA model is validated. The research can provide support for machining deformation control and machining simulation model verification.

The aim of this paper is to present a finite element method to predict buckling characteristics of paper honeycomb sandwich panels with composite skins under dynamic axial compression via ANSYS/LS-DYNA. First of all, some problems of the conventional method using honeycomb plate theory, sandwich laminboard theory and equivalent panel theory were pointed out. In order to develop an effective predicting method, by assuming appropriate periodic boundary condition on the edges, a simplified finite element model on hexagonal structure of a unit cell for sandwich panels was developed utilizing the 3D finite element method. The effective Young's modulus of the cellular wall was obtained from the result of the test on the honeycomb core. Several useful conclusions are drawn about the axial crushing of honeycomb sandwich composites and unit cell and can be used to guide the design of composite structures. The paper further attempts to explain numerical results are well consistent with the corresponding experimental ones.

A new two-dimensional network model is proposed as a micromechanics model to simulate paper’s failure process due to sequentially breakages of fibers and/or bonds. Paper is approximated as a network composed of fibers any two of which link to each other by their intersecting point, namely so-called bond. Fibers distribute along three particular directions, leading to network’s macro-level isotropy. In the framework of finite element method, nodes correspond to fiber-to-fiber bonds, while elements are fiber segments between every two neighboring nodes and described by Timoshenko beam theory. Element breaks when its equivalent internal tensile stress reaches the tensile strength of fiber. Strength of nodes, i.e. fiber-to-fiber bonds is assumed to be dependant on shearing interaction between fibers, considering the dominant interaction is shearing in a plane problem. Numerical examples show the model’s capacity of reflecting basic failure characteristic in paper. Influences of fiber length and the ratio of fiber strength to bond strength are analyzed in detail.

In order to understand the influence of the thicknesses of Kraft paper honeycomb core and medium density fiberboard skins on the stiffness of the sandwich panel, the corresponding finite element models for the resulting sandwich panels were developed. The material properties for the core and skin components of these finite element models were determined using the published data and specifications. It was found that a decrease in the thickness ratio of the core to skin layer (shelling ratio) resulted in an increase in the modulus of elasticity and shear modulus of the sandwich panels. The increase was significant when the shelling ratio was smaller than six. Cell size only affected the modulus of elasticity of the sandwich panels under the flat-wise compression and panel’s inter-laminar shear modulus. Regression equations relating the stiffness of the sandwich panels to the shelling ratio and core cell size were obtained using the finite element model simulated results and were found to compare well with the existing models for layered wood composites.

Honeycomb paper core stretching is an important process in paper core manufacture because the performance and the quality of paperboard are greatly enhanced when the honeycomb hole is stretched to a regular hexagon structure. In view of the above, first the finite element method is used to compare the mechanical performances of honeycomb paperboards of different aperture ratios, and the aperture ratio, which has an important influence on the performance of the honeycomb paper, is explained. Next, a paper core stretching simulation is carried out by means of the dynamic software; thus the variation trend of the stretching force, the stretching speed, and the lateral shrinkage needed in paper core manufacture of different specifications can be obtained. This research can provide useful instruction in the actual manufacture of honeycomb paper core.

The theory of natural frequencies were acquired from vibration experiment, meanwhile, the first order frequencies of honeycomb sandwich structure composites were obtained by using the sandwich laminboard theory and equivalent panel theory via the finite element software ANSYS. The simulation results were compared to the experiment results to get the error of calculation of the two different equivalent methods, thereby we can select more appropriate equivalent method to ensure the veracity of the result analysis and provide a reference for the optimization design of the fiber-paper honeycomb sandwich structure composites.

In this study, a computational micromechanics material model for the unloading behavior of paper and other nonwoven materials is presented. The asymptotic fiber and bond (AFB) model for paper elastic–plastic behavior [Sinha, S.K., Perkins, R.W., 1995. Micromechanics constitutive model for use in finite element analysis, In: Proceedings of the 1995, Joint ASME Applied Mechanics and Materials Summer Meeting, Los Angeles, CA, USA, Jun 28–30, 1995] has been extended to model the unloading process through a computational algorithm and implemented using the UMAT subroutine in ABAQUS finite element code. For every unloading increment, the material model assumes elastic unloading with a slope equal to the initial elastic modulus. The Jacobian matrix of the constitutive model is updated at every unloading increment by applying the incremental form of AFB model for a planar element with an elastic fiber and bond condition. A uniaxial tensile and a biaxial Mullen burst loading–unloading experiments were carried out for a paperboard sample and simulated using the model. The stress–strain curve and residual strain for the uniaxial loading were in good agreement with experimental results. The finite element model of the burst test with the AFB unloading material model predicted the general shape of the pressure versus deflection curve. However, the model over predicted the residual deflection by more than 50%. The loading portion of the pressure–deflection curve had a significant offset from experimental curves, and the nonlinearity in the unloading curve towards the end was not predicted. The discrepancies with experimental results are attributed to the burst test itself, model parameter estimation inadequacies, boundary conditions used in the FEA, and neglecting time-dependant effects. Nevertheless, the model can be useful in parametric studies relating microstructure to unloading behavior in structural problems.

Bending resistance of single honeycomb paper-core under axial dynamic load has been analyzed to meet the need of honeycomb paperboard produce. First, the models were built after buckling theory analysis. Dynamic characteristics of compressive process were analyzed in the FEA software. It was indicated that: When the height of model was lower than a certain value, the process was divided into four parts: linear elastic phase, elastic-plasticity phase, plasticity collapse phase and densification phase. However, when the height of model was above than the certain value, the model was easy to bend in the intermediate region. Some results such as force and shearing stress had been gotten. At last, the compressive process was verified by experiment, which was bigger value due to air and glue water existed in honeycomb core.

A skew of a paper transferred by rubber rollers in printers is simulated by FEM software. Effects of an imbalance of preload, an imbalance distribution of coefficient of friction and a front tension on the paper skew are investigated and how to determine the skew direction are shown. A simulation model is composed of a feed roller, a preload roller and a paper. The feed roller is rotated forcibly by a certain degree at every calculation step and a deformation, displacement and strain of the paper and rollers are calculated. A series of calculation results is shown as a motion simulation. The results show that the paper skews to the smaller preload side, to the smaller coefficient of friction side, or to the opposite side of the front tension. Further, effects of a skew prevention guide plate is simulated.

Paper angle, environment friendly packaging material, has been mainly used as an edge protector, But, in the future, paper angle will be applied to package design of heavy product such as strength reinforcement or unit load system (ULS). Therefore. understanding of buckling behavior fur angle itself, compression strength and quality standard are required. The objectives of this study were to characterize the buckling behavior by theoretical and finite element analysis, and to develop compression strength model by compression test for symetric and asymetric paper angle. Based on the result of theoretical and finite element analysis, as applied load level was bigger and/or the length of angle was longer, incresing rate of buckling of asymmetric paper angle was higher than that of symmetric paper angle. Decreasing rate of minimum principal moment of inertia significantly increased as the extent of asymmetric angle increased, and buckling orientation of angle was open- direction near the small web. Incresing rate of maximum compression strength (MCS) for thickness of angle decreased as the web size increased in symmetric angle. MCS of asymmetric angle of 4357 and 3367 decreased and , and change of buckling increased and , respectively.

A classic hygro-viscoelastic constitutive model applicable for the analysis of time and humidity-dependent stresses of paper structures using the finite element method (FEM) was investigated. For t ...

The rolling of a cylindrical drum on a stack of separate paper sheets is studied using the finite element method. A two-dimensional model under plane strain conditions is considered. The material of the sheets is modelled by a linearly elastic orthotropic constitutive law. The friction between the various contacting surfaces is modelled by the conventional Coulomb's law. As a result of the FEM-calculations, the time development of the displacements, stresses and strains of the paper layers is obtained. The slip behaviour at the various contacting surfaces is presented. The micro-slip pattern of the contacting surfaces in the nip area and, particularly, at the trailing edge of the nip, seems to be the main reason for the tightening effect of the nip. The results are compared to the corresponding results for a solid elastic block under the rolling cylinder.

This paper describes theoretical and experimental studies of the paper transportation characteristics of a long rubber-layered roller and a long steel roller. In a paper transport mechanism with long rollers, normal force distribution in the longitudinal direction arises due to the bending deformation of the roller core and the inequality of the clamping loads applied at both ends of the rollers. First, this normal force distribution was numerically analyzed by finite element method using calculated results of rubber deformation. Next, the friction drive characteristics between rubber and steel rollers was numerically analyzed. The velocity ratio between rubber and steel rollers was measured for various clamping loads experimentally. It was shown that the proposed analytical method can predict the velocity ratio between rubber and steel rollers precisely. Finally, the paper skewing due to the inequality of the clamping loads was numericaly analyzed. The paper skew angle was measured for various clamping loads experimentally. It was shown that the proposed analytical method can predict the paper skew angle precisely.

Finite element analysis of the hip implant is conducted in this paper for representative femoral cross-section geometries and development of stress in the presence of bone cement is elucidated. Differences in cement stresses generated by varying implant cross-sections were compared with conventional features derived from representative implants. The analysis was performed under idealized implant assemblies by constraining the implant movement in the assembly. The cross-sections and implant geometries used are generic and intended to be representative of available geometries. This paper is a part of student research projects, prepared from a series of activities in biomedical implant research currently underway at Ohio Northern and Arkansas Tech Universities.

A paper transport mechanism that generates tractive force in the cross direction perpendicular to the paper transport direction was developed. The mechanics of this mechanism were then investigated by using the finite element method (FEM). A pair of tapered rubber rollers is the key point of the mechanism. Each roller has two tapered surfaces that thin out in the same direction. The thin sides of both tapered rollers face each other symmetrically to form the center of the transport mechanism. A cylindrical steel roller is pressed toward the tapered roller by a spring. Paper sheets are nipped between the tapered rubber roller and the cylindrical steel roller. On being pressed, the tapered roller is bent around the mid point of the side of the roller because of it has an asymmetrical cross section. The bend first produces shear stress on the contacting area perpendicular to the transport direction. Second, it produces a bulgy deformation so the roller shape is pressed out in the same direction. These processes generate tractive force on the paper. However, the tapered roller generates not only a tractive force but also a twisting moment. Therefore, one roller has two tapered surfaces to cancel the twisting moment. FEM analysis indicates that the tractive force could be estimated within 20% error in comparison with the measured value. The advantages of the new mechanism are that rubber rollers are used in almost all paper-handling equipment and simply cutting two tapers can generate tractive force. This mechanism improves transport reliability preventing wrinkles and slack.

The seismic design of extended pile shafts for the combined effects of dynamic shaking and liquefaction-induced lateral spreading is investigated using nonlinear dynamic finite element analyses (NDA). Results of NDA parameter studies are used to illustrate how inertia and lateral spreading loads combine during shaking. The NDA results are used to evaluate equivalent static analysis (ESA) methods. Implications for design practice are discussed.

fatigue category E in the unreinforced configuration to the infinite fatigue life range. Test results also showed that the fatigue strength of the bond layer was drastically improved by introducing breather cloth material within the bond layer. The paper “Advanced Numerical Modeling of Cracked Tubular K-Joints: BEM and FEM Comparison” by Borges et al. investigates a critical aspect in the design of tubular bridges: the fatigue performance of the structural joints. The estimation of a fatigue-crack life using the linear elastic fracture mechanics (LEFM) theory involves the calculation of stress intensity factors (SIF) at a number of discrete crack depths. The most direct way is to carry out modeling by either the finite-element method (FEM) or the boundary-element method (BEM). For tubular joints commonly found in tubular bridges and off-shore structures, because of the complicated geometry resulting from the tubes’ intersection and welding, the construction of the numerical model often becomes a complex process. This paper presents two different model-construction techniques that have been developed independently at the Swiss Federal Institute of Technology (EPFL) and the Nanyang Technological University (NTU), Singapore, which are based on the BEM and the FEM, respectively. The SIF values obtained by these two methods are compared. It is found that so long as consistent geometrical models are employed, compatible SIF values could be obtained by both approaches. The best and the most consistent values are obtained for the deepest point along the crack front. These values should be used for fatigue-life computations. In the paper “Fatigue Reliability Assess

Paper feeding systems with rubber-covered roller drive are widely used in information processing devices such as copy machines, printers and ATM. It is important in their designs to control the paper velocity with precision. Accordingly, the experimental verification is carried out to estimate the effects of the normal load between two rollers, the back tension of a paper sheet and also the change of the frictional coefficient on the velocity ratios of the paper translation to the roller rotation. Next, the behaviors of a rubber-covered roller driving a loaded paper sheet together with a rigid roller are simulated in transition from the micro-slip contact to the rolling contact with non-linear finite element analyses. And furthermore, the variations of the shearing stress distributions and the deformations of the rubber as well as the local slippage in the various kinds of conditions are investigated by enforcing the rotating condition on the rubber-covered roller. As a result, the effects of the normall load, the tension force and the driving configuration on the velocity ratios are studied by using the presented mechanical model, which is based on the deformation mode and the micro-slip zone in the contact nip.

A simple analytical model for calculating the nonlinear deformations of a corrugated core (fluting) during out-of-plane compression is developed. The results from the analytical model are compared to a more comprehensive finite-element model and to experiments. A connection between the boundary conditions and the damage state of the corrugated board is discussed. Including a modified set of boundary conditions gives an almost perfect match of the initial stiffness to the experimental results, indicating that the core might be significantly damaged as a result of the manufacturing process. Possibly, the strength of corrugated boards might be increased about 20% if one could avoid damaging the fluting during the manufacturing process.

Imperfections in a rotor-bearing system may cause undesirable subcritical resonances occurring when the rotating speed of the rotor is a fraction of the natural frequency of the system. These resonances arise partly from rotor imperfections and partly from bearing imperfections. This study demonstrates that the subcritical twice-running-speed vibrations originating from bearing waviness may be investigated by combining a simplified rotor model with a detailed bearing model, using a finite element method. The rotor-bearing system under investigation is a roller test rig consisting of the tube roll of a paper machine supported by spherical roller bearings. The bearing waviness from the second to the fourth orders is emulated as accurately as possible in the finite element model. This is achieved by measuring the waviness of the real bearings and then incorporating the measurement results into a simulation model. The tube roll of the test rig is modeled as a symmetric tube, neglecting the effects of the uneven mass and stiffness distribution of the roll. The contact between the rotor and the bearings is described using nonlinear Hertzian contact theory. The subcritical responses of the system are studied by means of time integration, and the results are converted into the frequency domain using fast Fourier transformation. The results of the analysis are compared with the measurement results for the subcritical responses of the roll. The agreement between the simulation and experimental results of the studied system can be observed even though rotor imperfections are not considered.